Commit Graph

441 Commits

Author SHA1 Message Date
Linus Torvalds 36492b7141 Detect unused tracepoints for v6.19:
If a tracepoint is defined but never used (TRACE_EVENT() created but no
 trace_<tracepoint>() called), it can take up to or more than 5K of memory
 each. This can add up as there are around a hundred unused tracepoints with
 various configs. That is 500K of wasted memory.
 
 Add a make build parameter of "UT=1" to have the build warn if an unused
 tracepoint is detected in the build. This allows detection of unused
 tracepoints to be upstream so that outreachy and the mentoring project can
 have new developers look for fixing them, without having these warnings
 suddenly show up when someone upgrades their kernel. When all known unused
 tracepoints are removed, then the "UT=1" build parameter can be removed and
 unused tracepoints will always warn. This will catch new unused tracepoints
 after the current ones have been removed.
 
 - Separate out elf functions from sorttable.c
 
   Move out the ELF parsing functions from sorttable.c so that the tracing
   tooling can use it.
 
 - Add a tracepoint verifier tool to the build process
 
   If "UT=1" is added to the kernel command line, any unused tracepoints will
   trigger a warning at build time.
 
 - Do not warn about unused tracepoints for tracepoints that are exported
 
   There are sever cases where a tracepoint is created by the kernel and used
   by modules. Since there's no easy way to detect if these are truly unused
   since the users are in modules, if a tracepoint is exported, assume it
   will eventually be used by a module. Note, there's not many exported
   tracepoints so this should not be a problem to ignore them.
 
 - Have building of modules also detect unused tracepoints
 
   Do not only check the main vmlinux for unused tracepoints, also check
   modules. If a module is defining a tracepoint it should be using it.
 
 - Add the tracepoint-update program to the ignore file
 
   The new tracepoint-update program needs to be ignored by git.
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Merge tag 'tracepoints-v6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull unused tracepoints update from Steven Rostedt:
 "Detect unused tracepoints.

  If a tracepoint is defined but never used (TRACE_EVENT() created but
  no trace_<tracepoint>() called), it can take up to or more than 5K of
  memory each. This can add up as there are around a hundred unused
  tracepoints with various configs. That is 500K of wasted memory.

  Add a make build parameter of "UT=1" to have the build warn if an
  unused tracepoint is detected in the build. This allows detection of
  unused tracepoints to be upstream so that outreachy and the mentoring
  project can have new developers look for fixing them, without having
  these warnings suddenly show up when someone upgrades their kernel.

  When all known unused tracepoints are removed, then the "UT=1" build
  parameter can be removed and unused tracepoints will always warn. This
  will catch new unused tracepoints after the current ones have been
  removed.

  Summary:

   - Separate out elf functions from sorttable.c

     Move out the ELF parsing functions from sorttable.c so that the
     tracing tooling can use it.

   - Add a tracepoint verifier tool to the build process

     If "UT=1" is added to the kernel command line, any unused
     tracepoints will trigger a warning at build time.

   - Do not warn about unused tracepoints for tracepoints that are
     exported

     There are sever cases where a tracepoint is created by the kernel
     and used by modules. Since there's no easy way to detect if these
     are truly unused since the users are in modules, if a tracepoint is
     exported, assume it will eventually be used by a module. Note,
     there's not many exported tracepoints so this should not be a
     problem to ignore them.

   - Have building of modules also detect unused tracepoints

     Do not only check the main vmlinux for unused tracepoints, also
     check modules. If a module is defining a tracepoint it should be
     using it.

   - Add the tracepoint-update program to the ignore file

     The new tracepoint-update program needs to be ignored by git"

* tag 'tracepoints-v6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  scripts: add tracepoint-update to the list of ignores files
  tracing: Add warnings for unused tracepoints for modules
  tracing: Allow tracepoint-update.c to work with modules
  tracepoint: Do not warn for unused event that is exported
  tracing: Add a tracepoint verification check at build time
  sorttable: Move ELF parsing into scripts/elf-parse.[ch]
2025-12-05 09:37:41 -08:00
Linus Torvalds 63e6995005 objtool updates for v6.19:
- klp-build livepatch module generation (Josh Poimboeuf)
 
    Introduce new objtool features and a klp-build
    script to generate livepatch modules using a
    source .patch as input.
 
    This builds on concepts from the longstanding out-of-tree
    kpatch project which began in 2012 and has been used for
    many years to generate livepatch modules for production kernels.
    However, this is a complete rewrite which incorporates
    hard-earned lessons from 12+ years of maintaining kpatch.
 
    Key improvements compared to kpatch-build:
 
     - Integrated with objtool: Leverages objtool's existing control-flow
       graph analysis to help detect changed functions.
 
     - Works on vmlinux.o: Supports late-linked objects, making it
       compatible with LTO, IBT, and similar.
 
     - Simplified code base: ~3k fewer lines of code.
 
     - Upstream: No more out-of-tree #ifdef hacks, far less cruft.
 
     - Cleaner internals: Vastly simplified logic for symbol/section/reloc
       inclusion and special section extraction.
 
     - Robust __LINE__ macro handling: Avoids false positive binary diffs
       caused by the __LINE__ macro by introducing a fix-patch-lines script
       which injects #line directives into the source .patch to preserve
       the original line numbers at compile time.
 
  - Disassemble code with libopcodes instead of running objdump
    (Alexandre Chartre)
 
  - Disassemble support (-d option to objtool) by Alexandre Chartre,
    which supports the decoding of various Linux kernel code generation
    specials such as alternatives:
 
       17ef:  sched_balance_find_dst_group+0x62f                 mov    0x34(%r9),%edx
       17f3:  sched_balance_find_dst_group+0x633               | <alternative.17f3>             | X86_FEATURE_POPCNT
       17f3:  sched_balance_find_dst_group+0x633               | call   0x17f8 <__sw_hweight64> | popcnt %rdi,%rax
       17f8:  sched_balance_find_dst_group+0x638                 cmp    %eax,%edx
 
    ... jump table alternatives:
 
       1895:  sched_use_asym_prio+0x5                            test   $0x8,%ch
       1898:  sched_use_asym_prio+0x8                            je     0x18a9 <sched_use_asym_prio+0x19>
       189a:  sched_use_asym_prio+0xa                          | <jump_table.189a>                        | JUMP
       189a:  sched_use_asym_prio+0xa                          | jmp    0x18ae <sched_use_asym_prio+0x1e> | nop2
       189c:  sched_use_asym_prio+0xc                            mov    $0x1,%eax
       18a1:  sched_use_asym_prio+0x11                           and    $0x80,%ecx
 
    ... exception table alternatives:
 
     native_read_msr:
       5b80:  native_read_msr+0x0                                                     mov    %edi,%ecx
       5b82:  native_read_msr+0x2                                                   | <ex_table.5b82> | EXCEPTION
       5b82:  native_read_msr+0x2                                                   | rdmsr           | resume at 0x5b84 <native_read_msr+0x4>
       5b84:  native_read_msr+0x4                                                     shl    $0x20,%rdx
 
    .... x86 feature flag decoding (also see the X86_FEATURE_POPCNT
         example in sched_balance_find_dst_group() above):
 
       2faaf:  start_thread_common.constprop.0+0x1f                                    jne    0x2fba4 <start_thread_common.constprop.0+0x114>
       2fab5:  start_thread_common.constprop.0+0x25                                  | <alternative.2fab5>                  | X86_FEATURE_ALWAYS                                  | X86_BUG_NULL_SEG
       2fab5:  start_thread_common.constprop.0+0x25                                  | jmp    0x2faba <.altinstr_aux+0x2f4> | jmp    0x4b0 <start_thread_common.constprop.0+0x3f> | nop5
       2faba:  start_thread_common.constprop.0+0x2a                                    mov    $0x2b,%eax
 
    ... NOP sequence shortening:
 
       1048e2:  snapshot_write_finalize+0xc2                                            je     0x104917 <snapshot_write_finalize+0xf7>
       1048e4:  snapshot_write_finalize+0xc4                                            nop6
       1048ea:  snapshot_write_finalize+0xca                                            nop11
       1048f5:  snapshot_write_finalize+0xd5                                            nop11
       104900:  snapshot_write_finalize+0xe0                                            mov    %rax,%rcx
       104903:  snapshot_write_finalize+0xe3                                            mov    0x10(%rdx),%rax
 
    ... and much more.
 
  - Function validation tracing support (Alexandre Chartre)
 
  - Various -ffunction-sections fixes (Josh Poimboeuf)
 
  - Clang AutoFDO (Automated Feedback-Directed Optimizations) support (Josh Poimboeuf)
 
  - Misc fixes and cleanups (Borislav Petkov, Chen Ni,
    Dylan Hatch, Ingo Molnar, John Wang, Josh Poimboeuf,
    Pankaj Raghav, Peter Zijlstra, Thorsten Blum)
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'objtool-core-2025-12-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull objtool updates from Ingo Molnar:

 - klp-build livepatch module generation (Josh Poimboeuf)

   Introduce new objtool features and a klp-build script to generate
   livepatch modules using a source .patch as input.

   This builds on concepts from the longstanding out-of-tree kpatch
   project which began in 2012 and has been used for many years to
   generate livepatch modules for production kernels. However, this is a
   complete rewrite which incorporates hard-earned lessons from 12+
   years of maintaining kpatch.

   Key improvements compared to kpatch-build:

    - Integrated with objtool: Leverages objtool's existing control-flow
      graph analysis to help detect changed functions.

    - Works on vmlinux.o: Supports late-linked objects, making it
      compatible with LTO, IBT, and similar.

    - Simplified code base: ~3k fewer lines of code.

    - Upstream: No more out-of-tree #ifdef hacks, far less cruft.

    - Cleaner internals: Vastly simplified logic for
      symbol/section/reloc inclusion and special section extraction.

