diff options
author | Steven Rostedt <srostedt@redhat.com> | 2008-11-15 08:39:05 +0100 |
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committer | Steven Rostedt <srostedt@redhat.com> | 2008-11-20 19:52:53 +0100 |
commit | 7cc45e64323c8a1042f56e6a8d1dc982f98d52a8 (patch) | |
tree | 4402eb9bdaca4087a92f5003cfa655e6293dc890 /arch/powerpc/kernel/ftrace.c | |
parent | powerpc/ppc64: ftrace, handle module trampolines for dyn ftrace (diff) | |
download | linux-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.c | 101 |
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); } |