Re: [PATCH v11 04/19] perf capstone: Determine architecture from e_machine

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] Compiling `perf` with Capstone < 4.0 will fail with undeclared identifiers `CS_ARCH_RISCV` and `CS_MODE_RISCV*`.
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commit 408e93bdddd7f0b1d7be6fe9fd0af6c070a4e302
Author: Ian Rogers <irogers@google.com>

perf capstone: Determine architecture from e_machine

Avoid the use of arch string that is imprecise and use the e_machine. Do
more e_machine to capstone machine translations adding MIPS and RISCV.
Remove unnecessary maybe_unused annotations.

> diff --git a/tools/perf/util/capstone.c b/tools/perf/util/capstone.c
> index 25cf6e15ec272..5ad537fea4360 100644
> --- a/tools/perf/util/capstone.c
> +++ b/tools/perf/util/capstone.c

[ ... ]

> +static bool e_machine_to_capstone(uint16_t e_machine, bool is64, bool is_big_endian,
> +				  enum cs_arch *arch, enum cs_mode *mode)
> +{
> +	*mode = is_big_endian ? CS_MODE_BIG_ENDIAN : CS_MODE_LITTLE_ENDIAN;
> +
> +	switch (e_machine) {

[ ... ]

> +	case EM_SPARCV9:
> +		*arch = CS_ARCH_SPARC;
> +		*mode |= CS_MODE_V9;
> +		return true;
> +	case EM_RISCV:
> +		*arch = CS_ARCH_RISCV;
> +		*mode |= (is64 ? CS_MODE_RISCV64 : CS_MODE_RISCV32) | CS_MODE_RISCVC;

[Severity: Low]
Will compiling perf with Capstone versions older than 4.0 fail here?

Capstone introduced RISC-V support in version 4.0. Because the build system
feature test for Capstone in tools/build/feature/test-libcapstone.c only
checks for x86 support, it seems it will successfully compile with Capstone
3.0 and define HAVE_LIBCAPSTONE_SUPPORT.

If HAVE_LIBCAPSTONE_SUPPORT is defined but the system has Capstone 3.0,
using CS_ARCH_RISCV directly will cause a hard compiler error.

Should there be an updated feature test for Capstone 4.0, or version guards
around the RISC-V specific code?

> +		return true;
> +	default:
> +		return false;
> +	}
> +}

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Sashiko AI review · https://sashiko.dev/#/patchset/20260602062452.2583619-1-irogers@google.com?part=4