    - Robust __LINE__ macro handling: Avoids false positive binary diffs
      caused by the __LINE__ macro by introducing a fix-patch-lines
      script which injects #line directives into the source .patch to
      preserve the original line numbers at compile time.

 - Disassemble code with libopcodes instead of running objdump
   (Alexandre Chartre)

 - Disassemble support (-d option to objtool) by Alexandre Chartre,
   which supports the decoding of various Linux kernel code generation
   specials such as alternatives:

      17ef:  sched_balance_find_dst_group+0x62f                 mov    0x34(%r9),%edx
      17f3:  sched_balance_find_dst_group+0x633               | <alternative.17f3>             | X86_FEATURE_POPCNT
      17f3:  sched_balance_find_dst_group+0x633               | call   0x17f8 <__sw_hweight64> | popcnt %rdi,%rax
      17f8:  sched_balance_find_dst_group+0x638                 cmp    %eax,%edx

   ... jump table alternatives:

      1895:  sched_use_asym_prio+0x5                            test   $0x8,%ch
      1898:  sched_use_asym_prio+0x8                            je     0x18a9 <sched_use_asym_prio+0x19>
      189a:  sched_use_asym_prio+0xa                          | <jump_table.189a>                        | JUMP
      189a:  sched_use_asym_prio+0xa                          | jmp    0x18ae <sched_use_asym_prio+0x1e> | nop2
      189c:  sched_use_asym_prio+0xc                            mov    $0x1,%eax
      18a1:  sched_use_asym_prio+0x11                           and    $0x80,%ecx

   ... exception table alternatives:

    native_read_msr:
      5b80:  native_read_msr+0x0                                                     mov    %edi,%ecx
      5b82:  native_read_msr+0x2                                                   | <ex_table.5b82> | EXCEPTION
      5b82:  native_read_msr+0x2                                                   | rdmsr           | resume at 0x5b84 <native_read_msr+0x4>
      5b84:  native_read_msr+0x4                                                     shl    $0x20,%rdx

   .... x86 feature flag decoding (also see the X86_FEATURE_POPCNT
        example in sched_balance_find_dst_group() above):

      2faaf:  start_thread_common.constprop.0+0x1f                                    jne    0x2fba4 <start_thread_common.constprop.0+0x114>
      2fab5:  start_thread_common.constprop.0+0x25                                  | <alternative.2fab5>                  | X86_FEATURE_ALWAYS                                  | X86_BUG_NULL_SEG
      2fab5:  start_thread_common.constprop.0+0x25                                  | jmp    0x2faba <.altinstr_aux+0x2f4> | jmp    0x4b0 <start_thread_common.constprop.0+0x3f> | nop5
      2faba:  start_thread_common.constprop.0+0x2a                                    mov    $0x2b,%eax

   ... NOP sequence shortening:

      1048e2:  snapshot_write_finalize+0xc2                                            je     0x104917 <snapshot_write_finalize+0xf7>
      1048e4:  snapshot_write_finalize+0xc4                                            nop6
      1048ea:  snapshot_write_finalize+0xca                                            nop11
      1048f5:  snapshot_write_finalize+0xd5                                            nop11
      104900:  snapshot_write_finalize+0xe0                                            mov    %rax,%rcx
      104903:  snapshot_write_finalize+0xe3                                            mov    0x10(%rdx),%rax

   ... and much more.

 - Function validation tracing support (Alexandre Chartre)

 - Various -ffunction-sections fixes (Josh Poimboeuf)

 - Clang AutoFDO (Automated Feedback-Directed Optimizations) support
   (Josh Poimboeuf)

 - Misc fixes and cleanups (Borislav Petkov, Chen Ni, Dylan Hatch, Ingo
   Molnar, John Wang, Josh Poimboeuf, Pankaj Raghav, Peter Zijlstra,
   Thorsten Blum)

* tag 'objtool-core-2025-12-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (129 commits)
  objtool: Fix segfault on unknown alternatives
  objtool: Build with disassembly can fail when including bdf.h
  objtool: Trim trailing NOPs in alternative
  objtool: Add wide output for disassembly
  objtool: Compact output for alternatives with one instruction
  objtool: Improve naming of group alternatives
  objtool: Add Function to get the name of a CPU feature
  objtool: Provide access to feature and flags of group alternatives
  objtool: Fix address references in alternatives
  objtool: Disassemble jump table alternatives
  objtool: Disassemble exception table alternatives
  objtool: Print addresses with alternative instructions
  objtool: Disassemble group alternatives
  objtool: Print headers for alternatives
  objtool: Preserve alternatives order
  objtool: Add the --disas=<function-pattern> action
  objtool: Do not validate IBT for .return_sites and .call_sites
  objtool: Improve tracing of alternative instructions
  objtool: Add functions to better name alternatives
  objtool: Identify the different types of alternatives
  ...
2025-12-01 20:18:59 -08:00
Linus Torvalds b04b2e7a61 vfs-6.19-rc1.misc
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Merge tag 'vfs-6.19-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull misc vfs updates from Christian Brauner:
 "Features:

   - Cheaper MAY_EXEC handling for path lookup. This elides MAY_WRITE
     permission checks during path lookup and adds the
     IOP_FASTPERM_MAY_EXEC flag so filesystems like btrfs can avoid
     expensive permission work.

   - Hide dentry_cache behind runtime const machinery.

   - Add German Maglione as virtiofs co-maintainer.

  Cleanups:

   - Tidy up and inline step_into() and walk_component() for improved
     code generation.

   - Re-enable IOCB_NOWAIT writes to files. This refactors file
     timestamp update logic, fixing a layering bypass in btrfs when
     updating timestamps on device files and improving FMODE_NOCMTIME
     handling in VFS now that nfsd started using it.

   - Path lookup optimizations extracting slowpaths into dedicated
     routines and adding branch prediction hints for mntput_no_expire(),
     fd_install(), lookup_slow(), and various other hot paths.

   - Enable clang's -fms-extensions flag, requiring a JFS rename to
     avoid conflicts.

   - Remove spurious exports in fs/file_attr.c.

   - Stop duplicating union pipe_index declaration. This depends on the
     shared kbuild branch that brings in -fms-extensions support which
     is merged into this branch.

   - Use MD5 library instead of crypto_shash in ecryptfs.

   - Use largest_zero_folio() in iomap_dio_zero().

   - Replace simple_strtol/strtoul with kstrtoint/kstrtouint in init and
     initrd code.

   - Various typo fixes.

  Fixes:

   - Fix emergency sync for btrfs. Btrfs requires an explicit sync_fs()
     call with wait == 1 to commit super blocks. The emergency sync path
     never passed this, leaving btrfs data uncommitted during emergency
     sync.

   - Use local kmap in watch_queue's post_one_notification().

   - Add hint prints in sb_set_blocksize() for LBS dependency on THP"

* tag 'vfs-6.19-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (35 commits)
  MAINTAINERS: add German Maglione as virtiofs co-maintainer
  fs: inline step_into() and walk_component()
  fs: tidy up step_into() & friends before inlining
  orangefs: use inode_update_timestamps directly
  btrfs: fix the comment on btrfs_update_time
  btrfs: use vfs_utimes to update file timestamps
  fs: export vfs_utimes
  fs: lift the FMODE_NOCMTIME check into file_update_time_flags
  fs: refactor file timestamp update logic
  include/linux/fs.h: trivial fix: regualr -> regular
  fs/splice.c: trivial fix: pipes -> pipe's
  fs: mark lookup_slow() as noinline
  fs: add predicts based on nd->depth
  fs: move mntput_no_expire() slowpath into a dedicated routine
  fs: remove spurious exports in fs/file_attr.c
  watch_queue: Use local kmap in post_one_notification()
  fs: touch up predicts in path lookup
  fs: move fd_install() slowpath into a dedicated routine and provide commentary
  fs: hide dentry_cache behind runtime const machinery
  fs: touch predicts in do_dentry_open()
  ...
2025-12-01 08:44:26 -08:00
Josh Poimboeuf 93863f3f85 kbuild: Check for functions with ambiguous -ffunction-sections section names
Commit 9c7dc1dd89 ("objtool: Warn on functions with ambiguous
-ffunction-sections section names") only works for drivers which are
compiled on architectures supported by objtool.

Make a script to perform the same check for all architectures.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://patch.msgid.link/a6a49644a34964f7e02f3a8ce43af03e72817180.1763669451.git.jpoimboe@kernel.org
2025-11-21 10:04:10 +01:00
Josh Poimboeuf 9c7dc1dd89 objtool: Warn on functions with ambiguous -ffunction-sections section names
When compiled with -ffunction-sections, a function named startup() will
be placed in .text.startup.  However, .text.startup is also used by the
compiler for functions with __attribute__((constructor)).

That creates an ambiguity for the vmlinux linker script, which needs to
differentiate those two cases.

Similar naming conflicts exist for functions named exit(), split(),
unlikely(), hot() and unknown().

One potential solution would be to use '#ifdef CC_USING_FUNCTION_SECTIONS'
to create two distinct implementations of the TEXT_MAIN macro.  However,
-ffunction-sections can be (and is) enabled or disabled on a per-object
basis (for example via ccflags-y or AUTOFDO_PROFILE).

So the recently unified TEXT_MAIN macro (commit 1ba9f89794
("vmlinux.lds: Unify TEXT_MAIN, DATA_MAIN, and related macros")) is
necessary.  This means there's no way for the linker script to
disambiguate things.

Instead, use objtool to warn on any function names whose resulting
section names might create ambiguity when the kernel is compiled (in
whole or in part) with -ffunction-sections.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: live-patching@vger.kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://patch.msgid.link/65fedea974fe14be487c8867a0b8d0e4a294ce1e.1762991150.git.jpoimboe@kernel.org
2025-11-13 08:03:10 +01:00
Josh Poimboeuf f6a8919d61 vmlinux.lds: Fix TEXT_MAIN to include .text.start and friends
Since:

  6568f14cb5 ("vmlinux.lds: Exclude .text.startup and .text.exit from TEXT_MAIN")

the TEXT_MAIN macro uses a series of patterns to prevent the
.text.startup[.*] and .text.exit[.*] sections from getting
linked into the vmlinux runtime .text.

