[PATCH] kprobes: Temporary disarming of reentrant probe for ppc64
This patch includes ppc64 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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@ -36,12 +36,10 @@
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#include <asm/kdebug.h>
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#include <asm/sstep.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_saved_msr;
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static struct kprobe *kprobe_prev;
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static unsigned long kprobe_status_prev, kprobe_saved_msr_prev;
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static struct pt_regs jprobe_saved_regs;
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int arch_prepare_kprobe(struct kprobe *p)
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@ -93,6 +91,20 @@ static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
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regs->nip = (unsigned long)&p->ainsn.insn;
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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_saved_msr_prev = kprobe_saved_msr;
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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_saved_msr = kprobe_saved_msr_prev;
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}
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static inline int kprobe_handler(struct pt_regs *regs)
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{
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struct kprobe *p;
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@ -111,9 +123,19 @@ static inline 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->nip = (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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current_kprobe = p;
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kprobe_saved_msr = regs->msr;
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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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@ -195,13 +217,21 @@ 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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resume_execution(current_kprobe, regs);
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regs->msr |= kprobe_saved_msr;
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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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