[PATCH 0/5] powerpc: ftrace updates to previous patch series

[PATCH 0/5] powerpc: ftrace updates to previous patch series

[Steven Rostedt]

Paul,

This patch series addresses the issues you brought up as well as
adds some more enhancements and fixes. This series is added on
top of the previous patch series.

The new patches are: (and are posted now)
5987225... powerpc/ppc32: static ftrace fixes for PPC32
382d6db... powerpc: ftrace, use create_branch
d7d0ab8... powerpc: ftrace, added missing icache flush
10ec622... powerpc: ftrace, fix cast aliasing and add code verification
d208ca5... powerpc: ftrace, do nothing in mcount call for dyn ftrace

The patches you already commented on:
5c4f5d7... powerpc/ppc32: ftrace, dynamic ftrace to handle modules
a73af3e... powerpc/ppc64: ftrace, handle module trampolines for dyn ftrace
009104f... powerpc: ftrace, use probe_kernel API to modify code
a352036... powerpc: ftrace, convert to new dynamic ftrace arch API
6d07bb4... powerpc: ftrace, do not latency trace idle

Note, I also fixed the spelling of your name in the change log of commit
a352036... powerpc: ftrace, convert to new dynamic ftrace arch API

I'm only posting the new patches. I've tested this on both my
PPC64 and my PPC32 boxes.  You can test this as well by checking out
my tip/ppc branch which is based off of an older version of tip
and has the ppc dynamic ftrace code enabled. That branch is not to pull
from, but is there for you to try out this code if you like.

The previous patch series, which have not changed except for the 
spelling fix of Paul's last name, can be found here:

  http://lkml.org/lkml/2008/11/20/356


The following patches are in:

  git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace.git

    branch: ppc/ftrace


Steven Rostedt (5):
      powerpc: ftrace, do nothing in mcount call for dyn ftrace
      powerpc: ftrace, fix cast aliasing and add code verification
      powerpc: ftrace, added missing icache flush
      powerpc: ftrace, use create_branch
      powerpc/ppc32: static ftrace fixes for PPC32

----
 arch/powerpc/kernel/Makefile   |    1 +
 arch/powerpc/kernel/entry_32.S |   40 ++-------
 arch/powerpc/kernel/entry_64.S |   12 ---
 arch/powerpc/kernel/ftrace.c   |  182 +++++++++++++++++++---------------------
 arch/powerpc/lib/Makefile      |    3 +
 5 files changed, 98 insertions(+), 140 deletions(-)

[PATCH 1/5] powerpc: ftrace, do nothing in mcount call for dyn ftrace

[Steven Rostedt]

From: Steven Rostedt <srostedt@redhat.com>

Impact: quicken mcount calls that are not replaced by dyn ftrace

Dynamic ftrace no longer does on the fly recording of mcount locations.
The mcount locations are now found at compile time. The mcount
function no longer needs to store registers and call a stub function.
It can now just simply return.

Since there are some functions that do not get converted to a nop
(.init sections and other code that may disappear), this patch should
help speed up that code.

Also, the stub for mcount on PowerPC 32 can not be a simple branch
link register like it is on PowerPC 64. According to the ABI specification:

"The _mcount routine is required to restore the link register from
 the stack so that the profiling code can be inserted transparently,
 whether or not the profiled function saves the link register itself."

This means that we must restore the link register that was used
to make the call to mcount.  The minimal mcount function for PPC32
ends up being:

 mcount:
        mflr    r0
        mtctr   r0
        lwz     r0, 4(r1)
        mtlr    r0
        bctr

Where we move the link register used to call mcount into the
ctr register, and then restore the link register from the stack.
Then we use the ctr register to jump back to the mcount caller.
The r0 register is free for us to use.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
---
 arch/powerpc/kernel/entry_32.S |   40 +++++++++-------------------------------
 arch/powerpc/kernel/entry_64.S |   12 ------------
 2 files changed, 9 insertions(+), 43 deletions(-)

diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 7ecc0d1..6f7eb7e 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -1162,39 +1162,17 @@ machine_check_in_rtas:
 #ifdef CONFIG_DYNAMIC_FTRACE
 _GLOBAL(mcount)
 _GLOBAL(_mcount)
-	stwu	r1,-48(r1)
-	stw	r3, 12(r1)
-	stw	r4, 16(r1)
-	stw	r5, 20(r1)
-	stw	r6, 24(r1)
-	mflr	r3
-	stw	r7, 28(r1)
-	mfcr	r5
-	stw	r8, 32(r1)
-	stw	r9, 36(r1)
-	stw	r10,40(r1)
-	stw	r3, 44(r1)
-	stw	r5, 8(r1)
-	subi	r3, r3, MCOUNT_INSN_SIZE
-	.globl mcount_call
-mcount_call:
-	bl	ftrace_stub
-	nop
-	lwz	r6, 8(r1)
-	lwz	r0, 44(r1)
-	lwz	r3, 12(r1)
+	/*
+	 * It is required that _mcount on PPC32 must preserve the
+	 * link register. But we have r0 to play with. We use r0
+	 * to push the return address back to the caller of mcount
+	 * into the ctr register, restore the link register and
+	 * then jump back using the ctr register.
+	 */
+	mflr	r0
 	mtctr	r0
-	lwz	r4, 16(r1)
-	mtcr	r6
-	lwz	r5, 20(r1)
-	lwz	r6, 24(r1)
-	lwz	r0, 52(r1)
-	lwz	r7, 28(r1)
-	lwz	r8, 32(r1)
+	lwz	r0, 4(r1)
 	mtlr	r0
-	lwz	r9, 36(r1)
-	lwz	r10,40(r1)
-	addi	r1, r1, 48
 	bctr
 
 _GLOBAL(ftrace_caller)
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index e6d5284..b00982e 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -888,18 +888,6 @@ _GLOBAL(enter_prom)
 #ifdef CONFIG_DYNAMIC_FTRACE
 _GLOBAL(mcount)
 _GLOBAL(_mcount)
-	/* Taken from output of objdump from lib64/glibc */
-	mflr	r3
-	stdu	r1, -112(r1)
-	std	r3, 128(r1)
-	subi	r3, r3, MCOUNT_INSN_SIZE
-	.globl mcount_call
-mcount_call:
-	bl	ftrace_stub
-	nop
-	ld	r0, 128(r1)
-	mtlr	r0
-	addi	r1, r1, 112
 	blr
 
 _GLOBAL(ftrace_caller)
-- 
1.5.6.5

-- 

[PATCH 2/5] powerpc: ftrace, fix cast aliasing and add code verification

[Steven Rostedt]

From: Steven Rostedt <srostedt@redhat.com>

Impact: clean up and robustness addition

This patch addresses the comments made by Paul Mackerras.
It removes the type casting between unsigned int and unsigned char
pointers, and replaces them with a use of all unsigned int.

