linux-kernel - Re: [PATCH] s390: Add '-std=gnu11' to decompressor and purgatory CFLAGS

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250123082918.7753-A-hca@linux.ibm.com>
Date: Thu, 23 Jan 2025 09:29:18 +0100
From: Heiko Carstens <hca@...ux.ibm.com>
To: Nathan Chancellor <nathan@...nel.org>
Cc: Vasily Gorbik <gor@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Sven Schnelle <svens@...ux.ibm.com>, linux-s390@...r.kernel.org,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] s390: Add '-std=gnu11' to decompressor and purgatory
 CFLAGS

On Wed, Jan 22, 2025 at 07:54:27PM -0700, Nathan Chancellor wrote:
> GCC changed the default C standard dialect from gnu17 to gnu23,
> which should not have impacted the kernel because it explicitly requests
> the gnu11 standard in the main Makefile. However, there are certain
> places in the s390 code that use their own CFLAGS without a '-std='
> value, which break with this dialect change because of the kernel's own
> definitions of bool, false, and true conflicting with the C23 reserved
> keywords.
> 
>   include/linux/stddef.h:11:9: error: cannot use keyword 'false' as enumeration constant
>      11 |         false   = 0,
>         |         ^~~~~
>   include/linux/stddef.h:11:9: note: 'false' is a keyword with '-std=c23' onwards
>   include/linux/types.h:35:33: error: 'bool' cannot be defined via 'typedef'
>      35 | typedef _Bool                   bool;
>         |                                 ^~~~
>   include/linux/types.h:35:33: note: 'bool' is a keyword with '-std=c23' onwards
> 
> Add '-std=gnu11' to the decompressor and purgatory CFLAGS to eliminate
> these errors and make the C standard version of these areas match the
> rest of the kernel.
> 
> Cc: stable@...r.kernel.org
> Signed-off-by: Nathan Chancellor <nathan@...nel.org>
> ---

Thanks!
Tested-by: Heiko Carstens <hca@...ux.ibm.com>

Alexander, can you pick this up, please?

> I only see one other error in various files with a recent GCC 15.0.1
> snapshot, which I can eliminate by dropping the version part of the
> condition for CONFIG_GCC_ASM_FLAG_OUTPUT_BROKEN. Is this a regression of
> the fix for the problem of GCC 14.2.0 or is something else doing on
> here?
> 
>   arch/s390/include/asm/bitops.h: Assembler messages:
>   arch/s390/include/asm/bitops.h:60: Error: operand 1: syntax error; missing ')' after base register
>   arch/s390/include/asm/bitops.h:60: Error: operand 2: syntax error; ')' not allowed here
>   arch/s390/include/asm/bitops.h:60: Error: junk at end of line: `,4'

That is I bug I recently introduced.
The patch below fixes that. Thanks for reporting!

>From 2f58027ec1302714bb4d728b08dc5c88498d18b1 Mon Sep 17 00:00:00 2001
From: Heiko Carstens <hca@...ux.ibm.com>
Date: Thu, 23 Jan 2025 09:14:15 +0100
Subject: [PATCH] s390/bitops: Use correct constraint for arch_test_bit()
 inline assembly

Use the "Q" instead of "R" constraint to correctly reflect the instruction
format of the tm instruction: the first operand is a memory reference
without index register and short displacement. The "R" constraint indicates
a memory reference with index register instead.

This may lead to compile errors like:

  arch/s390/include/asm/bitops.h: Assembler messages:
  arch/s390/include/asm/bitops.h:60: Error: operand 1: syntax error; missing ')' after base register
  arch/s390/include/asm/bitops.h:60: Error: operand 2: syntax error; ')' not allowed here
  arch/s390/include/asm/bitops.h:60: Error: junk at end of line: `,4'

Reported-by: Nathan Chancellor <nathan@...nel.org>
Closes: https://lore.kernel.org/r/20250122-s390-fix-std-for-gcc-15-v1-1-8b00cadee083@kernel.org
Fixes: b2bc1b1a77c0 ("s390/bitops: Provide optimized arch_test_bit()")
Signed-off-by: Heiko Carstens <hca@...ux.ibm.com>
---
 arch/s390/include/asm/bitops.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/s390/include/asm/bitops.h b/arch/s390/include/asm/bitops.h
index 15aa64e3020e..d5125296ade2 100644
--- a/arch/s390/include/asm/bitops.h
+++ b/arch/s390/include/asm/bitops.h
@@ -60,7 +60,7 @@ static __always_inline bool arch_test_bit(unsigned long nr, const volatile unsig
 		asm volatile(
 			"	tm	%[addr],%[mask]\n"
 			: "=@cc" (cc)
-			: [addr] "R" (*addr), [mask] "I" (mask)
+			: [addr] "Q" (*addr), [mask] "I" (mask)
 			);
 		return cc == 3;
 	}
-- 
2.45.2