From: Wu Zhangjin <wuzhangjin@xxxxxxxxx>
With the help of uasm, this patch encodes the instructions of dynamic
Function Tracer in ftrace_dyn_arch_init() when initializing it.
As a result, we can remove the dynamic encoding of instructions in
ftrace_make_nop()/call(), ftrace_enable_ftrace_graph_caller() and remove
the macro jump_insn_encode() and at last, reduces the overhead of
dynamic Function Tracer and also make the source code looks better.
Signed-off-by: Wu Zhangjin <wuzhangjin@xxxxxxxxx>
---
arch/mips/kernel/ftrace.c | 93 +++++++++++++++++++++++---------------------
1 files changed, 49 insertions(+), 44 deletions(-)
diff --git a/arch/mips/kernel/ftrace.c b/arch/mips/kernel/ftrace.c
index b1b8fec..c4042ca 100644
--- a/arch/mips/kernel/ftrace.c
+++ b/arch/mips/kernel/ftrace.c
@@ -2,7 +2,7 @@
* Code for replacing ftrace calls with jumps.
*
* Copyright (C) 2007-2008 Steven Rostedt <srostedt@xxxxxxxxxx>
- * Copyright (C) 2009 DSLab, Lanzhou University, China
+ * Copyright (C) 2009, 2010 DSLab, Lanzhou University, China
* Author: Wu Zhangjin <wuzhangjin@xxxxxxxxx>
*
* Thanks goes to Steven Rostedt for writing the original x86 version.
@@ -12,21 +12,46 @@
#include <linux/init.h>
#include <linux/ftrace.h>
-#include <asm/cacheflush.h>
#include <asm/asm.h>
#include <asm/asm-offsets.h>
+#include <asm/cacheflush.h>
+#include <asm/uasm.h>
#ifdef CONFIG_DYNAMIC_FTRACE
#define JAL 0x0c000000 /* jump & link: ip --> ra, jump to target */
#define ADDR_MASK 0x03ffffff /* op_code|addr : 31...26|25 ....0 */
-#define jump_insn_encode(op_code, addr) \
- ((unsigned int)((op_code) | (((addr) >> 2) & ADDR_MASK)))
#define INSN_B_1F_4 0x10000004 /* b 1f; offset = 4 */
#define INSN_B_1F_5 0x10000005 /* b 1f; offset = 5 */
#define INSN_NOP 0x00000000 /* nop */
-#define INSN_JAL(addr) jump_insn_encode(JAL, addr)
+#define INSN_JAL(addr) \
+ ((unsigned int)(JAL | (((addr) >> 2) & ADDR_MASK)))
+
+static unsigned int insn_jal_ftrace_caller __read_mostly;
+static unsigned int insn_lui_v1_hi16_mcount __read_mostly;
+static unsigned int insn_j_ftrace_graph_caller __maybe_unused __read_mostly;
+
+static inline void ftrace_dyn_arch_init_insns(void)
+{
+ u32 *buf;
+ unsigned int v1;
+
+ /* lui v1, hi16_mcount */
+ v1 = 3;
+ buf = (u32 *)&insn_lui_v1_hi16_mcount;
+ UASM_i_LA_mostly(&buf, v1, MCOUNT_ADDR);
+
+ /* jal (ftrace_caller + 8), jump over the first two instruction */
+ buf = (u32 *)&insn_jal_ftrace_caller;
+ uasm_i_jal(&buf, (FTRACE_ADDR + 8));
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ /* j ftrace_graph_caller */
+ buf = (u32 *)&insn_j_ftrace_graph_caller;
+ uasm_i_j(&buf, (unsigned long)ftrace_graph_caller);
+#endif
+}
static int ftrace_modify_code(unsigned long ip, unsigned int new_code)
{
@@ -43,30 +68,20 @@ static int ftrace_modify_code(unsigned long ip, unsigned int new_code)
return 0;
}
-static int lui_v1;
-static int jal_mcount;
-
int ftrace_make_nop(struct module *mod,
struct dyn_ftrace *rec, unsigned long addr)
{
unsigned int new;
- int faulted;
unsigned long ip = rec->ip;
- /* We have compiled module with -mlong-calls, but compiled the kernel
- * without it, we need to cope with them respectively. */
+ /*
+ * We have compiled module with -mlong-calls, but compiled the kernel
+ * without it, we need to cope with them respectively.
