diff options
author | Wu Zhangjin <wuzhangjin@gmail.com> | 2011-01-19 19:28:27 (GMT) |
---|---|---|
committer | Ralf Baechle <ralf@linux-mips.org> | 2011-03-14 20:07:24 (GMT) |
commit | 9a620a559be65023b5fd5d0eaf37dae884c4f404 (patch) | |
tree | 3c7e7d69c6ee14088ac8bf08499d9e8afce2710c /arch/mips/kernel/ftrace.c | |
parent | 52bd080d5c87af556bf71e3b07bdd8586166c43b (diff) | |
download | linux-fsl-qoriq-9a620a559be65023b5fd5d0eaf37dae884c4f404.tar.xz |
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 <wuzhangjin@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2006/
Signed-off-by: Ralf Baechle <ralf@duck.linux-mips.net>
Diffstat (limited to 'arch/mips/kernel/ftrace.c')
-rw-r--r-- | 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); |