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Commit 6794c782 authored by Steven Rostedt's avatar Steven Rostedt Committed by Benjamin Herrenschmidt
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powerpc64: port of the function graph tracer 



This is a port of the function graph tracer that was written by
Frederic Weisbecker for the x86.

This only works for PPC64 at the moment and only for static tracing.
PPC32 and dynamic function graph tracing support will come later.

The trace produces a visual calling of functions:

 # tracer: function_graph
 #
 # CPU  DURATION                  FUNCTION CALLS
 # |     |   |                     |   |   |   |
  0)   2.224 us    |                        }
  0) ! 271.024 us  |                      }
  0) ! 320.080 us  |                    }
  0) ! 324.656 us  |                  }
  0) ! 329.136 us  |                }
  0)               |                .put_prev_task_fair() {
  0)               |                  .update_curr() {
  0)   2.240 us    |                    .update_min_vruntime();
  0)   6.512 us    |                  }
  0)   2.528 us    |                  .__enqueue_entity();
  0) + 15.536 us   |                }
  0)               |                .pick_next_task_fair() {
  0)   2.032 us    |                  .__pick_next_entity();
  0)   2.064 us    |                  .__clear_buddies();
  0)               |                  .set_next_entity() {
  0)   2.672 us    |                    .__dequeue_entity();
  0)   6.864 us    |                  }

Geoff Lavand tested on PS3.

Tested-by: default avatarGeoff Levand <geoffrey.levand@am.sony.com>
Acked-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 17be5b3d

arch/powerpc/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -111,6 +111,7 @@ config PPC 
	select HAVE_FTRACE_MCOUNT_RECORD

	select HAVE_DYNAMIC_FTRACE

	select HAVE_FUNCTION_TRACER

	select HAVE_FUNCTION_GRAPH_TRACER if !DYNAMIC_FTRACE && PPC64

	select ARCH_WANT_OPTIONAL_GPIOLIB

	select HAVE_IDE

	select HAVE_IOREMAP_PROT

arch/powerpc/kernel/Makefile

+4 −5
Original line number Diff line number Diff line
@@ -18,12 +18,10 @@ CFLAGS_REMOVE_cputable.o = -pg -mno-sched-epilog 
CFLAGS_REMOVE_prom_init.o = -pg -mno-sched-epilog

CFLAGS_REMOVE_btext.o = -pg -mno-sched-epilog

CFLAGS_REMOVE_prom.o = -pg -mno-sched-epilog



ifdef CONFIG_DYNAMIC_FTRACE

# dynamic ftrace setup.

# do not trace tracer code

CFLAGS_REMOVE_ftrace.o = -pg -mno-sched-epilog

endif



# timers used by tracing

CFLAGS_REMOVE_time.o = -pg -mno-sched-epilog

endif



obj-y				:= cputable.o ptrace.o syscalls.o \
@@ -95,6 +93,7 @@ obj-$(CONFIG_AUDIT) += audit.o 
obj64-$(CONFIG_AUDIT)		+= compat_audit.o



obj-$(CONFIG_DYNAMIC_FTRACE)	+= ftrace.o

obj-$(CONFIG_FUNCTION_GRAPH_TRACER)	+= ftrace.o



obj-$(CONFIG_8XX_MINIMAL_FPEMU) += softemu8xx.o

arch/powerpc/kernel/entry_64.S

+55 −3
Original line number Diff line number Diff line
@@ -931,13 +931,65 @@ _GLOBAL(_mcount) 
	ld	r5,0(r5)

	mtctr	r5

	bctrl



	nop





#ifdef CONFIG_FUNCTION_GRAPH_TRACER

	b	ftrace_graph_caller

#endif

	ld	r0, 128(r1)

	mtlr	r0

	addi	r1, r1, 112

_GLOBAL(ftrace_stub)

	blr



#endif

#endif
 
#endif /* CONFIG_DYNAMIC_FTRACE */



#ifdef CONFIG_FUNCTION_GRAPH_TRACER

ftrace_graph_caller:

	/* load r4 with local address */

	ld	r4, 128(r1)

	subi	r4, r4, MCOUNT_INSN_SIZE



	/* get the parent address */

	ld	r11, 112(r1)

	addi	r3, r11, 16



	bl	.prepare_ftrace_return

	nop



	ld	r0, 128(r1)

	mtlr	r0

	addi	r1, r1, 112

	blr



_GLOBAL(return_to_handler)

	/* need to save return values */

	std	r4,  -32(r1)

	std	r3,  -24(r1)

	/* save TOC */

	std	r2,  -16(r1)

	std	r31, -8(r1)

	mr	r31, r1

	stdu	r1, -112(r1)



	/* update the TOC */

	LOAD_REG_IMMEDIATE(r4,ftrace_return_to_handler)

	ld	r2, 8(r4)



	bl	.ftrace_return_to_handler

	nop



	/* return value has real return address */

	mtlr	r3



	ld	r1, 0(r1)

	ld	r4,  -32(r1)

	ld	r3,  -24(r1)

	ld	r2,  -16(r1)

	ld	r31, -8(r1)



	/* Jump back to real return address */

	blr

#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

#endif /* CONFIG_FUNCTION_TRACER */

arch/powerpc/kernel/ftrace.c

+77 −2
Original line number Diff line number Diff line
@@ -5,6 +5,9 @@ 
 *

 * Thanks goes out to P.A. Semi, Inc for supplying me with a PPC64 box.