Verification that the jump is indeed made to a trampoline has also
been added.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
---
 arch/powerpc/kernel/ftrace.c |  121 ++++++++++++++++++++++-------------------
 1 files changed, 65 insertions(+), 56 deletions(-)

diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c
index 3271cd6..ea454a0 100644
--- a/arch/powerpc/kernel/ftrace.c
+++ b/arch/powerpc/kernel/ftrace.c
@@ -162,26 +162,25 @@ static int
 __ftrace_make_nop(struct module *mod,
 		  struct dyn_ftrace *rec, unsigned long addr)
 {
-	unsigned char replaced[MCOUNT_INSN_SIZE * 2];
-	unsigned int *op = (unsigned *)&replaced;
-	unsigned char jmp[8];
-	unsigned long *ptr = (unsigned long *)&jmp;
+	unsigned int op;
+	unsigned int jmp[5];
+	unsigned long ptr;
 	unsigned long ip = rec->ip;
 	unsigned long tramp;
 	int offset;
 
 	/* read where this goes */
-	if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
+	if (probe_kernel_read(&op, (void *)ip, sizeof(int)))
 		return -EFAULT;
 
 	/* Make sure that that this is still a 24bit jump */
-	if (!is_bl_op(*op)) {
-		printk(KERN_ERR "Not expected bl: opcode is %x\n", *op);
+	if (!is_bl_op(op)) {
+		printk(KERN_ERR "Not expected bl: opcode is %x\n", op);
 		return -EINVAL;
 	}
 
 	/* lets find where the pointer goes */
-	tramp = find_bl_target(ip, *op);
+	tramp = find_bl_target(ip, op);
 
 	/*
 	 * On PPC64 the trampoline looks like:
@@ -200,19 +199,25 @@ __ftrace_make_nop(struct module *mod,
 	DEBUGP("ip:%lx jumps to %lx r2: %lx", ip, tramp, mod->arch.toc);
 
 	/* Find where the trampoline jumps to */
-	if (probe_kernel_read(jmp, (void *)tramp, 8)) {
+	if (probe_kernel_read(jmp, (void *)tramp, sizeof(jmp))) {
 		printk(KERN_ERR "Failed to read %lx\n", tramp);
 		return -EFAULT;
 	}
 
-	DEBUGP(" %08x %08x",
-	       (unsigned)(*ptr >> 32),
-	       (unsigned)*ptr);
+	DEBUGP(" %08x %08x", jmp[0], jmp[1]);
+
+	/* verify that this is what we expect it to be */
+	if (((jmp[0] & 0xffff0000) != 0x3d820000) ||
+	    ((jmp[1] & 0xffff0000) != 0x398c0000) ||
+	    (jmp[2] != 0xf8410028) ||
+	    (jmp[3] != 0xe96c0020) ||
+	    (jmp[4] != 0xe84c0028)) {
+		printk(KERN_ERR "Not a trampoline\n");
+		return -EINVAL;
+	}
 
-	offset = (unsigned)jmp[2] << 24 |
-		(unsigned)jmp[3] << 16 |
-		(unsigned)jmp[6] << 8 |
-		(unsigned)jmp[7];
+	offset = (unsigned)((unsigned short)jmp[0]) << 16 |
+		(unsigned)((unsigned short)jmp[1]);
 
 	DEBUGP(" %x ", offset);
 
@@ -225,13 +230,13 @@ __ftrace_make_nop(struct module *mod,
 		return -EFAULT;
 	}
 
-	DEBUGP(" %08x %08x\n",
-	       (unsigned)(*ptr >> 32),
-	       (unsigned)*ptr);
+	DEBUGP(" %08x %08x\n", jmp[0], jmp[1]);
+
+	ptr = ((unsigned long)jmp[0] << 32) + jmp[1];
 
 	/* This should match what was called */
-	if (*ptr != GET_ADDR(addr)) {
-		printk(KERN_ERR "addr does not match %lx\n", *ptr);
+	if (ptr != GET_ADDR(addr)) {
+		printk(KERN_ERR "addr does not match %lx\n", ptr);
 		return -EINVAL;
 	}
 
@@ -240,11 +245,11 @@ __ftrace_make_nop(struct module *mod,
 	 *  0xe8, 0x41, 0x00, 0x28   ld r2,40(r1)
 	 * This needs to be turned to a nop too.
 	 */
-	if (probe_kernel_read(replaced, (void *)(ip+4), MCOUNT_INSN_SIZE))
+	if (probe_kernel_read(&op, (void *)(ip+4), MCOUNT_INSN_SIZE))
 		return -EFAULT;
 
-	if (*op != 0xe8410028) {
-		printk(KERN_ERR "Next line is not ld! (%08x)\n", *op);
+	if (op != 0xe8410028) {
+		printk(KERN_ERR "Next line is not ld! (%08x)\n", op);
 		return -EINVAL;
 	}
 
@@ -261,9 +266,9 @@ __ftrace_make_nop(struct module *mod,
 	 *   ld r2,40(r1)
 	 *  1:
 	 */
-	op[0] = 0x48000008;	/* b +8 */
+	op = 0x48000008;	/* b +8 */
 
-	if (probe_kernel_write((void *)ip, replaced, MCOUNT_INSN_SIZE))
+	if (probe_kernel_write((void *)ip, &op, MCOUNT_INSN_SIZE))
 		return -EPERM;
 
 	return 0;
@@ -274,46 +279,52 @@ static int
 __ftrace_make_nop(struct module *mod,
 		  struct dyn_ftrace *rec, unsigned long addr)
 {
-	unsigned char replaced[MCOUNT_INSN_SIZE];
-	unsigned int *op = (unsigned *)&replaced;
-	unsigned char jmp[8];
-	unsigned int *ptr = (unsigned int *)&jmp;
+	unsigned int op;
+	unsigned int jmp[4];
 	unsigned long ip = rec->ip;
 	unsigned long tramp;
-	int offset;
 
-	if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
+	if (probe_kernel_read(&op, (void *)ip, MCOUNT_INSN_SIZE))
 		return -EFAULT;
 
 	/* Make sure that that this is still a 24bit jump */
-	if (!is_bl_op(*op)) {
-		printk(KERN_ERR "Not expected bl: opcode is %x\n", *op);
+	if (!is_bl_op(op)) {
+		printk(KERN_ERR "Not expected bl: opcode is %x\n", op);
 		return -EINVAL;
 	}
 
 	/* lets find where the pointer goes */
-	tramp = find_bl_target(ip, *op);
+	tramp = find_bl_target(ip, op);
 
 	/*
 	 * On PPC32 the trampoline looks like:
-	 * lis r11,sym@ha
-	 * addi r11,r11,sym@l
-	 * mtctr r11
-	 * bctr
+	 *  0x3d, 0x60, 0x00, 0x00  lis r11,sym@ha
+	 *  0x39, 0x6b, 0x00, 0x00  addi r11,r11,sym@l
+	 *  0x7d, 0x69, 0x03, 0xa6  mtctr r11
+	 *  0x4e, 0x80, 0x04, 0x20  bctr
 	 */
 
 	DEBUGP("ip:%lx jumps to %lx", ip, tramp);
 
 	/* Find where the trampoline jumps to */
-	if (probe_kernel_read(jmp, (void *)tramp, 8)) {
+	if (probe_kernel_read(jmp, (void *)tramp, sizeof(jmp))) {
 		printk(KERN_ERR "Failed to read %lx\n", tramp);
 		return -EFAULT;
 	}
 
-	DEBUGP(" %08x %08x ", ptr[0], ptr[1]);
+	DEBUGP(" %08x %08x ", jmp[0], jmp[1]);
+
+	/* verify that this is what we expect it to be */
+	if (((jmp[0] & 0xffff0000) != 0x3d600000) ||
+	    ((jmp[1] & 0xffff0000) != 0x396b0000) ||
+	    (jmp[2] != 0x7d6903a6) ||
+	    (jmp[3] != 0x4e800420)) {
+		printk(KERN_ERR "Not a trampoline\n");
+		return -EINVAL;
+	}
 
-	tramp = (ptr[1] & 0xffff) |
-		((ptr[0] & 0xffff) << 16);
+	tramp = (jmp[1] & 0xffff) |
+		((jmp[0] & 0xffff) << 16);
 	if (tramp & 0x8000)
 		tramp -= 0x10000;
 
@@ -326,9 +337,9 @@ __ftrace_make_nop(struct module *mod,
 		return -EINVAL;
 	}
 
-	op[0] = PPC_NOP_INSTR;
+	op = PPC_NOP_INSTR;
 
