[PATCH] gas: fix silent failure of .cfi_sections .sframe on unsupported targets

Jens Remus jremus@linux.ibm.com
Fri Mar 13 13:23:04 GMT 2026 

On 3/13/2026 9:16 AM, Jens Remus wrote:
> On 3/12/2026 8:54 PM, Indu Bhagat wrote:
>> On 3/10/26 5:23 AM, Jens Remus wrote:
>>> On 3/10/2026 7:07 AM, Indu Bhagat via Binutils wrote:
>>>> [Resending as I messed up one of the email in the to list in the
>>>> previous attempt].
>>>>
>>>> Starting in Binutils 2.46, the .cfi_sections .sframe directive failed
>>>> silently when targeting unsupported architectures (e.g., i386 or even
>>>> x32 on x86_64).  This happened because the sframe_as_bad macro only
>>>> checked for the command-line flag --gsframe (GEN_SFRAME_ENABLED) and
>>>> ignored the explicit request via the assembler directive
>>>> (CFI_EMIT_sframe).
>>>>
>>>> This patch ensures that an error is emitted (for unsupported targets) if
>>>> SFrame is requested via either the command line or the .cfi_sections
>>>> directive, while maintaining silence for 'opportunistic' sframe
>>>> generation (GEN_SFRAME_CONFIG_ENABLED).
>>>>
>>>> Add two testcases:
>>>>    - cfi-sframe-x86_64-err-1.d: usage of --32 with .cfi_sections .sframe,
>>>>    - cfi-sframe-x86_64-err-2.d: usage of --gsframe --32 without
>>>>      .cfi_sections .sframe
>>>> GAS is expected to error out in both the cases.
>>>>
>>>> This fixes PR gas/33962 - .cfi_sections directive with .sframe on
>>>> unsupported targets does not error.
>>>>
>>>> gas/
>>>>     PR gas/33962
>>>>     * dw2gencfi.c (dot_cfi_sections): Ensure as_bad is called if
>>>>     SFrame was explicitly requested via directive.
>>>>     * gen-sframe.h: Remove sframe_as_bad macro.
>>>> gas/testsuite/
>>>>     PR gas/33962
>>>>     * gas/cfi-sframe/cfi-sframe-x86_64-err-1.s: New test.
>>>>     * gas/cfi-sframe/cfi-sframe-x86_64-err-1.d: New test.
>>>>     * gas/cfi-sframe/cfi-sframe-x86_64-err-2.s: New test.
>>>>     * gas/cfi-sframe/cfi-sframe-x86_64-err-1.d: New test.
>>>>     * gas/cfi-sframe/cfi-sframe.exp: Run the new tests.
>>>
>>> Thank you for fixing this issue!
>>>
>>>
>>>> diff --git a/gas/dw2gencfi.c b/gas/dw2gencfi.c
>>>
>>>> @@ -2620,9 +2620,18 @@ cfi_finish (void)
>>>>       }
>>>>         else
>>>>   #endif
>>>> -    /* Avoid erroring with DEFAULT_SFRAME for non-default options, like
>>>> -       -32 on x86_64.  */
>>>> -    sframe_as_bad ("%s", _(".sframe not supported for target"));
>>>> +    /* Issue an error for unsupported targets, like --32 on x86_64.  Avoid
>>>> +       erroring when default-enabled at configure-time though, because we
>>>> +       interpret default-enabled as "opportunistic SFrames".  Users don't
>>>> +       want to be bothered by something preventing emission of SFrames in
>>>> +       such a case.  */
>>>> +    {
>>>> +      if (flag_gen_sframe == GEN_SFRAME_ENABLED
>>>
>>> This issues an error for --gsframe[-N].
>>>
>>
>> Yes. Because command line takes precedence.
>>
>>>> +          || ((all_cfi_sections & CFI_EMIT_sframe) != 0
>>>> +          && flag_gen_sframe != GEN_SFRAME_DISABLED
>>>> +          && flag_gen_sframe != GEN_SFRAME_CONFIG_ENABLED))
>>>
>>> IIUC this issues an error for .cfi_sections .sframe, but only if not
>>> --gsframe=no, which takes precedence, and not 'opportunistic' SFrame
>>> generation (GEN_SFRAME_CONFIG_ENABLED).
>>>
>>
>> Correct.
>>
>>> Why should .cfi_sections .sframe be ignored when used with
>>> 'opportunistic' SFrame generation (GEN_SFRAME_CONFIG_ENABLED)?
>>>
>>
>> Umm, .cfi_sections .sframe is not being ignored with
>> GEN_SFRAME_CONFIG_ENABLED, its only that the error is silenced when
>> this occurs for unsupported target.
> 
> Sorry, my wording was odd.  I meant: Why is an error for .cfi_sections
> .sframe being silenced with GEN_SFRAME_CONFIG_ENABLED?
> 
>> I think you meant to ask why silence that error:
>> 'Opportunistic' SFrame is for the use case of distro wide builds.  If
>> there is user code that builds with --32 or --x32 (in case x86_64),
>> and gas is built with --enable-default-sframe, there will be errors of
>> unsupported target.  These are considered noise in this setup, and
>> hence the desire to silence them.
> 
> I understand and completely agree that if gas is built with
> --enable-default-sframe it should silence any SFrame related warnings/
> errors, that result from the 'opportunistic' SFrame generation
> (GEN_SFRAME_CONFIG_ENABLED).  That is whenever SFrame is generated
> solely because of that configure option.
> 
> My point is that if gas option --gsframe[-3] is specified or
> .cfi_sections .sframe is coded, then SFrame is generated because the
> user explicitly requested so and then it should not matter whether the
> assembler is built with 'opportunistic' SFrame generation
> (GEN_SFRAME_CONFIG_ENABLED) whether issue an error.
> 
>> Does that make sense ?
> 
> No.  Whenever explicitly requesting SFrame generation and this is not
> supported an error/warning should be the result.  The only exception
> should be 'opportunistic' SFrame generation (GEN_SFRAME_CONFIG_ENABLED)
> from my POV (but not if it is explicitly requested).

