Re: [PATCH] perf riscv: Add perf_regs_load and enable the dwarf unwind test

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [Medium] Unchecked dereference of `regs` when `perf_sample__user_regs()` fails to allocate.
- [Low] Missing explicit inclusion of <stdlib.h> for standard memory allocation functions, violating musl compatibility guidelines.
--

commit d76f4341bf568ee75224d45323c5c8e122fd3e66
Author: Chen Pei <cp0613@linux.alibaba.com>
Subject: perf riscv: Add perf_regs_load and enable the dwarf unwind test

This commit adds perf_regs_load and an architecture-specific unwind sample
helper for riscv. It also wires riscv into the dwarf unwind test gates so 
that unwinding tests can be executed on riscv architectures.

> diff --git a/tools/perf/arch/riscv/tests/dwarf-unwind.c b/tools/perf/arch/riscv/tests/dwarf-unwind.c
> new file mode 100644
> index 0000000000000..e981b21f918d2
> --- /dev/null
> +++ b/tools/perf/arch/riscv/tests/dwarf-unwind.c
> @@ -0,0 +1,64 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <string.h>
> +#include "perf_regs.h"
> +#include "thread.h"
> +#include "map.h"
> +#include "maps.h"
> +#include "event.h"
> +#include "debug.h"
> +#include "tests/tests.h"
> +
> +#define STACK_SIZE 8192
> +
> +static int sample_ustack(struct perf_sample *sample,
> +		struct thread *thread, u64 *regs)
> +{
> +	struct stack_dump *stack = &sample->user_stack;
> +	struct map *map;
> +	unsigned long sp;
> +	u64 stack_size, *buf;
> +
> +	buf = malloc(STACK_SIZE);

[Severity: Low]
Does this file need to explicitly include <stdlib.h>? Since musl libc
enforces strict POSIX header inclusions, missing the declaration for
malloc could lead to a build failure regression on musl libc systems.

[ ... ]

> +int test__arch_unwind_sample(struct perf_sample *sample,
> +		struct thread *thread)
> +{
> +	struct regs_dump *regs = perf_sample__user_regs(sample);
> +	u64 *buf;
> +
> +	buf = calloc(PERF_REGS_MAX, sizeof(u64));

[Severity: Low]
Similarly, does this calloc require an explicit include of <stdlib.h> to
ensure compatibility with musl libc systems?

> +	if (!buf) {
> +		pr_debug("failed to allocate sample uregs data\n");
> +		return -1;
> +	}
> +
> +	perf_regs_load(buf);
> +	regs->abi  = PERF_SAMPLE_REGS_ABI;

[Severity: Medium]
Can perf_sample__user_regs() return NULL here?

If memory allocation fails within perf_sample__user_regs() (which uses 
zalloc), the returned NULL pointer would be unconditionally dereferenced 
on this line when setting regs->abi.

Could this regression cause a segmentation fault in the perf test tool 
under memory constraints?

> +	regs->regs = buf;
> +	regs->mask = PERF_REGS_MASK;
> +
> +	return sample_ustack(sample, thread, buf);
> +}

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260914124145.1257-1-cp0613@linux.alibaba.com?part=1