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Commit 0dc036c9 authored by Ananth N Mavinakayanahalli's avatar Ananth N Mavinakayanahalli Committed by Linus Torvalds
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[PATCH] Kprobes: Track kprobe on a per_cpu basis - ppc64 changes 



PPC64 changes to track kprobe execution on a per-cpu basis.  We now track the
kprobe state machine independently on each cpu using an arch specific kprobe
control block.

Signed-off-by: default avatarAnanth N Mavinakayanahalli <ananth@in.ibm.com>
Signed-off-by: default avatarAnil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 8a5c4dc5

arch/ppc64/kernel/kprobes.c

+54 −40
Original line number Diff line number Diff line
@@ -37,12 +37,8 @@ 
#include <asm/sstep.h>



static DECLARE_MUTEX(kprobe_mutex);



static struct kprobe *current_kprobe;

static unsigned long kprobe_status, kprobe_saved_msr;

static struct kprobe *kprobe_prev;

static unsigned long kprobe_status_prev, kprobe_saved_msr_prev;

static struct pt_regs jprobe_saved_regs;

DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;

DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);



int __kprobes arch_prepare_kprobe(struct kprobe *p)

{
@@ -108,18 +104,25 @@ static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs) 
		regs->nip = (unsigned long)p->ainsn.insn;

}



static inline void save_previous_kprobe(void)

static inline void save_previous_kprobe(struct kprobe_ctlblk *kcb)

{

	kcb->prev_kprobe.kp = kprobe_running();

	kcb->prev_kprobe.status = kcb->kprobe_status;

	kcb->prev_kprobe.saved_msr = kcb->kprobe_saved_msr;

}



static inline void restore_previous_kprobe(struct kprobe_ctlblk *kcb)

{

	kprobe_prev = current_kprobe;

	kprobe_status_prev = kprobe_status;

	kprobe_saved_msr_prev = kprobe_saved_msr;

	__get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;

	kcb->kprobe_status = kcb->prev_kprobe.status;

	kcb->kprobe_saved_msr = kcb->prev_kprobe.saved_msr;

}



static inline void restore_previous_kprobe(void)

static inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs,

				struct kprobe_ctlblk *kcb)

{

	current_kprobe = kprobe_prev;

	kprobe_status = kprobe_status_prev;

	kprobe_saved_msr = kprobe_saved_msr_prev;

	__get_cpu_var(current_kprobe) = p;

	kcb->kprobe_saved_msr = regs->msr;

}



void __kprobes arch_prepare_kretprobe(struct kretprobe *rp,
@@ -145,6 +148,7 @@ static inline int kprobe_handler(struct pt_regs *regs) 
	struct kprobe *p;

	int ret = 0;

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

	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();



	/* Check we're not actually recursing */

	if (kprobe_running()) {
@@ -153,10 +157,10 @@ static inline int kprobe_handler(struct pt_regs *regs) 
		p = get_kprobe(addr);

		if (p) {

			kprobe_opcode_t insn = *p->ainsn.insn;

			if (kprobe_status == KPROBE_HIT_SS &&

			if (kcb->kprobe_status == KPROBE_HIT_SS &&

					is_trap(insn)) {

				regs->msr &= ~MSR_SE;

				regs->msr |= kprobe_saved_msr;

				regs->msr |= kcb->kprobe_saved_msr;

				unlock_kprobes();

				goto no_kprobe;

			}
@@ -166,15 +170,15 @@ static inline int kprobe_handler(struct pt_regs *regs) 
			 * just single step on the instruction of the new probe

			 * without calling any user handlers.

			 */

			save_previous_kprobe();

			current_kprobe = p;

			kprobe_saved_msr = regs->msr;

			save_previous_kprobe(kcb);

			set_current_kprobe(p, regs, kcb);

			kcb->kprobe_saved_msr = regs->msr;

			p->nmissed++;

			prepare_singlestep(p, regs);

			kprobe_status = KPROBE_REENTER;

			kcb->kprobe_status = KPROBE_REENTER;

			return 1;

		} else {

			p = current_kprobe;

			p = __get_cpu_var(current_kprobe);

			if (p->break_handler && p->break_handler(p, regs)) {

				goto ss_probe;

			}
@@ -214,16 +218,15 @@ static inline int kprobe_handler(struct pt_regs *regs) 
	 * in post_kprobe_handler().

