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Commit 91fc862c authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Jon Medhurst
Browse files

arm: kprobes: Skip single-stepping in recursing path if possible 



Kprobes/arm skips single-stepping (moreover handling the event)
if the conditional instruction must not be executed. This
also apply the rule when we hit the recursing kprobe, so
that kprobe does not count nmissed up in that case.

Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarJon Medhurst <tixy@linaro.org>
parent f3fbd7ec

arch/arm/probes/kprobes/core.c

+10 −9
Original line number Diff line number Diff line
@@ -266,7 +266,15 @@ void __kprobes kprobe_handler(struct pt_regs *regs) 
#endif



	if (p) {

		if (cur) {

		if (!p->ainsn.insn_check_cc(regs->ARM_cpsr)) {

			/*

			 * Probe hit but conditional execution check failed,

			 * so just skip the instruction and continue as if

			 * nothing had happened.

			 * In this case, we can skip recursing check too.

			 */

			singlestep_skip(p, regs);

		} else if (cur) {

			/* Kprobe is pending, so we're recursing. */

			switch (kcb->kprobe_status) {

			case KPROBE_HIT_ACTIVE:
@@ -289,7 +297,7 @@ void __kprobes kprobe_handler(struct pt_regs *regs) 
				/* impossible cases */

				BUG();

			}

		} else if (p->ainsn.insn_check_cc(regs->ARM_cpsr)) {

		} else {

			/* Probe hit and conditional execution check ok. */

			set_current_kprobe(p);

			kcb->kprobe_status = KPROBE_HIT_ACTIVE;
@@ -310,13 +318,6 @@ void __kprobes kprobe_handler(struct pt_regs *regs) 
				}

				reset_current_kprobe();

			}

		} else {

			/*

			 * Probe hit but conditional execution check failed,

			 * so just skip the instruction and continue as if

			 * nothing had happened.

			 */

			singlestep_skip(p, regs);

		}

	} else if (cur) {

		/* We probably hit a jprobe.  Call its break handler. */