diff options
Diffstat (limited to 'arch/powerpc/kernel/kprobes.c')
| -rw-r--r-- | arch/powerpc/kernel/kprobes.c | 149 |
1 files changed, 127 insertions, 22 deletions
diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c index fa3cfd90c83a..160ae0fa7d0d 100644 --- a/arch/powerpc/kernel/kprobes.c +++ b/arch/powerpc/kernel/kprobes.c @@ -51,6 +51,77 @@ bool arch_within_kprobe_blacklist(unsigned long addr) addr < (unsigned long)__head_end); } +kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset) +{ + kprobe_opcode_t *addr; + +#ifdef PPC64_ELF_ABI_v2 + /* PPC64 ABIv2 needs local entry point */ + addr = (kprobe_opcode_t *)kallsyms_lookup_name(name); + if (addr && !offset) { +#ifdef CONFIG_KPROBES_ON_FTRACE + unsigned long faddr; + /* + * Per livepatch.h, ftrace location is always within the first + * 16 bytes of a function on powerpc with -mprofile-kernel. + */ + faddr = ftrace_location_range((unsigned long)addr, + (unsigned long)addr + 16); + if (faddr) + addr = (kprobe_opcode_t *)faddr; + else +#endif + addr = (kprobe_opcode_t *)ppc_function_entry(addr); + } +#elif defined(PPC64_ELF_ABI_v1) + /* + * 64bit powerpc ABIv1 uses function descriptors: + * - Check for the dot variant of the symbol first. + * - If that fails, try looking up the symbol provided. + * + * This ensures we always get to the actual symbol and not + * the descriptor. + * + * Also handle <module:symbol> format. + */ + char dot_name[MODULE_NAME_LEN + 1 + KSYM_NAME_LEN]; + const char *modsym; + bool dot_appended = false; + if ((modsym = strchr(name, ':')) != NULL) { + modsym++; + if (*modsym != '\0' && *modsym != '.') { + /* Convert to <module:.symbol> */ + strncpy(dot_name, name, modsym - name); + dot_name[modsym - name] = '.'; + dot_name[modsym - name + 1] = '\0'; + strncat(dot_name, modsym, + sizeof(dot_name) - (modsym - name) - 2); + dot_appended = true; + } else { + dot_name[0] = '\0'; + strncat(dot_name, name, sizeof(dot_name) - 1); + } + } else if (name[0] != '.') { + dot_name[0] = '.'; + dot_name[1] = '\0'; + strncat(dot_name, name, KSYM_NAME_LEN - 2); + dot_appended = true; + } else { + dot_name[0] = '\0'; + strncat(dot_name, name, KSYM_NAME_LEN - 1); + } + addr = (kprobe_opcode_t *)kallsyms_lookup_name(dot_name); + if (!addr && dot_appended) { + /* Let's try the original non-dot symbol lookup */ + addr = (kprobe_opcode_t *)kallsyms_lookup_name(name); + } +#else + addr = (kprobe_opcode_t *)kallsyms_lookup_name(name); +#endif + + return addr; +} + int arch_prepare_kprobe(struct kprobe *p) { int ret = 0; @@ -144,6 +215,19 @@ static nokprobe_inline void set_current_kprobe(struct kprobe *p, struct pt_regs kcb->kprobe_saved_msr = regs->msr; } +bool arch_function_offset_within_entry(unsigned long offset) +{ +#ifdef PPC64_ELF_ABI_v2 +#ifdef CONFIG_KPROBES_ON_FTRACE + return offset <= 16; +#else + return offset <= 8; +#endif +#else + return !offset; +#endif +} + void arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs) { ri->ret_addr = (kprobe_opcode_t *)regs->link; @@ -153,6 +237,36 @@ void arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs) } NOKPROBE_SYMBOL(arch_prepare_kretprobe); +int try_to_emulate(struct kprobe *p, struct pt_regs *regs) +{ + int ret; + unsigned int insn = *p->ainsn.insn; + + /* regs->nip is also adjusted if emulate_step returns 1 */ + ret = emulate_step(regs, insn); + if (ret > 0) { + /* + * Once this instruction has been boosted + * successfully, set the boostable flag + */ + if (unlikely(p->ainsn.boostable == 0)) + p->ainsn.boostable = 1; + } else if (ret < 0) { + /* + * We don't allow kprobes on mtmsr(d)/rfi(d), etc. + * So, we should never get here... but, its still + * good to catch them, just in case... + */ + printk("Can't step on instruction %x\n", insn); + BUG(); + } else if (ret == 0) + /* This instruction can't be boosted */ + p->ainsn.boostable = -1; + + return ret; +} +NOKPROBE_SYMBOL(try_to_emulate); + int kprobe_handler(struct pt_regs *regs) { struct kprobe *p; @@ -193,6 +307,14 @@ int kprobe_handler(struct pt_regs *regs) kprobes_inc_nmissed_count(p); prepare_singlestep(p, regs); kcb->kprobe_status = KPROBE_REENTER; + if (p->ainsn.boostable >= 0) { + ret = try_to_emulate(p, regs); + + if (ret > 0) { + restore_previous_kprobe(kcb); + return 1; + } + } return 1; } else { if (*addr != BREAKPOINT_INSTRUCTION) { @@ -209,7 +331,9 @@ int kprobe_handler(struct pt_regs *regs) } p = __this_cpu_read(current_kprobe); if (p->break_handler && p->break_handler(p, regs)) { - goto ss_probe; + if (!skip_singlestep(p, regs, kcb)) + goto ss_probe; + ret = 1; } } goto no_kprobe; @@ -247,18 +371,9 @@ int kprobe_handler(struct pt_regs *regs) ss_probe: if (p->ainsn.boostable >= 0) { - unsigned int insn = *p->ainsn.insn; + ret = try_to_emulate(p, regs); - /* regs->nip is also adjusted if emulate_step returns 1 */ - ret = emulate_step(regs, insn); if (ret > 0) { - /* - * Once this instruction has been boosted - * successfully, set the boostable flag - */ - if (unlikely(p->ainsn.boostable == 0)) - p->ainsn.boostable = 1; - if (p->post_handler) p->post_handler(p, regs, 0); @@ -266,17 +381,7 @@ ss_probe: reset_current_kprobe(); preempt_enable_no_resched(); return 1; - } else if (ret < 0) { - /* - * We don't allow kprobes on mtmsr(d)/rfi(d), etc. - * So, we should never get here... but, its still - * good to catch them, just in case... - */ - printk("Can't step on instruction %x\n", insn); - BUG(); - } else if (ret == 0) - /* This instruction can't be boosted */ - p->ainsn.boostable = -1; + } } prepare_singlestep(p, regs); kcb->kprobe_status = KPROBE_HIT_SS; |