That commit is a tad too aggressive: it also inadvertently filters out
valid runtime text sections like .text.start and
.text.start.constprop.0, which can be generated for a function named
start() when -ffunction-sections is enabled.

As a result, those sections become orphans when building with
CONFIG_LD_DEAD_CODE_DATA_ELIMINATION for arm:

  arm-linux-gnueabi-ld: warning: orphan section `.text.start.constprop.0' from `drivers/usb/host/sl811-hcd.o' being placed in section `.text.start.constprop.0'
  arm-linux-gnueabi-ld: warning: orphan section `.text.start.constprop.0' from `drivers/media/dvb-frontends/drxk_hard.o' being placed in section `.text.start.constprop.0'
  arm-linux-gnueabi-ld: warning: orphan section `.text.start' from `drivers/media/dvb-frontends/stv0910.o' being placed in section `.text.start'
  arm-linux-gnueabi-ld: warning: orphan section `.text.start.constprop.0' from `drivers/media/pci/ddbridge/ddbridge-sx8.o' being placed in section `.text.start.constprop.0'

Fix that by explicitly adding the partial "substring" sections (.text.s,
.text.st, .text.sta, etc) and their cloned derivatives.

While this unfortunately means that TEXT_MAIN continues to grow,
these changes are ultimately necessary for proper support of
-ffunction-sections.

Fixes: 6568f14cb5 ("vmlinux.lds: Exclude .text.startup and .text.exit from TEXT_MAIN")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: live-patching@vger.kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://patch.msgid.link/cd588144e63df901a656b06b566855019c4a931d.1762991150.git.jpoimboe@kernel.org
Closes: https://lore.kernel.org/oe-kbuild-all/202511040812.DFGedJiy-lkp@intel.com/
2025-11-13 08:03:09 +01:00
Ingo Molnar d851f2b2b2 Linux 6.18-rc5
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Merge tag 'v6.18-rc5' into objtool/core, to pick up fixes

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2025-11-13 07:58:43 +01:00
Mateusz Guzik 21b561dab1
fs: hide dentry_cache behind runtime const machinery
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://patch.msgid.link/20251105153622.758836-1-mjguzik@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
2025-11-12 12:19:09 +01:00
Josh Poimboeuf 6568f14cb5 vmlinux.lds: Exclude .text.startup and .text.exit from TEXT_MAIN
An ftrace warning was reported in ftrace_init_ool_stub():

   WARNING: arch/powerpc/kernel/trace/ftrace.c:234 at ftrace_init_ool_stub+0x188/0x3f4, CPU#0: swapper/0

The problem is that the linker script is placing .text.startup in .text
rather than in .init.text, due to an inadvertent match of the TEXT_MAIN
'.text.[0-9a-zA-Z_]*' pattern.

This bug existed for some configurations before, but is only now coming
to light due to the TEXT_MAIN macro unification in commit 1ba9f89794
("vmlinux.lds: Unify TEXT_MAIN, DATA_MAIN, and related macros").

The .text.startup section consists of constructors which are used by
KASAN, KCSAN, and GCOV.  The constructors are only called during boot,
so .text.startup is supposed to match the INIT_TEXT pattern so it can be
placed in .init.text and freed after init.  But since INIT_TEXT comes
*after* TEXT_MAIN in the linker script, TEXT_MAIN needs to manually
exclude .text.startup.

Update TEXT_MAIN to exclude .text.startup (and its .text.startup.*
variant from -ffunction-sections), along with .text.exit and
.text.exit.* which should match EXIT_TEXT.

Specifically, use a series of more specific glob patterns to match
generic .text.* sections (for -ffunction-sections) while explicitly
excluding .text.startup[.*] and .text.exit[.*].

Also update INIT_TEXT and EXIT_TEXT to explicitly match their
-ffunction-sections variants (.text.startup.* and .text.exit.*).

Fixes: 1ba9f89794 ("vmlinux.lds: Unify TEXT_MAIN, DATA_MAIN, and related macros")
Closes: https://lore.kernel.org/72469502-ca37-4287-90b9-a751cecc498c@linux.ibm.com
Reported-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Debugged-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Link: https://patch.msgid.link/07f74b4e5c43872572b7def30f2eac45f28675d9.1761872421.git.jpoimboe@kernel.org
2025-10-31 11:19:21 +01:00
Dimitri John Ledkov d50f210913
kbuild: align modinfo section for Secureboot Authenticode EDK2 compat
Previously linker scripts would always generate vmlinuz that has sections
aligned. And thus padded (correct Authenticode calculation) and unpadded
calculation would be same. As in https://github.com/rhboot/pesign userspace
tool would produce the same authenticode digest for both of the following
commands:

    pesign --padding --hash --in ./arch/x86_64/boot/bzImage
    pesign --nopadding --hash --in ./arch/x86_64/boot/bzImage

The commit 3e86e4d74c ("kbuild: keep .modinfo section in
vmlinux.unstripped") added .modinfo section of variable length. Depending
on kernel configuration it may or may not be aligned.

All userspace signing tooling correctly pads such section to calculation
spec compliant authenticode digest.

However, if bzImage is not further processed and is attempted to be loaded
directly by EDK2 firmware, it calculates unpadded Authenticode digest and
fails to correct accept/reject such kernel builds even when propoer
Authenticode values are enrolled in db/dbx. One can say EDK2 requires
aligned/padded kernels in Secureboot.

Thus add ALIGN(8) to the .modinfo section, to esure kernels irrespective of
modinfo contents can be loaded by all existing EDK2 firmware builds.

Fixes: 3e86e4d74c ("kbuild: keep .modinfo section in vmlinux.unstripped")
Cc: stable@vger.kernel.org
Signed-off-by: Dimitri John Ledkov <dimitri.ledkov@surgut.co.uk>
Link: https://patch.msgid.link/20251026202100.679989-1-dimitri.ledkov@surgut.co.uk
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
2025-10-27 16:21:24 -07:00
Steven Rostedt e30f8e61e2 tracing: Add a tracepoint verification check at build time
If a tracepoint is defined via DECLARE_TRACE() or TRACE_EVENT() but never
called (via the trace_<tracepoint>() function), its metadata is still
around in memory and not discarded.

When created via TRACE_EVENT() the situation is worse because the
TRACE_EVENT() creates metadata that can be around 5k per trace event.
Having unused trace events causes several thousand of wasted bytes.

Add a verifier that injects a string of the name of the tracepoint it
calls that is added to the discarded section "__tracepoint_check".
For every builtin tracepoint, its name (which is saved in the in-memory
section "__tracepoint_strings") will have its name also in the
"__tracepoint_check" section if it is used.

Add a new program that is run on build called tracepoint-update. This is
executed on the vmlinux.o before the __tracepoint_check section is
discarded (the section is discarded before vmlinux is created). This
program will create an array of each string in the __tracepoint_check
section and then sort it. Then it will walk the strings in the
__tracepoint_strings section and do a binary search to check if its name
is in the __tracepoint_check section. If it is not, then it is unused and
a warning is printed.

Note, this currently only handles tracepoints that are builtin and not in
modules.

Enabling this currently with a given config produces:

warning: tracepoint 'sched_move_numa' is unused.
warning: tracepoint 'sched_stick_numa' is unused.
warning: tracepoint 'sched_swap_numa' is unused.
warning: tracepoint 'pelt_hw_tp' is unused.
warning: tracepoint 'pelt_irq_tp' is unused.
warning: tracepoint 'rcu_preempt_task' is unused.
warning: tracepoint 'rcu_unlock_preempted_task' is unused.
warning: tracepoint 'xdp_bulk_tx' is unused.
warning: tracepoint 'xdp_redirect_map' is unused.
warning: tracepoint 'xdp_redirect_map_err' is unused.
warning: tracepoint 'vma_mas_szero' is unused.
warning: tracepoint 'vma_store' is unused.
warning: tracepoint 'hugepage_set_pmd' is unused.
warning: tracepoint 'hugepage_set_pud' is unused.
warning: tracepoint 'hugepage_update_pmd' is unused.
warning: tracepoint 'hugepage_update_pud' is unused.
warning: tracepoint 'block_rq_remap' is unused.
warning: tracepoint 'xhci_dbc_handle_event' is unused.
warning: tracepoint 'xhci_dbc_handle_transfer' is unused.
warning: tracepoint 'xhci_dbc_gadget_ep_queue' is unused.
warning: tracepoint 'xhci_dbc_alloc_request' is unused.
warning: tracepoint 'xhci_dbc_free_request' is unused.
warning: tracepoint 'xhci_dbc_queue_request' is unused.
warning: tracepoint 'xhci_dbc_giveback_request' is unused.
warning: tracepoint 'tcp_ao_wrong_maclen' is unused.
warning: tracepoint 'tcp_ao_mismatch' is unused.
warning: tracepoint 'tcp_ao_key_not_found' is unused.
warning: tracepoint 'tcp_ao_rnext_request' is unused.
warning: tracepoint 'tcp_ao_synack_no_key' is unused.
warning: tracepoint 'tcp_ao_snd_sne_update' is unused.
warning: tracepoint 'tcp_ao_rcv_sne_update' is unused.

Some of the above is totally unused but others are not used due to their
"trace_" functions being inside configs, in which case, the defined
tracepoints should also be inside those same configs. Others are
architecture specific but defined in generic code, where they should
either be moved to the architecture or be surrounded by #ifdef for the
architectures they are for.

This tool could be updated to process modules in the future.

I'd like to thank Mathieu Desnoyers for suggesting using strings instead
of pointers, as using pointers in vmlinux.o required handling relocations
and it required implementing almost a full feature linker to do so.

