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Message-Id: <20180115064742.25324-4-alankao@andestech.com>
Date: Mon, 15 Jan 2018 14:47:39 +0800
From: Alan Kao <nonerkao@...il.com>
To: Palmer Dabbelt <palmer@...ive.com>, Albert Ou <albert@...ive.com>,
Christoph Hellwig <hch@....de>,
Steven Rostedt <rostedt@...dmis.org>,
Ingo Molnar <mingo@...hat.com>,
Masahiro Yamada <yamada.masahiro@...ionext.com>,
Kamil Rytarowski <n54@....com>,
Andrew Morton <akpm@...ux-foundation.org>,
patches@...ups.riscv.org, linux-kernel@...r.kernel.org
Cc: Alan Kao <alankao@...estech.com>,
Greentime Hu <greentime@...estech.com>
Subject: [PATCH v2 3/6] riscv/ftrace: Add dynamic function graph tracer support
Once the function_graph tracer is enabled, a filtered function has the
following call sequence:
* ftracer_caller ==> on/off by ftrace_make_call/ftrace_make_nop
* ftrace_graph_caller
* ftrace_graph_call ==> on/off by ftrace_en/disable_ftrace_graph_caller
* prepare_ftrace_return
Considering the following DYNAMIC_FTRACE_WITH_REGS feature, it would be
more extendable to have a ftrace_graph_caller function, instead of
calling prepare_ftrace_return directly in ftrace_caller.
Cc: Greentime Hu <greentime@...estech.com>
Signed-off-by: Alan Kao <alankao@...estech.com>
---
arch/riscv/kernel/ftrace.c | 25 +++++++++++++++-
arch/riscv/kernel/mcount-dyn.S | 65 ++++++++++++++++++++++++++++++++++++++++++
2 files changed, 89 insertions(+), 1 deletion(-)
diff --git a/arch/riscv/kernel/ftrace.c b/arch/riscv/kernel/ftrace.c
index 311c287433c9..dce1286af9b0 100644
--- a/arch/riscv/kernel/ftrace.c
+++ b/arch/riscv/kernel/ftrace.c
@@ -51,7 +51,7 @@ static int __ftrace_modify_call(unsigned long hook_pos, unsigned long target,
unsigned int nops[2] = {NOP4, NOP4};
int ret = 0;
- /* when ftrace_make_nop is called */
+ /* for ftrace_make_nop and ftrace_disable_ftrace_graph_caller */
if (!enable)
ret = ftrace_check_current_call(hook_pos, calls);
@@ -105,6 +105,7 @@ int __init ftrace_dyn_arch_init(void)
}
#endif
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
/*
* Most of this function is copied from arm64.
*/
@@ -137,3 +138,25 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
return;
*parent = return_hooker;
}
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+extern void ftrace_graph_call(void);
+int ftrace_enable_ftrace_graph_caller(void)
+{
+ int ret = ftrace_check_current_call((unsigned long)&ftrace_graph_call,
+ NULL);
+
+ if (ret)
+ return ret;
+
+ return __ftrace_modify_call((unsigned long)&ftrace_graph_call,
+ (unsigned long)&prepare_ftrace_return, true);
+}
+
+int ftrace_disable_ftrace_graph_caller(void)
+{
+ return __ftrace_modify_call((unsigned long)&ftrace_graph_call,
+ (unsigned long)&prepare_ftrace_return, false);
+}
+#endif /* CONFIG_DYNAMIC_FTRACE */
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
diff --git a/arch/riscv/kernel/mcount-dyn.S b/arch/riscv/kernel/mcount-dyn.S
index 57f80fe09cbd..64e715d4e180 100644
--- a/arch/riscv/kernel/mcount-dyn.S
+++ b/arch/riscv/kernel/mcount-dyn.S
@@ -14,18 +14,63 @@
.text
.macro SAVE_ABI_STATE
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ addi sp, sp, -48
+ sd s0, 32(sp)
+ sd ra, 40(sp)
+ addi s0, sp, 48
+ sd t0, 24(sp)
+ sd t1, 16(sp)
+#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
+ sd t2, 8(sp)
+#endif
+#else
addi sp, sp, -16
sd s0, 0(sp)
sd ra, 8(sp)
addi s0, sp, 16
+#endif
.endm
.macro RESTORE_ABI_STATE
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ ld s0, 32(sp)
+ ld ra, 40(sp)
+ addi sp, sp, 48
+#else
ld ra, 8(sp)
ld s0, 0(sp)
addi sp, sp, 16
+#endif
.endm
+ .macro RESTORE_GRAPH_ARGS
+ ld a0, 24(sp)
+ ld a1, 16(sp)
+#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
+ ld a2, 8(sp)
+#endif
+ .endm
+
+ENTRY(ftrace_graph_caller)
+ addi sp, sp, -16
+ sd s0, 0(sp)
+ sd ra, 8(sp)
+ addi s0, sp, 16
+ftrace_graph_call:
+ .global ftrace_graph_call
+ /*
+ * Calling ftrace_enable/disable_ftrace_graph_caller would overwrite the
+ * nops below. Check ftrace_modify_all_code for details.
+ */
+ addi x0, x0, 0
+ addi x0, x0, 0
+ ld ra, 8(sp)
+ ld s0, 0(sp)
+ addi sp, sp, 16
+ ret
+ENDPROC(ftrace_graph_caller)
+
ENTRY(ftrace_caller)
/*
* a0: the address in the caller when calling ftrace_caller
@@ -33,6 +78,20 @@ ENTRY(ftrace_caller)
*/
ld a1, -8(s0)
addi a0, ra, -MCOUNT_INSN_SIZE
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ /*
+ * the graph tracer (specifically, prepare_ftrace_return) needs these
+ * arguments but for now the function tracer occupies the regs, so we
+ * save them in temporary regs to recover later.
+ */
+ addi t0, s0, -8
+ mv t1, a0
+#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
+ ld t2, -16(s0)
+#endif
+#endif
+
SAVE_ABI_STATE
ftrace_call:
.global ftrace_call
@@ -47,6 +106,12 @@ ftrace_call:
*/
addi x0, x0, 0
addi x0, x0, 0
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ RESTORE_GRAPH_ARGS
+ call ftrace_graph_caller
+#endif
+
RESTORE_ABI_STATE
ret
ENDPROC(ftrace_caller)
--
2.15.1
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