Suppressing the ".sframe not supported for target" error in case of
.cfi_sections .sframe if gas is configured with 'opportunistic' SFrame
generation (--enable-default-sframe / GEN_SFRAME_CONFIG_ENABLED) can't
be right, as that would suppress an error that would otherwise be
emitted.  With your patch applied and gas built for x86-64:

gas with --disable-default-sframe (default) errors out, which is
expected:

$ printf ".cfi_sections .sframe\n.cfi_startproc\n.cfi_endproc\n" | as --32 ; echo $?
Assembler messages:
{standard input}: Error: .sframe not supported for target
1

gas with --enable-default-sframe suppresses this error, which is
unexpected as 'opportunistic' SFrame generation should not suppress
errors that would otherwise be issued:

$ printf ".cfi_sections .sframe\n.cfi_startproc\n.cfi_endproc\n" | as --32 ; echo $?
0

>>>> +        as_bad (_(".sframe not supported for target"));
>>>> +    }
>>>>       }
>>>>       if ((all_cfi_sections & CFI_EMIT_debug_frame) != 0)
>>>
>>>> diff --git a/gas/gen-sframe.h b/gas/gen-sframe.h
>>>
>>>> @@ -21,16 +21,6 @@
>>>>   #ifndef GENSFRAME_H
>>>>   #define GENSFRAME_H
>>>>   -/* Errors shouldn't be emitted either if SFrames are default-enabled, as
>>>> -   we interpret default-enabled as "opportunistic SFrames".  Users don't
>>>> -   want to be bothered by something preventing emission of SFrames in
>>>> -   such a case.  */
>>>> -#define sframe_as_bad(format, ...) \
>>>> -  do {                           \
>>>> -    if (flag_gen_sframe == GEN_SFRAME_ENABLED) \
>>>> -      as_bad (format, __VA_ARGS__);            \
>>>> -  } while (0)
>>>> -
>>>>   /* The entity is not tracked.  */
>>>>   #define SFRAME_FRE_ELEM_LOC_NONE    0
>>>>   /* The location of the tracked entity is based on a register.  May or may not
> Thanks and regards,
> Jens

Regards,
Jens
-- 
Jens Remus
Linux on Z Development (D3303)
jremus@de.ibm.com / jremus@linux.ibm.com

IBM Deutschland Research & Development GmbH; Vorsitzender des Aufsichtsrats: Wolfgang Wendt; Geschäftsführung: David Faller; Sitz der Gesellschaft: Ehningen; Registergericht: Amtsgericht Stuttgart, HRB 243294
IBM Data Privacy Statement: https://www.ibm.com/privacy/

More information about the Binutils mailing list