[PATCH 1/8] ARM: ftrace: ensure that ADR take Thumb bit into account

[Nick Desaulniers]

On Tue, Jan 25, 2022 at 7:37 AM Ard Biesheuvel <ardb at kernel.org> wrote:
>
> Using ADR to take the address of 'ftrace_stub' via a local label
> produces an address that has the Thumb bit cleared, which means the
> subsequent comparison is guaranteed to fail. Instead, use the badr
> macro, which forces the Thumb bit to be set.
>
> Fixes: a3ba87a61499 ("ARM: 6316/1: ftrace: add Thumb-2 support")
> Signed-off-by: Ard Biesheuvel <ardb at kernel.org>

Reviewed-by: Nick Desaulniers <ndesaulniers at google.com>

> ---
>  arch/arm/kernel/entry-ftrace.S | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm/kernel/entry-ftrace.S b/arch/arm/kernel/entry-ftrace.S
> index a74289ebc803..f4886fb6e9ba 100644
> --- a/arch/arm/kernel/entry-ftrace.S
> +++ b/arch/arm/kernel/entry-ftrace.S
> @@ -40,7 +40,7 @@
>         mcount_enter
>         ldr     r0, =ftrace_trace_function
>         ldr     r2, [r0]
> -       adr     r0, .Lftrace_stub
> +       badr    r0, .Lftrace_stub
>         cmp     r0, r2
>         bne     1f
>
> --
> 2.30.2
>


-- 
Thanks,
~Nick Desaulniers