To enable this check, run the build with: make UT=1

Note, when all the existing unused tracepoints are removed from the build,
the "UT=1" will be removed and this will always be enabled when
tracepoints are configured to warn on any new tracepoints. The reason this
isn't always enabled now is because it will introduce a lot of warnings
for the current unused tracepoints, and all bisects would end at this
commit for those warnings.

Link: https://lore.kernel.org/all/20250528114549.4d8a5e03@gandalf.local.home/

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nicolas Schier <nicolas.schier@linux.dev>
Cc: Nick Desaulniers <nick.desaulniers+lkml@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Link: https://lore.kernel.org/20251022004452.920728129@kernel.org
Suggested-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> # for using strings instead of pointers
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2025-10-24 16:43:14 -04:00
Josh Poimboeuf 1ba9f89794 vmlinux.lds: Unify TEXT_MAIN, DATA_MAIN, and related macros
TEXT_MAIN, DATA_MAIN and friends are defined differently depending on
whether certain config options enable -ffunction-sections and/or
-fdata-sections.

There's no technical reason for that beyond voodoo coding.  Keeping the
separate implementations adds unnecessary complexity, fragments the
logic, and increases the risk of subtle bugs.

Unify the macros by using the same input section patterns across all
configs.

This is a prerequisite for the upcoming livepatch klp-build tooling
which will manually enable -ffunction-sections and -fdata-sections via
KCFLAGS.

Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2025-10-14 14:45:21 -07:00
Linus Torvalds 7f70725741 Kbuild updates for 6.18
- Extend modules.builtin.modinfo to include module aliases from
   MODULE_DEVICE_TABLE for builtin modules so that userspace tools (such
   as kmod) can verify that a particular module alias will be handled by
   a builtin module.
 
 - Bump the minimum version of LLVM for building the kernel to 15.0.0.
 
 - Upgrade several userspace API checks in headers_check.pl to errors.
 
 - Unify and consolidate CONFIG_WERROR / W=e handling.
 
 - Turn assembler and linker warnings into errors with CONFIG_WERROR /
   W=e.
 
 - Respect CONFIG_WERROR / W=e when building userspace programs
   (userprogs).
 
 - Enable -Werror unconditionally when building host programs
   (hostprogs).
 
 - Support copy_file_range() and data segment alignment in gen_init_cpio
   to improve performance on filesystems that support reflinks such as
   btrfs and XFS.
 
 - Miscellaneous small changes to scripts and configuration files.
 
 Signed-off-by: Nathan Chancellor <nathan@kernel.org>
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Merge tag 'kbuild-6.18-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux

Pull Kbuild updates from Nathan Chancellor:

 - Extend modules.builtin.modinfo to include module aliases from
   MODULE_DEVICE_TABLE for builtin modules so that userspace tools (such
   as kmod) can verify that a particular module alias will be handled by
   a builtin module

 - Bump the minimum version of LLVM for building the kernel to 15.0.0

 - Upgrade several userspace API checks in headers_check.pl to errors

 - Unify and consolidate CONFIG_WERROR / W=e handling

 - Turn assembler and linker warnings into errors with CONFIG_WERROR /
   W=e

 - Respect CONFIG_WERROR / W=e when building userspace programs
   (userprogs)

 - Enable -Werror unconditionally when building host programs
   (hostprogs)

 - Support copy_file_range() and data segment alignment in gen_init_cpio
   to improve performance on filesystems that support reflinks such as
   btrfs and XFS

 - Miscellaneous small changes to scripts and configuration files

* tag 'kbuild-6.18-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux: (47 commits)
  modpost: Initialize builtin_modname to stop SIGSEGVs
  Documentation: kbuild: note CONFIG_DEBUG_EFI in reproducible builds
  kbuild: vmlinux.unstripped should always depend on .vmlinux.export.o
  modpost: Create modalias for builtin modules
  modpost: Add modname to mod_device_table alias
  scsi: Always define blogic_pci_tbl structure
  kbuild: extract modules.builtin.modinfo from vmlinux.unstripped
  kbuild: keep .modinfo section in vmlinux.unstripped
  kbuild: always create intermediate vmlinux.unstripped
  s390: vmlinux.lds.S: Reorder sections
  KMSAN: Remove tautological checks
  objtool: Drop noinstr hack for KCSAN_WEAK_MEMORY
  lib/Kconfig.debug: Drop CLANG_VERSION check from DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
  riscv: Remove ld.lld version checks from many TOOLCHAIN_HAS configs
  riscv: Unconditionally use linker relaxation
  riscv: Remove version check for LTO_CLANG selects
  powerpc: Drop unnecessary initializations in __copy_inst_from_kernel_nofault()
  mips: Unconditionally select ARCH_HAS_CURRENT_STACK_POINTER
  arm64: Remove tautological LLVM Kconfig conditions
  ARM: Clean up definition of ARM_HAS_GROUP_RELOCS
  ...
2025-10-01 20:58:51 -07:00
Linus Torvalds d2b2fea350 asm-generic: updates for 6.18
Two small patches for the asm-generic header files: Varad Gautam improves
 the MMIO tracing to be faster when the tracepoints are built into the
 kernel but disabled, while Qi Xi updates the DO_ONCE logic so that
 clearing the WARN_ONCE() flags does not change the other DO_ONCE users.
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Merge tag 'asm-generic-6.18' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic

Pull asm-generic updates from Arnd Bergmann:
 "Two small patches for the asm-generic header files: Varad Gautam
  improves the MMIO tracing to be faster when the tracepoints are built
  into the kernel but disabled, while Qi Xi updates the DO_ONCE logic so
  that clearing the WARN_ONCE() flags does not change the other DO_ONCE
  users"

* tag 'asm-generic-6.18' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic:
  once: fix race by moving DO_ONCE to separate section
  asm-generic/io.h: Skip trace helpers if rwmmio events are disabled
2025-10-01 17:47:16 -07:00
Qi Xi edcc8a38b5
once: fix race by moving DO_ONCE to separate section
The commit c2c60ea37e ("once: use __section(".data.once")") moved
DO_ONCE's ___done variable to .data.once section, which conflicts with
DO_ONCE_LITE() that also uses the same section.

This creates a race condition when clear_warn_once is used:

Thread 1 (DO_ONCE)             Thread 2 (DO_ONCE)
__do_once_start
    read ___done (false)
    acquire once_lock
execute func
__do_once_done
    write ___done (true)      __do_once_start
    release once_lock             // Thread 3 clear_warn_once reset ___done
                                  read ___done (false)
                                  acquire once_lock
                              execute func
schedule once_work            __do_once_done
once_deferred: OK             write ___done (true)
static_branch_disable         release once_lock
                              schedule once_work
                              once_deferred:
                                  BUG_ON(!static_key_enabled)

DO_ONCE_LITE() in once_lite.h is used by WARN_ON_ONCE() and other warning
macros. Keep its ___done flag in the .data..once section and allow resetting
by clear_warn_once, as originally intended.

In contrast, DO_ONCE() is used for functions like get_random_once() and
relies on its ___done flag for internal synchronization. We should not reset
DO_ONCE() by clear_warn_once.

Fix it by isolating DO_ONCE's ___done into a separate .data..do_once section,
shielding it from clear_warn_once.

Fixes: c2c60ea37e ("once: use __section(".data.once")")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Qi Xi <xiqi2@huawei.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2025-09-25 08:01:16 +02:00
Kees Cook 23ef9d4397 kcfi: Rename CONFIG_CFI_CLANG to CONFIG_CFI
The kernel's CFI implementation uses the KCFI ABI specifically, and is
not strictly tied to a particular compiler. In preparation for GCC
supporting KCFI, rename CONFIG_CFI_CLANG to CONFIG_CFI (along with
associated options).

Use new "transitional" Kconfig option for old CONFIG_CFI_CLANG that will
enable CONFIG_CFI during olddefconfig.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20250923213422.1105654-3-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
2025-09-24 14:29:14 -07:00
Masahiro Yamada 3e86e4d74c
kbuild: keep .modinfo section in vmlinux.unstripped
Keep the .modinfo section during linking, but strip it from the final
vmlinux.

Adjust scripts/mksysmap to exclude modinfo symbols from kallsyms.

This change will allow the next commit to extract the .modinfo section
from the vmlinux.unstripped intermediate.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Alexey Gladkov <legion@kernel.org>
Reviewed-by: Nicolas Schier <nsc@kernel.org>
Link: https://patch.msgid.link/aaf67c07447215463300fccaa758904bac42f992.1758182101.git.legion@kernel.org
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
2025-09-24 09:10:44 -07:00
Steven Rostedt 4d6d0a6263 tracing: Remove redundant config HAVE_FTRACE_MCOUNT_RECORD
Ftrace is tightly coupled with architecture specific code because it
requires the use of trampolines written in assembly. This means that when
a new feature or optimization is made, it must be done for all
architectures. To simplify the approach, CONFIG_HAVE_FTRACE_* configs are
added to denote which architecture has the new enhancement so that other
architectures can still function until they too have been updated.

The CONFIG_HAVE_FTRACE_MCOUNT was added to help simplify the
DYNAMIC_FTRACE work, but now every architecture that implements
DYNAMIC_FTRACE also has HAVE_FTRACE_MCOUNT set too, making it redundant
with the HAVE_DYNAMIC_FTRACE.

Remove the HAVE_FTRACE_MCOUNT config and use DYNAMIC_FTRACE directly where
applicable.

