linux-kernel - Re: [PATCH 17/20] perf tools: Support to show SSP register

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Message-ID: <CAP-5=fV-+3dU1CtUAYazv5L6VfNwDxv1C9Q=tQXzve9nqpaqrw@mail.gmail.com>
Date: Thu, 23 Jan 2025 08:15:28 -0800
From: Ian Rogers <irogers@...gle.com>
To: Dapeng Mi <dapeng1.mi@...ux.intel.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Adrian Hunter <adrian.hunter@...el.com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Kan Liang <kan.liang@...ux.intel.com>, 
	Andi Kleen <ak@...ux.intel.com>, Eranian Stephane <eranian@...gle.com>, linux-kernel@...r.kernel.org, 
	linux-perf-users@...r.kernel.org, Dapeng Mi <dapeng1.mi@...el.com>
Subject: Re: [PATCH 17/20] perf tools: Support to show SSP register

On Wed, Jan 22, 2025 at 10:21 PM Dapeng Mi <dapeng1.mi@...ux.intel.com> wrote:
>
> Add SSP register support.
>
> Signed-off-by: Dapeng Mi <dapeng1.mi@...ux.intel.com>
> ---
>  tools/arch/x86/include/uapi/asm/perf_regs.h    | 4 +++-
>  tools/perf/arch/x86/util/perf_regs.c           | 2 ++
>  tools/perf/util/intel-pt.c                     | 2 +-
>  tools/perf/util/perf-regs-arch/perf_regs_x86.c | 2 ++
>  4 files changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/tools/arch/x86/include/uapi/asm/perf_regs.h b/tools/arch/x86/include/uapi/asm/perf_regs.h
> index 7c9d2bb3833b..158e353070c3 100644
> --- a/tools/arch/x86/include/uapi/asm/perf_regs.h
> +++ b/tools/arch/x86/include/uapi/asm/perf_regs.h
> @@ -27,9 +27,11 @@ enum perf_event_x86_regs {
>         PERF_REG_X86_R13,
>         PERF_REG_X86_R14,
>         PERF_REG_X86_R15,
> +       PERF_REG_X86_SSP,

nit: Would it be worth a comment here? SSP may not be apparent to
everyone. Perhaps something like:
```
/* Shadow stack pointer (SSP) present on Clearwater Forest and newer models. */
```
>         /* These are the limits for the GPRs. */
>         PERF_REG_X86_32_MAX = PERF_REG_X86_GS + 1,
> -       PERF_REG_X86_64_MAX = PERF_REG_X86_R15 + 1,
> +       PERF_REG_X86_64_MAX = PERF_REG_X86_SSP + 1,
> +       PERF_REG_INTEL_PT_MAX = PERF_REG_X86_R15 + 1,

nit: It's a little peculiar to me the "+1" here - but that's
pre-existing. Perhaps comments above here too:
```
/* The MAX_REG_X86_64 used generally, for PEBS, etc. */
PERF_REG_X86_64_MAX = PERF_REG_X86_SSP + 1,
/* The MAX_REG_INTEL_PT ignores the SSP register. */
PERF_REG_INTEL_PT_MAX = PERF_REG_X86_R15 + 1,
```
Otherwise:
Reviewed-by: Ian Rogers <irogers@...gle.com>

Thanks,
Ian

>
>         /* These all need two bits set because they are 128bit */
>         PERF_REG_X86_XMM0  = 32,
> diff --git a/tools/perf/arch/x86/util/perf_regs.c b/tools/perf/arch/x86/util/perf_regs.c
> index 12fd93f04802..9f492568f3b4 100644
> --- a/tools/perf/arch/x86/util/perf_regs.c
> +++ b/tools/perf/arch/x86/util/perf_regs.c
> @@ -36,6 +36,8 @@ static const struct sample_reg sample_reg_masks[] = {
>         SMPL_REG(R14, PERF_REG_X86_R14),
>         SMPL_REG(R15, PERF_REG_X86_R15),
>  #endif
> +       SMPL_REG(SSP, PERF_REG_X86_SSP),
> +
>         SMPL_REG2(XMM0, PERF_REG_X86_XMM0),
>         SMPL_REG2(XMM1, PERF_REG_X86_XMM1),
>         SMPL_REG2(XMM2, PERF_REG_X86_XMM2),
> diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
> index 30be6dfe09eb..86196275c1e7 100644
> --- a/tools/perf/util/intel-pt.c
> +++ b/tools/perf/util/intel-pt.c
> @@ -2139,7 +2139,7 @@ static u64 *intel_pt_add_gp_regs(struct regs_dump *intr_regs, u64 *pos,
>         u32 bit;
>         int i;
>
> -       for (i = 0, bit = 1; i < PERF_REG_X86_64_MAX; i++, bit <<= 1) {
> +       for (i = 0, bit = 1; i < PERF_REG_INTEL_PT_MAX; i++, bit <<= 1) {
>                 /* Get the PEBS gp_regs array index */
>                 int n = pebs_gp_regs[i] - 1;
>
> diff --git a/tools/perf/util/perf-regs-arch/perf_regs_x86.c b/tools/perf/util/perf-regs-arch/perf_regs_x86.c
> index 708954a9d35d..9a909f02bc04 100644
> --- a/tools/perf/util/perf-regs-arch/perf_regs_x86.c
> +++ b/tools/perf/util/perf-regs-arch/perf_regs_x86.c
> @@ -54,6 +54,8 @@ const char *__perf_reg_name_x86(int id)
>                 return "R14";
>         case PERF_REG_X86_R15:
>                 return "R15";
> +       case PERF_REG_X86_SSP:
> +               return "ssp";
>
>  #define XMM(x) \
>         case PERF_REG_X86_XMM ## x:     \
> --
> 2.40.1
>