diff options
Diffstat (limited to 'arch/i386/kernel/kprobes.c')
| -rw-r--r-- | arch/i386/kernel/kprobes.c | 62 |
1 files changed, 49 insertions, 13 deletions
diff --git a/arch/i386/kernel/kprobes.c b/arch/i386/kernel/kprobes.c index b8e2bae0ab4f..3762f6b35ab2 100644 --- a/arch/i386/kernel/kprobes.c +++ b/arch/i386/kernel/kprobes.c @@ -37,12 +37,10 @@ #include <asm/kdebug.h> #include <asm/desc.h> -/* kprobe_status settings */ -#define KPROBE_HIT_ACTIVE 0x00000001 -#define KPROBE_HIT_SS 0x00000002 - static struct kprobe *current_kprobe; static unsigned long kprobe_status, kprobe_old_eflags, kprobe_saved_eflags; +static struct kprobe *kprobe_prev; +static unsigned long kprobe_status_prev, kprobe_old_eflags_prev, kprobe_saved_eflags_prev; static struct pt_regs jprobe_saved_regs; static long *jprobe_saved_esp; /* copy of the kernel stack at the probe fire time */ @@ -93,6 +91,31 @@ void arch_remove_kprobe(struct kprobe *p) { } +static inline void save_previous_kprobe(void) +{ + kprobe_prev = current_kprobe; + kprobe_status_prev = kprobe_status; + kprobe_old_eflags_prev = kprobe_old_eflags; + kprobe_saved_eflags_prev = kprobe_saved_eflags; +} + +static inline void restore_previous_kprobe(void) +{ + current_kprobe = kprobe_prev; + kprobe_status = kprobe_status_prev; + kprobe_old_eflags = kprobe_old_eflags_prev; + kprobe_saved_eflags = kprobe_saved_eflags_prev; +} + +static inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs) +{ + current_kprobe = p; + kprobe_saved_eflags = kprobe_old_eflags + = (regs->eflags & (TF_MASK | IF_MASK)); + if (is_IF_modifier(p->opcode)) + kprobe_saved_eflags &= ~IF_MASK; +} + static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs) { regs->eflags |= TF_MASK; @@ -184,9 +207,18 @@ static int kprobe_handler(struct pt_regs *regs) unlock_kprobes(); goto no_kprobe; } - arch_disarm_kprobe(p); - regs->eip = (unsigned long)p->addr; - ret = 1; + /* We have reentered the kprobe_handler(), since + * another probe was hit while within the handler. + * We here save the original kprobes variables and + * just single step on the instruction of the new probe + * without calling any user handlers. + */ + save_previous_kprobe(); + set_current_kprobe(p, regs); + p->nmissed++; + prepare_singlestep(p, regs); + kprobe_status = KPROBE_REENTER; + return 1; } else { p = current_kprobe; if (p->break_handler && p->break_handler(p, regs)) { @@ -221,11 +253,7 @@ static int kprobe_handler(struct pt_regs *regs) } kprobe_status = KPROBE_HIT_ACTIVE; - current_kprobe = p; - kprobe_saved_eflags = kprobe_old_eflags - = (regs->eflags & (TF_MASK | IF_MASK)); - if (is_IF_modifier(p->opcode)) - kprobe_saved_eflags &= ~IF_MASK; + set_current_kprobe(p, regs); if (p->pre_handler && p->pre_handler(p, regs)) /* handler has already set things up, so skip ss setup */ @@ -370,14 +398,22 @@ static inline int post_kprobe_handler(struct pt_regs *regs) if (!kprobe_running()) return 0; - if (current_kprobe->post_handler) + if ((kprobe_status != KPROBE_REENTER) && current_kprobe->post_handler) { + kprobe_status = KPROBE_HIT_SSDONE; current_kprobe->post_handler(current_kprobe, regs, 0); + } if (current_kprobe->post_handler != trampoline_post_handler) resume_execution(current_kprobe, regs); regs->eflags |= kprobe_saved_eflags; + /*Restore back the original saved kprobes variables and continue. */ + if (kprobe_status == KPROBE_REENTER) { + restore_previous_kprobe(); + goto out; + } unlock_kprobes(); +out: preempt_enable_no_resched(); /* |