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This patch adds full support for ftrace for PowerPC (both 64 and 32 bit).
This includes dynamic tracing and function filtering.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
---
arch/powerpc/Kconfig | 5
arch/powerpc/kernel/Makefile | 14 ++
arch/powerpc/kernel/entry_32.S | 130 ++++++++++++++++++++++++
arch/powerpc/kernel/entry_64.S | 62 +++++++++++
arch/powerpc/kernel/ftrace.c | 165 +++++++++++++++++++++++++++++++
arch/powerpc/kernel/io.c | 3
arch/powerpc/kernel/irq.c | 6 -
arch/powerpc/kernel/setup_32.c | 11 +-
arch/powerpc/kernel/setup_64.c | 5
arch/powerpc/platforms/powermac/Makefile | 5
kernel/trace/trace_selftest.c | 11 +-
11 files changed, 406 insertions(+), 11 deletions(-)
Index: linux-sched-devel.git/arch/powerpc/kernel/io.c
===================================================================
--- linux-sched-devel.git.orig/arch/powerpc/kernel/io.c 2008-05-14 19:30:53.000000000 -0700
+++ linux-sched-devel.git/arch/powerpc/kernel/io.c 2008-05-14 19:31:48.000000000 -0700
@@ -120,7 +120,8 @@ EXPORT_SYMBOL(_outsl_ns);
#define IO_CHECK_ALIGN(v,a) ((((unsigned long)(v)) & ((a) - 1)) == 0)
-void _memset_io(volatile void __iomem *addr, int c, unsigned long n)
+notrace void
+_memset_io(volatile void __iomem *addr, int c, unsigned long n)
{
void *p = (void __force *)addr;
u32 lc = c;
Index: linux-sched-devel.git/arch/powerpc/kernel/Makefile
===================================================================
--- linux-sched-devel.git.orig/arch/powerpc/kernel/Makefile 2008-05-14 19:30:53.000000000 -0700
+++ linux-sched-devel.git/arch/powerpc/kernel/Makefile 2008-05-14 19:31:56.000000000 -0700
@@ -12,6 +12,18 @@ CFLAGS_prom_init.o += -fPIC
CFLAGS_btext.o += -fPIC
endif
+ifdef CONFIG_FTRACE
+# Do not trace early boot code
+CFLAGS_REMOVE_cputable.o = -pg
+CFLAGS_REMOVE_prom_init.o = ...From: Steven Rostedt <rostedt@goodmis.org> Yikes, that's really expensive. Can't you do a tail call and let the function you end up calling do all the callee-saved register pops onto the stack? That's what I did on sparc. --
Well, at least with dynamic ftrace, it's only expensive when tracing is Not sure PPC has such a thing. I'm only a hobby PPC hacker (did it full time in another life). If there is such a way, I'll be happy to Ack any So that was your secret! ;-) -- Steve --
The PPC32 ABI seems to (unfortunately) suggest that, with mcount, all registers are callee-saved (except for the modifiable-during-function-linkage registers like r0, r11, and r12) -- so mcount has to save the registers that the callee won't (because they're normally volatile). -Scott --
Hi Steven, =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= I don't grok what you're doing with CALL_BACK, you add it in places and subtract in others - and it looks like you could do neither, but I haven't And that. 0x03fffffe should be 0x03fffffc, if you set bit 1 you'll end with a "bla" i= nstruction, ie. branch absolute and link. That shouldn't happen as long as ip and addr = are properly aligned, but still. In fact I think you should just use create_function_call() or create_branch= () from We already have a #define for .long, it's called PPC_LONG (asm/asm-compat.h= ) =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= Can you please put the extern in a header, and the EXPORT_SYMBOL in arch/po= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= Ditto. cheers --=20 Michael Ellerman OzLabs, IBM Australia Development Lab wwweb: http://michael.ellerman.id.au phone: +61 2 6212 1183 (tie line 70 21183) We do not inherit the earth from our ancestors, we borrow it from our children. - S.M.A.R.T Person
Not running at the linked address... might be causing trouble. Ben. --
I figured it was something like that, so I didn't look too deep into it, and decided that it was best just not to trace it. -- Steve --
