[PATCH] kprobes: Temporary disarming of reentrant probe for i386
This patch includes i386 architecture specific changes to support temporary disarming on reentrancy of probes. Signed-of-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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@ -37,12 +37,10 @@
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#include <asm/kdebug.h>
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#include <asm/desc.h>
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/* kprobe_status settings */
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#define KPROBE_HIT_ACTIVE 0x00000001
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#define KPROBE_HIT_SS 0x00000002
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static struct kprobe *current_kprobe;
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static unsigned long kprobe_status, kprobe_old_eflags, kprobe_saved_eflags;
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static struct kprobe *kprobe_prev;
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static unsigned long kprobe_status_prev, kprobe_old_eflags_prev, kprobe_saved_eflags_prev;
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static struct pt_regs jprobe_saved_regs;
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static long *jprobe_saved_esp;
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/* copy of the kernel stack at the probe fire time */
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@ -93,6 +91,31 @@ void arch_remove_kprobe(struct kprobe *p)
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{
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}
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static inline void save_previous_kprobe(void)
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{
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kprobe_prev = current_kprobe;
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kprobe_status_prev = kprobe_status;
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kprobe_old_eflags_prev = kprobe_old_eflags;
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kprobe_saved_eflags_prev = kprobe_saved_eflags;
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}
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static inline void restore_previous_kprobe(void)
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{
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current_kprobe = kprobe_prev;
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kprobe_status = kprobe_status_prev;
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kprobe_old_eflags = kprobe_old_eflags_prev;
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kprobe_saved_eflags = kprobe_saved_eflags_prev;
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}
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static inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs)
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{
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current_kprobe = p;
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kprobe_saved_eflags = kprobe_old_eflags
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= (regs->eflags & (TF_MASK | IF_MASK));
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if (is_IF_modifier(p->opcode))
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kprobe_saved_eflags &= ~IF_MASK;
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}
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static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
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{
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regs->eflags |= TF_MASK;
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@ -184,9 +207,18 @@ static int kprobe_handler(struct pt_regs *regs)
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unlock_kprobes();
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goto no_kprobe;
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}
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arch_disarm_kprobe(p);
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regs->eip = (unsigned long)p->addr;
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ret = 1;
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/* We have reentered the kprobe_handler(), since
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* another probe was hit while within the handler.
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* We here save the original kprobes variables and
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* just single step on the instruction of the new probe
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* without calling any user handlers.
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*/
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save_previous_kprobe();
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set_current_kprobe(p, regs);
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p->nmissed++;
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prepare_singlestep(p, regs);
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kprobe_status = KPROBE_REENTER;
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return 1;
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} else {
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p = current_kprobe;
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if (p->break_handler && p->break_handler(p, regs)) {
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@ -221,11 +253,7 @@ static int kprobe_handler(struct pt_regs *regs)
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}
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kprobe_status = KPROBE_HIT_ACTIVE;
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current_kprobe = p;
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kprobe_saved_eflags = kprobe_old_eflags
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= (regs->eflags & (TF_MASK | IF_MASK));
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if (is_IF_modifier(p->opcode))
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kprobe_saved_eflags &= ~IF_MASK;
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set_current_kprobe(p, regs);
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if (p->pre_handler && p->pre_handler(p, regs))
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/* handler has already set things up, so skip ss setup */
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@ -370,14 +398,22 @@ static inline int post_kprobe_handler(struct pt_regs *regs)
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if (!kprobe_running())
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return 0;
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if (current_kprobe->post_handler)
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if ((kprobe_status != KPROBE_REENTER) && current_kprobe->post_handler) {
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kprobe_status = KPROBE_HIT_SSDONE;
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current_kprobe->post_handler(current_kprobe, regs, 0);
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}
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if (current_kprobe->post_handler != trampoline_post_handler)
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resume_execution(current_kprobe, regs);
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regs->eflags |= kprobe_saved_eflags;
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/*Restore back the original saved kprobes variables and continue. */
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if (kprobe_status == KPROBE_REENTER) {
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restore_previous_kprobe();
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goto out;
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}
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unlock_kprobes();
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out:
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preempt_enable_no_resched();
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/*
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