+ */
if (ip & 0x40000000) {
- /* record it for ftrace_make_call */
- if (lui_v1 == 0) {
- /* lui_v1 = *(unsigned int *)ip; */
- safe_load_code(lui_v1, ip, faulted);
-
- if (unlikely(faulted))
- return -EFAULT;
- }
-
#if defined(KBUILD_MCOUNT_RA_ADDRESS) && defined(CONFIG_32BIT)
- /* lui v1, hi_16bit_of_mcount --> b 1f (0x10000005)
+ /*
+ * lui v1, hi_16bit_of_mcount --> b 1f (0x10000005)
* addiu v1, v1, low_16bit_of_mcount
* move at, ra
* move $12, ra_address
@@ -76,7 +91,8 @@ int ftrace_make_nop(struct module *mod,
*/
new = INSN_B_1F_5;
#else
- /* lui v1, hi_16bit_of_mcount --> b 1f (0x10000004)
+ /*
+ * lui v1, hi_16bit_of_mcount --> b 1f (0x10000004)
* addiu v1, v1, low_16bit_of_mcount
* move at, ra
* jalr v1
@@ -86,36 +102,22 @@ int ftrace_make_nop(struct module *mod,
new = INSN_B_1F_4;
#endif
} else {
- /* record/calculate it for ftrace_make_call */
- if (jal_mcount == 0) {
- /* We can record it directly like this:
- * jal_mcount = *(unsigned int *)ip;
- * Herein, jump over the first two nop instructions */
- jal_mcount = INSN_JAL(MCOUNT_ADDR + 8);
- }
-
- /* move at, ra
- * jalr v1 --> nop
+ /*
+ * move at, ra
+ * jal _mcount --> nop
*/
new = INSN_NOP;
}
return ftrace_modify_code(ip, new);
}
-static int modified; /* initialized as 0 by default */
-
int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
unsigned int new;
unsigned long ip = rec->ip;
- /* We just need to remove the "b ftrace_stub" at the fist time! */
- if (modified == 0) {
- modified = 1;
- ftrace_modify_code(addr, INSN_NOP);
- }
/* ip, module: 0xc0000000, kernel: 0x80000000 */
- new = (ip & 0x40000000) ? lui_v1 : jal_mcount;
+ new = (ip & 0x40000000) ? insn_lui_v1_hi16_mcount : insn_jal_ftrace_caller;
return ftrace_modify_code(ip, new);
}
@@ -133,6 +135,12 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
int __init ftrace_dyn_arch_init(void *data)
{
+ /* Encode the instructions when booting */
+ ftrace_dyn_arch_init_insns();
+
+ /* Remove "b ftrace_stub" to ensure ftrace_caller() is executed */
+ ftrace_modify_code(MCOUNT_ADDR, INSN_NOP);
+
/* The return code is retured via data */
*(unsigned long *)data = 0;
@@ -145,15 +153,12 @@ int __init ftrace_dyn_arch_init(void *data)
#ifdef CONFIG_DYNAMIC_FTRACE
extern void ftrace_graph_call(void);
-#define JMP 0x08000000 /* jump to target directly */
-#define CALL_FTRACE_GRAPH_CALLER \
- jump_insn_encode(JMP, (unsigned long)(&ftrace_graph_caller))
#define FTRACE_GRAPH_CALL_IP ((unsigned long)(&ftrace_graph_call))
int ftrace_enable_ftrace_graph_caller(void)
{
return ftrace_modify_code(FTRACE_GRAPH_CALL_IP,
- CALL_FTRACE_GRAPH_CALLER);
+ insn_j_ftrace_graph_caller);
}
int ftrace_disable_ftrace_graph_caller(void)
--
1.7.0.4