-	if (probe_kernel_write((void *)ip, replaced, MCOUNT_INSN_SIZE))
+	if (probe_kernel_write((void *)ip, &op, MCOUNT_INSN_SIZE))
 		return -EPERM;
 
 	return 0;
@@ -384,13 +395,12 @@ int ftrace_make_nop(struct module *mod,
 static int
 __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 {
-	unsigned char replaced[MCOUNT_INSN_SIZE * 2];
-	unsigned int *op = (unsigned *)&replaced;
+	unsigned int op[2];
 	unsigned long ip = rec->ip;
 	unsigned long offset;
 
 	/* read where this goes */
-	if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE * 2))
+	if (probe_kernel_read(op, (void *)ip, MCOUNT_INSN_SIZE * 2))
 		return -EFAULT;
 
 	/*
@@ -425,7 +435,7 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 
 	DEBUGP("write to %lx\n", rec->ip);
 
-	if (probe_kernel_write((void *)ip, replaced, MCOUNT_INSN_SIZE * 2))
+	if (probe_kernel_write((void *)ip, op, MCOUNT_INSN_SIZE * 2))
 		return -EPERM;
 
 	return 0;
@@ -434,18 +444,17 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 static int
 __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 {
-	unsigned char replaced[MCOUNT_INSN_SIZE];
-	unsigned int *op = (unsigned *)&replaced;
+	unsigned int op;
 	unsigned long ip = rec->ip;
 	unsigned long offset;
 
 	/* read where this goes */
-	if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
+	if (probe_kernel_read(&op, (void *)ip, MCOUNT_INSN_SIZE))
 		return -EFAULT;
 
 	/* It should be pointing to a nop */
-	if (op[0] != PPC_NOP_INSTR) {
-		printk(KERN_ERR "Expected NOP but have %x\n", op[0]);
+	if (op != PPC_NOP_INSTR) {
+		printk(KERN_ERR "Expected NOP but have %x\n", op);
 		return -EINVAL;
 	}
 
@@ -465,11 +474,11 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 	}
 
 	/* Set to "bl addr" */
-	op[0] = branch_offset(offset);
+	op = branch_offset(offset);
 
 	DEBUGP("write to %lx\n", rec->ip);
 
-	if (probe_kernel_write((void *)ip, replaced, MCOUNT_INSN_SIZE))
+	if (probe_kernel_write((void *)ip, &op, MCOUNT_INSN_SIZE))
 		return -EPERM;
 
 	return 0;
-- 
1.5.6.5

-- 

[PATCH 3/5] powerpc: ftrace, added missing icache flush

[Steven Rostedt]

From: Steven Rostedt <srostedt@redhat.com>

Impact: fix to PowerPC code modification

After modifying code it is essential to flush the icache. This patch
adds the missing flush.

Reported-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
---
 arch/powerpc/kernel/ftrace.c |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c
index ea454a0..a4640e4 100644
--- a/arch/powerpc/kernel/ftrace.c
+++ b/arch/powerpc/kernel/ftrace.c
@@ -271,6 +271,9 @@ __ftrace_make_nop(struct module *mod,
 	if (probe_kernel_write((void *)ip, &op, MCOUNT_INSN_SIZE))
 		return -EPERM;
 
+
+	flush_icache_range(ip, ip + 8);
+
 	return 0;
 }
 
@@ -342,6 +345,8 @@ __ftrace_make_nop(struct module *mod,
 	if (probe_kernel_write((void *)ip, &op, MCOUNT_INSN_SIZE))
 		return -EPERM;
 
+	flush_icache_range(ip, ip + 8);
+
 	return 0;
 }
 #endif /* PPC64 */
@@ -438,6 +443,8 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 	if (probe_kernel_write((void *)ip, op, MCOUNT_INSN_SIZE * 2))
 		return -EPERM;
 
+	flush_icache_range(ip, ip + 8);
+
 	return 0;
 }
 #else
@@ -481,6 +488,8 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 	if (probe_kernel_write((void *)ip, &op, MCOUNT_INSN_SIZE))
 		return -EPERM;
 
+	flush_icache_range(ip, ip + 8);
+
 	return 0;
 }
 #endif /* CONFIG_PPC64 */
-- 
1.5.6.5

-- 

[PATCH 4/5] powerpc: ftrace, use create_branch

[Steven Rostedt]

From: Steven Rostedt <srostedt@redhat.com>

Impact: clean up

Paul Mackerras pointed out that the code to determine if the branch
can reach the destination is incorrect. Michael Ellerman suggested
to pull out the code from create_branch and use that.

Simply using create_branch is probably the best.

Reported-by: Michael Ellerman <michael@ellerman.id.au>
Reported-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
---
 arch/powerpc/kernel/ftrace.c |   54 +++++++++--------------------------------
 1 files changed, 12 insertions(+), 42 deletions(-)

diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c
index a4640e4..5355244 100644
--- a/arch/powerpc/kernel/ftrace.c
+++ b/arch/powerpc/kernel/ftrace.c
@@ -114,19 +114,9 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code,
  */
 static int test_24bit_addr(unsigned long ip, unsigned long addr)
 {
-	long diff;
 
-	/*
-	 * Can we get to addr from ip in 24 bits?
-	 *  (26 really, since we mulitply by 4 for 4 byte alignment)
-	 */
-	diff = addr - ip;
-
-	/*
-	 * Return true if diff is less than 1 << 25
-	 *  and greater than -1 << 26.
-	 */
-	return (diff < (1 << 25)) && (diff > (-1 << 26));
+	/* use the create_branch to verify that this offset can be branched */
+	return create_branch((unsigned int *)ip, addr, 0);
 }
 
 static int is_bl_op(unsigned int op)
@@ -134,11 +124,6 @@ static int is_bl_op(unsigned int op)
 	return (op & 0xfc000003) == 0x48000001;
 }
 
-static int test_offset(unsigned long offset)
-{
-	return (offset + 0x2000000 > 0x3ffffff) || ((offset & 3) != 0);
-}
-
 static unsigned long find_bl_target(unsigned long ip, unsigned int op)
 {
 	static int offset;
@@ -151,12 +136,6 @@ static unsigned long find_bl_target(unsigned long ip, unsigned int op)
 	return ip + (long)offset;
 }
 
-static unsigned int branch_offset(unsigned long offset)
-{
-	/* return "bl ip+offset" */
-	return 0x48000001 | (offset & 0x03fffffc);
-}
-
 #ifdef CONFIG_PPC64
 static int
 __ftrace_make_nop(struct module *mod,
@@ -402,7 +381,6 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 {
 	unsigned int op[2];
 	unsigned long ip = rec->ip;
-	unsigned long offset;
 
 	/* read where this goes */
 	if (probe_kernel_read(op, (void *)ip, MCOUNT_INSN_SIZE * 2))
@@ -424,17 +402,14 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 		return -EINVAL;
 	}
 
-	/* now calculate a jump to the ftrace caller trampoline */
-	offset = rec->arch.mod->arch.tramp - ip;
-
-	if (test_offset(offset)) {
-		printk(KERN_ERR "REL24 %li out of range!\n",
-		       (long int)offset);
+	/* create the branch to the trampoline */
+	op[0] = create_branch((unsigned int *)ip,
+			      rec->arch.mod->arch.tramp, BRANCH_SET_LINK);
+	if (!op[0]) {
+		printk(KERN_ERR "REL24 out of range!\n");
 		return -EINVAL;
 	}
 
-	/* Set to "bl addr" */
-	op[0] = branch_offset(offset);
 	/* ld r2,40(r1) */
 	op[1] = 0xe8410028;
 
@@ -453,7 +428,6 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 {
 	unsigned int op;
 	unsigned long ip = rec->ip;
-	unsigned long offset;
 
 	/* read where this goes */
 	if (probe_kernel_read(&op, (void *)ip, MCOUNT_INSN_SIZE))
@@ -471,18 +445,14 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 		return -EINVAL;
 	}
 
