Re: [PATCH 02/14] ARM: patch: fix BE32 compilation

[Linus Walleij]

On Tue, Sep 28, 2021 at 5:42 PM Arnd Bergmann <arnd@xxxxxxxxxx> wrote:

> From: Arnd Bergmann <arnd@xxxxxxxx>
>
> On BE32 kernels, the __opcode_to_mem_thumb32() interface is intentionally
> not defined, but it is referenced whenever runtime patching is enabled
> for the kernel, which may be for ftrace, jump label, kprobes or kgdb:
>
> arch/arm/kernel/patch.c: In function '__patch_text_real':
> arch/arm/kernel/patch.c:94:32: error: implicit declaration of function '__opcode_to_mem_thumb32' [-Werror=implicit-function-declaration]
>    94 |                         insn = __opcode_to_mem_thumb32(insn);
>       |                                ^~~~~~~~~~~~~~~~~~~~~~~
>
> Since BE32 kernels never run Thumb2 code, we never end up using the
> result of this call, so providing an extern declaration without
> a definition makes it build correctly.
>
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>

Looks good to me!
Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>

Yours,
Linus Walleij