 *

 * Added function graph tracer code, taken from x86 that was written

 * by Frederic Weisbecker, and ported to PPC by Steven Rostedt.

 *

 */



#include <linux/spinlock.h>
@@ -20,8 +23,6 @@ 
#include <asm/code-patching.h>

#include <asm/ftrace.h>



static unsigned int ftrace_nop = PPC_NOP_INSTR;



#ifdef CONFIG_PPC32

# define GET_ADDR(addr) addr

#else
@@ -29,6 +30,8 @@ static unsigned int ftrace_nop = PPC_NOP_INSTR; 
# define GET_ADDR(addr) (*(unsigned long *)addr)

#endif



#ifdef CONFIG_DYNAMIC_FTRACE

static unsigned int ftrace_nop = PPC_NOP_INSTR;



static unsigned int ftrace_calc_offset(long ip, long addr)

{
@@ -525,3 +528,75 @@ int __init ftrace_dyn_arch_init(void *data) 


	return 0;

}

#endif /* CONFIG_DYNAMIC_FTRACE */



#ifdef CONFIG_FUNCTION_GRAPH_TRACER



/*

 * Hook the return address and push it in the stack of return addrs

 * in current thread info.

 */

void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)

{

	unsigned long old;

	unsigned long long calltime;

	int faulted;

	struct ftrace_graph_ent trace;

	unsigned long return_hooker = (unsigned long)

				&return_to_handler;



	if (unlikely(atomic_read(&current->tracing_graph_pause)))

		return;



	return_hooker = GET_ADDR(return_hooker);



	/*

	 * Protect against fault, even if it shouldn't

	 * happen. This tool is too much intrusive to

	 * ignore such a protection.

	 */

	asm volatile(

		"1: " PPC_LL "%[old], 0(%[parent])\n"

		"2: " PPC_STL "%[return_hooker], 0(%[parent])\n"

		"   li %[faulted], 0\n"

		"3:"



		".section .fixup, \"ax\"\n"

		"4: li %[faulted], 1\n"

		"   b 3b\n"

		".previous\n"



		".section __ex_table,\"a\"\n"

			PPC_LONG_ALIGN "\n"

			PPC_LONG "1b,4b\n"

			PPC_LONG "2b,4b\n"

		".previous"



		: [old] "=r" (old), [faulted] "=r" (faulted)

		: [parent] "r" (parent), [return_hooker] "r" (return_hooker)

		: "memory"

	);



	if (unlikely(faulted)) {

		ftrace_graph_stop();

		WARN_ON(1);

		return;

	}



	calltime = cpu_clock(raw_smp_processor_id());



	if (ftrace_push_return_trace(old, calltime,

				self_addr, &trace.depth) == -EBUSY) {

		*parent = old;

		return;

	}



	trace.func = self_addr;



	/* Only trace if the calling function expects to */

	if (!ftrace_graph_entry(&trace)) {

		current->curr_ret_stack--;

		*parent = old;

	}

}

#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

arch/powerpc/kernel/process.c

+16 −0
Original line number Diff line number Diff line
@@ -33,6 +33,7 @@ 
#include <linux/mqueue.h>

#include <linux/hardirq.h>

#include <linux/utsname.h>

#include <linux/ftrace.h>

#include <linux/kernel_stat.h>



#include <asm/pgtable.h>
@@ -1008,6 +1009,14 @@ void show_stack(struct task_struct *tsk, unsigned long *stack) 
	unsigned long sp, ip, lr, newsp;

	int count = 0;

	int firstframe = 1;

#ifdef CONFIG_FUNCTION_GRAPH_TRACER

	int curr_frame = current->curr_ret_stack;

	extern void return_to_handler(void);

	unsigned long addr = (unsigned long)return_to_handler;

#ifdef CONFIG_PPC64

	addr = *(unsigned long*)addr;

#endif

#endif



	sp = (unsigned long) stack;

	if (tsk == NULL)
@@ -1030,6 +1039,13 @@ void show_stack(struct task_struct *tsk, unsigned long *stack) 
		ip = stack[STACK_FRAME_LR_SAVE];

		if (!firstframe || ip != lr) {

			printk("["REG"] ["REG"] %pS", sp, ip, (void *)ip);

#ifdef CONFIG_FUNCTION_GRAPH_TRACER

			if (ip == addr && curr_frame >= 0) {

				printk(" (%pS)",

				       (void *)current->ret_stack[curr_frame].ret);

				curr_frame--;

			}

#endif

			if (firstframe)

				printk(" (unreliable)");

			printk("\n");