-	/* now calculate a jump to the ftrace caller trampoline */
-	offset = rec->arch.mod->arch.tramp - ip;
-
-	if (test_offset(offset)) {
-		printk(KERN_ERR "REL24 %li out of range!\n",
-		       (long int)offset);
+	/* create the branch to the trampoline */
+	op = create_branch((unsigned int *)ip,
+			   rec->arch.mod->arch.tramp, BRANCH_SET_LINK);
+	if (!op) {
+		printk(KERN_ERR "REL24 out of range!\n");
 		return -EINVAL;
 	}
 
-	/* Set to "bl addr" */
-	op = branch_offset(offset);
-
 	DEBUGP("write to %lx\n", rec->ip);
 
 	if (probe_kernel_write((void *)ip, &op, MCOUNT_INSN_SIZE))
-- 
1.5.6.5

-- 

Re: [PATCH 4/5] powerpc: ftrace, use create_branch

[Michael Ellerman]

[-- Attachment #1: Type: text/plain, Size: 826 bytes --]

On Wed, 2008-11-26 at 16:58 -0500, Steven Rostedt wrote:
> plain text document attachment
> (0004-powerpc-ftrace-use-create_branch.patch)
> From: Steven Rostedt <srostedt@redhat.com>
> 
> Impact: clean up
> 
> Paul Mackerras pointed out that the code to determine if the branch
> can reach the destination is incorrect. Michael Ellerman suggested
> to pull out the code from create_branch and use that.
> 
> Simply using create_branch is probably the best.

You're right, that's a lot simpler :)

Acked-by: Michael Ellerman <michael@ellerman.id.au>

cheers

-- 
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

[-- Attachment #2: This is a digitally signed message part --]
[-- Type: application/pgp-signature, Size: 197 bytes --]

[PATCH 5/5] powerpc/ppc32: static ftrace fixes for PPC32

[Steven Rostedt]

From: Steven Rostedt <rostedt@gollum.(none)>

Impact: fix for PowerPC 32 code

There were some early init code that was not safe for static
ftrace to boot on my PowerBook. This code must only use relative
addressing, and static mcount performs a compare of the
ftrace_trace_function pointer, and gets that with an absolute address.
In the early init boot up code, this will cause a fault.

This patch removes tracing from the files containing the offending
functions.

Signed-off-by: Steven Rostedt <rostedt@gollum.(none)>
---
 arch/powerpc/kernel/Makefile |    1 +
 arch/powerpc/lib/Makefile    |    3 +++
 2 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index 92673b4..d17edb4 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -17,6 +17,7 @@ ifdef CONFIG_FUNCTION_TRACER
 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.
diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
index d69912c..8db3527 100644
--- a/arch/powerpc/lib/Makefile
+++ b/arch/powerpc/lib/Makefile
@@ -6,6 +6,9 @@ ifeq ($(CONFIG_PPC64),y)
 EXTRA_CFLAGS		+= -mno-minimal-toc
 endif
 
+CFLAGS_REMOVE_code-patching.o = -pg
+CFLAGS_REMOVE_feature-fixups.o = -pg
+
 obj-y			:= string.o alloc.o \
 			   checksum_$(CONFIG_WORD_SIZE).o
 obj-$(CONFIG_PPC32)	+= div64.o copy_32.o crtsavres.o
-- 
1.5.6.5

-- 

Re: [PATCH 5/5] powerpc/ppc32: static ftrace fixes for PPC32

[Steven Rostedt]

On Wed, 26 Nov 2008, Steven Rostedt wrote:

> From: Steven Rostedt <rostedt@gollum.(none)>

Ah, I need to add GIT_AUTHOR on my PowerBook. And yes, it's name
is gollum ;-)

I'll fix this and push it again.

-- Steve

> 
> Impact: fix for PowerPC 32 code
> 
> There were some early init code that was not safe for static
> ftrace to boot on my PowerBook. This code must only use relative
> addressing, and static mcount performs a compare of the
> ftrace_trace_function pointer, and gets that with an absolute address.
> In the early init boot up code, this will cause a fault.
> 
> This patch removes tracing from the files containing the offending
> functions.
> 
> Signed-off-by: Steven Rostedt <rostedt@gollum.(none)>
> ---
>  arch/powerpc/kernel/Makefile |    1 +
>  arch/powerpc/lib/Makefile    |    3 +++
>  2 files changed, 4 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
> index 92673b4..d17edb4 100644
> --- a/arch/powerpc/kernel/Makefile
> +++ b/arch/powerpc/kernel/Makefile
> @@ -17,6 +17,7 @@ ifdef CONFIG_FUNCTION_TRACER
>  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.
> diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
> index d69912c..8db3527 100644
> --- a/arch/powerpc/lib/Makefile
> +++ b/arch/powerpc/lib/Makefile
> @@ -6,6 +6,9 @@ ifeq ($(CONFIG_PPC64),y)
>  EXTRA_CFLAGS		+= -mno-minimal-toc
>  endif
>  
> +CFLAGS_REMOVE_code-patching.o = -pg
> +CFLAGS_REMOVE_feature-fixups.o = -pg
> +
>  obj-y			:= string.o alloc.o \
>  			   checksum_$(CONFIG_WORD_SIZE).o
>  obj-$(CONFIG_PPC32)	+= div64.o copy_32.o crtsavres.o
> -- 
> 1.5.6.5
> 
> -- 
> 
> 

Re: [PATCH 0/5] powerpc: ftrace updates to previous patch series

[Steven Rostedt]

On Wed, 26 Nov 2008, Steven Rostedt wrote:

> Paul,
> 
> This patch series addresses the issues you brought up as well as
> adds some more enhancements and fixes. This series is added on
> top of the previous patch series.
> 
> The new patches are: (and are posted now)
> 5987225... powerpc/ppc32: static ftrace fixes for PPC32

The new commit id with the fix in Author and SoB is:
fd90db4bdc1ccf71927365cd634188cec4d7b151
 powerpc/ppc32: static ftrace fixes for 

-- Steve

> 382d6db... powerpc: ftrace, use create_branch
> d7d0ab8... powerpc: ftrace, added missing icache flush
> 10ec622... powerpc: ftrace, fix cast aliasing and add code verification
> d208ca5... powerpc: ftrace, do nothing in mcount call for dyn ftrace
> 
> The patches you already commented on:
> 5c4f5d7... powerpc/ppc32: ftrace, dynamic ftrace to handle modules
> a73af3e... powerpc/ppc64: ftrace, handle module trampolines for dyn ftrace
> 009104f... powerpc: ftrace, use probe_kernel API to modify code
> a352036... powerpc: ftrace, convert to new dynamic ftrace arch API
> 6d07bb4... powerpc: ftrace, do not latency trace idle
> 

Re: [PATCH 0/5] powerpc: ftrace updates to previous patch series

[Ingo Molnar]

* Steven Rostedt <rostedt@goodmis.org> wrote:

> On Wed, 26 Nov 2008, Steven Rostedt wrote:
> 
> > Paul,
> > 
> > This patch series addresses the issues you brought up as well as
> > adds some more enhancements and fixes. This series is added on
> > top of the previous patch series.
> > 
> > The new patches are: (and are posted now)
> > 5987225... powerpc/ppc32: static ftrace fixes for PPC32
> 
> The new commit id with the fix in Author and SoB is:
> fd90db4bdc1ccf71927365cd634188cec4d7b151
>  powerpc/ppc32: static ftrace fixes for 

Steve, you rebased the previous commits, and that's a no-no. I sorted it 
all out, find below the stable URI for stuff that we'd like Paul to pull 
shortly before the merge window.

