Re: [PATCH v5 13/24] x86/vdso: Enable the vdsocheck tool

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] The AllowedRelocations list for EM_386 is missing bindings::R_386_PLT32, which can cause valid 32-bit VDSO builds to fail.
--

commit d74c76b651e13f383612ff619529355d8cc73129
Author: Thomas Weißschuh <thomas.weissschuh@linutronix.de>

x86/vdso: Enable the vdsocheck tool

The vdsocheck tool validates the object files and final .so library
and detects incompatible relocations. This commit wires it up for the
x86 architecture.

> diff --git a/lib/vdso/check/vdsocheck.rs b/lib/vdso/check/vdsocheck.rs
> index f4c0730bc976d..1174d896a68b9 100644
> --- a/lib/vdso/check/vdsocheck.rs
> +++ b/lib/vdso/check/vdsocheck.rs
> @@ -34,6 +34,20 @@ fn is_ignored_section(&self, section: &elf::Section<'_>) -> bool {
>  
>  fn allowed_relocations_for_machine(machine: u16) -> Option<AllowedRelocations<'static>> {
>      match machine as u32 {
> +        bindings::EM_386 => AllowedRelocations {
> +            in_object_file: &[
> +                bindings::R_386_PC32,
> +                bindings::R_386_GOTOFF,
> +                bindings::R_386_GOTPC,
> +            ],

[Severity: Low]
Is the AllowedRelocations list for EM_386 missing bindings::R_386_PLT32 here?

The vdsocheck tool validates object files during the kernel build. If a
compiler generates R_386_PLT32 relocations for local function calls in PIC
code (which is common in many GCC versions), the build will fail because
this relocation is not in the allowlist.

For 64-bit VDSO (EM_X86_64), bindings::R_X86_64_PLT32 is explicitly allowed
just below. Additionally, the kernel's relocs tool treats R_386_PLT32 as
equivalent to R_386_PC32 because it is a standard PC-relative relocation
emitted by GCC for function calls.

Could omitting it from vdsocheck cause spurious build failures on valid
32-bit C code?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260908-vdso-absolute-reloc-v5-0-3a93791af1cf@linutronix.de?part=13