Re: [PATCH -tip v5 06/10] kprobes/x86: Cleanup save/restore registers

Frederic Weisbecker
2009-11-24T02:51:16Z

On Mon, Nov 23, 2009 at 06:22:04PM -0500, Masami Hiramatsu wrote:
> +#ifdef CONFIG_X86_64
> +#define SAVE_REGS_STRING \
> + /* Skip cs, ip, orig_ax. */ \
> + " subq $24, %rsp\n" \
> + " pushq %rdi\n" \
> + " pushq %rsi\n" \
> + " pushq %rdx\n" \
> + " pushq %rcx\n" \
> + " pushq %rax\n" \
> + " pushq %r8\n" \
> + " pushq %r9\n" \
> + " pushq %r10\n" \
> + " pushq %r11\n" \
> + " pushq %rbx\n" \
> + " pushq %rbp\n" \
> + " pushq %r12\n" \
> + " pushq %r13\n" \
> + " pushq %r14\n" \
> + " pushq %r15\n"
> +#define RESTORE_REGS_STRING \
> + " popq %r15\n" \
> + " popq %r14\n" \
> + " popq %r13\n" \
> + " popq %r12\n" \
> + " popq %rbp\n" \
> + " popq %rbx\n" \
> + " popq %r11\n" \
> + " popq %r10\n" \
> + " popq %r9\n" \
> + " popq %r8\n" \
> + " popq %rax\n" \
> + " popq %rcx\n" \
> + " popq %rdx\n" \
> + " popq %rsi\n" \
> + " popq %rdi\n" \

BTW, do you really need to push/pop every registers
before/after calling a probe handler?

Is it possible to only save/restore the scratch ones?