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-rw-r--r--arch/mips/kernel/ftrace.c24
-rw-r--r--arch/mips/kernel/mcount.S14
2 files changed, 31 insertions, 7 deletions
diff --git a/arch/mips/kernel/ftrace.c b/arch/mips/kernel/ftrace.c
index e363fc69aab..68b067040d8 100644
--- a/arch/mips/kernel/ftrace.c
+++ b/arch/mips/kernel/ftrace.c
@@ -148,6 +148,7 @@ int ftrace_disable_ftrace_graph_caller(void)
#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 */
@@ -201,6 +202,8 @@ unsigned long ftrace_get_parent_addr(unsigned long self_addr,
return 0;
}
+#endif
+
/*
* Hook the return address and push it in the stack of return addrs
* in current thread info.
@@ -218,19 +221,26 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
return;
/* "parent" is the stack address saved the return address of the caller
- * of _mcount, for a leaf function not save the return address in the
- * stack address, so, we "emulate" one in _mcount's stack space, and
- * hijack it directly, but for a non-leaf function, it will save the
- * return address to the its stack space, so, we can not hijack the
- * "parent" directly, but need to find the real stack address,
+ * of _mcount.
+ *
+ * if the gcc < 4.5, a leaf function does not save the return address
+ * in the stack address, so, we "emulate" one in _mcount's stack space,
+ * and hijack it directly, but for a non-leaf function, it save the
+ * return address to the its own stack space, we can not hijack it
+ * directly, but need to find the real stack address,
* ftrace_get_parent_addr() does it!
+ *
+ * if gcc>= 4.5, with the new -mmcount-ra-address option, for a
+ * non-leaf function, the location of the return address will be saved
+ * to $12 for us, and for a leaf function, only put a zero into $12. we
+ * do it in ftrace_graph_caller of mcount.S.
*/
/* old = *parent; */
safe_load_stack(old, parent, faulted);
if (unlikely(faulted))
goto out;
-
+#ifndef KBUILD_MCOUNT_RA_ADDRESS
parent = (unsigned long *)ftrace_get_parent_addr(self_addr, old,
(unsigned long)parent,
fp);
@@ -238,7 +248,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
* ra, stop function graph tracer and return */
if (parent == 0)
goto out;
-
+#endif
/* *parent = return_hooker; */
safe_store_stack(return_hooker, parent, faulted);
if (unlikely(faulted))
diff --git a/arch/mips/kernel/mcount.S b/arch/mips/kernel/mcount.S
index 522e91c688f..0a9cfdb271d 100644
--- a/arch/mips/kernel/mcount.S
+++ b/arch/mips/kernel/mcount.S
@@ -70,6 +70,9 @@ _mcount:
nop
MCOUNT_SAVE_REGS
+#ifdef KBUILD_MCOUNT_RA_ADDRESS
+ PTR_S t0, PT_R12(sp) /* t0 saved the location of the return address(at) by -mmcount-ra-address */
+#endif
move a0, ra /* arg1: next ip, selfaddr */
.globl ftrace_call
@@ -133,11 +136,22 @@ ftrace_stub:
NESTED(ftrace_graph_caller, PT_SIZE, ra)
#ifdef CONFIG_DYNAMIC_FTRACE
PTR_L a1, PT_R31(sp) /* load the original ra from the stack */
+#ifdef KBUILD_MCOUNT_RA_ADDRESS
+ PTR_L t0, PT_R12(sp) /* load the original t0 from the stack */
+#endif
#else
MCOUNT_SAVE_REGS
move a1, ra /* arg2: next ip, selfaddr */
#endif
+
+#ifdef KBUILD_MCOUNT_RA_ADDRESS
+ bnez t0, 1f /* non-leaf func: t0 saved the location of the return address */
+ nop
+ PTR_LA t0, PT_R1(sp) /* leaf func: get the location of at(old ra) from our own stack */
+1: move a0, t0 /* arg1: the location of the return address */
+#else
PTR_LA a0, PT_R1(sp) /* arg1: &AT -> a0 */
+#endif
jal prepare_ftrace_return
#ifdef CONFIG_FRAME_POINTER
move a2, fp /* arg3: frame pointer */