Link: https://lore.kernel.org/all/20250703154916.48e3ada7@gandalf.local.home/

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/20250704104838.27a18690@gandalf.local.home
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2025-07-22 20:15:56 -04:00
Linus Torvalds 90b83efa67 bpf-next-6.16
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Merge tag 'bpf-next-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

Pull bpf updates from Alexei Starovoitov:

 - Fix and improve BTF deduplication of identical BTF types (Alan
   Maguire and Andrii Nakryiko)

 - Support up to 12 arguments in BPF trampoline on arm64 (Xu Kuohai and
   Alexis Lothoré)

 - Support load-acquire and store-release instructions in BPF JIT on
   riscv64 (Andrea Parri)

 - Fix uninitialized values in BPF_{CORE,PROBE}_READ macros (Anton
   Protopopov)

 - Streamline allowed helpers across program types (Feng Yang)

 - Support atomic update for hashtab of BPF maps (Hou Tao)

 - Implement json output for BPF helpers (Ihor Solodrai)

 - Several s390 JIT fixes (Ilya Leoshkevich)

 - Various sockmap fixes (Jiayuan Chen)

 - Support mmap of vmlinux BTF data (Lorenz Bauer)

 - Support BPF rbtree traversal and list peeking (Martin KaFai Lau)

 - Tests for sockmap/sockhash redirection (Michal Luczaj)

 - Introduce kfuncs for memory reads into dynptrs (Mykyta Yatsenko)

 - Add support for dma-buf iterators in BPF (T.J. Mercier)

 - The verifier support for __bpf_trap() (Yonghong Song)

* tag 'bpf-next-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (135 commits)
  bpf, arm64: Remove unused-but-set function and variable.
  selftests/bpf: Add tests with stack ptr register in conditional jmp
  bpf: Do not include stack ptr register in precision backtracking bookkeeping
  selftests/bpf: enable many-args tests for arm64
  bpf, arm64: Support up to 12 function arguments
  bpf: Check rcu_read_lock_trace_held() in bpf_map_lookup_percpu_elem()
  bpf: Avoid __bpf_prog_ret0_warn when jit fails
  bpftool: Add support for custom BTF path in prog load/loadall
  selftests/bpf: Add unit tests with __bpf_trap() kfunc
  bpf: Warn with __bpf_trap() kfunc maybe due to uninitialized variable
  bpf: Remove special_kfunc_set from verifier
  selftests/bpf: Add test for open coded dmabuf_iter
  selftests/bpf: Add test for dmabuf_iter
  bpf: Add open coded dmabuf iterator
  bpf: Add dmabuf iterator
  dma-buf: Rename debugfs symbols
  bpf: Fix error return value in bpf_copy_from_user_dynptr
  libbpf: Use mmap to parse vmlinux BTF from sysfs
  selftests: bpf: Add a test for mmapable vmlinux BTF
  btf: Allow mmap of vmlinux btf
  ...
2025-05-28 15:52:42 -07:00
Lorenz Bauer a539e2a6d5 btf: Allow mmap of vmlinux btf
User space needs access to kernel BTF for many modern features of BPF.
Right now each process needs to read the BTF blob either in pieces or
as a whole. Allow mmaping the sysfs file so that processes can directly
access the memory allocated for it in the kernel.

remap_pfn_range is used instead of vm_insert_page due to aarch64
compatibility issues.

Signed-off-by: Lorenz Bauer <lmb@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Tested-by: Alan Maguire <alan.maguire@oracle.com>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Link: https://lore.kernel.org/bpf/20250520-vmlinux-mmap-v5-1-e8c941acc414@isovalent.com
2025-05-23 10:06:28 -07:00
Ard Biesheuvel 092071e0f6 vmlinux.lds: Include .data.rel[.local] into .data section
When running in -fPIC mode, the compiler may decide to emit statically
initialized data objects into .data.rel or .data.rel.local if they
contain absolute references to global or local objects, respectively,
which require fixing up at load time.

This distinction is irrelevant for the kernel, so fold .data.rel and
.data.rel.local into .data.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Dionna Amalie Glaze <dionnaglaze@google.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Kevin Loughlin <kevinloughlin@google.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lore.kernel.org/r/20250418141253.2601348-9-ardb+git@google.com
2025-04-22 09:12:00 +02:00
Linus Torvalds 71b639af06 x86/fpu updates for v6.15:
- Improve crypto performance by making kernel-mode FPU reliably usable
    in softirqs ((Eric Biggers)
 
  - Fully optimize out WARN_ON_FPU() (Eric Biggers)
 
  - Initial steps to support Support Intel APX (Advanced Performance Extensions)
    (Chang S. Bae)
 
  - Fix KASAN for arch_dup_task_struct() (Benjamin Berg)
 
  - Refine and simplify the FPU magic number check during signal return
    (Chang S. Bae)
 
  - Fix inconsistencies in guest FPU xfeatures (Chao Gao, Stanislav Spassov)
 
  - selftests/x86/xstate: Introduce common code for testing extended states
    (Chang S. Bae)
 
  - Misc fixes and cleanups (Borislav Petkov, Colin Ian King, Uros Bizjak)
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'x86-fpu-2025-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86/fpu updates from Ingo Molnar:

 - Improve crypto performance by making kernel-mode FPU reliably usable
   in softirqs ((Eric Biggers)

 - Fully optimize out WARN_ON_FPU() (Eric Biggers)

 - Initial steps to support Support Intel APX (Advanced Performance
   Extensions) (Chang S. Bae)

 - Fix KASAN for arch_dup_task_struct() (Benjamin Berg)

 - Refine and simplify the FPU magic number check during signal return
   (Chang S. Bae)

 - Fix inconsistencies in guest FPU xfeatures (Chao Gao, Stanislav
   Spassov)

 - selftests/x86/xstate: Introduce common code for testing extended
   states (Chang S. Bae)

 - Misc fixes and cleanups (Borislav Petkov, Colin Ian King, Uros
   Bizjak)

* tag 'x86-fpu-2025-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/fpu/xstate: Fix inconsistencies in guest FPU xfeatures
  x86/fpu: Clarify the "xa" symbolic name used in the XSTATE* macros
  x86/fpu: Use XSAVE{,OPT,C,S} and XRSTOR{,S} mnemonics in xstate.h
  x86/fpu: Improve crypto performance by making kernel-mode FPU reliably usable in softirqs
  x86/fpu/xstate: Simplify print_xstate_features()
  x86/fpu: Refine and simplify the magic number check during signal return
  selftests/x86/xstate: Fix spelling mistake "hader" -> "header"
  x86/fpu: Avoid copying dynamic FP state from init_task in arch_dup_task_struct()
  vmlinux.lds.h: Remove entry to place init_task onto init_stack
  selftests/x86/avx: Add AVX tests
  selftests/x86/xstate: Clarify supported xstates
  selftests/x86/xstate: Consolidate test invocations into a single entry
  selftests/x86/xstate: Introduce signal ABI test
  selftests/x86/xstate: Refactor ptrace ABI test
  selftests/x86/xstate: Refactor context switching test
  selftests/x86/xstate: Enumerate and name xstate components
  selftests/x86/xstate: Refactor XSAVE helpers for general use
  selftests/x86: Consolidate redundant signal helper functions
  x86/fpu: Fix guest FPU state buffer allocation size
  x86/fpu: Fully optimize out WARN_ON_FPU()
2025-03-24 22:27:18 -07:00
Uros Bizjak 6d536cad0d x86/percpu: Fix __per_cpu_hot_end marker
Make __per_cpu_hot_end marker point to the end of the percpu cache
hot data, not to the end of the percpu cache hot section.

This fixes CONFIG_MPENTIUM4 case where X86_L1_CACHE_SHIFT
is set to 7 (128 bytes).

Also update assert message accordingly.

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Link: https://lore.kernel.org/r/20250304173455.89361-1-ubizjak@gmail.com

Closes: https://lore.kernel.org/lkml/Z8a-NVJs-pm5W-mG@gmail.com/
2025-03-04 20:30:33 +01:00
Brian Gerst ab2bb9c084 percpu: Introduce percpu hot section
Add a subsection to the percpu data for frequently accessed variables
that should remain cached on each processor.  These varables should not
be accessed from other processors to avoid cacheline bouncing.

This will replace the pcpu_hot struct on x86, and open up similar
functionality to other architectures and the kernel core.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250303165246.2175811-2-brgerst@gmail.com
2025-03-04 20:30:33 +01:00
Ingo Molnar cfdaa618de Merge branch 'x86/cpu' into x86/asm, to pick up dependent commits
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2025-03-04 11:19:21 +01:00
Linus Torvalds ad69e02128 Fix an objtool false positive, and objtool related
build warnings that happens on PIE-enabled architectures
 such as LoongArch.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'objtool-urgent-2025-02-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull objtool fixes from Ingo Molnar:
 "Fix an objtool false positive, and objtool related build warnings that
  happens on PIE-enabled architectures such as LoongArch"

* tag 'objtool-urgent-2025-02-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Add bch2_trans_unlocked_or_in_restart_error() to bcachefs noreturns
  objtool: Fix C jump table annotations for Clang
  vmlinux.lds: Ensure that const vars with relocations are mapped R/O
2025-02-28 16:45:36 -08:00
Benjamin Berg 2ec01bd715 vmlinux.lds.h: Remove entry to place init_task onto init_stack
Since commit 0eb5085c38 ("arch: remove ARCH_TASK_STRUCT_ON_STACK")
there is no option that would allow placing task_struct on the stack.
Remove the unused linker script entry.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20241217202745.1402932-2-benjamin@sipsolutions.net
2025-02-26 14:02:21 +01:00
Ard Biesheuvel 68f3ea7ee1 vmlinux.lds: Ensure that const vars with relocations are mapped R/O
In the kernel, there are architectures (x86, arm64) that perform
boot-time relocation (for KASLR) without relying on PIE codegen. In this
case, all const global objects are emitted into .rodata, including const
objects with fields that will be fixed up by the boot-time relocation
code.  This implies that .rodata (and .text in some cases) need to be
writable at boot, but they will usually be mapped read-only as soon as
the boot completes.

When using PIE codegen, the compiler will emit const global objects into
.data.rel.ro rather than .rodata if the object contains fields that need
such fixups at boot-time. This permits the linker to annotate such
regions as requiring read-write access only at load time, but not at
execution time (in user space), while keeping .rodata truly const (in
user space, this is important for reducing the CoW footprint of dynamic
executables).

