[PATCHv2 2/4] arm64: Treat handle_arch_irq as a function pointer

[mark.rutland@arm.com (Mark Rutland)]

Hi Laura,

On Mon, Jun 02, 2014 at 09:57:36PM +0100, Laura Abbott 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 readonly. Move it to the data section.
> 
> Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
> ---
>  arch/arm64/kernel/entry.S | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
> index 39ac630..7c8ea1f 100644
> --- a/arch/arm64/kernel/entry.S
> +++ b/arch/arm64/kernel/entry.S
> @@ -139,7 +139,8 @@ tsk	.req	x28		// current thread_info
>   * Interrupt handling.
>   */
>  	.macro	irq_handler
> -	ldr	x1, handle_arch_irq
> +	ldr	x1, =handle_arch_irq
> +	ldr	x1, [x1]
>  	mov	x0, sp
>  	blr	x1
>  	.endm
> @@ -678,5 +679,8 @@ ENTRY(sys_rt_sigreturn_wrapper)
>  	b	sys_rt_sigreturn
>  ENDPROC(sys_rt_sigreturn_wrapper)
>  
> -ENTRY(handle_arch_irq)
> +	.data
> +	.globl handle_arch_irq
> +	.align 4
> +handle_arch_irq:
>  	.quad	0

Rather than having to set the alignment and section manually, would
something like the below work, moving the definition into kernel/irq.c?

Cheers,
Mark.

---->8----
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 39ac630..d378fc0 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -139,7 +139,8 @@ tsk .req    x28             // current thread_info
  * Interrupt handling.
  */
        .macro  irq_handler
-       ldr     x1, handle_arch_irq
+       ldr     x1, =handle_arch_irq
+       ldr     x1, [x1]
        mov     x0, sp
        blr     x1
        .endm
@@ -677,6 +678,3 @@ 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 0f08dfd..e4fedbc 100644
--- a/arch/arm64/kernel/irq.c
+++ b/arch/arm64/kernel/irq.c
@@ -67,6 +67,8 @@ void handle_IRQ(unsigned int irq, struct pt_regs *regs)
        set_irq_regs(old_regs);
 }
 
+void (*handle_arch_irq)(struct pt_regs *) = NULL;
+
 void __init set_handle_irq(void (*handle_irq)(struct pt_regs *))
 {
        if (handle_arch_irq)