Commit 6e5fd3a2 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Ingo Molnar
Browse files

powerpc/kprobes: Don't call the ->break_handler() in powerpc kprobes code 



Don't call the ->break_handler() from the powerpc kprobes code,
because it was only used by jprobes which got removed.

This also removes skip_singlestep() and embeds it in the
caller, kprobe_ftrace_handler(), which simplifies regs->nip
operation around there.

Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-arch@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lore.kernel.org/lkml/152942477127.15209.8982613703787878618.stgit@devbox


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent c9abd554

arch/powerpc/include/asm/kprobes.h

+0 −10
Original line number Diff line number Diff line
@@ -102,16 +102,6 @@ extern int kprobe_exceptions_notify(struct notifier_block *self, 
extern int kprobe_fault_handler(struct pt_regs *regs, int trapnr);

extern int kprobe_handler(struct pt_regs *regs);

extern int kprobe_post_handler(struct pt_regs *regs);

#ifdef CONFIG_KPROBES_ON_FTRACE

extern int skip_singlestep(struct kprobe *p, struct pt_regs *regs,

			   struct kprobe_ctlblk *kcb);

#else

static inline int skip_singlestep(struct kprobe *p, struct pt_regs *regs,

				  struct kprobe_ctlblk *kcb)

{

	return 0;

}

#endif

#else

static inline int kprobe_handler(struct pt_regs *regs) { return 0; }

static inline int kprobe_post_handler(struct pt_regs *regs) { return 0; }

arch/powerpc/kernel/kprobes-ftrace.c

+12 −34
Original line number Diff line number Diff line
@@ -25,35 +25,6 @@ 
#include <linux/preempt.h>

#include <linux/ftrace.h>



static nokprobe_inline

int __skip_singlestep(struct kprobe *p, struct pt_regs *regs,

		      struct kprobe_ctlblk *kcb, unsigned long orig_nip)

{

	/*

	 * Emulate singlestep (and also recover regs->nip)

	 * as if there is a nop

	 */

	regs->nip = (unsigned long)p->addr + MCOUNT_INSN_SIZE;

	if (unlikely(p->post_handler)) {

		kcb->kprobe_status = KPROBE_HIT_SSDONE;

		p->post_handler(p, regs, 0);

	}

	__this_cpu_write(current_kprobe, NULL);

	if (orig_nip)

		regs->nip = orig_nip;

	return 1;

}



int skip_singlestep(struct kprobe *p, struct pt_regs *regs,

		    struct kprobe_ctlblk *kcb)

{

	if (kprobe_ftrace(p))

		return __skip_singlestep(p, regs, kcb, 0);

	else

		return 0;

}

NOKPROBE_SYMBOL(skip_singlestep);



/* Ftrace callback handler for kprobes */

void kprobe_ftrace_handler(unsigned long nip, unsigned long parent_nip,

			   struct ftrace_ops *ops, struct pt_regs *regs)
@@ -71,8 +42,6 @@ void kprobe_ftrace_handler(unsigned long nip, unsigned long parent_nip, 
	if (kprobe_running()) {

		kprobes_inc_nmissed_count(p);

	} else {

		unsigned long orig_nip = regs->nip;



		/*

		 * On powerpc, NIP is *before* this instruction for the

		 * pre handler
@@ -81,9 +50,18 @@ void kprobe_ftrace_handler(unsigned long nip, unsigned long parent_nip, 


		__this_cpu_write(current_kprobe, p);

		kcb->kprobe_status = KPROBE_HIT_ACTIVE;

		if (!p->pre_handler || !p->pre_handler(p, regs))

			__skip_singlestep(p, regs, kcb, orig_nip);

		else {

		if (!p->pre_handler || !p->pre_handler(p, regs)) {

			/*

			 * Emulate singlestep (and also recover regs->nip)

			 * as if there is a nop

			 */

			regs->nip += MCOUNT_INSN_SIZE;

			if (unlikely(p->post_handler)) {

				kcb->kprobe_status = KPROBE_HIT_SSDONE;

				p->post_handler(p, regs, 0);

			}

			__this_cpu_write(current_kprobe, NULL);

		} else {

			/*

			 * If pre_handler returns !0, it sets regs->nip and

			 * resets current kprobe. In this case, we should not

arch/powerpc/kernel/kprobes.c

+11 −20
Original line number Diff line number Diff line
@@ -317,10 +317,10 @@ int kprobe_handler(struct pt_regs *regs) 
			}

			prepare_singlestep(p, regs);

			return 1;

		} else {

			if (*addr != BREAKPOINT_INSTRUCTION) {

		} 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
@@ -328,14 +328,6 @@ int kprobe_handler(struct pt_regs *regs) 
			 * handling of this interrupt is appropriate

			 */

			ret = 1;

				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;

			}

		}

		goto no_kprobe;

	}
@@ -370,7 +362,6 @@ int kprobe_handler(struct pt_regs *regs) 
		/* handler has already set things up, so skip ss setup */

		return 1;



ss_probe:

	if (p->ainsn.boostable >= 0) {

		ret = try_to_emulate(p, regs);

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