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microblaze: ftrace: Add dynamic trace support 

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.

Steven ACK that scripts/recordmcount.pl part.

Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Michal Simek <monstr@monstr.eu>
This commit is contained in:
Michal Simek 2009-12-10 14:15:44 +01:00
parent 6d9e60ce30
commit 7d241ff056
6 changed files with 181 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/microblaze/Kconfig
View File

@ -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

11
arch/microblaze/include/asm/ftrace.h
View File

@ -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 */

2
arch/microblaze/kernel/Makefile
View File

@ -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

151
arch/microblaze/kernel/ftrace.c Normal file
View File

@ -0,0 +1,151 @@
/*
* Ftrace support for Microblaze.
*
* Copyright (C) 2009 Michal Simek <monstr@monstr.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 */

13
arch/microblaze/kernel/mcount.S
View File

@ -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 */

3
scripts/recordmcount.pl
View File

@ -295,6 +295,9 @@ 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";
}