diff options
Diffstat (limited to 'arch/powerpc/kernel/ftrace.c')
| -rw-r--r-- | arch/powerpc/kernel/ftrace.c | 103 |
1 files changed, 87 insertions, 16 deletions
diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c index 62899fbae703..9dac18dabd03 100644 --- a/arch/powerpc/kernel/ftrace.c +++ b/arch/powerpc/kernel/ftrace.c @@ -61,8 +61,11 @@ ftrace_modify_code(unsigned long ip, unsigned int old, unsigned int new) return -EFAULT; /* Make sure it is what we expect it to be */ - if (replaced != old) + if (replaced != old) { + pr_err("%p: replaced (%#x) != old (%#x)", + (void *)ip, replaced, old); return -EINVAL; + } /* replace the text with the new text */ if (patch_instruction((unsigned int *)ip, new)) @@ -108,11 +111,13 @@ __ftrace_make_nop(struct module *mod, { unsigned long entry, ptr, tramp; unsigned long ip = rec->ip; - unsigned int op; + unsigned int op, pop; /* read where this goes */ - if (probe_kernel_read(&op, (void *)ip, sizeof(int))) + if (probe_kernel_read(&op, (void *)ip, sizeof(int))) { + pr_err("Fetching opcode failed.\n"); return -EFAULT; + } /* Make sure that that this is still a 24bit jump */ if (!is_bl_op(op)) { @@ -152,10 +157,42 @@ __ftrace_make_nop(struct module *mod, * * Use a b +8 to jump over the load. */ - op = 0x48000008; /* b +8 */ - if (patch_instruction((unsigned int *)ip, op)) + pop = PPC_INST_BRANCH | 8; /* b +8 */ + + /* + * Check what is in the next instruction. We can see ld r2,40(r1), but + * on first pass after boot we will see mflr r0. + */ + if (probe_kernel_read(&op, (void *)(ip+4), MCOUNT_INSN_SIZE)) { + pr_err("Fetching op failed.\n"); + return -EFAULT; + } + + if (op != PPC_INST_LD_TOC) { + unsigned int inst; + + if (probe_kernel_read(&inst, (void *)(ip - 4), 4)) { + pr_err("Fetching instruction at %lx failed.\n", ip - 4); + return -EFAULT; + } + + /* We expect either a mlfr r0, or a std r0, LRSAVE(r1) */ + if (inst != PPC_INST_MFLR && inst != PPC_INST_STD_LR) { + pr_err("Unexpected instructions around bl _mcount\n" + "when enabling dynamic ftrace!\t" + "(%08x,bl,%08x)\n", inst, op); + return -EINVAL; + } + + /* When using -mkernel_profile there is no load to jump over */ + pop = PPC_INST_NOP; + } + + if (patch_instruction((unsigned int *)ip, pop)) { + pr_err("Patching NOP failed.\n"); return -EPERM; + } return 0; } @@ -281,16 +318,15 @@ int ftrace_make_nop(struct module *mod, #ifdef CONFIG_MODULES #ifdef CONFIG_PPC64 +/* + * Examine the existing instructions for __ftrace_make_call. + * They should effectively be a NOP, and follow formal constraints, + * depending on the ABI. Return false if they don't. + */ +#ifndef CC_USING_MPROFILE_KERNEL static int -__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) +expected_nop_sequence(void *ip, unsigned int op0, unsigned int op1) { - unsigned int op[2]; - void *ip = (void *)rec->ip; - - /* read where this goes */ - if (probe_kernel_read(op, ip, sizeof(op))) - return -EFAULT; - /* * We expect to see: * @@ -300,8 +336,34 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) * The load offset is different depending on the ABI. For simplicity * just mask it out when doing the compare. */ - if ((op[0] != 0x48000008) || ((op[1] & 0xffff0000) != 0xe8410000)) { - pr_err("Unexpected call sequence: %x %x\n", op[0], op[1]); + if ((op0 != 0x48000008) || ((op1 & 0xffff0000) != 0xe8410000)) + return 0; + return 1; +} +#else +static int +expected_nop_sequence(void *ip, unsigned int op0, unsigned int op1) +{ + /* look for patched "NOP" on ppc64 with -mprofile-kernel */ + if (op0 != PPC_INST_NOP) + return 0; + return 1; +} +#endif + +static int +__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) +{ + unsigned int op[2]; + void *ip = (void *)rec->ip; + + /* read where this goes */ + if (probe_kernel_read(op, ip, sizeof(op))) + return -EFAULT; + + if (!expected_nop_sequence(ip, op[0], op[1])) { + pr_err("Unexpected call sequence at %p: %x %x\n", + ip, op[0], op[1]); return -EINVAL; } @@ -324,7 +386,16 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) return 0; } -#else + +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS +int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, + unsigned long addr) +{ + return ftrace_make_call(rec, addr); +} +#endif + +#else /* !CONFIG_PPC64: */ static int __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) { |