Subject: Re: [PATCH v7 20/28] powerpc: Make test_translate_branch() independent of instruction length

From: Alistair Popple <[email-masked]>
Date: Tue, 05 May 2020 12:40:06 +1000

I guess this could change if there were prefixed branch instructions, but there 
aren't so:

Reviewed-by: Alistair Popple <[email-masked]>

On Friday, 1 May 2020 1:42:12 PM AEST Jordan Niethe wrote:
> test_translate_branch() uses two pointers to instructions within a
> buffer, p and q, to test patch_branch(). The pointer arithmetic done on
> them assumes a size of 4. This will not work if the instruction length
> changes. Instead do the arithmetic relative to the void * to the buffer.
> 
> Signed-off-by: Jordan Niethe <[email-masked]>
> ---
> v4: New to series
> ---
>  arch/powerpc/lib/code-patching.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/powerpc/lib/code-patching.c
> b/arch/powerpc/lib/code-patching.c index 110f710500c8..5b2f66d06b1e 100644
> --- a/arch/powerpc/lib/code-patching.c
> +++ b/arch/powerpc/lib/code-patching.c
> @@ -569,7 +569,7 @@ static void __init test_branch_bform(void)
>  static void __init test_translate_branch(void)
>  {
>  	unsigned long addr;
> -	struct ppc_inst *p, *q;
> +	void *p, *q;
>  	struct ppc_inst instr;
>  	void *buf;
> 
> @@ -583,7 +583,7 @@ static void __init test_translate_branch(void)
>  	addr = (unsigned long)p;
>  	patch_branch(p, addr, 0);
>  	check(instr_is_branch_to_addr(p, addr));
> -	q = p + 1;
> +	q = p + 4;
>  	translate_branch(&instr, q, p);
>  	patch_instruction(q, instr);
>  	check(instr_is_branch_to_addr(q, addr));
> @@ -639,7 +639,7 @@ static void __init test_translate_branch(void)
>  	create_cond_branch(&instr, p, addr, 0);
>  	patch_instruction(p, instr);
>  	check(instr_is_branch_to_addr(p, addr));
> -	q = p + 1;
> +	q = buf + 4;
>  	translate_branch(&instr, q, p);
>  	patch_instruction(q, instr);
>  	check(instr_is_branch_to_addr(q, addr));