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Date: Sat, 6 Nov 2010 23:55:53 +0530
From: Rabin Vincent <rabin@....in>
To: linux-arm-kernel@...ts.infradead.org
Cc: Steven Rostedt <rostedt@...dmis.org>,
Frederic Weisbecker <fweisbec@...il.com>,
Tim Bird <tim.bird@...sony.com>, linux-kernel@...r.kernel.org,
Rabin Vincent <rabin@....in>
Subject: [PATCH 5/6] ARM: ftrace: graph tracer + dynamic ftrace
Support the graph tracer + dynamic ftrace combination on ARM.
Signed-off-by: Rabin Vincent <rabin@....in>
---
arch/arm/kernel/entry-common.S | 12 +++++++
arch/arm/kernel/ftrace.c | 69 +++++++++++++++++++++++++++++++++++++---
2 files changed, 76 insertions(+), 5 deletions(-)
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 9f17662..aae802e 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -183,12 +183,24 @@ ENDPROC(ret_from_fork)
ftrace_call\suffix:
bl ftrace_stub
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ .globl ftrace_graph_call\suffix
+ftrace_graph_call\suffix:
+ mov r0, r0
+#endif
+
mcount_exit
.endm
.macro __ftrace_graph_caller
sub r0, fp, #4 @ &lr of instrumented routine (&parent)
+#ifdef CONFIG_DYNAMIC_FTRACE
+ @ called from __ftrace_caller, saved in mcount_enter
+ ldr r1, [sp, #16] @ instrumented routine (func)
+#else
+ @ called from __mcount, untouched in lr
mov r1, lr @ instrumented routine (func)
+#endif
sub r1, r1, #MCOUNT_INSN_SIZE
mov r2, fp @ frame pointer
bl prepare_ftrace_return
diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
index 7a702a5..c0062ad 100644
--- a/arch/arm/kernel/ftrace.c
+++ b/arch/arm/kernel/ftrace.c
@@ -60,9 +60,9 @@ static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr)
}
#endif
-/* construct a branch (BL) instruction to addr */
#ifdef CONFIG_THUMB2_KERNEL
-static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
+static unsigned long ftrace_gen_branch(unsigned long pc, unsigned long addr,
+ bool link)
{
unsigned long s, j1, j2, i1, i2, imm10, imm11;
unsigned long first, second;
@@ -84,15 +84,22 @@ static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
j2 = (!i2) ^ s;
first = 0xf000 | (s << 10) | imm10;
- second = 0xd000 | (j1 << 13) | (j2 << 11) | imm11;
+ second = 0x9000 | (j1 << 13) | (j2 << 11) | imm11;
+ if (link)
+ second |= 1 << 14;
return (second << 16) | first;
}
#else
-static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
+static unsigned long ftrace_gen_branch(unsigned long pc, unsigned long addr,
+ bool link)
{
+ unsigned long opcode = 0xea000000;
long offset;
+ if (link)
+ opcode |= 1 << 24;
+
offset = (long)addr - (long)(pc + 8);
if (unlikely(offset < -33554432 || offset > 33554428)) {
/* Can't generate branches that far (from ARM ARM). Ftrace
@@ -104,10 +111,15 @@ static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
offset = (offset >> 2) & 0x00ffffff;
- return 0xeb000000 | offset;
+ return opcode | offset;
}
#endif
+static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
+{
+ return ftrace_gen_branch(pc, addr, true);
+}
+
static int ftrace_modify_code(unsigned long pc, unsigned long old,
unsigned long new)
{
@@ -226,4 +238,51 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
*parent = old;
}
}
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+extern unsigned long ftrace_graph_call;
+extern unsigned long ftrace_graph_call_old;
+extern void ftrace_graph_caller_old(void);
+
+static int __ftrace_modify_caller(unsigned long *callsite,
+ void (*func) (void), bool enable)
+{
+ unsigned long caller_fn = (unsigned long) func;
+ unsigned long pc = (unsigned long) callsite;
+ unsigned long branch = ftrace_gen_branch(pc, caller_fn, false);
+ unsigned long nop = 0xe1a00000; /* mov r0, r0 */
+ unsigned long old = enable ? nop : branch;
+ unsigned long new = enable ? branch : nop;
+
+ return ftrace_modify_code(pc, old, new);
+}
+
+static int ftrace_modify_graph_caller(bool enable)
+{
+ int ret;
+
+ ret = __ftrace_modify_caller(&ftrace_graph_call,
+ ftrace_graph_caller,
+ enable);
+
+#ifdef CONFIG_OLD_MCOUNT
+ if (!ret)
+ ret = __ftrace_modify_caller(&ftrace_graph_call_old,
+ ftrace_graph_caller_old,
+ enable);
+#endif
+
+ return ret;
+}
+
+int ftrace_enable_ftrace_graph_caller(void)
+{
+ return ftrace_modify_graph_caller(true);
+}
+
+int ftrace_disable_ftrace_graph_caller(void)
+{
+ return ftrace_modify_graph_caller(false);
+}
+#endif /* CONFIG_DYNAMIC_FTRACE */
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
--
1.7.2.3
--
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