From: Michael Ellerman <mpe@ellerman.id.au>
To: Josh Poimboeuf <jpoimboe@kernel.org>, linux-kernel@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Heiko Carstens <hca@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Alexander Gordeev <agordeev@linux.ibm.com>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Sven Schnelle <svens@linux.ibm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
linux-arm-kernel@lists.infradead.org,
linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org,
linux-s390@vger.kernel.org
Subject: Re: [PATCH] bug: Use normal relative pointers in 'struct bug_entry'
Date: Mon, 09 May 2022 22:31:14 +1000 [thread overview]
Message-ID: <871qx2ubu5.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <afddb4548e93f6458ec1d9ec185a834c348eda33.1651798983.git.jpoimboe@kernel.org>
Josh Poimboeuf <jpoimboe@kernel.org> writes:
> With CONFIG_GENERIC_BUG_RELATIVE_POINTERS, the addr/file relative
> pointers are calculated weirdly: based on the beginning of the bug_entry
> struct address, rather than their respective pointer addresses.
>
> Make the relative pointers less surprising to both humans and tools by
> calculating them the normal way.
>
> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
> ---
...
> diff --git a/arch/powerpc/include/asm/bug.h b/arch/powerpc/include/asm/bug.h
> index ecbae1832de3..76252576d889 100644
> --- a/arch/powerpc/include/asm/bug.h
> +++ b/arch/powerpc/include/asm/bug.h
> @@ -13,7 +13,8 @@
> #ifdef CONFIG_DEBUG_BUGVERBOSE
> .macro __EMIT_BUG_ENTRY addr,file,line,flags
> .section __bug_table,"aw"
> -5001: .4byte \addr - 5001b, 5002f - 5001b
> +5001: .4byte \addr - .
> + .4byte 5002f - .
> .short \line, \flags
> .org 5001b+BUG_ENTRY_SIZE
> .previous
> @@ -24,7 +25,7 @@
> #else
> .macro __EMIT_BUG_ENTRY addr,file,line,flags
> .section __bug_table,"aw"
> -5001: .4byte \addr - 5001b
> +5001: .4byte \addr - .
> .short \flags
> .org 5001b+BUG_ENTRY_SIZE
> .previous
Embarrassingly, we have another copy of the logic, used in the C
versions, they need updating too:
diff --git a/arch/powerpc/include/asm/bug.h b/arch/powerpc/include/asm/bug.h
index ecbae1832de3..3fde35fd67f8 100644
--- a/arch/powerpc/include/asm/bug.h
+++ b/arch/powerpc/include/asm/bug.h
@@ -49,14 +49,14 @@
#ifdef CONFIG_DEBUG_BUGVERBOSE
#define _EMIT_BUG_ENTRY \
".section __bug_table,\"aw\"\n" \
- "2:\t.4byte 1b - 2b, %0 - 2b\n" \
+ "2:\t.4byte 1b - ., %0 - .\n" \
"\t.short %1, %2\n" \
".org 2b+%3\n" \
".previous\n"
#else
#define _EMIT_BUG_ENTRY \
".section __bug_table,\"aw\"\n" \
- "2:\t.4byte 1b - 2b\n" \
+ "2:\t.4byte 1b - .\n" \
"\t.short %2\n" \
".org 2b+%3\n" \
".previous\n"
With that added it seems to be working correctly for me.
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
cheers
next prev parent reply other threads:[~2022-05-09 12:31 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-06 1:09 [PATCH] bug: Use normal relative pointers in 'struct bug_entry' Josh Poimboeuf
2022-05-06 7:45 ` Peter Zijlstra
2022-05-06 9:17 ` Sven Schnelle
2022-05-06 10:40 ` Mark Rutland
2022-05-09 12:31 ` Michael Ellerman [this message]
2022-05-09 19:20 ` Josh Poimboeuf
2022-05-10 10:38 ` Catalin Marinas
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