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authorSteven Rostedt <srostedt@redhat.com>2008-11-25 14:06:19 -0800
committerIngo Molnar <mingo@elte.hu>2008-11-28 14:08:01 +0100
commit0029ff87529dff01a4b9c5bf380a0caacb5f7418 (patch)
tree143534dbd52f76ae008b3abc21256c00d4d9fa9b /arch/powerpc/kernel/ftrace.c
parentec682cef2d2c1a25a198d32a87fe2649da671d1e (diff)
powerpc: ftrace, use create_branch
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> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/powerpc/kernel/ftrace.c')
-rw-r--r--arch/powerpc/kernel/ftrace.c54
1 files changed, 12 insertions, 42 deletions
diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c
index a4640e4f117..5355244c99f 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))