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authorSteven Rostedt <srostedt@redhat.com>2008-11-15 08:39:05 +0100
committerSteven Rostedt <srostedt@redhat.com>2008-11-20 19:52:53 +0100
commit7cc45e64323c8a1042f56e6a8d1dc982f98d52a8 (patch)
tree4402eb9bdaca4087a92f5003cfa655e6293dc890 /arch/powerpc/kernel/ftrace.c
parentpowerpc/ppc64: ftrace, handle module trampolines for dyn ftrace (diff)
downloadlinux-7cc45e64323c8a1042f56e6a8d1dc982f98d52a8.tar.xz
linux-7cc45e64323c8a1042f56e6a8d1dc982f98d52a8.zip
powerpc/ppc32: ftrace, dynamic ftrace to handle modules
Impact: add ability to trace modules on 32 bit PowerPC This patch performs the necessary trampoline calls to handle modules with dynamic ftrace on 32 bit PowerPC. Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Diffstat (limited to 'arch/powerpc/kernel/ftrace.c')
-rw-r--r--arch/powerpc/kernel/ftrace.c101
1 files changed, 95 insertions, 6 deletions
diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c
index 1aec559bdfcb..3271cd698e4c 100644
--- a/arch/powerpc/kernel/ftrace.c
+++ b/arch/powerpc/kernel/ftrace.c
@@ -274,7 +274,63 @@ static int
__ftrace_make_nop(struct module *mod,
struct dyn_ftrace *rec, unsigned long addr)
{
- /* Ignore modules for PPC32 (for now) */
+ unsigned char replaced[MCOUNT_INSN_SIZE];
+ unsigned int *op = (unsigned *)&replaced;
+ unsigned char jmp[8];
+ unsigned int *ptr = (unsigned int *)&jmp;
+ unsigned long ip = rec->ip;
+ unsigned long tramp;
+ int offset;
+
+ if (probe_kernel_read(replaced, (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:
+ * lis r11,sym@ha
+ * addi r11,r11,sym@l
+ * mtctr r11
+ * bctr
+ */
+
+ DEBUGP("ip:%lx jumps to %lx", ip, tramp);
+
+ /* Find where the trampoline jumps to */
+ if (probe_kernel_read(jmp, (void *)tramp, 8)) {
+ printk(KERN_ERR "Failed to read %lx\n", tramp);
+ return -EFAULT;
+ }
+
+ DEBUGP(" %08x %08x ", ptr[0], ptr[1]);
+
+ tramp = (ptr[1] & 0xffff) |
+ ((ptr[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[0] = PPC_NOP_INSTR;
+
+ if (probe_kernel_write((void *)ip, replaced, MCOUNT_INSN_SIZE))
+ return -EPERM;
+
return 0;
}
#endif /* PPC64 */
@@ -297,7 +353,6 @@ int ftrace_make_nop(struct module *mod,
return ftrace_modify_code(ip, old, new);
}
-#ifdef CONFIG_PPC64
/*
* Out of range jumps are called from modules.
* We should either already have a pointer to the module
@@ -320,7 +375,6 @@ int ftrace_make_nop(struct module *mod,
/* nothing to do if mod == rec->arch.mod */
} else
mod = rec->arch.mod;
-#endif /* CONFIG_PPC64 */
return __ftrace_make_nop(mod, rec, addr);
@@ -380,7 +434,44 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
static int
__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
- /* PPC32 ignores modules for now */
+ unsigned char replaced[MCOUNT_INSN_SIZE];
+ unsigned int *op = (unsigned *)&replaced;
+ unsigned long ip = rec->ip;
+ unsigned long offset;
+
+ /* read where this goes */
+ if (probe_kernel_read(replaced, (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]);
+ 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;
+ }
+
+ /* 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);
+ return -EINVAL;
+ }
+
+ /* Set to "bl addr" */
+ op[0] = branch_offset(offset);
+
+ DEBUGP("write to %lx\n", rec->ip);
+
+ if (probe_kernel_write((void *)ip, replaced, MCOUNT_INSN_SIZE))
+ return -EPERM;
+
return 0;
}
#endif /* CONFIG_PPC64 */
@@ -402,7 +493,6 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
return ftrace_modify_code(ip, old, new);
}
-#ifdef CONFIG_PPC64
/*
* Out of range jumps are called from modules.
* Being that we are converting from nop, it had better
@@ -412,7 +502,6 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
printk(KERN_ERR "No module loaded\n");
return -EINVAL;
}
-#endif
return __ftrace_make_call(rec, addr);
}