[PATCH -v4 7/9] tracing: add dynamic function tracer support for MIPS
From: Wu Zhangjin
Date: Wed Oct 21 2009 - 10:35:54 EST
dynamic function tracer need to replace "nop" to "jumps & links" and
something reversely.
in linux-mips64, there will be some local symbols, whose name are
prefixed by $L, which need to be filtered. thanks goes to Steven for
writing the mips64-specific function_regex.
Signed-off-by: Wu Zhangjin <wuzj@xxxxxxxxxx>
---
arch/mips/Kconfig | 2 +
arch/mips/include/asm/ftrace.h | 10 ++++
arch/mips/kernel/Makefile | 3 +-
arch/mips/kernel/ftrace.c | 107 ++++++++++++++++++++++++++++++++++++++++
arch/mips/kernel/mcount.S | 31 ++++++++++++
scripts/recordmcount.pl | 22 ++++++++
6 files changed, 174 insertions(+), 1 deletions(-)
create mode 100644 arch/mips/kernel/ftrace.c
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index a9bd992..147fbbc 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -6,6 +6,8 @@ config MIPS
select HAVE_ARCH_KGDB
select HAVE_FUNCTION_TRACER
select HAVE_FUNCTION_TRACE_MCOUNT_TEST
+ select HAVE_DYNAMIC_FTRACE
+ select HAVE_FTRACE_MCOUNT_RECORD
# Horrible source of confusion. Die, die, die ...
select EMBEDDED
select RTC_LIB if !LEMOTE_FULOONG2E
diff --git a/arch/mips/include/asm/ftrace.h b/arch/mips/include/asm/ftrace.h
index 5f8ebcf..b4970c9 100644
--- a/arch/mips/include/asm/ftrace.h
+++ b/arch/mips/include/asm/ftrace.h
@@ -19,6 +19,16 @@
extern void _mcount(void);
#define mcount _mcount
+#ifdef CONFIG_DYNAMIC_FTRACE
+/* reloction of mcount call site is the same as the address */
+static inline unsigned long ftrace_call_adjust(unsigned long addr)
+{
+ return addr;
+}
+
+struct dyn_arch_ftrace {
+};
+#endif /* CONFIG_DYNAMIC_FTRACE */
#endif /* __ASSEMBLY__ */
#endif /* CONFIG_FUNCTION_TRACER */
#endif /* _ASM_MIPS_FTRACE_H */
diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile
index 38e704a..3cda3ab 100644
--- a/arch/mips/kernel/Makefile
+++ b/arch/mips/kernel/Makefile
@@ -10,6 +10,7 @@ obj-y += cpu-probe.o branch.o entry.o genex.o irq.o process.o \
ifdef CONFIG_FUNCTION_TRACER
CFLAGS_REMOVE_trace_clock.o = -pg
+CFLAGS_REMOVE_ftrace.o = -pg
CFLAGS_REMOVE_early_printk.o = -pg
endif
@@ -30,7 +31,7 @@ obj-$(CONFIG_STACKTRACE) += stacktrace.o
obj-$(CONFIG_MODULES) += mips_ksyms.o module.o
obj-$(CONFIG_FTRACE) += trace_clock.o
-obj-$(CONFIG_FUNCTION_TRACER) += mcount.o
+obj-$(CONFIG_FUNCTION_TRACER) += mcount.o ftrace.o
obj-$(CONFIG_CPU_LOONGSON2) += r4k_fpu.o r4k_switch.o
obj-$(CONFIG_CPU_MIPS32) += r4k_fpu.o r4k_switch.o
diff --git a/arch/mips/kernel/ftrace.c b/arch/mips/kernel/ftrace.c
new file mode 100644
index 0000000..1e44865
--- /dev/null
+++ b/arch/mips/kernel/ftrace.c
@@ -0,0 +1,107 @@
+/*
+ * Code for replacing ftrace calls with jumps.
+ *
+ * Copyright (C) 2007-2008 Steven Rostedt <srostedt@xxxxxxxxxx>
+ * Copyright (C) 2009 DSLab, Lanzhou University, China
+ * Author: Wu Zhangjin <wuzj@xxxxxxxxxx>
+ *
+ * Thanks goes to Steven Rostedt for writing the original x86 version.
+ */
+
+#include <linux/uaccess.h>
+#include <linux/init.h>
+#include <linux/ftrace.h>
+
+#include <asm/cacheflush.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 */
+
+#ifdef CONFIG_CPU_LOONGSON2
+static unsigned int ftrace_nop = 0x00020021;
+#else
+static unsigned int ftrace_nop = 0x00000000;
+#endif
+
+static unsigned char *ftrace_call_replace(unsigned long op_code,
+ unsigned long addr)
+{
+ static unsigned int op;
+
+ op = op_code | ((addr >> 2) & ADDR_MASK);
+
+ return (unsigned char *)&op;
+}
+
+static unsigned char *ftrace_nop_replace(void)
+{
+ return (unsigned char *)&ftrace_nop;
+}
+
+static int
+ftrace_modify_code(unsigned long ip, unsigned char *old_code,
+ unsigned char *new_code)
+{
+ unsigned char replaced[MCOUNT_INSN_SIZE];
+
+ /* read the text we want to modify */
+ if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
+ return -EFAULT;
+
+ /* Make sure it is what we expect it to be */
+ if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
+ return -EINVAL;
+
+ /* replace the text with the new text */
+ if (probe_kernel_write((void *)ip, new_code, MCOUNT_INSN_SIZE))
+ return -EPERM;
+
+ flush_icache_range(ip, ip + 8);
+
+ return 0;
+}
+
+int ftrace_make_nop(struct module *mod,
+ struct dyn_ftrace *rec, unsigned long addr)
+{
+ unsigned char *new, *old;
+
+ old = ftrace_call_replace(JAL, addr);
+ new = ftrace_nop_replace();
+
+ return ftrace_modify_code(rec->ip, old, new);
+}
+
+int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
+{
+ unsigned char *new, *old;
+
+ old = ftrace_nop_replace();
+ new = ftrace_call_replace(JAL, addr);
+
+ return ftrace_modify_code(rec->ip, old, new);
+}
+
+int ftrace_update_ftrace_func(ftrace_func_t func)
+{
+ unsigned long ip = (unsigned long)(&ftrace_call);
+ unsigned char old[MCOUNT_INSN_SIZE], *new;
+ int ret;
+
+ memcpy(old, &ftrace_call, MCOUNT_INSN_SIZE);
+ new = ftrace_call_replace(JAL, (unsigned long)func);
+ ret = ftrace_modify_code(ip, old, new);
+
+ return ret;
+}
+
+int __init ftrace_dyn_arch_init(void *data)
+{
+ /* The return code is retured via data */
+ *(unsigned long *)data = 0;
+
+ return 0;
+}
+#endif /* CONFIG_DYNAMIC_FTRACE */
diff --git a/arch/mips/kernel/mcount.S b/arch/mips/kernel/mcount.S
index 82e54ab..30637e6 100644
--- a/arch/mips/kernel/mcount.S
+++ b/arch/mips/kernel/mcount.S
@@ -67,6 +67,35 @@
move ra, AT
.endm
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+LEAF(_mcount)
+ RESTORE_SP_FOR_32BIT
+ RETURN_BACK
+ END(_mcount)
+
+NESTED(ftrace_caller, PT_SIZE, ra)
+ RESTORE_SP_FOR_32BIT
+ lw t0, function_trace_stop
+ bnez t0, ftrace_stub
+ nop
+
+ MCOUNT_SAVE_REGS
+
+ MCOUNT_SET_ARGS
+ .globl ftrace_call
+ftrace_call:
+ jal ftrace_stub
+ nop
+
+ MCOUNT_RESTORE_REGS
+ .globl ftrace_stub
+ftrace_stub:
+ RETURN_BACK
+ END(ftrace_caller)
+
+#else /* ! CONFIG_DYNAMIC_FTRACE */
+
NESTED(_mcount, PT_SIZE, ra)
RESTORE_SP_FOR_32BIT
lw t0, function_trace_stop
@@ -94,5 +123,7 @@ ftrace_stub:
RETURN_BACK
END(_mcount)
+#endif /* ! CONFIG_DYNAMIC_FTRACE */
+
.set at
.set reorder
diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
index daee038..511c3a2 100755
--- a/scripts/recordmcount.pl
+++ b/scripts/recordmcount.pl
@@ -245,6 +245,28 @@ if ($arch eq "x86_64") {
$ld .= " -m elf64_sparc";
$cc .= " -m64";
$objcopy .= " -O elf64-sparc";
+
+} elsif ($arch eq "mips") {
+ $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s_mcount\$";
+ $objdump .= " -Melf-trad".$endian."mips ";
+
+ if ($endian eq "big") {
+ $endian = " -EB ";
+ $ld .= " -melf".$bits."btsmip";
+ } else {
+ $endian = " -EL ";
+ $ld .= " -melf".$bits."ltsmip";
+ }
+
+ $cc .= " -mno-abicalls -fno-pic -mabi=" . $bits . $endian;
+ $ld .= $endian;
+
+ if ($bits == 64) {
+ $function_regex =
+ "^([0-9a-fA-F]+)\\s+<(.|[^\$]L.*?|\$[^L].*?|[^\$][^L].*?)>:";
+ $type = ".dword";
+ }
+
} else {
die "Arch $arch is not supported with CONFIG_FTRACE_MCOUNT_RECORD";
}
--
1.6.2.1
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