This distinction does not matter for the kernel, but it does imply that
const data will end up in writable memory if the .data.rel.ro sections
are not treated in a special way, as they will end up in the writable
.data segment by default.

So emit .data.rel.ro into the .rodata segment.

Cc: stable@vger.kernel.org
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250221135704.431269-5-ardb+git@google.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2025-02-25 09:46:15 -08:00
Brian Gerst 4b00c1160a percpu: Remove __per_cpu_load
__per_cpu_load is now always equal to __per_cpu_start.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250123190747.745588-15-brgerst@gmail.com
2025-02-18 10:16:00 +01:00
Brian Gerst e23cff6861 percpu: Remove PERCPU_VADDR()
x86-64 was the last user.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250123190747.745588-14-brgerst@gmail.com
2025-02-18 10:15:57 +01:00
Brian Gerst 95b0916118 percpu: Remove PER_CPU_FIRST_SECTION
x86-64 was the last user.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250123190747.745588-13-brgerst@gmail.com
2025-02-18 10:15:53 +01:00
Masahiro Yamada 4c56eb33e6 kbuild: keep symbols for symbol_get() even with CONFIG_TRIM_UNUSED_KSYMS
Linus observed that the symbol_request(utf8_data_table) call fails when
CONFIG_UNICODE=y and CONFIG_TRIM_UNUSED_KSYMS=y.

symbol_get() relies on the symbol data being present in the ksymtab for
symbol lookups. However, EXPORT_SYMBOL_GPL(utf8_data_table) is dropped
due to CONFIG_TRIM_UNUSED_KSYMS, as no module references it in this case.

Probably, this has been broken since commit dbacb0ef67 ("kconfig option
for TRIM_UNUSED_KSYMS").

This commit addresses the issue by leveraging modpost. Symbol names
passed to symbol_get() are recorded in the special .no_trim_symbol
section, which is then parsed by modpost to forcibly keep such symbols.
The .no_trim_symbol section is discarded by the linker scripts, so there
is no impact on the size of the final vmlinux or modules.

This commit cannot resolve the issue for direct calls to __symbol_get()
because the symbol name is not known at compile-time.

Although symbol_get() may eventually be deprecated, this workaround
should be good enough meanwhile.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2025-02-06 01:08:58 +09:00
Masahiro Yamada dbefa1f31a Rename .data.once to .data..once to fix resetting WARN*_ONCE
Commit b1fca27d38 ("kernel debug: support resetting WARN*_ONCE")
added support for clearing the state of once warnings. However,
it is not functional when CONFIG_LD_DEAD_CODE_DATA_ELIMINATION or
CONFIG_LTO_CLANG is enabled, because .data.once matches the
.data.[0-9a-zA-Z_]* pattern in the DATA_MAIN macro.

Commit cb87481ee8 ("kbuild: linker script do not match C names unless
LD_DEAD_CODE_DATA_ELIMINATION is configured") was introduced to suppress
the issue for the default CONFIG_LD_DEAD_CODE_DATA_ELIMINATION=n case,
providing a minimal fix for stable backporting. We were aware this did
not address the issue for CONFIG_LD_DEAD_CODE_DATA_ELIMINATION=y. The
plan was to apply correct fixes and then revert cb87481ee8. [1]

Seven years have passed since then, yet the #ifdef workaround remains in
place. Meanwhile, commit b1fca27d38 introduced the .data.once section,
and commit dc5723b02e ("kbuild: add support for Clang LTO") extended
the #ifdef.

Using a ".." separator in the section name fixes the issue for
CONFIG_LD_DEAD_CODE_DATA_ELIMINATION and CONFIG_LTO_CLANG.

[1]: https://lore.kernel.org/linux-kbuild/CAK7LNASck6BfdLnESxXUeECYL26yUDm0cwRZuM4gmaWUkxjL5g@mail.gmail.com/

Fixes: b1fca27d38 ("kernel debug: support resetting WARN*_ONCE")
Fixes: dc5723b02e ("kbuild: add support for Clang LTO")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2024-11-27 09:38:27 +09:00
Masahiro Yamada bb43a59944 Rename .data.unlikely to .data..unlikely
Commit 7ccaba5314 ("consolidate WARN_...ONCE() static variables")
was intended to collect all .data.unlikely sections into one chunk.
However, this has not worked when CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
or CONFIG_LTO_CLANG is enabled, because .data.unlikely matches the
.data.[0-9a-zA-Z_]* pattern in the DATA_MAIN macro.

Commit cb87481ee8 ("kbuild: linker script do not match C names unless
LD_DEAD_CODE_DATA_ELIMINATION is configured") was introduced to suppress
the issue for the default CONFIG_LD_DEAD_CODE_DATA_ELIMINATION=n case,
providing a minimal fix for stable backporting. We were aware this did
not address the issue for CONFIG_LD_DEAD_CODE_DATA_ELIMINATION=y. The
plan was to apply correct fixes and then revert cb87481ee8. [1]

Seven years have passed since then, yet the #ifdef workaround remains in
place.

Using a ".." separator in the section name fixes the issue for
CONFIG_LD_DEAD_CODE_DATA_ELIMINATION and CONFIG_LTO_CLANG.

[1]: https://lore.kernel.org/linux-kbuild/CAK7LNASck6BfdLnESxXUeECYL26yUDm0cwRZuM4gmaWUkxjL5g@mail.gmail.com/

Fixes: cb87481ee8 ("kbuild: linker script do not match C names unless LD_DEAD_CODE_DATA_ELIMINATION is configured")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2024-11-27 09:38:27 +09:00
Rong Xu d5dc958361 kbuild: Add Propeller configuration for kernel build
Add the build support for using Clang's Propeller optimizer. Like
AutoFDO, Propeller uses hardware sampling to gather information
about the frequency of execution of different code paths within a
binary. This information is then used to guide the compiler's
optimization decisions, resulting in a more efficient binary.

The support requires a Clang compiler LLVM 19 or later, and the
create_llvm_prof tool
(https://github.com/google/autofdo/releases/tag/v0.30.1). This
commit is limited to x86 platforms that support PMU features
like LBR on Intel machines and AMD Zen3 BRS.

Here is an example workflow for building an AutoFDO+Propeller
optimized kernel:

1) Build the kernel on the host machine, with AutoFDO and Propeller
   build config
      CONFIG_AUTOFDO_CLANG=y
      CONFIG_PROPELLER_CLANG=y
   then
      $ make LLVM=1 CLANG_AUTOFDO_PROFILE=<autofdo_profile>

“<autofdo_profile>” is the profile collected when doing a non-Propeller
AutoFDO build. This step builds a kernel that has the same optimization
level as AutoFDO, plus a metadata section that records basic block
information. This kernel image runs as fast as an AutoFDO optimized
kernel.

2) Install the kernel on test/production machines.

3) Run the load tests. The '-c' option in perf specifies the sample
   event period. We suggest using a suitable prime number,
   like 500009, for this purpose.
   For Intel platforms:
      $ perf record -e BR_INST_RETIRED.NEAR_TAKEN:k -a -N -b -c <count> \
        -o <perf_file> -- <loadtest>
   For AMD platforms:
      The supported system are: Zen3 with BRS, or Zen4 with amd_lbr_v2
      # To see if Zen3 support LBR:
      $ cat proc/cpuinfo | grep " brs"
      # To see if Zen4 support LBR:
      $ cat proc/cpuinfo | grep amd_lbr_v2
      # If the result is yes, then collect the profile using:
      $ perf record --pfm-events RETIRED_TAKEN_BRANCH_INSTRUCTIONS:k -a \
        -N -b -c <count> -o <perf_file> -- <loadtest>

4) (Optional) Download the raw perf file to the host machine.

5) Generate Propeller profile:
   $ create_llvm_prof --binary=<vmlinux> --profile=<perf_file> \
     --format=propeller --propeller_output_module_name \
     --out=<propeller_profile_prefix>_cc_profile.txt \
     --propeller_symorder=<propeller_profile_prefix>_ld_profile.txt

   “create_llvm_prof” is the profile conversion tool, and a prebuilt
   binary for linux can be found on
   https://github.com/google/autofdo/releases/tag/v0.30.1 (can also build
   from source).

   "<propeller_profile_prefix>" can be something like
   "/home/user/dir/any_string".

   This command generates a pair of Propeller profiles:
   "<propeller_profile_prefix>_cc_profile.txt" and
   "<propeller_profile_prefix>_ld_profile.txt".

6) Rebuild the kernel using the AutoFDO and Propeller profile files.
      CONFIG_AUTOFDO_CLANG=y
      CONFIG_PROPELLER_CLANG=y
   and
      $ make LLVM=1 CLANG_AUTOFDO_PROFILE=<autofdo_profile> \
        CLANG_PROPELLER_PROFILE_PREFIX=<propeller_profile_prefix>

Co-developed-by: Han Shen <shenhan@google.com>
Signed-off-by: Han Shen <shenhan@google.com>
Signed-off-by: Rong Xu <xur@google.com>
Suggested-by: Sriraman Tallam <tmsriram@google.com>
Suggested-by: Krzysztof Pszeniczny <kpszeniczny@google.com>
Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Suggested-by: Stephane Eranian <eranian@google.com>
Tested-by: Yonghong Song <yonghong.song@linux.dev>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2024-11-27 09:38:27 +09:00
Rong Xu 2fd65f7afd AutoFDO: Enable machine function split optimization for AutoFDO
Enable the machine function split optimization for AutoFDO in Clang.

Machine function split (MFS) is a pass in the Clang compiler that
splits a function into hot and cold parts. The linker groups all
cold blocks across functions together. This decreases hot code
fragmentation and improves iCache and iTLB utilization.

MFS requires a profile so this is enabled only for the AutoFDO builds.

