Re: [PATCH v4 25/39] unwind_user/sframe: Show file name in debug output

Jens Remus
2025-01-30T16:18:01Z

On 22.01.2025 03:31, Josh Poimboeuf wrote:
> When debugging sframe issues, the error messages aren't all that helpful
> without knowing what file a corresponding .sframe section belongs to.
> Prefix debug output strings with the file name.
>
> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

> diff --git a/kernel/unwind/sframe_debug.h b/kernel/unwind/sframe_debug.h

> +static inline void dbg_init(struct sframe_section *sec)
> +{
> + struct mm_struct *mm = current->mm;
> + struct vm_area_struct *vma;
> +
> + guard(mmap_read_lock)(mm);
> + vma = vma_lookup(mm, sec->sframe_start);
> + if (!vma)
> + sec->filename = kstrdup("(vma gone???)", GFP_KERNEL);
> + else if (vma->vm_file)
> + sec->filename = kstrdup_quotable_file(vma->vm_file, GFP_KERNEL);
> + else if (!vma->vm_mm)

This condition does not appear to work for vdso on s390. The following
does:

else if (in_range(sec->sframe_start, current->mm->context.vdso_base, vdso_text_size()))

> + sec->filename = kstrdup("(vdso)", GFP_KERNEL);
> + else
> + sec->filename = kstrdup("(anonymous)", GFP_KERNEL);
> +}

Regards,
Jens
--
Jens Remus
Linux on Z Development (D3303)
+49-7031-16-1128 Office
jremus@de.ibm.com

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