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| author | Christophe Leroy <christophe.leroy@csgroup.eu> | 2023-07-12 23:45:02 +1000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2023-07-17 10:35:28 +1000 |
| commit | b49e578b9314db051da0ad72bba24094193f9bd0 (patch) | |
| tree | cfa5f2bbb5b7b52555a8db33ded6aac20b4d03de /arch/powerpc/kernel | |
| parent | b59c9dc4d9d47b3c4572d826603fde507055b656 (diff) | |
| download | linux-stable-b49e578b9314db051da0ad72bba24094193f9bd0.tar.gz linux-stable-b49e578b9314db051da0ad72bba24094193f9bd0.tar.bz2 linux-stable-b49e578b9314db051da0ad72bba24094193f9bd0.zip | |
Revert "powerpc/bug: Provide better flexibility to WARN_ON/__WARN_FLAGS() with asm goto"
This partly reverts commit 1e688dd2a3d6759d416616ff07afc4bb836c4213.
That commit aimed at optimising the code around generation of
WARN_ON/BUG_ON but this leads to a lot of dead code erroneously
generated by GCC.
That dead code becomes a problem when we start using objtool validation
because objtool will abort validation with a warning as soon as it
detects unreachable code. This is because unreachable code might
be the indication that objtool doesn't properly decode object text.
text data bss dec hex filename
9551585 3627834 224376 13403795 cc8693 vmlinux.before
9535281 3628358 224376 13388015 cc48ef vmlinux.after
Once this change is reverted, in a standard configuration (pmac32 +
function tracer) the text is reduced by 16k which is around 1.7%
We already had problem with it when starting to use objtool on powerpc
as a replacement for recordmcount, see commit 93e3f45a2631 ("powerpc:
Fix __WARN_FLAGS() for use with Objtool")
There is also a problem with at least GCC 12, on ppc64_defconfig +
CONFIG_CC_OPTIMIZE_FOR_SIZE=y + CONFIG_DEBUG_SECTION_MISMATCH=y :
LD .tmp_vmlinux.kallsyms1
powerpc64-linux-ld: net/ipv4/tcp_input.o:(__ex_table+0xc4): undefined reference to `.L2136'
make[2]: *** [scripts/Makefile.vmlinux:36: vmlinux] Error 1
make[1]: *** [/home/chleroy/linux-powerpc/Makefile:1238: vmlinux] Error 2
Taking into account that other problems are encountered with that
'asm goto' in WARN_ON(), including build failures, keeping that
change is not worth it allthough it is primarily a compiler bug.
Revert it for now.
mpe: Retain EMIT_WARN_ENTRY as a synonym for EMIT_BUG_ENTRY to reduce
churn, as there are now nearly as many uses of EMIT_WARN_ENTRY as
EMIT_BUG_ENTRY.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: Naveen N Rao <naveen@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230712134552.534955-1-mpe@ellerman.id.au
Diffstat (limited to 'arch/powerpc/kernel')
| -rw-r--r-- | arch/powerpc/kernel/traps.c | 9 |
1 files changed, 2 insertions, 7 deletions
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c index e59ec6d32d37..7ef147e2a20d 100644 --- a/arch/powerpc/kernel/traps.c +++ b/arch/powerpc/kernel/traps.c @@ -1508,13 +1508,8 @@ static void do_program_check(struct pt_regs *regs) if (!(regs->msr & MSR_PR) && /* not user-mode */ report_bug(bugaddr, regs) == BUG_TRAP_TYPE_WARN) { - const struct exception_table_entry *entry; - - entry = search_exception_tables(bugaddr); - if (entry) { - regs_set_return_ip(regs, extable_fixup(entry) + regs->nip - bugaddr); - return; - } + regs_add_return_ip(regs, 4); + return; } if (cpu_has_feature(CPU_FTR_DEXCR_NPHIE) && user_mode(regs)) { |