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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: Geoff Levand <geoffrey.levand@am.sony.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Steven Rostedt 2009-02-09 21:10:27 -08:00 committed by Benjamin Herrenschmidt
parent 17be5b3ddf
commit 6794c78243
6 changed files with 154 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/powerpc/Kconfig
View File

@ -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

9
arch/powerpc/kernel/Makefile
View File

@ -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

58
arch/powerpc/kernel/entry_64.S
View File

@ -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 */

79
arch/powerpc/kernel/ftrace.c
View File

@ -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 */

16
arch/powerpc/kernel/process.c
View File

@ -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");

1
arch/powerpc/kernel/vmlinux.lds.S
View File

@ -58,6 +58,7 @@ SECTIONS
SCHED_TEXT
LOCK_TEXT
KPROBES_TEXT
IRQENTRY_TEXT
#ifdef CONFIG_PPC32
*(.got1)