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Message-ID: <8c185fe0-cc43-1cd9-ea1d-0e0f34ad1828@linux.vnet.ibm.com>
Date: Mon, 29 Aug 2022 11:16:37 +0530
From: Sathvika Vasireddy <sv@...ux.vnet.ibm.com>
To: Christophe Leroy <christophe.leroy@...roup.eu>,
Sathvika Vasireddy <sv@...ux.ibm.com>,
"linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>
Cc: "jpoimboe@...hat.com" <jpoimboe@...hat.com>,
"peterz@...radead.org" <peterz@...radead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"aik@...abs.ru" <aik@...abs.ru>,
"mpe@...erman.id.au" <mpe@...erman.id.au>,
"mingo@...hat.com" <mingo@...hat.com>,
"rostedt@...dmis.org" <rostedt@...dmis.org>,
"mbenes@...e.cz" <mbenes@...e.cz>,
"npiggin@...il.com" <npiggin@...il.com>,
"chenzhongjin@...wei.com" <chenzhongjin@...wei.com>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"naveen.n.rao@...ux.vnet.ibm.com" <naveen.n.rao@...ux.vnet.ibm.com>
Subject: Re: [PATCH 01/16] powerpc: Replace unreachable() with it's builtin
variant in WARN_ON()
Hi Christophe,
On 26/08/22 15:48, Christophe Leroy wrote:
>
> Le 08/08/2022 à 13:48, Sathvika Vasireddy a écrit :
>> objtool is throwing *unannotated intra-function call*
>> warnings with a few instructions that are marked
>> unreachable. Replace unreachable() with __builtin_unreachable()
>> to fix these warnings, as the codegen remains same
>> with unreachable() and __builtin_unreachable().
>>
>> Signed-off-by: Sathvika Vasireddy <sv@...ux.ibm.com>
>> ---
>> arch/powerpc/include/asm/bug.h | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/include/asm/bug.h b/arch/powerpc/include/asm/bug.h
>> index 61a4736355c2..074be1a78c56 100644
>> --- a/arch/powerpc/include/asm/bug.h
>> +++ b/arch/powerpc/include/asm/bug.h
>> @@ -99,7 +99,7 @@
>> __label__ __label_warn_on; \
>> \
>> WARN_ENTRY("twi 31, 0, 0", BUGFLAG_WARNING | (flags), __label_warn_on); \
>> - unreachable(); \
>> + __builtin_unreachable(); \
> Should you add barrier_before_unreachable() before
> __builtin_unreachable() to avoid stack bombs ?
>
> See commit 173a3efd3edb ("bug.h: work around GCC PR82365 in BUG()")
Yes, adding barrier_before_unreachable() before __builtin_unreachable()
works around the build issues reported at
https://lkml.org/lkml/2022/8/25/418.
I'll post a v2 with this change.
Thanks for the suggestion!
- Sathvika
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