From 9a620a559be65023b5fd5d0eaf37dae884c4f404 Mon Sep 17 00:00:00 2001 From: Wu Zhangjin Date: Thu, 20 Jan 2011 03:28:27 +0800 Subject: [PATCH] MIPS, Tracing: Speed up function graph tracer 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 comparison. Signed-off-by: Wu Zhangjin Cc: Steven Rostedt Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/2006/ Signed-off-by: Ralf Baechle --- arch/mips/kernel/ftrace.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/arch/mips/kernel/ftrace.c b/arch/mips/kernel/ftrace.c index 5a84a1f11231..635c1dcdc4fc 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); -- 2.20.1