Re: [PATCH 5.15 v3 02/16] x86/speculation: Simplify and make CALL_NOSPEC consistent

[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: cfceff8526a426948b53445c02bcb98453c7330d

Status in newer kernel trees:
6.14.y | Present (different SHA1: 010c4a461c1d)
6.12.y | Present (different SHA1: ca16a0acacd7)
6.6.y | Present (different SHA1: ffe12f8aa62c)
6.1.y | Present (different SHA1: 7f6da764325a)

Note: The patch differs from the upstream commit:
---
1:  cfceff8526a42 ! 1:  cf7360bfe0353 x86/speculation: Simplify and make CALL_NOSPEC consistent
    @@ Metadata
      ## Commit message ##
         x86/speculation: Simplify and make CALL_NOSPEC consistent
     
    +    commit cfceff8526a426948b53445c02bcb98453c7330d upstream.
    +
         CALL_NOSPEC macro is used to generate Spectre-v2 mitigation friendly
         indirect branches. At compile time the macro defaults to indirect branch,
         and at runtime those can be patched to thunk based mitigations.
    @@ Commit message
         calls.
     
         Make CALL_NOSPEC consistent with the rest of the kernel, default to
    -    retpoline thunk at compile time when CONFIG_MITIGATION_RETPOLINE is
    +    retpoline thunk at compile time when CONFIG_RETPOLINE is
         enabled.
     
    +      [ 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>
         Cc: Andrew Cooper <andrew.cooper3@citrix.com
    @@ Commit message
         Link: https://lore.kernel.org/r/20250228-call-nospec-v3-1-96599fed0f33@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.
       */
     -# define CALL_NOSPEC						\
     -	ALTERNATIVE_2(						\
    @@ arch/x86/include/asm/nospec-branch.h: static inline void call_depth_return_thunk
     -	ANNOTATE_RETPOLINE_SAFE					\
     -	"call *%[thunk_target]\n",				\
     -	X86_FEATURE_RETPOLINE_LFENCE)
    -+#ifdef CONFIG_MITIGATION_RETPOLINE
    ++#ifdef CONFIG_RETPOLINE
     +#define CALL_NOSPEC	"call __x86_indirect_thunk_%V[thunk_target]\n"
     +#else
     +#define CALL_NOSPEC	"call *%[thunk_target]\n"
---

Results of testing on various branches:

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