Hi Michael, I really appreciate this. It's been a few years since I did any real PPC The -pg flag makes calls to the mcount code. I didn't look too deeply, but at least in my first prototypes the early boot up code would crash when calling mcount. I found that simply keeping them from calling mcount made things OK. Perhaps I'm just hiding the problem, but the tracing wont I tried hard to make most of the complex logic stay in generic code. What dynamic ftrace does is at start up the code is simply a nop. Then after initialization of ftrace, it calls kstop-machine that will call into the arch code to convert the nop to a call to a "record_ip" function. That record_ip function will start recording the return address of the mcount function (__builtin_return_address(0)). Then later, once a second the ftraced wakes up and checks if any new functions have been recorded. If they have been, then it calls kstop_machine againg and for each recorded function, it passes in the address that was recorded. The arch is responsible for knowning how to translate the __builtin_return_address(0) into the address of the location of the call, to be able to modify that code. On boot up, all functions call "mcount". The ftraced daemon will convert those calls to nop, and when tracing is enabled, then they will be converted to point directly to the tracing function. Actually, I think Ingo added this into the generic code. I'll see what's Ditto too ;-) Thanks a lot for you feedback! -- Steve --
This patch cleans up the ftrace code in PowerPC based on the comments from
Michael Ellerman.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
---
-0700 |binary
arch/powerpc/kernel/entry_32.S | 11 ++---------
arch/powerpc/kernel/ftrace.c | 8 +++++++-
arch/powerpc/kernel/ppc_ksyms.c | 5 +++++
arch/powerpc/kernel/setup_32.c | 5 -----
arch/powerpc/kernel/setup_64.c | 5 -----
include/asm-powerpc/ftrace.h | 6 ++++++
6 files changed, 20 insertions(+), 20 deletions(-)
Index: linux-tip.git/arch/powerpc/kernel/entry_32.S
===================================================================
--- linux-tip.git.orig/arch/powerpc/kernel/entry_32.S 2008-05-22 09:17:51.000000000 -0700
+++ linux-tip.git/arch/powerpc/kernel/entry_32.S 2008-05-22 09:18:21.000000000 -0700
@@ -1129,18 +1129,11 @@ _GLOBAL(_mcount)
stw r5, 8(r1)
LOAD_REG_ADDR(r5, ftrace_trace_function)
-#if 0
- mtctr r3
- mr r1, r5
- bctrl
-#endif
lwz r5,0(r5)
-#if 1
+
mtctr r5
bctrl
-#else
- bl ftrace_stub
-#endif
+
nop
lwz r6, 8(r1)
Index: linux-tip.git/arch/powerpc/kernel/ftrace.c
===================================================================
--- linux-tip.git.orig/arch/powerpc/kernel/ftrace.c 2008-05-22 09:19:12.000000000 -0700
+++ linux-tip.git/arch/powerpc/kernel/ftrace.c 2008-05-22 09:29:45.000000000 -0700
@@ -51,10 +51,16 @@ notrace unsigned char *ftrace_call_repla
{
static unsigned int op;
+ /*
+ * It would be nice to just use create_function_call, but that will
+ * update the code itself. Here we need to just return the
+ * instruction that is going to be modified, without modifying the
+ * code.
+ */
addr = GET_ADDR(addr);
/* Set to "bl addr" */
- op = 0x48000001 | (ftrace_calc_offset(ip, addr) & 0x03fffffe);
+ op = 0x48000001 | (ftrace_calc_offset(ip, addr) & 0x03fffffc);
/*
* No locking needed, this must be called via kstop_machine
Index: ...Hi Steven, Thanks for that. I posted some patches last week, also in my git tree[1], that should allow you to use create_branch() in your code (and also facilitate some other things I wanted to do). I also added a #define for NOP also. If/when my patches go into powerpc-next I'll do a patch against linux-next for ftrace to use them. cheers [1]: http://git.kernel.org/?p=3Dlinux/kernel/git/mpe/linux-2.6.git;a=3Dsumm= ary --=20 Michael Ellerman OzLabs, IBM Australia Development Lab wwweb: http://michael.ellerman.id.au phone: +61 2 6212 1183 (tie line 70 21183) We do not inherit the earth from our ancestors, we borrow it from our children. - S.M.A.R.T Person