Thanks,

	Ingo

-------------------------->
Please pull the latest tracing/powerpc git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git tracing/powerpc

 Thanks,

	Ingo

------------------>
Steven Rostedt (10):
      powerpc: ftrace, do not latency trace idle
      powerpc: ftrace, convert to new dynamic ftrace arch API
      powerpc: ftrace, use probe_kernel API to modify code
      powerpc/ppc64: ftrace, handle module trampolines for dyn ftrace
      powerpc/ppc32: ftrace, dynamic ftrace to handle modules
      powerpc: ftrace, do nothing in mcount call for dyn ftrace
      powerpc: ftrace, fix cast aliasing and add code verification
      powerpc: ftrace, added missing icache flush
      powerpc: ftrace, use create_branch
      powerpc/ppc32: static ftrace fixes for PPC32


 arch/powerpc/include/asm/ftrace.h |   14 +-
 arch/powerpc/include/asm/module.h |   16 ++-
 arch/powerpc/kernel/Makefile      |    1 +
 arch/powerpc/kernel/entry_32.S    |   40 +---
 arch/powerpc/kernel/entry_64.S    |   12 -
 arch/powerpc/kernel/ftrace.c      |  461 +++++++++++++++++++++++++++++++++----
 arch/powerpc/kernel/idle.c        |    5 +
 arch/powerpc/kernel/module_32.c   |   10 +
 arch/powerpc/kernel/module_64.c   |   13 +
 arch/powerpc/lib/Makefile         |    3 +
 10 files changed, 490 insertions(+), 85 deletions(-)

diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h
index b298f7a..e5f2ae8 100644
--- a/arch/powerpc/include/asm/ftrace.h
+++ b/arch/powerpc/include/asm/ftrace.h
@@ -7,7 +7,19 @@
 
 #ifndef __ASSEMBLY__
 extern void _mcount(void);
-#endif
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+static inline unsigned long ftrace_call_adjust(unsigned long addr)
+{
+       /* reloction of mcount call site is the same as the address */
+       return addr;
+}
+
+struct dyn_arch_ftrace {
+	struct module *mod;
+};
+#endif /*  CONFIG_DYNAMIC_FTRACE */
+#endif /* __ASSEMBLY__ */
 
 #endif
 
diff --git a/arch/powerpc/include/asm/module.h b/arch/powerpc/include/asm/module.h
index e5f14b1..0845488 100644
--- a/arch/powerpc/include/asm/module.h
+++ b/arch/powerpc/include/asm/module.h
@@ -34,11 +34,19 @@ struct mod_arch_specific {
 #ifdef __powerpc64__
 	unsigned int stubs_section;	/* Index of stubs section in module */
 	unsigned int toc_section;	/* What section is the TOC? */
-#else
+#ifdef CONFIG_DYNAMIC_FTRACE
+	unsigned long toc;
+	unsigned long tramp;
+#endif
+
+#else /* powerpc64 */
 	/* Indices of PLT sections within module. */
 	unsigned int core_plt_section;
 	unsigned int init_plt_section;
+#ifdef CONFIG_DYNAMIC_FTRACE
+	unsigned long tramp;
 #endif
+#endif /* powerpc64 */
 
 	/* List of BUG addresses, source line numbers and filenames */
 	struct list_head bug_list;
@@ -68,6 +76,12 @@ struct mod_arch_specific {
 #    endif	/* MODULE */
 #endif
 
+#ifdef CONFIG_DYNAMIC_FTRACE
+#    ifdef MODULE
+	asm(".section .ftrace.tramp,\"ax\",@nobits; .align 3; .previous");
+#    endif	/* MODULE */
+#endif
+
 
 struct exception_table_entry;
 void sort_ex_table(struct exception_table_entry *start,
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index 92673b4..d17edb4 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -17,6 +17,7 @@ ifdef CONFIG_FUNCTION_TRACER
 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.
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 7ecc0d1..6f7eb7e 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -1162,39 +1162,17 @@ machine_check_in_rtas:
 #ifdef CONFIG_DYNAMIC_FTRACE
 _GLOBAL(mcount)
 _GLOBAL(_mcount)
-	stwu	r1,-48(r1)
-	stw	r3, 12(r1)
-	stw	r4, 16(r1)
-	stw	r5, 20(r1)
-	stw	r6, 24(r1)
-	mflr	r3
-	stw	r7, 28(r1)
-	mfcr	r5
-	stw	r8, 32(r1)
-	stw	r9, 36(r1)
-	stw	r10,40(r1)
-	stw	r3, 44(r1)
-	stw	r5, 8(r1)
-	subi	r3, r3, MCOUNT_INSN_SIZE
-	.globl mcount_call
-mcount_call:
-	bl	ftrace_stub
-	nop
-	lwz	r6, 8(r1)
-	lwz	r0, 44(r1)
-	lwz	r3, 12(r1)
+	/*
+	 * It is required that _mcount on PPC32 must preserve the
+	 * link register. But we have r0 to play with. We use r0
+	 * to push the return address back to the caller of mcount
+	 * into the ctr register, restore the link register and
+	 * then jump back using the ctr register.
+	 */
+	mflr	r0
 	mtctr	r0
-	lwz	r4, 16(r1)
-	mtcr	r6
-	lwz	r5, 20(r1)
-	lwz	r6, 24(r1)
-	lwz	r0, 52(r1)
-	lwz	r7, 28(r1)
-	lwz	r8, 32(r1)
+	lwz	r0, 4(r1)
 	mtlr	r0
-	lwz	r9, 36(r1)
-	lwz	r10,40(r1)
-	addi	r1, r1, 48
 	bctr
 
 _GLOBAL(ftrace_caller)
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index e6d5284..b00982e 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -888,18 +888,6 @@ _GLOBAL(enter_prom)
 #ifdef CONFIG_DYNAMIC_FTRACE
 _GLOBAL(mcount)
 _GLOBAL(_mcount)
-	/* Taken from output of objdump from lib64/glibc */
-	mflr	r3
-	stdu	r1, -112(r1)
-	std	r3, 128(r1)
-	subi	r3, r3, MCOUNT_INSN_SIZE
-	.globl mcount_call
-mcount_call:
-	bl	ftrace_stub
-	nop
-	ld	r0, 128(r1)
-	mtlr	r0
-	addi	r1, r1, 112
 	blr
 
 _GLOBAL(ftrace_caller)
diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c
index f4b006e..5355244 100644
--- a/arch/powerpc/kernel/ftrace.c
+++ b/arch/powerpc/kernel/ftrace.c
@@ -9,22 +9,30 @@
 
 #include <linux/spinlock.h>
 #include <linux/hardirq.h>
+#include <linux/uaccess.h>
+#include <linux/module.h>
 #include <linux/ftrace.h>
 #include <linux/percpu.h>
 #include <linux/init.h>
 #include <linux/list.h>
 
 #include <asm/cacheflush.h>
+#include <asm/code-patching.h>
 #include <asm/ftrace.h>
 
+#if 0
+#define DEBUGP printk
+#else
+#define DEBUGP(fmt , ...)	do { } while (0)
+#endif
 
-static unsigned int ftrace_nop = 0x60000000;
+static unsigned int ftrace_nop = PPC_NOP_INSTR;
 
 #ifdef CONFIG_PPC32
 # define GET_ADDR(addr) addr
 #else
 /* PowerPC64's functions are data that points to the functions */
-# define GET_ADDR(addr) *(unsigned long *)addr
+# define GET_ADDR(addr) (*(unsigned long *)addr)
 #endif
 
 
@@ -33,12 +41,12 @@ static unsigned int ftrace_calc_offset(long ip, long addr)
 	return (int)(addr - ip);
 }
 
-unsigned char *ftrace_nop_replace(void)
+static unsigned char *ftrace_nop_replace(void)
 {
 	return (char *)&ftrace_nop;
 }
 
-unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
+static unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
 {
 	static unsigned int op;
 
@@ -68,49 +76,422 @@ unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
 # define _ASM_PTR	" .long "
 #endif
 
-int
+static int
 ftrace_modify_code(unsigned long ip, unsigned char *old_code,
 		   unsigned char *new_code)
 {
-	unsigned replaced;
-	unsigned old = *(unsigned *)old_code;
-	unsigned new = *(unsigned *)new_code;
-	int faulted = 0;
+	unsigned char replaced[MCOUNT_INSN_SIZE];
 
 	/*
 	 * Note: Due to modules and __init, code can
 	 *  disappear and change, we need to protect against faulting
-	 *  as well as code changing.
+	 *  as well as code changing. We do this by using the
+	 *  probe_kernel_* functions.
 	 *
 	 * No real locking needed, this code is run through
-	 * kstop_machine.
+	 * kstop_machine, or before SMP starts.
 	 */
-	asm volatile (
-		"1: lwz		%1, 0(%2)\n"
-		"   cmpw	%1, %5\n"
-		"   bne		2f\n"
-		"   stwu	%3, 0(%2)\n"
-		"2:\n"
-		".section .fixup, \"ax\"\n"
-		"3:	li %0, 1\n"
-		"	b 2b\n"
-		".previous\n"
-		".section __ex_table,\"a\"\n"
-		_ASM_ALIGN "\n"
-		_ASM_PTR "1b, 3b\n"
-		".previous"
-		: "=r"(faulted), "=r"(replaced)
-		: "r"(ip), "r"(new),
-		  "0"(faulted), "r"(old)
-		: "memory");
-
-	if (replaced != old && replaced != new)
-		faulted = 2;
-
-	if (!faulted)
-		flush_icache_range(ip, ip + 8);
-
-	return faulted;
+
+	/* read the text we want to modify */
+	if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
+		return -EFAULT;
+
+	/* Make sure it is what we expect it to be */
+	if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
+		return -EINVAL;
+
+	/* replace the text with the new text */
+	if (probe_kernel_write((void *)ip, new_code, MCOUNT_INSN_SIZE))
+		return -EPERM;
+
+	flush_icache_range(ip, ip + 8);
+
+	return 0;
+}
+
+/*
+ * Helper functions that are the same for both PPC64 and PPC32.
+ */
+static int test_24bit_addr(unsigned long ip, unsigned long addr)
+{
+
+	/* use the create_branch to verify that this offset can be branched */
+	return create_branch((unsigned int *)ip, addr, 0);
+}
+
+static int is_bl_op(unsigned int op)
+{
+	return (op & 0xfc000003) == 0x48000001;
+}
+
+static unsigned long find_bl_target(unsigned long ip, unsigned int op)
+{
+	static int offset;
+
+	offset = (op & 0x03fffffc);
+	/* make it signed */
+	if (offset & 0x02000000)
+		offset |= 0xfe000000;
+
+	return ip + (long)offset;
+}
+
+#ifdef CONFIG_PPC64
+static int
+__ftrace_make_nop(struct module *mod,
+		  struct dyn_ftrace *rec, unsigned long addr)
+{
+	unsigned int op;
+	unsigned int jmp[5];
+	unsigned long ptr;
+	unsigned long ip = rec->ip;
+	unsigned long tramp;
+	int offset;
+
+	/* read where this goes */
+	if (probe_kernel_read(&op, (void *)ip, sizeof(int)))
+		return -EFAULT;
+
+	/* Make sure that that this is still a 24bit jump */
+	if (!is_bl_op(op)) {
+		printk(KERN_ERR "Not expected bl: opcode is %x\n", op);
+		return -EINVAL;
+	}
+
+	/* lets find where the pointer goes */
+	tramp = find_bl_target(ip, op);
+
+	/*
+	 * On PPC64 the trampoline looks like:
+	 * 0x3d, 0x82, 0x00, 0x00,    addis   r12,r2, <high>
+	 * 0x39, 0x8c, 0x00, 0x00,    addi    r12,r12, <low>
+	 *   Where the bytes 2,3,6 and 7 make up the 32bit offset
+	 *   to the TOC that holds the pointer.
+	 *   to jump to.
+	 * 0xf8, 0x41, 0x00, 0x28,    std     r2,40(r1)
+	 * 0xe9, 0x6c, 0x00, 0x20,    ld      r11,32(r12)
+	 *   The actually address is 32 bytes from the offset
+	 *   into the TOC.
+	 * 0xe8, 0x4c, 0x00, 0x28,    ld      r2,40(r12)
+	 */
+
+	DEBUGP("ip:%lx jumps to %lx r2: %lx", ip, tramp, mod->arch.toc);
+
+	/* Find where the trampoline jumps to */
+	if (probe_kernel_read(jmp, (void *)tramp, sizeof(jmp))) {
+		printk(KERN_ERR "Failed to read %lx\n", tramp);
+		return -EFAULT;
+	}
+
+	DEBUGP(" %08x %08x", jmp[0], jmp[1]);
+
+	/* verify that this is what we expect it to be */
+	if (((jmp[0] & 0xffff0000) != 0x3d820000) ||
+	    ((jmp[1] & 0xffff0000) != 0x398c0000) ||
+	    (jmp[2] != 0xf8410028) ||
+	    (jmp[3] != 0xe96c0020) ||
+	    (jmp[4] != 0xe84c0028)) {
+		printk(KERN_ERR "Not a trampoline\n");
+		return -EINVAL;
+	}
+
+	offset = (unsigned)((unsigned short)jmp[0]) << 16 |
+		(unsigned)((unsigned short)jmp[1]);
+
+	DEBUGP(" %x ", offset);
+
+	/* get the address this jumps too */
+	tramp = mod->arch.toc + offset + 32;
+	DEBUGP("toc: %lx", tramp);
+
+	if (probe_kernel_read(jmp, (void *)tramp, 8)) {
+		printk(KERN_ERR "Failed to read %lx\n", tramp);
+		return -EFAULT;
+	}
+
+	DEBUGP(" %08x %08x\n", jmp[0], jmp[1]);
+
+	ptr = ((unsigned long)jmp[0] << 32) + jmp[1];
+
+	/* This should match what was called */
+	if (ptr != GET_ADDR(addr)) {
+		printk(KERN_ERR "addr does not match %lx\n", ptr);
+		return -EINVAL;
+	}
+
+	/*
+	 * We want to nop the line, but the next line is
+	 *  0xe8, 0x41, 0x00, 0x28   ld r2,40(r1)
+	 * This needs to be turned to a nop too.
+	 */
+	if (probe_kernel_read(&op, (void *)(ip+4), MCOUNT_INSN_SIZE))
+		return -EFAULT;
+
+	if (op != 0xe8410028) {
+		printk(KERN_ERR "Next line is not ld! (%08x)\n", op);
+		return -EINVAL;
+	}
+
+	/*
+	 * Milton Miller pointed out that we can not blindly do nops.
+	 * If a task was preempted when calling a trace function,
+	 * the nops will remove the way to restore the TOC in r2
+	 * and the r2 TOC will get corrupted.
+	 */
+
+	/*
+	 * Replace:
+	 *   bl <tramp>  <==== will be replaced with "b 1f"
+	 *   ld r2,40(r1)
+	 *  1:
+	 */
+	op = 0x48000008;	/* b +8 */
+
+	if (probe_kernel_write((void *)ip, &op, MCOUNT_INSN_SIZE))
+		return -EPERM;
+
+
+	flush_icache_range(ip, ip + 8);
+
+	return 0;
+}
+
+#else /* !PPC64 */
+static int
+__ftrace_make_nop(struct module *mod,
+		  struct dyn_ftrace *rec, unsigned long addr)
+{
+	unsigned int op;
+	unsigned int jmp[4];
+	unsigned long ip = rec->ip;
+	unsigned long tramp;
+
