mirror of https://github.com/torvalds/linux.git
1e688dd2a3
Using asm goto in __WARN_FLAGS() and WARN_ON() allows more
flexibility to GCC.
For that add an entry to the exception table so that
program_check_exception() knowns where to resume execution
after a WARNING.
Here are two exemples. The first one is done on PPC32 (which
benefits from the previous patch), the second is on PPC64.
unsigned long test(struct pt_regs *regs)
{
int ret;
WARN_ON(regs->msr & MSR_PR);
return regs->gpr[3];
}
unsigned long test9w(unsigned long a, unsigned long b)
{
if (WARN_ON(!b))
return 0;
return a / b;
}
Before the patch:
000003a8 <test>:
3a8: 81 23 00 84 lwz r9,132(r3)
3ac: 71 29 40 00 andi. r9,r9,16384
3b0: 40 82 00 0c bne 3bc <test+0x14>
3b4: 80 63 00 0c lwz r3,12(r3)
3b8: 4e 80 00 20 blr
3bc: 0f e0 00 00 twui r0,0
3c0: 80 63 00 0c lwz r3,12(r3)
3c4: 4e 80 00 20 blr
0000000000000bf0 <.test9w>:
bf0: 7c 89 00 74 cntlzd r9,r4
bf4: 79 29 d1 82 rldicl r9,r9,58,6
bf8: 0b 09 00 00 tdnei r9,0
bfc: 2c 24 00 00 cmpdi r4,0
c00: 41 82 00 0c beq c0c <.test9w+0x1c>
c04: 7c 63 23 92 divdu r3,r3,r4
c08: 4e 80 00 20 blr
c0c: 38 60 00 00 li r3,0
c10: 4e 80 00 20 blr
After the patch:
000003a8 <test>:
3a8: 81 23 00 84 lwz r9,132(r3)
3ac: 71 29 40 00 andi. r9,r9,16384
3b0: 40 82 00 0c bne 3bc <test+0x14>
3b4: 80 63 00 0c lwz r3,12(r3)
3b8: 4e 80 00 20 blr
3bc: 0f e0 00 00 twui r0,0
0000000000000c50 <.test9w>:
c50: 7c 89 00 74 cntlzd r9,r4
c54: 79 29 d1 82 rldicl r9,r9,58,6
c58: 0b 09 00 00 tdnei r9,0
c5c: 7c 63 23 92 divdu r3,r3,r4
c60: 4e 80 00 20 blr
c70: 38 60 00 00 li r3,0
c74: 4e 80 00 20 blr
In the first exemple, we see GCC doesn't need to duplicate what
happens after the trap.
In the second exemple, we see that GCC doesn't need to emit a test
and a branch in the likely path in addition to the trap.
We've got some WARN_ON() in .softirqentry.text section so it needs
to be added in the OTHER_TEXT_SECTIONS in modpost.c
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/389962b1b702e3c78d169e59bcfac56282889173.1618331882.git.christophe.leroy@csgroup.eu
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| .. | ||
| atomic | ||
| basic | ||
| clang-tools | ||
| coccinelle | ||
| dtc | ||
| dummy-tools | ||
| gcc-plugins | ||
| gdb | ||
| genksyms | ||
| kconfig | ||
| ksymoops | ||
| mod | ||
| package | ||
| selinux | ||
| tracing | ||
| .gitignore | ||
| Kbuild.include | ||
| Kconfig.include | ||
| Lindent | ||
| Makefile | ||
| Makefile.asm-generic | ||
| Makefile.build | ||
| Makefile.clean | ||
| Makefile.compiler | ||
| Makefile.dtbinst | ||
| Makefile.extrawarn | ||
| Makefile.gcc-plugins | ||
| Makefile.headersinst | ||
| Makefile.host | ||
| Makefile.kasan | ||
| Makefile.kcov | ||
| Makefile.kcsan | ||
| Makefile.lib | ||
| Makefile.modfinal | ||
| Makefile.modinst | ||
| Makefile.modpost | ||
| Makefile.package | ||
| Makefile.ubsan | ||
| Makefile.userprogs | ||
| adjust_autoksyms.sh | ||
| as-version.sh | ||
| asn1_compiler.c | ||
| bin2c.c | ||
| bloat-o-meter | ||
| bootgraph.pl | ||
| bpf_doc.py | ||
| cc-can-link.sh | ||
| cc-version.sh | ||
| check-sysctl-docs | ||
| check_extable.sh | ||
| checkdeclares.pl | ||
| checkincludes.pl | ||
| checkkconfigsymbols.py | ||
| checkpatch.pl | ||
| checkstack.pl | ||
| checksyscalls.sh | ||
| checkversion.pl | ||
| cleanfile | ||
| cleanpatch | ||
| coccicheck | ||
| config | ||
| const_structs.checkpatch | ||
| decode_stacktrace.sh | ||
| decodecode | ||
| depmod.sh | ||
| dev-needs.sh | ||
| diffconfig | ||
| documentation-file-ref-check | ||
| export_report.pl | ||
| extract-cert.c | ||
| extract-ikconfig | ||
| extract-module-sig.pl | ||
| extract-sys-certs.pl | ||
| extract-vmlinux | ||
| extract_xc3028.pl | ||
| faddr2line | ||
| file-size.sh | ||
| find-unused-docs.sh | ||
| gcc-goto.sh | ||
| gcc-ld | ||
| gcc-x86_32-has-stack-protector.sh | ||
| gcc-x86_64-has-stack-protector.sh | ||
| gen_autoksyms.sh | ||
| gen_ksymdeps.sh | ||
| generate_initcall_order.pl | ||
| get_abi.pl | ||
| get_dvb_firmware | ||
| get_feat.pl | ||
| get_maintainer.pl | ||
| gfp-translate | ||
| headerdep.pl | ||
| headers_check.pl | ||
| headers_install.sh | ||
| insert-sys-cert.c | ||
| jobserver-exec | ||
| kallsyms.c | ||
| kernel-doc | ||
| ld-version.sh | ||
| leaking_addresses.pl | ||
| link-vmlinux.sh | ||
| makelst | ||
| markup_oops.pl | ||
| min-tool-version.sh | ||
| mkcompile_h | ||
| mksysmap | ||
| mkuboot.sh | ||
| module.lds.S | ||
| modules-check.sh | ||
| nsdeps | ||
| objdiff | ||
| parse-maintainers.pl | ||
| patch-kernel | ||
| profile2linkerlist.pl | ||
| prune-kernel | ||
| recordmcount.c | ||
| recordmcount.h | ||
| recordmcount.pl | ||
| remove-stale-files | ||
| setlocalversion | ||
| show_delta | ||
| sign-file.c | ||
| sorttable.c | ||
| sorttable.h | ||
| spdxcheck-test.sh | ||
| spdxcheck.py | ||
| spelling.txt | ||
| sphinx-pre-install | ||
| split-man.pl | ||
| stackdelta | ||
| stackusage | ||
| subarch.include | ||
| syscallhdr.sh | ||
| syscallnr.sh | ||
| syscalltbl.sh | ||
| tags.sh | ||
| tools-support-relr.sh | ||
| unifdef.c | ||
| ver_linux | ||
| xen-hypercalls.sh | ||
| xz_wrap.sh | ||