diff options
Diffstat (limited to 'arch/powerpc/kernel/kprobes.c')
-rw-r--r-- | arch/powerpc/kernel/kprobes.c | 122 |
1 files changed, 33 insertions, 89 deletions
diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c index ca5d5a081e75..5c60bb0f927f 100644 --- a/arch/powerpc/kernel/kprobes.c +++ b/arch/powerpc/kernel/kprobes.c @@ -317,25 +317,17 @@ int kprobe_handler(struct pt_regs *regs) } prepare_singlestep(p, regs); return 1; - } else { - if (*addr != BREAKPOINT_INSTRUCTION) { - /* If trap variant, then it belongs not to us */ - kprobe_opcode_t cur_insn = *addr; - if (is_trap(cur_insn)) - goto no_kprobe; - /* The breakpoint instruction was removed by - * another cpu right after we hit, no further - * handling of this interrupt is appropriate - */ - ret = 1; + } else if (*addr != BREAKPOINT_INSTRUCTION) { + /* If trap variant, then it belongs not to us */ + kprobe_opcode_t cur_insn = *addr; + + if (is_trap(cur_insn)) goto no_kprobe; - } - p = __this_cpu_read(current_kprobe); - if (p->break_handler && p->break_handler(p, regs)) { - if (!skip_singlestep(p, regs, kcb)) - goto ss_probe; - ret = 1; - } + /* The breakpoint instruction was removed by + * another cpu right after we hit, no further + * handling of this interrupt is appropriate + */ + ret = 1; } goto no_kprobe; } @@ -350,7 +342,7 @@ int kprobe_handler(struct pt_regs *regs) */ kprobe_opcode_t cur_insn = *addr; if (is_trap(cur_insn)) - goto no_kprobe; + goto no_kprobe; /* * The breakpoint instruction was removed right * after we hit it. Another cpu has removed @@ -366,11 +358,13 @@ int kprobe_handler(struct pt_regs *regs) kcb->kprobe_status = KPROBE_HIT_ACTIVE; set_current_kprobe(p, regs, kcb); - if (p->pre_handler && p->pre_handler(p, regs)) - /* handler has already set things up, so skip ss setup */ + if (p->pre_handler && p->pre_handler(p, regs)) { + /* handler changed execution path, so skip ss setup */ + reset_current_kprobe(); + preempt_enable_no_resched(); return 1; + } -ss_probe: if (p->ainsn.boostable >= 0) { ret = try_to_emulate(p, regs); @@ -455,29 +449,33 @@ static int trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs) } kretprobe_assert(ri, orig_ret_address, trampoline_address); - regs->nip = orig_ret_address; + /* - * Make LR point to the orig_ret_address. - * When the 'nop' inside the kretprobe_trampoline - * is optimized, we can do a 'blr' after executing the - * detour buffer code. + * We get here through one of two paths: + * 1. by taking a trap -> kprobe_handler() -> here + * 2. by optprobe branch -> optimized_callback() -> opt_pre_handler() -> here + * + * When going back through (1), we need regs->nip to be setup properly + * as it is used to determine the return address from the trap. + * For (2), since nip is not honoured with optprobes, we instead setup + * the link register properly so that the subsequent 'blr' in + * kretprobe_trampoline jumps back to the right instruction. + * + * For nip, we should set the address to the previous instruction since + * we end up emulating it in kprobe_handler(), which increments the nip + * again. */ + regs->nip = orig_ret_address - 4; regs->link = orig_ret_address; - reset_current_kprobe(); kretprobe_hash_unlock(current, &flags); - preempt_enable_no_resched(); hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) { hlist_del(&ri->hlist); kfree(ri); } - /* - * By returning a non-zero value, we are telling - * kprobe_handler() that we don't want the post_handler - * to run (and have re-enabled preemption) - */ - return 1; + + return 0; } NOKPROBE_SYMBOL(trampoline_probe_handler); @@ -607,60 +605,6 @@ unsigned long arch_deref_entry_point(void *entry) } NOKPROBE_SYMBOL(arch_deref_entry_point); -int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) -{ - struct jprobe *jp = container_of(p, struct jprobe, kp); - struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); - - memcpy(&kcb->jprobe_saved_regs, regs, sizeof(struct pt_regs)); - - /* setup return addr to the jprobe handler routine */ - regs->nip = arch_deref_entry_point(jp->entry); -#ifdef PPC64_ELF_ABI_v2 - regs->gpr[12] = (unsigned long)jp->entry; -#elif defined(PPC64_ELF_ABI_v1) - regs->gpr[2] = (unsigned long)(((func_descr_t *)jp->entry)->toc); -#endif - - /* - * jprobes use jprobe_return() which skips the normal return - * path of the function, and this messes up the accounting of the - * function graph tracer. - * - * Pause function graph tracing while performing the jprobe function. - */ - pause_graph_tracing(); - - return 1; -} -NOKPROBE_SYMBOL(setjmp_pre_handler); - -void __used jprobe_return(void) -{ - asm volatile("jprobe_return_trap:\n" - "trap\n" - ::: "memory"); -} -NOKPROBE_SYMBOL(jprobe_return); - -int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) -{ - struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); - - if (regs->nip != ppc_kallsyms_lookup_name("jprobe_return_trap")) { - pr_debug("longjmp_break_handler NIP (0x%lx) does not match jprobe_return_trap (0x%lx)\n", - regs->nip, ppc_kallsyms_lookup_name("jprobe_return_trap")); - return 0; - } - - memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs)); - /* It's OK to start function graph tracing again */ - unpause_graph_tracing(); - preempt_enable_no_resched(); - return 1; -} -NOKPROBE_SYMBOL(longjmp_break_handler); - static struct kprobe trampoline_p = { .addr = (kprobe_opcode_t *) &kretprobe_trampoline, .pre_handler = trampoline_probe_handler |