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Commit f8279621 authored by Kumar Gala's avatar Kumar Gala
Browse files

powerpc/booke: Add kprobes support for booke style processors 



This patch is based on work done by Madhvesh. R. Sulibhavi back in
March 2007.

We refactor some of the single step handling since it differs between
"classic" and "booke" powerpc cores.

Signed-off-by: default avatarKumar Gala <galak@kernel.crashing.org>
parent b76e59d1

Documentation/kprobes.txt

+1 −0
Original line number Diff line number Diff line
@@ -172,6 +172,7 @@ architectures: 
- ia64 (Does not support probes on instruction slot1.)

- sparc64 (Return probes not yet implemented.)

- arm

- ppc



3. Configuring Kprobes

arch/powerpc/kernel/kprobes.c

+19 −6
Original line number Diff line number Diff line
@@ -34,6 +34,13 @@ 
#include <asm/cacheflush.h>

#include <asm/sstep.h>

#include <asm/uaccess.h>

#include <asm/system.h>



#ifdef CONFIG_BOOKE

#define MSR_SINGLESTEP	(MSR_DE)

#else

#define MSR_SINGLESTEP	(MSR_SE)

#endif



DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;

DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
@@ -53,7 +60,8 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p) 
		ret = -EINVAL;

	}



	/* insn must be on a special executable page on ppc64 */

	/* insn must be on a special executable page on ppc64.  This is

	 * not explicitly required on ppc32 (right now), but it doesn't hurt */

	if (!ret) {

		p->ainsn.insn = get_insn_slot();

		if (!p->ainsn.insn)
@@ -100,7 +108,11 @@ static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs) 
	 * possible we'd get the single step reported for an exception handler

	 * like Decrementer or External Interrupt */

	regs->msr &= ~MSR_EE;

	regs->msr |= MSR_SE;

	regs->msr |= MSR_SINGLESTEP;

#ifdef CONFIG_BOOKE

	regs->msr &= ~MSR_CE;

	mtspr(SPRN_DBCR0, mfspr(SPRN_DBCR0) | DBCR0_IC | DBCR0_IDM);

#endif



	/*

	 * On powerpc we should single step on the original
@@ -163,7 +175,8 @@ static int __kprobes kprobe_handler(struct pt_regs *regs) 
			kprobe_opcode_t insn = *p->ainsn.insn;

			if (kcb->kprobe_status == KPROBE_HIT_SS &&

					is_trap(insn)) {

				regs->msr &= ~MSR_SE;

				/* Turn off 'trace' bits */

				regs->msr &= ~MSR_SINGLESTEP;

				regs->msr |= kcb->kprobe_saved_msr;

				goto no_kprobe;

			}
@@ -404,10 +417,10 @@ static int __kprobes post_kprobe_handler(struct pt_regs *regs) 


	/*

	 * if somebody else is singlestepping across a probe point, msr

	 * will have SE set, in which case, continue the remaining processing

	 * will have DE/SE set, in which case, continue the remaining processing

	 * of do_debug, as if this is not a probe hit.

	 */

	if (regs->msr & MSR_SE)

	if (regs->msr & MSR_SINGLESTEP)

		return 0;



	return 1;
@@ -430,7 +443,7 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) 
		 * normal page fault.

		 */

		regs->nip = (unsigned long)cur->addr;

		regs->msr &= ~MSR_SE;

		regs->msr &= ~MSR_SINGLESTEP; /* Turn off 'trace' bits */

		regs->msr |= kcb->kprobe_saved_msr;

		if (kcb->kprobe_status == KPROBE_REENTER)

			restore_previous_kprobe(kcb);

arch/powerpc/kernel/traps.c

+17 −9
Original line number Diff line number Diff line
@@ -1030,21 +1030,29 @@ void SoftwareEmulation(struct pt_regs *regs) 


#if defined(CONFIG_40x) || defined(CONFIG_BOOKE)



void DebugException(struct pt_regs *regs, unsigned long debug_status)

void __kprobes DebugException(struct pt_regs *regs, unsigned long debug_status)

{

	if (debug_status & DBSR_IC) {	/* instruction completion */

		regs->msr &= ~MSR_DE;

		if (user_mode(regs)) {

			current->thread.dbcr0 &= ~DBCR0_IC;

		} else {



		/* Disable instruction completion */

		mtspr(SPRN_DBCR0, mfspr(SPRN_DBCR0) & ~DBCR0_IC);

		/* Clear the instruction completion event */

		mtspr(SPRN_DBSR, DBSR_IC);



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

			       5, SIGTRAP) == NOTIFY_STOP) {

			return;

		}



		if (debugger_sstep(regs))

			return;



		if (user_mode(regs)) {

			current->thread.dbcr0 &= ~DBCR0_IC;

		}

		_exception(SIGTRAP, regs, TRAP_TRACE, 0);



		_exception(SIGTRAP, regs, TRAP_TRACE, regs->nip);

	}

}

#endif /* CONFIG_4xx || CONFIG_BOOKE */