Commit 7d241ff0 authored by Michal Simek's avatar Michal Simek
Browse files

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: default avatarSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: default avatarMichal Simek <monstr@monstr.eu>
parent 6d9e60ce

arch/microblaze/Kconfig

+2 −0
Original line number Diff line number Diff line
@@ -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

arch/microblaze/include/asm/ftrace.h

+11 −0
Original line number Diff line number Diff line
@@ -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 */

arch/microblaze/kernel/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -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

arch/microblaze/kernel/ftrace.c

0 → 100644
+151 −0
Original line number Diff line number Diff line 
/*

 * 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 */

arch/microblaze/kernel/mcount.S

+13 −0
Original line number Diff line number Diff line
@@ -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 */