Co-developed-by: Han Shen <shenhan@google.com>
Signed-off-by: Han Shen <shenhan@google.com>
Signed-off-by: Rong Xu <xur@google.com>
Suggested-by: Sriraman Tallam <tmsriram@google.com>
Suggested-by: Krzysztof Pszeniczny <kpszeniczny@google.com>
Tested-by: Yonghong Song <yonghong.song@linux.dev>
Tested-by: Yabin Cui <yabinc@google.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2024-11-27 09:38:27 +09:00
Rong Xu 0847420f5e AutoFDO: Enable -ffunction-sections for the AutoFDO build
Enable -ffunction-sections by default for the AutoFDO build.

With -ffunction-sections, the compiler places each function in its own
section named .text.function_name instead of placing all functions in
the .text section. In the AutoFDO build, this allows the linker to
utilize profile information to reorganize functions for improved
utilization of iCache and iTLB.

Co-developed-by: Han Shen <shenhan@google.com>
Signed-off-by: Han Shen <shenhan@google.com>
Signed-off-by: Rong Xu <xur@google.com>
Suggested-by: Sriraman Tallam <tmsriram@google.com>
Tested-by: Yonghong Song <yonghong.song@linux.dev>
Tested-by: Yabin Cui <yabinc@google.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2024-11-27 09:38:27 +09:00
Rong Xu db0b2991ae vmlinux.lds.h: Add markers for text_unlikely and text_hot sections
Add markers like __hot_text_start, __hot_text_end, __unlikely_text_start,
and __unlikely_text_end which will be included in System.map. These markers
indicate how the compiler groups functions, providing valuable information
to developers about the layout and optimization of the code.

Co-developed-by: Han Shen <shenhan@google.com>
Signed-off-by: Han Shen <shenhan@google.com>
Signed-off-by: Rong Xu <xur@google.com>
Suggested-by: Sriraman Tallam <tmsriram@google.com>
Tested-by: Yonghong Song <yonghong.song@linux.dev>
Tested-by: Yabin Cui <yabinc@google.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2024-11-27 09:38:27 +09:00
Rong Xu 0043ecea23 vmlinux.lds.h: Adjust symbol ordering in text output section
When the -ffunction-sections compiler option is enabled, each function
is placed in a separate section named .text.function_name rather than
putting all functions in a single .text section.

However, using -function-sections can cause problems with the
linker script. The comments included in include/asm-generic/vmlinux.lds.h
note these issues.:
  “TEXT_MAIN here will match .text.fixup and .text.unlikely if dead
   code elimination is enabled, so these sections should be converted
   to use ".." first.”

It is unclear whether there is a straightforward method for converting
a suffix to "..".

This patch modifies the order of subsections within the text output
section. Specifically, it changes current order:
  .text.hot, .text, .text_unlikely, .text.unknown, .text.asan
to the new order:
  .text.asan, .text.unknown, .text_unlikely, .text.hot, .text

Here is the rationale behind the new layout:

The majority of the code resides in three sections: .text.hot, .text,
and .text.unlikely, with .text.unknown containing a negligible amount.
.text.asan is only generated in ASAN builds.

The primary goal is to group code segments based on their execution
frequency (hotness).

First, we want to place .text.hot adjacent to .text. Since we cannot put
.text.hot after .text (Due to constraints with -ffunction-sections,
placing .text.hot after .text is problematic), we need to put
.text.hot before .text.

Then it comes to .text.unlikely, we cannot put it after .text (same
-ffunction-sections issue) . Therefore, we position .text.unlikely
before .text.hot.

.text.unknown and .tex.asan follow the same logic.

This revised ordering effectively reverses the original arrangement (for
.text.unlikely, .text.unknown, and .tex.asan), maintaining a similar level
of affinity between sections.

It also places .text.hot section at the beginning of a page to better
utilize the TLB entry.

Note that the limitation arises because the linker script employs glob
patterns instead of regular expressions for string matching. While there
is a method to maintain the current order using complex patterns, this
significantly complicates the pattern and increases the likelihood of
errors.

This patch also changes vmlinux.lds.S for the sparc64 architecture to
accommodate specific symbol placement requirements.

Co-developed-by: Han Shen <shenhan@google.com>
Signed-off-by: Han Shen <shenhan@google.com>
Signed-off-by: Rong Xu <xur@google.com>
Suggested-by: Sriraman Tallam <tmsriram@google.com>
Suggested-by: Krzysztof Pszeniczny <kpszeniczny@google.com>
Tested-by: Yonghong Song <yonghong.song@linux.dev>
Tested-by: Yabin Cui <yabinc@google.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2024-11-27 09:38:27 +09:00
Linus Torvalds 348325d644 asm-generic updates for 6.12
These are only two small patches, one cleanup for arch/alpha
 and a preparation patch cleaning up the handling of runtime
 constants in the linker scripts.
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Merge tag 'asm-generic-6.12' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic

Pull asm-generic updates from Arnd Bergmann:
 "These are only two small patches, one cleanup for arch/alpha and a
  preparation patch cleaning up the handling of runtime constants in the
  linker scripts"

* tag 'asm-generic-6.12' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic:
  runtime constants: move list of constants to vmlinux.lds.h
  alpha: no need to include asm/xchg.h twice
2024-09-26 11:54:40 -07:00
Tejun Heo 649e980dad Merge branch 'bpf/master' into for-6.12
Pull bpf/master to receive baebe9aaba ("bpf: allow passing struct
bpf_iter_<type> as kfunc arguments") and related changes in preparation for
the DSQ iterator patchset.

Signed-off-by: Tejun Heo <tj@kernel.org>
2024-09-04 11:41:32 -10:00
Jann Horn 92a10d3861 runtime constants: move list of constants to vmlinux.lds.h
Refactor the list of constant variables into a macro.
This should make it easier to add more constants in the future.

Signed-off-by: Jann Horn <jannh@google.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2024-08-19 09:48:14 +02:00
Linus Torvalds b6547e5486 runtime constants: deal with old decrepit linkers
The runtime constants linker script depended on documented linker
behavior [1]:

 "If an output section’s name is the same as the input section’s name
  and is representable as a C identifier, then the linker will
  automatically PROVIDE two symbols: __start_SECNAME and __stop_SECNAME,
  where SECNAME is the name of the section. These indicate the start
  address and end address of the output section respectively"

to just automatically define the symbol names for the bounds of the
runtime constant arrays.

It turns out that this isn't actually something we can rely on, with old
linkers not generating these automatic symbols.  It looks to have been
introduced in binutils-2.29 back in 2017, and we still support building
with versions all the way back to binutils-2.25 (from 2015).

And yes, Oleg actually seems to be using such ancient versions of
binutils.

So instead of depending on the implicit symbols from "section names
match and are representable C identifiers", just do this all manually.
It's not like it causes us any extra pain, we already have to do that
for all the other sections that we use that often have special
characters in them.

Reported-and-tested-by: Oleg Nesterov <oleg@redhat.com>
Link: https://sourceware.org/binutils/docs/ld/Input-Section-Example.html [1]
Link: https://lore.kernel.org/all/20240802114518.GA20924@redhat.com/
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2024-08-03 08:38:45 -07:00
Tejun Heo c8faf11cd1 Linux 6.11-rc1
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Merge tag 'v6.11-rc1' into for-6.12

Linux 6.11-rc1
2024-07-30 09:30:11 -10:00
Linus Torvalds ca83c61cb3 Kbuild updates for v6.11
- Remove tristate choice support from Kconfig
 
  - Stop using the PROVIDE() directive in the linker script
 
  - Reduce the number of links for the combination of CONFIG_DEBUG_INFO_BTF
    and CONFIG_KALLSYMS
 
  - Enable the warning for symbol reference to .exit.* sections by default
 
  - Fix warnings in RPM package builds
 
  - Improve scripts/make_fit.py to generate a FIT image with separate base
    DTB and overlays
 
  - Improve choice value calculation in Kconfig
 
  - Fix conditional prompt behavior in choice in Kconfig
 
  - Remove support for the uncommon EMAIL environment variable in Debian
    package builds
 
  - Remove support for the uncommon "name <email>" form for the DEBEMAIL
    environment variable
 
  - Raise the minimum supported GNU Make version to 4.0
 
  - Remove stale code for the absolute kallsyms
 
  - Move header files commonly used for host programs to scripts/include/
 
  - Introduce the pacman-pkg target to generate a pacman package used in
    Arch Linux
 
  - Clean up Kconfig
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Merge tag 'kbuild-v6.11' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild updates from Masahiro Yamada:

 - Remove tristate choice support from Kconfig

 - Stop using the PROVIDE() directive in the linker script

 - Reduce the number of links for the combination of CONFIG_KALLSYMS and
   CONFIG_DEBUG_INFO_BTF

 - Enable the warning for symbol reference to .exit.* sections by
   default

 - Fix warnings in RPM package builds

 - Improve scripts/make_fit.py to generate a FIT image with separate
   base DTB and overlays

 - Improve choice value calculation in Kconfig

 - Fix conditional prompt behavior in choice in Kconfig

 - Remove support for the uncommon EMAIL environment variable in Debian
   package builds

 - Remove support for the uncommon "name <email>" form for the DEBEMAIL
   environment variable

 - Raise the minimum supported GNU Make version to 4.0

 - Remove stale code for the absolute kallsyms

 - Move header files commonly used for host programs to scripts/include/

 - Introduce the pacman-pkg target to generate a pacman package used in
   Arch Linux

 - Clean up Kconfig

* tag 'kbuild-v6.11' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (65 commits)
  kbuild: doc: gcc to CC change
  kallsyms: change sym_entry::percpu_absolute to bool type
  kallsyms: unify seq and start_pos fields of struct sym_entry
  kallsyms: add more original symbol type/name in comment lines
  kallsyms: use \t instead of a tab in printf()
  kallsyms: avoid repeated calculation of array size for markers
  kbuild: add script and target to generate pacman package
  modpost: use generic macros for hash table implementation
  kbuild: move some helper headers from scripts/kconfig/ to scripts/include/
  Makefile: add comment to discourage tools/* addition for kernel builds
  kbuild: clean up scripts/remove-stale-files
  kconfig: recursive checks drop file/lineno
  kbuild: rpm-pkg: introduce a simple changelog section for kernel.spec
  kallsyms: get rid of code for absolute kallsyms
  kbuild: Create INSTALL_PATH directory if it does not exist
  kbuild: Abort make on install failures
  kconfig: remove 'e1' and 'e2' macros from expression deduplication
  kconfig: remove SYMBOL_CHOICEVAL flag
  kconfig: add const qualifiers to several function arguments
  kconfig: call expr_eliminate_yn() at least once in expr_eliminate_dups()
  ...
2024-07-23 14:32:21 -07:00
Linus Torvalds 527eff227d - In the series "treewide: Refactor heap related implementation",
Kuan-Wei Chiu has significantly reworked the min_heap library code and
   has taught bcachefs to use the new more generic implementation.
 
