Sorry, please ignore this one.
On Thu, Jan 20, 2011 at 3:28 AM, Wu Zhangjin <wuzhangjin@xxxxxxxxx> wrote:
> This simply moves the "ip-=4" statement down to the end of the do { ...
> } while (...); loop, which reduces one unneeded subtration and the
> subsequent memory loading and comparation. as a result, speed up the
> function a little.
>
> Signed-off-by: Wu Zhangjin <wuzhangjin@xxxxxxxxx>
> ---
> arch/mips/kernel/ftrace.c | 14 +++++++-------
> 1 files changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/arch/mips/kernel/ftrace.c b/arch/mips/kernel/ftrace.c
> index 5a84a1f..635c1dc 100644
> --- a/arch/mips/kernel/ftrace.c
> +++ b/arch/mips/kernel/ftrace.c
> @@ -200,19 +200,17 @@ unsigned long ftrace_get_parent_addr(unsigned long self_addr,
> int faulted;
>
> /*
> - * For module, move the ip from calling site of mcount to the
> - * instruction "lui v1, hi_16bit_of_mcount"(offset is 20), but for
> - * kernel, move to the instruction "move ra, at"(offset is 12)
> + * For module, move the ip from calling site of mcount after the
> + * instruction "lui v1, hi_16bit_of_mcount"(offset is 24), but for
> + * kernel, move after the instruction "move ra, at"(offset is 16)
> */
> - ip = self_addr - (in_module(self_addr) ? 20 : 12);
> + ip = self_addr - (in_module(self_addr) ? 24 : 16);
>
> /*
> * search the text until finding the non-store instruction or "s{d,w}
> * ra, offset(sp)" instruction
> */
> do {
> - ip -= 4;
> -
> /* get the code at "ip": code = *(unsigned int *)ip; */
> safe_load_code(code, ip, faulted);
>
> @@ -226,7 +224,9 @@ unsigned long ftrace_get_parent_addr(unsigned long self_addr,
> if ((code & S_R_SP) != S_R_SP)
> return parent_addr;
>
> - } while (((code & S_RA_SP) != S_RA_SP));
> + /* Move to the next instruction */
> + ip -= 4;
> + } while ((code & S_RA_SP) != S_RA_SP);
>
> sp = fp + (code & OFFSET_MASK);
>
> --
> 1.7.1
>
>
