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Commit ec097c84 authored by Roland McGrath's avatar Roland McGrath Committed by Benjamin Herrenschmidt
Browse files

powerpc: Add PTRACE_SINGLEBLOCK support 



Reworked by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

This adds block-step support on powerpc, including a PTRACE_SINGLEBLOCK
request for ptrace.

The BookE implementation is tweaked to fire a single step after a
block step in order to mimmic the server behaviour.

Signed-off-by: default avatarRoland McGrath <roland@redhat.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent dac4ccfb

arch/powerpc/include/asm/ptrace.h

+4 −0
Original line number Diff line number Diff line
@@ -135,7 +135,9 @@ do { \ 
 * These are defined as per linux/ptrace.h, which see.

 */

#define arch_has_single_step()	(1)

#define arch_has_block_step()	(!cpu_has_feature(CPU_FTR_601))

extern void user_enable_single_step(struct task_struct *);

extern void user_enable_block_step(struct task_struct *);

extern void user_disable_single_step(struct task_struct *);



#endif /* __ASSEMBLY__ */
@@ -288,4 +290,6 @@ extern void user_disable_single_step(struct task_struct *); 
#define PPC_PTRACE_PEEKUSR_3264  0x91

#define PPC_PTRACE_POKEUSR_3264  0x90



#define PTRACE_SINGLEBLOCK	0x100	/* resume execution until next branch */



#endif /* _ASM_POWERPC_PTRACE_H */

arch/powerpc/kernel/head_booke.h

+5 −5
Original line number Diff line number Diff line
@@ -256,7 +256,7 @@ label: 
	 * off DE in the DSRR1 value and clearing the debug status.	      \

	 */								      \

	mfspr	r10,SPRN_DBSR;		/* check single-step/branch taken */  \

	andis.	r10,r10,DBSR_IC@h;					      \

	andis.	r10,r10,(DBSR_IC|DBSR_BT)@h;				      \

	beq+	2f;							      \

									      \

	lis	r10,KERNELBASE@h;	/* check if exception in vectors */   \
@@ -271,7 +271,7 @@ label: 
									      \

	/* here it looks like we got an inappropriate debug exception. */     \

1:	rlwinm	r9,r9,0,~MSR_DE;	/* clear DE in the CDRR1 value */     \

	lis	r10,DBSR_IC@h;		/* clear the IC event */	      \

	lis	r10,(DBSR_IC|DBSR_BT)@h;	/* clear the IC event */      \

	mtspr	SPRN_DBSR,r10;						      \

	/* restore state and get out */					      \

	lwz	r10,_CCR(r11);						      \
@@ -309,7 +309,7 @@ label: 
	 * off DE in the CSRR1 value and clearing the debug status.	      \

	 */								      \

	mfspr	r10,SPRN_DBSR;		/* check single-step/branch taken */  \

	andis.	r10,r10,DBSR_IC@h;					      \

	andis.	r10,r10,(DBSR_IC|DBSR_BT)@h;				      \

	beq+	2f;							      \

									      \

	lis	r10,KERNELBASE@h;	/* check if exception in vectors */   \
@@ -324,7 +324,7 @@ label: 
									      \

	/* here it looks like we got an inappropriate debug exception. */     \

1:	rlwinm	r9,r9,0,~MSR_DE;	/* clear DE in the CSRR1 value */     \

	lis	r10,DBSR_IC@h;		/* clear the IC event */	      \

	lis	r10,(DBSR_IC|DBSR_BT)@h;	/* clear the IC event */      \

	mtspr	SPRN_DBSR,r10;						      \

	/* restore state and get out */					      \

	lwz	r10,_CCR(r11);						      \

arch/powerpc/kernel/ptrace.c

+21 −2
Original line number Diff line number Diff line
@@ -704,15 +704,34 @@ void user_enable_single_step(struct task_struct *task) 


	if (regs != NULL) {

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

		task->thread.dbcr0 &= ~DBCR0_BT;

		task->thread.dbcr0 |= DBCR0_IDM | DBCR0_IC;

		regs->msr |= MSR_DE;

#else

		regs->msr &= ~MSR_BE;

		regs->msr |= MSR_SE;

#endif

	}

	set_tsk_thread_flag(task, TIF_SINGLESTEP);

}



void user_enable_block_step(struct task_struct *task)

{

	struct pt_regs *regs = task->thread.regs;



	if (regs != NULL) {

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

		task->thread.dbcr0 &= ~DBCR0_IC;

		task->thread.dbcr0 = DBCR0_IDM | DBCR0_BT;

		regs->msr |= MSR_DE;

#else

		regs->msr &= ~MSR_SE;

		regs->msr |= MSR_BE;

#endif

	}

	set_tsk_thread_flag(task, TIF_SINGLESTEP);

}



void user_disable_single_step(struct task_struct *task)

{

	struct pt_regs *regs = task->thread.regs;
@@ -726,10 +745,10 @@ void user_disable_single_step(struct task_struct *task) 


	if (regs != NULL) {

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

		task->thread.dbcr0 &= ~(DBCR0_IC | DBCR0_IDM);

		task->thread.dbcr0 &= ~(DBCR0_IC | DBCR0_BT | DBCR0_IDM);

		regs->msr &= ~MSR_DE;

#else

		regs->msr &= ~MSR_SE;

		regs->msr &= ~(MSR_SE | MSR_BE);

#endif

	}

	clear_tsk_thread_flag(task, TIF_SINGLESTEP);

arch/powerpc/kernel/traps.c

+30 −4
Original line number Diff line number Diff line
@@ -1041,7 +1041,34 @@ void SoftwareEmulation(struct pt_regs *regs) 


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

{

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

	/* Hack alert: On BookE, Branch Taken stops on the branch itself, while

	 * on server, it stops on the target of the branch. In order to simulate

	 * the server behaviour, we thus restart right away with a single step

	 * instead of stopping here when hitting a BT

	 */

	if (debug_status & DBSR_BT) {

		regs->msr &= ~MSR_DE;



		/* Disable BT */

		mtspr(SPRN_DBCR0, mfspr(SPRN_DBCR0) & ~DBCR0_BT);

		/* Clear the BT event */

		mtspr(SPRN_DBSR, DBSR_BT);



		/* Do the single step trick only when coming from userspace */

		if (user_mode(regs)) {

			current->thread.dbcr0 &= ~DBCR0_BT;

			current->thread.dbcr0 |= DBCR0_IDM | DBCR0_IC;

			regs->msr |= MSR_DE;

			return;

		}



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

			       5, SIGTRAP) == NOTIFY_STOP) {

			return;

		}

		if (debugger_sstep(regs))

			return;

	} else if (debug_status & DBSR_IC) { 	/* Instruction complete */

		regs->msr &= ~MSR_DE;



		/* Disable instruction completion */
@@ -1057,9 +1084,8 @@ void __kprobes DebugException(struct pt_regs *regs, unsigned long debug_status) 
		if (debugger_sstep(regs))

			return;



		if (user_mode(regs)) {

			current->thread.dbcr0 &= ~DBCR0_IC;

		}

		if (user_mode(regs))

			current->thread.dbcr0 &= ~(DBCR0_IC);



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

	} else if (debug_status & (DBSR_DAC1R | DBSR_DAC1W)) {