[PATCHv4 1/7] arm64: Treat handle_arch_irq as a function pointer

[Ard Biesheuvel]

On 27 October 2014 21:12, Laura Abbott <lauraa at codeaurora.org> wrote:
> handle_arch_irq isn't actually text, it's just a function pointer.
> It doesn't need to be stored in the text section and doing so
> causes problems if we ever want to make the kernel text read only.
> Declare handle_arch_irq as a proper function pointer stored in
> the data section.
>
> Reviewed-by: Kees Cook <keescook at chromium.org>
> Signed-off-by: Laura Abbott <lauraa at codeaurora.org>

Acked-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>

> ---
> v4: style comments
> ---
>  arch/arm64/include/asm/irq.h | 1 -
>  arch/arm64/kernel/entry.S    | 6 ++----
>  arch/arm64/kernel/irq.c      | 2 ++
>  3 files changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm64/include/asm/irq.h b/arch/arm64/include/asm/irq.h
> index e1f7ecd..1eebf5b 100644
> --- a/arch/arm64/include/asm/irq.h
> +++ b/arch/arm64/include/asm/irq.h
> @@ -3,7 +3,6 @@
>
>  #include <asm-generic/irq.h>
>
> -extern void (*handle_arch_irq)(struct pt_regs *);
>  extern void migrate_irqs(void);
>  extern void set_handle_irq(void (*handle_irq)(struct pt_regs *));
>
> diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
> index 726b910..ee27f39 100644
> --- a/arch/arm64/kernel/entry.S
> +++ b/arch/arm64/kernel/entry.S
> @@ -168,7 +168,8 @@ tsk .req    x28             // current thread_info
>   * Interrupt handling.
>   */
>         .macro  irq_handler
> -       ldr     x1, handle_arch_irq
> +       adrp    x1, handle_arch_irq
> +       ldr     x1, [x1, #:lo12:handle_arch_irq]
>         mov     x0, sp
>         blr     x1
>         .endm
> @@ -695,6 +696,3 @@ ENTRY(sys_rt_sigreturn_wrapper)
>         mov     x0, sp
>         b       sys_rt_sigreturn
>  ENDPROC(sys_rt_sigreturn_wrapper)
> -
> -ENTRY(handle_arch_irq)
> -       .quad   0
> diff --git a/arch/arm64/kernel/irq.c b/arch/arm64/kernel/irq.c
> index 071a6ec..240b75c 100644
> --- a/arch/arm64/kernel/irq.c
> +++ b/arch/arm64/kernel/irq.c
> @@ -40,6 +40,8 @@ int arch_show_interrupts(struct seq_file *p, int prec)
>         return 0;
>  }
>
> +void (*handle_arch_irq)(struct pt_regs *) = NULL;
> +
>  void __init set_handle_irq(void (*handle_irq)(struct pt_regs *))
>  {
>         if (handle_arch_irq)
> --
> Qualcomm Innovation Center, Inc.
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project
>
>
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