+	if (probe_kernel_read(&op, (void *)ip, MCOUNT_INSN_SIZE))
+		return -EFAULT;
+
+	/* Make sure that that this is still a 24bit jump */
+	if (!is_bl_op(op)) {
+		printk(KERN_ERR "Not expected bl: opcode is %x\n", op);
+		return -EINVAL;
+	}
+
+	/* lets find where the pointer goes */
+	tramp = find_bl_target(ip, op);
+
+	/*
+	 * On PPC32 the trampoline looks like:
+	 *  0x3d, 0x60, 0x00, 0x00  lis r11,sym@ha
+	 *  0x39, 0x6b, 0x00, 0x00  addi r11,r11,sym@l
+	 *  0x7d, 0x69, 0x03, 0xa6  mtctr r11
+	 *  0x4e, 0x80, 0x04, 0x20  bctr
+	 */
+
+	DEBUGP("ip:%lx jumps to %lx", ip, tramp);
+
+	/* Find where the trampoline jumps to */
+	if (probe_kernel_read(jmp, (void *)tramp, sizeof(jmp))) {
+		printk(KERN_ERR "Failed to read %lx\n", tramp);
+		return -EFAULT;
+	}
+
+	DEBUGP(" %08x %08x ", jmp[0], jmp[1]);
+
+	/* verify that this is what we expect it to be */
+	if (((jmp[0] & 0xffff0000) != 0x3d600000) ||
+	    ((jmp[1] & 0xffff0000) != 0x396b0000) ||
+	    (jmp[2] != 0x7d6903a6) ||
+	    (jmp[3] != 0x4e800420)) {
+		printk(KERN_ERR "Not a trampoline\n");
+		return -EINVAL;
+	}
+
+	tramp = (jmp[1] & 0xffff) |
+		((jmp[0] & 0xffff) << 16);
+	if (tramp & 0x8000)
+		tramp -= 0x10000;
+
+	DEBUGP(" %x ", tramp);
+
+	if (tramp != addr) {
+		printk(KERN_ERR
+		       "Trampoline location %08lx does not match addr\n",
+		       tramp);
+		return -EINVAL;
+	}
+
+	op = PPC_NOP_INSTR;
+
+	if (probe_kernel_write((void *)ip, &op, MCOUNT_INSN_SIZE))
+		return -EPERM;
+
+	flush_icache_range(ip, ip + 8);
+
+	return 0;
+}
+#endif /* PPC64 */
+
+int ftrace_make_nop(struct module *mod,
+		    struct dyn_ftrace *rec, unsigned long addr)
+{
+	unsigned char *old, *new;
+	unsigned long ip = rec->ip;
+
+	/*
+	 * If the calling address is more that 24 bits away,
+	 * then we had to use a trampoline to make the call.
+	 * Otherwise just update the call site.
+	 */
+	if (test_24bit_addr(ip, addr)) {
+		/* within range */
+		old = ftrace_call_replace(ip, addr);
+		new = ftrace_nop_replace();
+		return ftrace_modify_code(ip, old, new);
+	}
+
+	/*
+	 * Out of range jumps are called from modules.
+	 * We should either already have a pointer to the module
+	 * or it has been passed in.
+	 */
+	if (!rec->arch.mod) {
+		if (!mod) {
+			printk(KERN_ERR "No module loaded addr=%lx\n",
+			       addr);
+			return -EFAULT;
+		}
+		rec->arch.mod = mod;
+	} else if (mod) {
+		if (mod != rec->arch.mod) {
+			printk(KERN_ERR
+			       "Record mod %p not equal to passed in mod %p\n",
+			       rec->arch.mod, mod);
+			return -EINVAL;
+		}
+		/* nothing to do if mod == rec->arch.mod */
+	} else
+		mod = rec->arch.mod;
+
+	return __ftrace_make_nop(mod, rec, addr);
+
+}
+
+#ifdef CONFIG_PPC64
+static int
+__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
+{
+	unsigned int op[2];
+	unsigned long ip = rec->ip;
+
+	/* read where this goes */
+	if (probe_kernel_read(op, (void *)ip, MCOUNT_INSN_SIZE * 2))
+		return -EFAULT;
+
+	/*
+	 * It should be pointing to two nops or
+	 *  b +8; ld r2,40(r1)
+	 */
+	if (((op[0] != 0x48000008) || (op[1] != 0xe8410028)) &&
+	    ((op[0] != PPC_NOP_INSTR) || (op[1] != PPC_NOP_INSTR))) {
+		printk(KERN_ERR "Expected NOPs but have %x %x\n", op[0], op[1]);
+		return -EINVAL;
+	}
+
+	/* If we never set up a trampoline to ftrace_caller, then bail */
+	if (!rec->arch.mod->arch.tramp) {
+		printk(KERN_ERR "No ftrace trampoline\n");
+		return -EINVAL;
+	}
+
+	/* create the branch to the trampoline */
+	op[0] = create_branch((unsigned int *)ip,
+			      rec->arch.mod->arch.tramp, BRANCH_SET_LINK);
+	if (!op[0]) {
+		printk(KERN_ERR "REL24 out of range!\n");
+		return -EINVAL;
+	}
+
+	/* ld r2,40(r1) */
+	op[1] = 0xe8410028;
+
+	DEBUGP("write to %lx\n", rec->ip);
+
+	if (probe_kernel_write((void *)ip, op, MCOUNT_INSN_SIZE * 2))
+		return -EPERM;
+
+	flush_icache_range(ip, ip + 8);
+
+	return 0;
+}
+#else
+static int
+__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
+{
+	unsigned int op;
+	unsigned long ip = rec->ip;
+
+	/* read where this goes */
+	if (probe_kernel_read(&op, (void *)ip, MCOUNT_INSN_SIZE))
+		return -EFAULT;
+
+	/* It should be pointing to a nop */
+	if (op != PPC_NOP_INSTR) {
+		printk(KERN_ERR "Expected NOP but have %x\n", op);
+		return -EINVAL;
+	}
+
+	/* If we never set up a trampoline to ftrace_caller, then bail */
+	if (!rec->arch.mod->arch.tramp) {
+		printk(KERN_ERR "No ftrace trampoline\n");
+		return -EINVAL;
+	}
+
+	/* create the branch to the trampoline */
+	op = create_branch((unsigned int *)ip,
+			   rec->arch.mod->arch.tramp, BRANCH_SET_LINK);
+	if (!op) {
+		printk(KERN_ERR "REL24 out of range!\n");
+		return -EINVAL;
+	}
+
+	DEBUGP("write to %lx\n", rec->ip);
+
+	if (probe_kernel_write((void *)ip, &op, MCOUNT_INSN_SIZE))
+		return -EPERM;
+
+	flush_icache_range(ip, ip + 8);
+
+	return 0;
+}
+#endif /* CONFIG_PPC64 */
+
+int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
+{
+	unsigned char *old, *new;
+	unsigned long ip = rec->ip;
+
+	/*
+	 * If the calling address is more that 24 bits away,
+	 * then we had to use a trampoline to make the call.
+	 * Otherwise just update the call site.
+	 */
+	if (test_24bit_addr(ip, addr)) {
+		/* within range */
+		old = ftrace_nop_replace();
+		new = ftrace_call_replace(ip, addr);
+		return ftrace_modify_code(ip, old, new);
+	}
+
+	/*
+	 * Out of range jumps are called from modules.
+	 * Being that we are converting from nop, it had better
+	 * already have a module defined.
+	 */
+	if (!rec->arch.mod) {
+		printk(KERN_ERR "No module loaded\n");
+		return -EINVAL;
+	}
+
+	return __ftrace_make_call(rec, addr);
 }
 
 int ftrace_update_ftrace_func(ftrace_func_t func)
@@ -128,10 +509,10 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
 
 int __init ftrace_dyn_arch_init(void *data)
 {
-	/* This is running in kstop_machine */
+	/* caller expects data to be zero */
+	unsigned long *p = data;
 