	 */

	preempt_disable();

	kprobe_status = KPROBE_HIT_ACTIVE;

	current_kprobe = p;

	kprobe_saved_msr = regs->msr;

	kcb->kprobe_status = KPROBE_HIT_ACTIVE;

	set_current_kprobe(p, regs, kcb);

	if (p->pre_handler && p->pre_handler(p, regs))

		/* handler has already set things up, so skip ss setup */

		return 1;



ss_probe:

	prepare_singlestep(p, regs);

	kprobe_status = KPROBE_HIT_SS;

	kcb->kprobe_status = KPROBE_HIT_SS;

	return 1;



no_kprobe:
@@ -292,6 +295,7 @@ int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs) 
	BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));

	regs->nip = orig_ret_address;



	reset_current_kprobe();

	unlock_kprobes();

	preempt_enable_no_resched();
@@ -324,22 +328,26 @@ static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs) 


static inline int post_kprobe_handler(struct pt_regs *regs)

{

	if (!kprobe_running())

	struct kprobe *cur = kprobe_running();

	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();



	if (!cur)

		return 0;



	if ((kprobe_status != KPROBE_REENTER) && current_kprobe->post_handler) {

		kprobe_status = KPROBE_HIT_SSDONE;

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

	if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {

		kcb->kprobe_status = KPROBE_HIT_SSDONE;

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

	}



	resume_execution(current_kprobe, regs);

	regs->msr |= kprobe_saved_msr;

	resume_execution(cur, regs);

	regs->msr |= kcb->kprobe_saved_msr;



	/*Restore back the original saved kprobes variables and continue. */

	if (kprobe_status == KPROBE_REENTER) {

		restore_previous_kprobe();

	if (kcb->kprobe_status == KPROBE_REENTER) {

		restore_previous_kprobe(kcb);

		goto out;

	}

	reset_current_kprobe();

	unlock_kprobes();

out:

	preempt_enable_no_resched();
@@ -358,15 +366,18 @@ out: 
/* Interrupts disabled, kprobe_lock held. */

static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)

{

	if (current_kprobe->fault_handler

	    && current_kprobe->fault_handler(current_kprobe, regs, trapnr))

	struct kprobe *cur = kprobe_running();

	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();



	if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))

		return 1;



	if (kprobe_status & KPROBE_HIT_SS) {

		resume_execution(current_kprobe, regs);

	if (kcb->kprobe_status & KPROBE_HIT_SS) {

		resume_execution(cur, regs);

		regs->msr &= ~MSR_SE;

		regs->msr |= kprobe_saved_msr;

		regs->msr |= kcb->kprobe_saved_msr;



		reset_current_kprobe();

		unlock_kprobes();

		preempt_enable_no_resched();

	}
@@ -411,8 +422,9 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self, 
int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)

{

	struct jprobe *jp = container_of(p, struct jprobe, kp);

	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();



	memcpy(&jprobe_saved_regs, regs, sizeof(struct pt_regs));

	memcpy(&kcb->jprobe_saved_regs, regs, sizeof(struct pt_regs));



	/* setup return addr to the jprobe handler routine */

	regs->nip = (unsigned long)(((func_descr_t *)jp->entry)->entry);
@@ -432,12 +444,14 @@ void __kprobes jprobe_return_end(void) 


int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)

{

	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();



	/*

	 * FIXME - we should ideally be validating that we got here 'cos

	 * of the "trap" in jprobe_return() above, before restoring the

	 * saved regs...

	 */

	memcpy(regs, &jprobe_saved_regs, sizeof(struct pt_regs));

	memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs));

	return 1;

}

include/asm-powerpc/kprobes.h

+15 −0
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ 
 */

#include <linux/types.h>

#include <linux/ptrace.h>

#include <linux/percpu.h>



struct pt_regs;
@@ -53,6 +54,20 @@ struct arch_specific_insn { 
	kprobe_opcode_t *insn;

};



struct prev_kprobe {

	struct kprobe *kp;

	unsigned long status;

	unsigned long saved_msr;

};



/* per-cpu kprobe control block */

struct kprobe_ctlblk {

	unsigned long kprobe_status;

	unsigned long kprobe_saved_msr;

	struct pt_regs jprobe_saved_regs;

	struct prev_kprobe prev_kprobe;

};



#ifdef CONFIG_KPROBES

extern int kprobe_exceptions_notify(struct notifier_block *self,

				    unsigned long val, void *data);