Commit 6cc89bad authored by Naveen N. Rao's avatar Naveen N. Rao Committed by Michael Ellerman
Browse files

powerpc/kprobes: Invoke handlers directly 



Invoke the kprobe handlers directly rather than through notify_die(), to
reduce path taken for handling kprobes. Similar to commit 6f6343f5
("kprobes/x86: Call exception handlers directly from do_int3/do_debug").

While at it, rename post_kprobe_handler() to kprobe_post_handler() for
more uniform naming.

Reported-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 82de5797

arch/powerpc/include/asm/kprobes.h

+7 −0
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ 
#include <asm/probes.h>

#include <asm/code-patching.h>



#ifdef CONFIG_KPROBES

#define  __ARCH_WANT_KPROBES_INSN_SLOT



struct pt_regs;
@@ -127,5 +128,11 @@ struct kprobe_ctlblk { 
extern int kprobe_exceptions_notify(struct notifier_block *self,

					unsigned long val, void *data);

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);

#else

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

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

#endif /* CONFIG_KPROBES */

#endif /* __KERNEL__ */

#endif	/* _ASM_POWERPC_KPROBES_H */

arch/powerpc/kernel/kprobes.c

+7 −22
Original line number Diff line number Diff line
@@ -140,13 +140,16 @@ void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, 
	regs->link = (unsigned long)kretprobe_trampoline;

}



static int __kprobes kprobe_handler(struct pt_regs *regs)

int __kprobes kprobe_handler(struct pt_regs *regs)

{

	struct kprobe *p;

	int ret = 0;

	unsigned int *addr = (unsigned int *)regs->nip;

	struct kprobe_ctlblk *kcb;



	if (user_mode(regs))

		return 0;



	/*

	 * We don't want to be preempted for the entire

	 * duration of kprobe processing
@@ -359,12 +362,12 @@ static int __kprobes trampoline_probe_handler(struct kprobe *p, 
 * single-stepped a copy of the instruction.  The address of this

 * copy is p->ainsn.insn.

 */

static int __kprobes post_kprobe_handler(struct pt_regs *regs)

int __kprobes kprobe_post_handler(struct pt_regs *regs)

{

	struct kprobe *cur = kprobe_running();

	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();



	if (!cur)

	if (!cur || user_mode(regs))

		return 0;



	/* make sure we got here for instruction we have a kprobe on */
@@ -470,25 +473,7 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) 
int __kprobes kprobe_exceptions_notify(struct notifier_block *self,

				       unsigned long val, void *data)

{

	struct die_args *args = (struct die_args *)data;

	int ret = NOTIFY_DONE;



	if (args->regs && user_mode(args->regs))

		return ret;



	switch (val) {

	case DIE_BPT:

		if (kprobe_handler(args->regs))

			ret = NOTIFY_STOP;

		break;

	case DIE_SSTEP:

		if (post_kprobe_handler(args->regs))

			ret = NOTIFY_STOP;

		break;

	default:

		break;

	}

	return ret;

	return NOTIFY_DONE;

}



unsigned long arch_deref_entry_point(void *entry)

arch/powerpc/kernel/traps.c

+13 −0
Original line number Diff line number Diff line
@@ -64,6 +64,7 @@ 
#include <asm/asm-prototypes.h>

#include <asm/hmi.h>

#include <sysdev/fsl_pci.h>

#include <asm/kprobes.h>



#if defined(CONFIG_DEBUGGER) || defined(CONFIG_KEXEC)

int (*__debugger)(struct pt_regs *regs) __read_mostly;
@@ -826,6 +827,9 @@ void single_step_exception(struct pt_regs *regs) 


	clear_single_step(regs);



	if (kprobe_post_handler(regs))

		return;



	if (notify_die(DIE_SSTEP, "single_step", regs, 5,

					5, SIGTRAP) == NOTIFY_STOP)

		goto bail;
@@ -1179,6 +1183,9 @@ void program_check_exception(struct pt_regs *regs) 
		if (debugger_bpt(regs))

			goto bail;



		if (kprobe_handler(regs))

			goto bail;



		/* trap exception */

		if (notify_die(DIE_BPT, "breakpoint", regs, 5, 5, SIGTRAP)

				== NOTIFY_STOP)
@@ -1747,6 +1754,9 @@ void DebugException(struct pt_regs *regs, unsigned long debug_status) 
			return;

		}



		if (kprobe_post_handler(regs))

			return;



		if (notify_die(DIE_SSTEP, "block_step", regs, 5,

			       5, SIGTRAP) == NOTIFY_STOP) {

			return;
@@ -1761,6 +1771,9 @@ void DebugException(struct pt_regs *regs, unsigned long debug_status) 
		/* Clear the instruction completion event */

		mtspr(SPRN_DBSR, DBSR_IC);



		if (kprobe_post_handler(regs))

			return;



		if (notify_die(DIE_SSTEP, "single_step", regs, 5,

			       5, SIGTRAP) == NOTIFY_STOP) {

			return;

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