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authorWu Zhangjin <wuzhangjin@gmail.com>2010-05-14 19:08:33 +0800
committerRalf Baechle <ralf@linux-mips.org>2010-07-05 17:17:30 +0100
commit68ccf7521dc89bfcf01432fd1bf8cb4d7d534e4c (patch)
tree9b2d38cabb56b069ae4993a19a8b68ed760f2525
parente424054000878d7eb11e44289242886d6e219d22 (diff)
MIPS: Tracing: Cleanup of function graph tracer
Cleans up comments and ftrace_get_parent_addr() of function graph tracer. Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com> Cc: linux-mips <linux-mips@linux-mips.org> Cc: David Daney <david.s.daney@gmail.com> Patchwork: http://patchwork.linux-mips.org/patch/1231/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
-rw-r--r--arch/mips/kernel/ftrace.c48
1 files changed, 26 insertions, 22 deletions
diff --git a/arch/mips/kernel/ftrace.c b/arch/mips/kernel/ftrace.c
index c4042cad836e..628e90b992d1 100644
--- a/arch/mips/kernel/ftrace.c
+++ b/arch/mips/kernel/ftrace.c
@@ -146,7 +146,7 @@ int __init ftrace_dyn_arch_init(void *data)
return 0;
}
-#endif /* CONFIG_DYNAMIC_FTRACE */
+#endif /* CONFIG_DYNAMIC_FTRACE */
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
@@ -166,9 +166,10 @@ int ftrace_disable_ftrace_graph_caller(void)
return ftrace_modify_code(FTRACE_GRAPH_CALL_IP, INSN_NOP);
}
-#endif /* !CONFIG_DYNAMIC_FTRACE */
+#endif /* CONFIG_DYNAMIC_FTRACE */
#ifndef KBUILD_MCOUNT_RA_ADDRESS
+
#define S_RA_SP (0xafbf << 16) /* s{d,w} ra, offset(sp) */
#define S_R_SP (0xafb0 << 16) /* s{d,w} R, offset(sp) */
#define OFFSET_MASK 0xffff /* stack offset range: 0 ~ PT_SIZE */
@@ -182,17 +183,17 @@ unsigned long ftrace_get_parent_addr(unsigned long self_addr,
unsigned int code;
int faulted;
- /* in module or kernel? */
- if (self_addr & 0x40000000) {
- /* module: move to the instruction "lui v1, HI_16BIT_OF_MCOUNT" */
- ip = self_addr - 20;
- } else {
- /* kernel: move to the instruction "move ra, at" */
- ip = self_addr - 12;
- }
+ /*
+ * 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)
+ */
+ ip = self_addr - ((self_addr & 0x40000000) ? 20 : 12);
- /* search the text until finding the non-store instruction or "s{d,w}
- * ra, offset(sp)" instruction */
+ /*
+ * search the text until finding the non-store instruction or "s{d,w}
+ * ra, offset(sp)" instruction
+ */
do {
ip -= 4;
@@ -201,10 +202,11 @@ unsigned long ftrace_get_parent_addr(unsigned long self_addr,
if (unlikely(faulted))
return 0;
-
- /* If we hit the non-store instruction before finding where the
+ /*
+ * If we hit the non-store instruction before finding where the
* ra is stored, then this is a leaf function and it does not
- * store the ra on the stack. */
+ * store the ra on the stack
+ */
if ((code & S_R_SP) != S_R_SP)
return parent_addr;
@@ -222,7 +224,7 @@ unsigned long ftrace_get_parent_addr(unsigned long self_addr,
return 0;
}
-#endif
+#endif /* !KBUILD_MCOUNT_RA_ADDRESS */
/*
* Hook the return address and push it in the stack of return addrs
@@ -240,7 +242,8 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
if (unlikely(atomic_read(&current->tracing_graph_pause)))
return;
- /* "parent" is the stack address saved the return address of the caller
+ /*
+ * "parent" is the stack address saved the return address of the caller
* of _mcount.
*
* if the gcc < 4.5, a leaf function does not save the return address
@@ -262,10 +265,11 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
goto out;
#ifndef KBUILD_MCOUNT_RA_ADDRESS
parent = (unsigned long *)ftrace_get_parent_addr(self_addr, old,
- (unsigned long)parent,
- fp);
- /* If fails when getting the stack address of the non-leaf function's
- * ra, stop function graph tracer and return */
+ (unsigned long)parent, fp);
+ /*
+ * If fails when getting the stack address of the non-leaf function's
+ * ra, stop function graph tracer and return
+ */
if (parent == 0)
goto out;
#endif
@@ -292,4 +296,4 @@ out:
ftrace_graph_stop();
WARN_ON(1);
}
-#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */