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Date: Mon, 23 Nov 2009 09:41:21 +0100
From: y@...str.eu
To: linux-kernel@...r.kernel.org
Cc: michal.simek@...alogix.com, wuzhangjin@...il.com, mingo@...e.hu,
rostedt@...dmis.org, Michal Simek <monstr@...str.eu>
Subject: [PATCH 3/5] microblaze: ftrace: Add dynamic trace support
From: Michal Simek <monstr@...str.eu>
With dynamic function tracer, by default, _mcount is defined as an
"empty" function, it returns directly without any more action. When
enabling it in user-space, it will jump to a real tracing
function(ftrace_caller), and do the real job for us.
Differ from the static function tracer, dynamic function tracer provides
two functions ftrace_make_call()/ftrace_make_nop() to enable/disable the
tracing of some indicated kernel functions(set_ftrace_filter).
In the kernel version, there is only one "_mcount" string for every
kernel function, so, we just need to match this one in mcount_regex of
scripts/recordmcount.pl.
For more information please look at code and Documentation/trace folder.
Signed-off-by: Michal Simek <monstr@...str.eu>
---
arch/microblaze/Kconfig | 2 +
arch/microblaze/include/asm/ftrace.h | 11 +++
arch/microblaze/kernel/Makefile | 2 +-
arch/microblaze/kernel/ftrace.c | 151 ++++++++++++++++++++++++++++++++++
arch/microblaze/kernel/mcount.S | 13 +++
scripts/recordmcount.pl | 3 +
6 files changed, 181 insertions(+), 1 deletions(-)
create mode 100644 arch/microblaze/kernel/ftrace.c
diff --git a/arch/microblaze/Kconfig b/arch/microblaze/Kconfig
index cccf3ad..102d73a 100644
--- a/arch/microblaze/Kconfig
+++ b/arch/microblaze/Kconfig
@@ -8,6 +8,8 @@ config MICROBLAZE
select HAVE_LMB
select HAVE_FUNCTION_TRACER
select HAVE_FUNCTION_TRACE_MCOUNT_TEST
+ select HAVE_DYNAMIC_FTRACE
+ select HAVE_FTRACE_MCOUNT_RECORD
select USB_ARCH_HAS_EHCI
select ARCH_WANT_OPTIONAL_GPIOLIB
diff --git a/arch/microblaze/include/asm/ftrace.h b/arch/microblaze/include/asm/ftrace.h
index 22beec5..fd2fa2e 100644
--- a/arch/microblaze/include/asm/ftrace.h
+++ b/arch/microblaze/include/asm/ftrace.h
@@ -11,5 +11,16 @@ extern void _mcount(void);
extern void ftrace_call_graph(void);
#endif
+#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 /* CONFIG_FUNCTION_TRACER */
#endif /* _ASM_MICROBLAZE_FTRACE */
diff --git a/arch/microblaze/kernel/Makefile b/arch/microblaze/kernel/Makefile
index d5ee326..b07594e 100644
--- a/arch/microblaze/kernel/Makefile
+++ b/arch/microblaze/kernel/Makefile
@@ -27,6 +27,6 @@ obj-$(CONFIG_HEART_BEAT) += heartbeat.o
obj-$(CONFIG_MODULES) += microblaze_ksyms.o module.o
obj-$(CONFIG_MMU) += misc.o
obj-$(CONFIG_STACKTRACE) += stacktrace.o
-obj-$(CONFIG_FUNCTION_TRACER) += mcount.o
+obj-$(CONFIG_FUNCTION_TRACER) += ftrace.o mcount.o
obj-y += entry$(MMU).o
diff --git a/arch/microblaze/kernel/ftrace.c b/arch/microblaze/kernel/ftrace.c
new file mode 100644
index 0000000..c1889b1
--- /dev/null
+++ b/arch/microblaze/kernel/ftrace.c
@@ -0,0 +1,151 @@
+/*
+ * Ftrace support for Microblaze.
+ *
+ * Copyright (C) 2009 Michal Simek <monstr@...str.eu>
+ * Copyright (C) 2009 PetaLogix
+ *
+ * Based on MIPS and PowerPC ftrace code
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+
+#include <asm/cacheflush.h>
+#include <linux/ftrace.h>
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+/* save value to addr - it is save to do it in asm */
+static int ftrace_modify_code(unsigned long addr, unsigned int value)
+{
+ int faulted = 0;
+
+ __asm__ __volatile__(" 1: swi %2, %1, 0; \
+ addik %0, r0, 0; \
+ 2: \
+ .section .fixup, \"ax\"; \
+ 3: brid 2b; \
+ addik %0, r0, 1; \
+ .previous; \
+ .section __ex_table,\"a\"; \
+ .word 1b,3b; \
+ .previous;" \
+ : "=r" (faulted)
+ : "r" (addr), "r" (value)
+ );
+
+ if (unlikely(faulted))
+ return -EFAULT;
+
+ return 0;
+}
+
+#define MICROBLAZE_NOP 0x80000000
+#define MICROBLAZE_BRI 0xb800000C
+
+static unsigned int recorded; /* if save was or not */
+static unsigned int imm; /* saving whole imm instruction */
+
+/* There are two approaches howto solve ftrace_make nop function - look below */
+#undef USE_FTRACE_NOP
+
+#ifdef USE_FTRACE_NOP
+static unsigned int bralid; /* saving whole bralid instruction */
+#endif
+
+int ftrace_make_nop(struct module *mod,
+ struct dyn_ftrace *rec, unsigned long addr)
+{
+ /* we have this part of code which we are working with
+ * b000c000 imm -16384
+ * b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount>
+ * 80000000 or r0, r0, r0
+ *
+ * The first solution (!USE_FTRACE_NOP-could be called branch solution)
+ * b000c000 bri 12 (0xC - jump to any other instruction)
+ * b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount>
+ * 80000000 or r0, r0, r0
+ * any other instruction
+ *
+ * The second solution (USE_FTRACE_NOP) - no jump just nops
+ * 80000000 or r0, r0, r0
+ * 80000000 or r0, r0, r0
+ * 80000000 or r0, r0, r0
+ */
+ int ret = 0;
+
+ if (recorded == 0) {
+ recorded = 1;
+ imm = *(unsigned int *)rec->ip;
+ pr_debug("%s: imm:0x%x\n", __func__, imm);
+#ifdef USE_FTRACE_NOP
+ bralid = *(unsigned int *)(rec->ip + 4);
+ pr_debug("%s: bralid 0x%x\n", __func__, bralid);
+#endif /* USE_FTRACE_NOP */
+ }
+
+#ifdef USE_FTRACE_NOP
+ ret = ftrace_modify_code(rec->ip, MICROBLAZE_NOP);
+ ret += ftrace_modify_code(rec->ip + 4, MICROBLAZE_NOP);
+#else /* USE_FTRACE_NOP */
+ ret = ftrace_modify_code(rec->ip, MICROBLAZE_BRI);
+#endif /* USE_FTRACE_NOP */
+ return ret;
+}
+
+static int ret_addr; /* initialized as 0 by default */
+
+/* I believe that first is called ftrace_make_nop before this function */
+int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
+{
+ int ret;
+ ret_addr = addr; /* saving where the barrier jump is */
+ pr_debug("%s: addr:0x%x, rec->ip: 0x%x, imm:0x%x\n",
+ __func__, (unsigned int)addr, (unsigned int)rec->ip, imm);
+ ret = ftrace_modify_code(rec->ip, imm);
+#ifdef USE_FTRACE_NOP
+ pr_debug("%s: bralid:0x%x\n", __func__, bralid);
+ ret += ftrace_modify_code(rec->ip + 4, bralid);
+#endif /* USE_FTRACE_NOP */
+ return ret;
+}
+
+int __init ftrace_dyn_arch_init(void *data)
+{
+ /* The return code is retured via data */
+ *(unsigned long *)data = 0;
+
+ return 0;
+}
+
+int ftrace_update_ftrace_func(ftrace_func_t func)
+{
+ unsigned long ip = (unsigned long)(&ftrace_call);
+ unsigned int upper = (unsigned int)func;
+ unsigned int lower = (unsigned int)func;
+ int ret = 0;
+
+ /* create proper saving to ftrace_call poll */
+ upper = 0xb0000000 + (upper >> 16); /* imm func_upper */
+ lower = 0x32800000 + (lower & 0xFFFF); /* addik r20, r0, func_lower */
+
+ pr_debug("%s: func=0x%x, ip=0x%x, upper=0x%x, lower=0x%x\n",
+ __func__, (unsigned int)func, (unsigned int)ip, upper, lower);
+
+ /* save upper and lower code */
+ ret = ftrace_modify_code(ip, upper);
+ ret += ftrace_modify_code(ip + 4, lower);
+
+ /* We just need to remove the rtsd r15, 8 by NOP */
+ BUG_ON(!ret_addr);
+ if (ret_addr)
+ ret += ftrace_modify_code(ret_addr, MICROBLAZE_NOP);
+ else
+ ret = 1; /* fault */
+
+ /* All changes are done - lets do caches consistent */
+ flush_icache();
+ return ret;
+}
+
+#endif /* CONFIG_DYNAMIC_FTRACE */
diff --git a/arch/microblaze/kernel/mcount.S b/arch/microblaze/kernel/mcount.S
index 97eef3e..30aaf8f 100644
--- a/arch/microblaze/kernel/mcount.S
+++ b/arch/microblaze/kernel/mcount.S
@@ -83,6 +83,12 @@ ENTRY(ftrace_stub)
nop;
ENTRY(_mcount)
+#ifdef CONFIG_DYNAMIC_FTRACE
+ENTRY(ftrace_caller)
+ /* MS: It is just barrier which is removed from C code */
+ rtsd r15, 8
+ nop
+#endif /* CONFIG_DYNAMIC_FTRACE */
SAVE_REGS
swi r15, r1, 0;
/* MS: HAVE_FUNCTION_TRACE_MCOUNT_TEST begin of checking */
@@ -90,12 +96,19 @@ ENTRY(_mcount)
bneid r5, end;
nop;
/* MS: HAVE_FUNCTION_TRACE_MCOUNT_TEST end of checking */
+#ifndef CONFIG_DYNAMIC_FTRACE
/* MS: test function trace if is taken or not */
lwi r20, r0, ftrace_trace_function;
addik r6, r0, ftrace_stub;
cmpu r5, r20, r6; /* ftrace_trace_function != ftrace_stub */
beqid r5, end; /* MS: not taken -> jump over */
nop;
+#else /* CONFIG_DYNAMIC_FTRACE */
+NOALIGN_ENTRY(ftrace_call)
+/* instruction for setup imm FUNC_part1, addik r20, r0, FUNC_part2 */
+ nop
+ nop
+#endif /* CONFIG_DYNAMIC_FTRACE */
/* static normal trace */
lwi r6, r1, 120; /* MS: load parent addr */
addik r5, r15, 0; /* MS: load current function addr */
diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
index 090d300..b30dabd 100755
--- a/scripts/recordmcount.pl
+++ b/scripts/recordmcount.pl
@@ -245,6 +245,9 @@ if ($arch eq "x86_64") {
$ld .= " -m elf64_sparc";
$cc .= " -m64";
$objcopy .= " -O elf64-sparc";
+} elsif ($arch eq "microblaze") {
+ # Microblaze calls '_mcount' instead of plain 'mcount'.
+ $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s_mcount\$";
} else {
die "Arch $arch is not supported with CONFIG_FTRACE_MCOUNT_RECORD";
}
--
1.5.5.1
--
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