-	ftrace_mcount_set(data);
+	*p = 0;
 
 	return 0;
 }
-
diff --git a/arch/powerpc/kernel/idle.c b/arch/powerpc/kernel/idle.c
index 31982d0..88d9c1d 100644
--- a/arch/powerpc/kernel/idle.c
+++ b/arch/powerpc/kernel/idle.c
@@ -69,10 +69,15 @@ void cpu_idle(void)
 				smp_mb();
 				local_irq_disable();
 
+				/* Don't trace irqs off for idle */
+				stop_critical_timings();
+
 				/* check again after disabling irqs */
 				if (!need_resched() && !cpu_should_die())
 					ppc_md.power_save();
 
+				start_critical_timings();
+
 				local_irq_enable();
 				set_thread_flag(TIF_POLLING_NRFLAG);
 
diff --git a/arch/powerpc/kernel/module_32.c b/arch/powerpc/kernel/module_32.c
index 2df91a0..f832773 100644
--- a/arch/powerpc/kernel/module_32.c
+++ b/arch/powerpc/kernel/module_32.c
@@ -22,6 +22,7 @@
 #include <linux/fs.h>
 #include <linux/string.h>
 #include <linux/kernel.h>
+#include <linux/ftrace.h>
 #include <linux/cache.h>
 #include <linux/bug.h>
 #include <linux/sort.h>
@@ -53,6 +54,9 @@ static unsigned int count_relocs(const Elf32_Rela *rela, unsigned int num)
 			r_addend = rela[i].r_addend;
 		}
 
+#ifdef CONFIG_DYNAMIC_FTRACE
+	_count_relocs++;	/* add one for ftrace_caller */
+#endif
 	return _count_relocs;
 }
 
@@ -306,5 +310,11 @@ int apply_relocate_add(Elf32_Shdr *sechdrs,
 			return -ENOEXEC;
 		}
 	}
+#ifdef CONFIG_DYNAMIC_FTRACE
+	module->arch.tramp =
+		do_plt_call(module->module_core,
+			    (unsigned long)ftrace_caller,
+			    sechdrs, module);
+#endif
 	return 0;
 }
diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c
index 1af2377..8992b03 100644
--- a/arch/powerpc/kernel/module_64.c
+++ b/arch/powerpc/kernel/module_64.c
@@ -20,6 +20,7 @@
 #include <linux/moduleloader.h>
 #include <linux/err.h>
 #include <linux/vmalloc.h>
+#include <linux/ftrace.h>
 #include <linux/bug.h>
 #include <asm/module.h>
 #include <asm/firmware.h>
@@ -163,6 +164,11 @@ static unsigned long get_stubs_size(const Elf64_Ehdr *hdr,
 		}
 	}
 
+#ifdef CONFIG_DYNAMIC_FTRACE
+	/* make the trampoline to the ftrace_caller */
+	relocs++;
+#endif
+
 	DEBUGP("Looks like a total of %lu stubs, max\n", relocs);
 	return relocs * sizeof(struct ppc64_stub_entry);
 }
@@ -441,5 +447,12 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
 		}
 	}
 
+#ifdef CONFIG_DYNAMIC_FTRACE
+	me->arch.toc = my_r2(sechdrs, me);
+	me->arch.tramp = stub_for_addr(sechdrs,
+				       (unsigned long)ftrace_caller,
+				       me);
+#endif
+
 	return 0;
 }
diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
index d69912c..8db3527 100644
--- a/arch/powerpc/lib/Makefile
+++ b/arch/powerpc/lib/Makefile
@@ -6,6 +6,9 @@ ifeq ($(CONFIG_PPC64),y)
 EXTRA_CFLAGS		+= -mno-minimal-toc
 endif
 
+CFLAGS_REMOVE_code-patching.o = -pg
+CFLAGS_REMOVE_feature-fixups.o = -pg
+
 obj-y			:= string.o alloc.o \
 			   checksum_$(CONFIG_WORD_SIZE).o
 obj-$(CONFIG_PPC32)	+= div64.o copy_32.o crtsavres.o

Re: [PATCH 0/5] powerpc: ftrace updates to previous patch series

[Steven Rostedt]

On Fri, 28 Nov 2008, Ingo Molnar wrote:

> 
> * Steven Rostedt <rostedt@goodmis.org> wrote:
> 
> > On Wed, 26 Nov 2008, Steven Rostedt wrote:
> > 
> > > Paul,
> > > 
> > > This patch series addresses the issues you brought up as well as
> > > adds some more enhancements and fixes. This series is added on
> > > top of the previous patch series.
> > > 
> > > The new patches are: (and are posted now)
> > > 5987225... powerpc/ppc32: static ftrace fixes for PPC32
> > 
> > The new commit id with the fix in Author and SoB is:
> > fd90db4bdc1ccf71927365cd634188cec4d7b151
> >  powerpc/ppc32: static ftrace fixes for 
> 
> Steve, you rebased the previous commits, and that's a no-no. I sorted it 
> all out, find below the stable URI for stuff that we'd like Paul to pull 
> shortly before the merge window.

Sorry, I rebased to edit the change log where I mispelled Paul's name.

-- Steve

Re: [PATCH 0/5] powerpc: ftrace updates to previous patch series

[Paul Mackerras]

Steven Rostedt writes:

> Sorry, I rebased to edit the change log where I mispelled Paul's name.

So, what commits should I be pulling into powerpc.git, or what patches
should I be committing, for dynamic ftrace on powerpc?

Paul.

Re: [PATCH 0/5] powerpc: ftrace updates to previous patch series

[Steven Rostedt]

On Fri, 19 Dec 2008, Paul Mackerras wrote:

> Steven Rostedt writes:
> 
> > Sorry, I rebased to edit the change log where I mispelled Paul's name.
> 
> So, what commits should I be pulling into powerpc.git, or what patches
> should I be committing, for dynamic ftrace on powerpc?

Ingo did not like the rebase and kept the original commits (the one with 
the change log with the incorrect spelling).

From: git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git
  tracing/powerpc
====================================
commit 8fd6e5a8c81e2e9b912ea33c8425a10729db469b
Author: Steven Rostedt <srostedt@redhat.com>
Date:   Fri Nov 14 16:21:19 2008 -0800

    powerpc: ftrace, convert to new dynamic ftrace arch API
    
    Impact: update to PowerPC ftrace arch API
    
    This patch converts PowerPC to use the new dynamic ftrace arch API.
    
    Thanks to Paul Mackennas for pointing out the mistakes of my original
    test_24bit_addr function.
    
    Signed-off-by: Steven Rostedt <srostedt@redhat.com>
====================================

The branch in my tree 'ppc/ftrace' has not been changed since. The only 
reason the commits in my tree are different than the ones in tip was 
because I rebased to fixed the spelling in the change log.

From: git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace.git
  ppc/ftrace
====================================
commit a3520364f9376943e4d6c76931bf4df8569fa555
Author: Steven Rostedt <srostedt@redhat.com>
Date:   Fri Nov 14 16:21:19 2008 -0800

    powerpc: ftrace, convert to new dynamic ftrace arch API
    
    Impact: update to PowerPC ftrace arch API
    
    This patch converts PowerPC to use the new dynamic ftrace arch API.
    
    Thanks to Paul Mackerras for pointing out the mistakes of my original
    test_24bit_addr function.
    
    Signed-off-by: Steven Rostedt <srostedt@redhat.com>
====================================

Take your pick for which to pull from.

Thanks,

-- Steve