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SubjectRe: [PATCH 1/1 fyi] tools headers x86 cpufeatures: Sync with the kernel sources to pick TDX, Zen, APIC MSR fence changes
On Thu, Apr 25, 2024 at 06:19:07PM -0300, Arnaldo Carvalho de Melo wrote:
> tldr; Just FYI, I'm carrying this on the perf tools tree.

Sorry about the subject line, reused from a previous sync, will fix it
up.

- Arnaldo

> Full explanation:
>
> There used to be no copies, with tools/ code using kernel headers
> directly. From time to time tools/perf/ broke due to legitimate kernel
> hacking. At some point Linus complained about such direct usage. Then we
> adopted the current model.
>
> The way these headers are used in perf are not restricted to just
> including them to compile something.
>
> There are sometimes used in scripts that convert defines into string
> tables, etc, so some change may break one of these scripts, or new MSRs
> may use some different #define pattern, etc.
>
> E.g.:
>
> $ ls -1 tools/perf/trace/beauty/*.sh | head -5
> tools/perf/trace/beauty/arch_errno_names.sh
> tools/perf/trace/beauty/drm_ioctl.sh
> tools/perf/trace/beauty/fadvise.sh
> tools/perf/trace/beauty/fsconfig.sh
> tools/perf/trace/beauty/fsmount.sh
> $
> $ tools/perf/trace/beauty/fadvise.sh
> static const char *fadvise_advices[] = {
> [0] = "NORMAL",
> [1] = "RANDOM",
> [2] = "SEQUENTIAL",
> [3] = "WILLNEED",
> [4] = "DONTNEED",
> [5] = "NOREUSE",
> };
> $
>
> The tools/perf/check-headers.sh script, part of the tools/ build
> process, points out changes in the original files.
>
> So its important not to touch the copies in tools/ when doing changes in
> the original kernel headers, that will be done later, when
> check-headers.sh inform about the change to the perf tools hackers.
>
> To pick the changes from:
>
> 95a6ccbdc7199a14 ("x86/bhi: Mitigate KVM by default")
> ec9404e40e8f3642 ("x86/bhi: Add BHI mitigation knob")
> be482ff9500999f5 ("x86/bhi: Enumerate Branch History Injection (BHI) bug")
> 0f4a837615ff925b ("x86/bhi: Define SPEC_CTRL_BHI_DIS_S")
> 7390db8aea0d64e9 ("x86/bhi: Add support for clearing branch history at syscall entry")
>
> This causes these perf files to be rebuilt and brings some X86_FEATURE
> that will be used when updating the copies of
> tools/arch/x86/lib/mem{cpy,set}_64.S with the kernel sources:
>
> CC /tmp/build/perf/bench/mem-memcpy-x86-64-asm.o
> CC /tmp/build/perf/bench/mem-memset-x86-64-asm.o
>
> And addresses this perf build warning:
>
> Warning: Kernel ABI header differences:
> diff -u tools/arch/x86/include/asm/cpufeatures.h arch/x86/include/asm/cpufeatures.h
>
> Cc: Adrian Hunter <adrian.hunter@intel.com>
> Cc: Daniel Sneddon <daniel.sneddon@linux.intel.com>
> Cc: Ian Rogers <irogers@google.com>
> Cc: Jiri Olsa <jolsa@kernel.org>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> ---
> tools/arch/x86/include/asm/cpufeatures.h | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/tools/arch/x86/include/asm/cpufeatures.h b/tools/arch/x86/include/asm/cpufeatures.h
> index a38f8f9ba6572912..3c7434329661c66e 100644
> --- a/tools/arch/x86/include/asm/cpufeatures.h
> +++ b/tools/arch/x86/include/asm/cpufeatures.h
> @@ -461,11 +461,15 @@
>
> /*
> * Extended auxiliary flags: Linux defined - for features scattered in various
> - * CPUID levels like 0x80000022, etc.
> + * CPUID levels like 0x80000022, etc and Linux defined features.
> *
> * Reuse free bits when adding new feature flags!
> */
> #define X86_FEATURE_AMD_LBR_PMC_FREEZE (21*32+ 0) /* AMD LBR and PMC Freeze */
> +#define X86_FEATURE_CLEAR_BHB_LOOP (21*32+ 1) /* "" Clear branch history at syscall entry using SW loop */
> +#define X86_FEATURE_BHI_CTRL (21*32+ 2) /* "" BHI_DIS_S HW control available */
> +#define X86_FEATURE_CLEAR_BHB_HW (21*32+ 3) /* "" BHI_DIS_S HW control enabled */
> +#define X86_FEATURE_CLEAR_BHB_LOOP_ON_VMEXIT (21*32+ 4) /* "" Clear branch history at vmexit using SW loop */
>
> /*
> * BUG word(s)
> @@ -515,4 +519,5 @@
> #define X86_BUG_SRSO X86_BUG(1*32 + 0) /* AMD SRSO bug */
> #define X86_BUG_DIV0 X86_BUG(1*32 + 1) /* AMD DIV0 speculation bug */
> #define X86_BUG_RFDS X86_BUG(1*32 + 2) /* CPU is vulnerable to Register File Data Sampling */
> +#define X86_BUG_BHI X86_BUG(1*32 + 3) /* CPU is affected by Branch History Injection */
> #endif /* _ASM_X86_CPUFEATURES_H */
> --
> 2.44.0
>

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