Re: [PATCH 5.15 v3 04/16] x86/speculation: Remove the extra #ifdef around CALL_NOSPEC

[Sasha Levin <sashal@kernel.org>]

[ Sasha's backport helper bot ]

Hi,

✅ All tests passed successfully. No issues detected.
No action required from the submitter.

The upstream commit SHA1 provided is correct: c8c81458863ab686cda4fe1e603fccaae0f12460

Status in newer kernel trees:
6.14.y | Not found
6.12.y | Present (different SHA1: 02a1d6e26129)
6.6.y | Present (different SHA1: 8149e4bc5b6a)
6.1.y | Present (different SHA1: 84e06e948fc5)

Note: The patch differs from the upstream commit:
---
1:  c8c81458863ab ! 1:  31b985df4b5be x86/speculation: Remove the extra #ifdef around CALL_NOSPEC
    @@ Metadata
      ## Commit message ##
         x86/speculation: Remove the extra #ifdef around CALL_NOSPEC
     
    +    commit c8c81458863ab686cda4fe1e603fccaae0f12460 upstream.
    +
         Commit:
     
           010c4a461c1d ("x86/speculation: Simplify and make CALL_NOSPEC consistent")
     
    -    added an #ifdef CONFIG_MITIGATION_RETPOLINE around the CALL_NOSPEC definition.
    -    This is not required as this code is already under a larger #ifdef.
    +    added an #ifdef CONFIG_RETPOLINE around the CALL_NOSPEC definition. This is
    +    not required as this code is already under a larger #ifdef.
     
         Remove the extra #ifdef, no functional change.
     
         vmlinux size remains same before and after this change:
     
    -     CONFIG_MITIGATION_RETPOLINE=y:
    +     CONFIG_RETPOLINE=y:
               text       data        bss         dec        hex    filename
           25434752    7342290    2301212    35078254    217406e    vmlinux.before
           25434752    7342290    2301212    35078254    217406e    vmlinux.after
     
    -     # CONFIG_MITIGATION_RETPOLINE is not set:
    +     # CONFIG_RETPOLINE is not set:
               text       data        bss         dec        hex    filename
           22943094    6214994    1550152    30708240    1d49210    vmlinux.before
           22943094    6214994    1550152    30708240    1d49210    vmlinux.after
     
    +      [ pawan: s/CONFIG_MITIGATION_RETPOLINE/CONFIG_RETPOLINE/ ]
    +
         Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
         Signed-off-by: Ingo Molnar <mingo@kernel.org>
         Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
         Link: https://lore.kernel.org/r/20250320-call-nospec-extra-ifdef-v1-1-d9b084d24820@linux.intel.com
     
      ## arch/x86/include/asm/nospec-branch.h ##
    -@@ arch/x86/include/asm/nospec-branch.h: static inline void call_depth_return_thunk(void) {}
    +@@ arch/x86/include/asm/nospec-branch.h: extern retpoline_thunk_t __x86_indirect_thunk_array[];
       * Inline asm uses the %V modifier which is only in newer GCC
    -  * which is ensured when CONFIG_MITIGATION_RETPOLINE is defined.
    +  * which is ensured when CONFIG_RETPOLINE is defined.
       */
    --#ifdef CONFIG_MITIGATION_RETPOLINE
    +-#ifdef CONFIG_RETPOLINE
      #define CALL_NOSPEC	__CS_PREFIX("%V[thunk_target]")	\
      			"call __x86_indirect_thunk_%V[thunk_target]\n"
     -#else
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-6.1.y        |  Success    |  Success   |