 - Yury Norov's series "Cleanup cpumask.h inclusion in core headers"
   reworks the cpumask and nodemask headers to make things generally more
   rational.
 
 - Kuan-Wei Chiu has sent along some maintenance work against our sorting
   library code in the series "lib/sort: Optimizations and cleanups".
 
 - More library maintainance work from Christophe Jaillet in the series
   "Remove usage of the deprecated ida_simple_xx() API".
 
 - Ryusuke Konishi continues with the nilfs2 fixes and clanups in the
   series "nilfs2: eliminate the call to inode_attach_wb()".
 
 - Kuan-Ying Lee has some fixes to the gdb scripts in the series "Fix GDB
   command error".
 
 - Plus the usual shower of singleton patches all over the place.  Please
   see the relevant changelogs for details.
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Merge tag 'mm-nonmm-stable-2024-07-21-15-07' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull non-MM updates from Andrew Morton:

 - In the series "treewide: Refactor heap related implementation",
   Kuan-Wei Chiu has significantly reworked the min_heap library code
   and has taught bcachefs to use the new more generic implementation.

 - Yury Norov's series "Cleanup cpumask.h inclusion in core headers"
   reworks the cpumask and nodemask headers to make things generally
   more rational.

 - Kuan-Wei Chiu has sent along some maintenance work against our
   sorting library code in the series "lib/sort: Optimizations and
   cleanups".

 - More library maintainance work from Christophe Jaillet in the series
   "Remove usage of the deprecated ida_simple_xx() API".

 - Ryusuke Konishi continues with the nilfs2 fixes and clanups in the
   series "nilfs2: eliminate the call to inode_attach_wb()".

 - Kuan-Ying Lee has some fixes to the gdb scripts in the series "Fix
   GDB command error".

 - Plus the usual shower of singleton patches all over the place. Please
   see the relevant changelogs for details.

* tag 'mm-nonmm-stable-2024-07-21-15-07' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (98 commits)
  ia64: scrub ia64 from poison.h
  watchdog/perf: properly initialize the turbo mode timestamp and rearm counter
  tsacct: replace strncpy() with strscpy()
  lib/bch.c: use swap() to improve code
  test_bpf: convert comma to semicolon
  init/modpost: conditionally check section mismatch to __meminit*
  init: remove unused __MEMINIT* macros
  nilfs2: Constify struct kobj_type
  nilfs2: avoid undefined behavior in nilfs_cnt32_ge macro
  math: rational: add missing MODULE_DESCRIPTION() macro
  lib/zlib: add missing MODULE_DESCRIPTION() macro
  fs: ufs: add MODULE_DESCRIPTION()
  lib/rbtree.c: fix the example typo
  ocfs2: add bounds checking to ocfs2_check_dir_entry()
  fs: add kernel-doc comments to ocfs2_prepare_orphan_dir()
  coredump: simplify zap_process()
  selftests/fpu: add missing MODULE_DESCRIPTION() macro
  compiler.h: simplify data_race() macro
  build-id: require program headers to be right after ELF header
  resource: add missing MODULE_DESCRIPTION()
  ...
2024-07-21 17:56:22 -07:00
Linus Torvalds d80f2996b8 asm-generic updates for 6.11
Most of this is part of my ongoing work to clean up the system call
 tables. In this bit, all of the newer architectures are converted to
 use the machine readable syscall.tbl format instead in place of complex
 macros in include/uapi/asm-generic/unistd.h.
 
 This follows an earlier series that fixed various API mismatches
 and in turn is used as the base for planned simplifications.
 
 The other two patches are dead code removal and a warning fix.
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Merge tag 'asm-generic-6.11' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic

Pull asm-generic updates from Arnd Bergmann:
 "Most of this is part of my ongoing work to clean up the system call
  tables. In this bit, all of the newer architectures are converted to
  use the machine readable syscall.tbl format instead in place of
  complex macros in include/uapi/asm-generic/unistd.h.

  This follows an earlier series that fixed various API mismatches and
  in turn is used as the base for planned simplifications.

  The other two patches are dead code removal and a warning fix"

* tag 'asm-generic-6.11' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic:
  vmlinux.lds.h: catch .bss..L* sections into BSS")
  fixmap: Remove unused set_fixmap_offset_io()
  riscv: convert to generic syscall table
  openrisc: convert to generic syscall table
  nios2: convert to generic syscall table
  loongarch: convert to generic syscall table
  hexagon: use new system call table
  csky: convert to generic syscall table
  arm64: rework compat syscall macros
  arm64: generate 64-bit syscall.tbl
  arm64: convert unistd_32.h to syscall.tbl format
  arc: convert to generic syscall table
  clone3: drop __ARCH_WANT_SYS_CLONE3 macro
  kbuild: add syscall table generation to scripts/Makefile.asm-headers
  kbuild: verify asm-generic header list
  loongarch: avoid generating extra header files
  um: don't generate asm/bpf_perf_event.h
  csky: drop asm/gpio.h wrapper
  syscalls: add generic scripts/syscall.tbl
2024-07-16 12:09:03 -07:00
Masahiro Yamada c442db3f49 kbuild: remove PROVIDE() for kallsyms symbols
This reimplements commit 951bcae6c5 ("kallsyms: Avoid weak references
for kallsyms symbols") because I am not a big fan of PROVIDE().

As an alternative solution, this commit prepends one more kallsyms step.

    KSYMS   .tmp_vmlinux.kallsyms0.S          # added
    AS      .tmp_vmlinux.kallsyms0.o          # added
    LD      .tmp_vmlinux.btf
    BTF     .btf.vmlinux.bin.o
    LD      .tmp_vmlinux.kallsyms1
    NM      .tmp_vmlinux.kallsyms1.syms
    KSYMS   .tmp_vmlinux.kallsyms1.S
    AS      .tmp_vmlinux.kallsyms1.o
    LD      .tmp_vmlinux.kallsyms2
    NM      .tmp_vmlinux.kallsyms2.syms
    KSYMS   .tmp_vmlinux.kallsyms2.S
    AS      .tmp_vmlinux.kallsyms2.o
    LD      vmlinux

Step 0 takes /dev/null as input, and generates .tmp_vmlinux.kallsyms0.o,
which has a valid kallsyms format with the empty symbol list, and can be
linked to vmlinux. Since it is really small, the added compile-time cost
is negligible.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
2024-07-16 01:08:36 +09:00
Masahiro Yamada 73db3abdca init/modpost: conditionally check section mismatch to __meminit*
This reverts commit eb8f689046 ("Use separate sections for __dev/
_cpu/__mem code/data").

Check section mismatch to __meminit* only when CONFIG_MEMORY_HOTPLUG=n.

With this change, the linker script and modpost become simpler, and we
can get rid of the __ref annotations from the memory hotplug code.

[sfr@canb.auug.org.au: remove MEM_KEEP from arch/powerpc/kernel/vmlinux.lds.S]
  Link: https://lkml.kernel.org/r/20240710093213.2aefb25f@canb.auug.org.au
Link: https://lkml.kernel.org/r/20240706160511.2331061-2-masahiroy@kernel.org
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-07-12 16:39:52 -07:00
Christophe Leroy 1a7b7326d5
vmlinux.lds.h: catch .bss..L* sections into BSS")
Commit 9a427556fb ("vmlinux.lds.h: catch compound literals into
data and BSS") added catches for .data..L* and .rodata..L* but missed
.bss..L*

Since commit 5431fdd2c1 ("ptrace: Convert ptrace_attach() to use
lock guards") the following appears at build:

  LD      .tmp_vmlinux.kallsyms1
powerpc64-linux-ld: warning: orphan section `.bss..Lubsan_data33' from `kernel/ptrace.o' being placed in section `.bss..Lubsan_data33'
  NM      .tmp_vmlinux.kallsyms1.syms
  KSYMS   .tmp_vmlinux.kallsyms1.S
  AS      .tmp_vmlinux.kallsyms1.S
  LD      .tmp_vmlinux.kallsyms2
powerpc64-linux-ld: warning: orphan section `.bss..Lubsan_data33' from `kernel/ptrace.o' being placed in section `.bss..Lubsan_data33'
  NM      .tmp_vmlinux.kallsyms2.syms
  KSYMS   .tmp_vmlinux.kallsyms2.S
  AS      .tmp_vmlinux.kallsyms2.S
  LD      vmlinux
powerpc64-linux-ld: warning: orphan section `.bss..Lubsan_data33' from `kernel/ptrace.o' being placed in section `.bss..Lubsan_data33'

Lets add .bss..L* to BSS_MAIN macro to catch those sections into BSS.

Fixes: 9a427556fb ("vmlinux.lds.h: catch compound literals into data and BSS")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202404031349.nmKhyuUG-lkp@intel.com/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2024-07-12 08:52:45 +02:00