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| author | Sathvika Vasireddy <sv@linux.ibm.com> | 2022-11-14 23:27:39 +0530 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2022-11-15 20:11:47 +1100 |
| commit | 93e3f45a26310e3f3f8558be40df411e23ab742c (patch) | |
| tree | 66ad72a9f15229681721ddbd5b9fca20e0ebfd5a /arch/powerpc | |
| parent | 247f34f7b80357943234f93f247a1ae6b6c3a740 (diff) | |
| download | linux-93e3f45a26310e3f3f8558be40df411e23ab742c.tar.gz linux-93e3f45a26310e3f3f8558be40df411e23ab742c.tar.bz2 linux-93e3f45a26310e3f3f8558be40df411e23ab742c.zip | |
powerpc: Fix __WARN_FLAGS() for use with Objtool
Commit 1e688dd2a3d675 ("powerpc/bug: Provide better flexibility to
WARN_ON/__WARN_FLAGS() with asm goto") updated __WARN_FLAGS() to use asm
goto, and added a call to 'unreachable()' after the asm goto for optimal
code generation. With CONFIG_OBJTOOL enabled, 'annotate_unreachable()'
statement in 'unreachable()' tries to note down the location of the
subsequent instruction in a separate elf section to aid code flow
analysis. However, on powerpc, this results in gcc emitting a call to a
symbol of size 0. This results in objtool complaining of "unannotated
intra-function call" since the target symbol is not a valid function
call destination.
Objtool wants this annotation for code flow analysis, which we are not
yet enabling on powerpc. As such, expand the call to 'unreachable()' in
__WARN_FLAGS() without annotate_unreachable():
barrier_before_unreachable();
__builtin_unreachable();
This still results in optimal code generation for __WARN_FLAGS(), while
getting rid of the objtool warning.
We still need barrier_before_unreachable() to work around gcc bugs 82365
and 106751:
- https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365
- https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106751
Tested-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Sathvika Vasireddy <sv@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221114175754.1131267-2-sv@linux.ibm.com
Diffstat (limited to 'arch/powerpc')
| -rw-r--r-- | arch/powerpc/include/asm/bug.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/powerpc/include/asm/bug.h b/arch/powerpc/include/asm/bug.h index 61a4736355c2..ef42adb44aa3 100644 --- a/arch/powerpc/include/asm/bug.h +++ b/arch/powerpc/include/asm/bug.h @@ -99,7 +99,8 @@ __label__ __label_warn_on; \ \ WARN_ENTRY("twi 31, 0, 0", BUGFLAG_WARNING | (flags), __label_warn_on); \ - unreachable(); \ + barrier_before_unreachable(); \ + __builtin_unreachable(); \ \ __label_warn_on: \ break; \ |