mirror of https://github.com/torvalds/linux.git
63e6995005
- 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
...
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||
|---|---|---|
| .. | ||
| atomic | ||
| bash-completion | ||
| basic | ||
| clang-tools | ||
| coccinelle | ||
| crypto | ||
| dtc | ||
| dummy-tools | ||
| gcc-plugins | ||
| gdb | ||
| gendwarfksyms | ||
| genksyms | ||
| include | ||
| ipe | ||
| kconfig | ||
| ksymoops | ||
| lib | ||
| livepatch | ||
| mod | ||
| package | ||
| selinux | ||
| tracing | ||
| .gitignore | ||
| Kbuild.include | ||
| Kconfig.include | ||
| Lindent | ||
| Makefile | ||
| Makefile.asm-headers | ||
| Makefile.autofdo | ||
| Makefile.btf | ||
| Makefile.build | ||
| Makefile.clang | ||
| Makefile.clean | ||
| Makefile.compiler | ||
| Makefile.debug | ||
| Makefile.defconf | ||
| Makefile.dtbinst | ||
| Makefile.dtbs | ||
| Makefile.extrawarn | ||
| Makefile.gcc-plugins | ||
| Makefile.headersinst | ||
| Makefile.host | ||
| Makefile.kasan | ||
| Makefile.kcov | ||
| Makefile.kcsan | ||
| Makefile.kmsan | ||
| Makefile.kstack_erase | ||
| Makefile.lib | ||
| Makefile.modfinal | ||
| Makefile.modinst | ||
| Makefile.modpost | ||
| Makefile.package | ||
| Makefile.propeller | ||
| Makefile.randstruct | ||
| Makefile.ubsan | ||
| Makefile.userprogs | ||
| Makefile.vdsoinst | ||
| Makefile.vmlinux | ||
| Makefile.vmlinux_o | ||
| as-version.sh | ||
| asn1_compiler.c | ||
| bloat-o-meter | ||
| bootgraph.pl | ||
| bpf_doc.py | ||
| build-version | ||
| cc-can-link.sh | ||
| cc-version.sh | ||
| check-function-names.sh | ||
| check-git | ||
| check-sysctl-docs | ||
| check-uapi.sh | ||
| check-variable-fonts.sh | ||
| check_extable.sh | ||
| checkdeclares.pl | ||
| checkincludes.pl | ||
| checkkconfigsymbols.py | ||
| checkpatch.pl | ||
| checkstack.pl | ||
| checksyscalls.sh | ||
| checktransupdate.py | ||
| checkversion.pl | ||
| cleanfile | ||
| cleanpatch | ||
| coccicheck | ||
| config | ||
| const_structs.checkpatch | ||
| decode_stacktrace.sh | ||
| decodecode | ||
| depmod.sh | ||
| dev-needs.sh | ||
| diffconfig | ||
| documentation-file-ref-check | ||
| extract-fwblobs | ||
| extract-ikconfig | ||
| extract-module-sig.pl | ||
| extract-sys-certs.pl | ||
| extract-vmlinux | ||
| extract_xc3028.pl | ||
| faddr2line | ||
| file-size.sh | ||
| find-unused-docs.sh | ||
| gen-crc-consts.py | ||
| gen-randstruct-seed.sh | ||
| gen_packed_field_checks.c | ||
| generate_builtin_ranges.awk | ||
| generate_initcall_order.pl | ||
| generate_rust_analyzer.py | ||
| generate_rust_target.rs | ||
| get_abi.py | ||
| get_dvb_firmware | ||
| get_feat.pl | ||
| get_maintainer.pl | ||
| gfp-translate | ||
| git-resolve.sh | ||
| git.orderFile | ||
| head-object-list.txt | ||
| headerdep.pl | ||
| headers_install.sh | ||
| insert-sys-cert.c | ||
| install.sh | ||
| integer-wrap-ignore.scl | ||
| jobserver-exec | ||
| kallsyms.c | ||
| kernel-doc | ||
| kernel-doc.pl | ||
| kernel-doc.py | ||
| ld-version.sh | ||
| leaking_addresses.pl | ||
| link-vmlinux.sh | ||
| macro_checker.py | ||
| make_fit.py | ||
| makelst | ||
| markup_oops.pl | ||
| min-tool-version.sh | ||
| misc-check | ||
| mkcompile_h | ||
| mksysmap | ||
| mkuboot.sh | ||
| module-common.c | ||
| module.lds.S | ||
| modules-check.sh | ||
| nsdeps | ||
| objdiff | ||
| objdump-func | ||
| orc_hash.sh | ||
| pahole-version.sh | ||
| parse-maintainers.pl | ||
| patch-kernel | ||
| profile2linkerlist.pl | ||
| prune-kernel | ||
| recordmcount.c | ||
| recordmcount.h | ||
| recordmcount.pl | ||
| relocs_check.sh | ||
| remove-stale-files | ||
| rust_is_available.sh | ||
| rust_is_available_bindgen_0_66.h | ||
| rust_is_available_bindgen_libclang.h | ||
| rust_is_available_bindgen_libclang_concat.h | ||
| rust_is_available_test.py | ||
| rustc-llvm-version.sh | ||
| rustc-version.sh | ||
| rustdoc_test_builder.rs | ||
| rustdoc_test_gen.rs | ||
| setlocalversion | ||
| show_delta | ||
| sign-file.c | ||
| sorttable.c | ||
| spdxcheck-test.sh | ||
| spdxcheck.py | ||
| spdxexclude | ||
| spelling.txt | ||
| sphinx-build-wrapper | ||
| sphinx-pre-install | ||
| split-man.pl | ||
| ssl-common.h | ||
| stackdelta | ||
| stackusage | ||
| subarch.include | ||
| syscall.tbl | ||
| syscallhdr.sh | ||
| syscallnr.sh | ||
| syscalltbl.sh | ||
| tags.sh | ||
| test_doc_build.py | ||
| tools-support-relr.sh | ||
| unifdef.c | ||
| ver_linux | ||
| verify_builtin_ranges.awk | ||
| xen-hypercalls.sh | ||
| xz_wrap.sh | ||