Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 62edab90 authored by K.Prasad's avatar K.Prasad Committed by Frederic Weisbecker
Browse files

hw-breakpoints: reset bits in dr6 after the corresponding exception is handled 



This patch resets the bit in dr6 after the corresponding exception is
handled in code, so that we keep a clean track of the current virtual debug
status register.

[ Impact: keep track of breakpoints triggering completion ]

Signed-off-by: default avatarK.Prasad <prasad@linux.vnet.ibm.com>
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
parent 0722db01

arch/x86/kernel/hw_breakpoint.c

+11 −2
Original line number Diff line number Diff line
@@ -314,8 +314,12 @@ int __kprobes hw_breakpoint_handler(struct die_args *args) 
{

	int i, cpu, rc = NOTIFY_STOP;

	struct hw_breakpoint *bp;

	/* The DR6 value is stored in args->err */

	unsigned long dr7, dr6 = args->err;

	unsigned long dr7, dr6;

	unsigned long *dr6_p;



	/* The DR6 value is pointed by args->err */

	dr6_p = (unsigned long *)ERR_PTR(args->err);

	dr6 = *dr6_p;



	/* Do an early return if no trap bits are set in DR6 */

	if ((dr6 & DR_TRAP_BITS) == 0)
@@ -351,6 +355,11 @@ int __kprobes hw_breakpoint_handler(struct die_args *args) 
			if (bp)

				rc = NOTIFY_DONE;

		}

		/*

		 * Reset the 'i'th TRAP bit in dr6 to denote completion of

		 * exception handling

		 */

		(*dr6_p) &= ~(DR_TRAP0 << i);

		/*

		 * bp can be NULL due to lazy debug register switching

		 * or due to the delay between updates of hbp_kernel_pos

arch/x86/kernel/kgdb.c

+6 −0
Original line number Diff line number Diff line
@@ -43,6 +43,7 @@ 
#include <linux/smp.h>

#include <linux/nmi.h>



#include <asm/debugreg.h>

#include <asm/apicdef.h>

#include <asm/system.h>
@@ -434,6 +435,11 @@ single_step_cont(struct pt_regs *regs, struct die_args *args) 
			"resuming...\n");

	kgdb_arch_handle_exception(args->trapnr, args->signr,

				   args->err, "c", "", regs);

	/*

	 * Reset the BS bit in dr6 (pointed by args->err) to

	 * denote completion of processing

	 */

	(*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP;



	return NOTIFY_STOP;

}

arch/x86/kernel/kprobes.c

+8 −1
Original line number Diff line number Diff line
@@ -54,6 +54,7 @@ 
#include <asm/pgtable.h>

#include <asm/uaccess.h>

#include <asm/alternative.h>

#include <asm/debugreg.h>



void jprobe_return_end(void);
@@ -967,8 +968,14 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self, 
			ret = NOTIFY_STOP;

		break;

	case DIE_DEBUG:

		if (post_kprobe_handler(args->regs))

		if (post_kprobe_handler(args->regs)) {

			/*

			 * Reset the BS bit in dr6 (pointed by args->err) to

			 * denote completion of processing

			 */

			(*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP;

			ret = NOTIFY_STOP;

		}

		break;

	case DIE_GPF:

		/*

arch/x86/kernel/traps.c

+2 −2
Original line number Diff line number Diff line
@@ -545,7 +545,7 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code) 
	/* Store the virtualized DR6 value */

	tsk->thread.debugreg6 = dr6;



	if (notify_die(DIE_DEBUG, "debug", regs, dr6, error_code,

	if (notify_die(DIE_DEBUG, "debug", regs, PTR_ERR(&dr6), error_code,

							SIGTRAP) == NOTIFY_STOP)

		return;

arch/x86/mm/kmmio.c

+7 −1
Original line number Diff line number Diff line
@@ -540,8 +540,14 @@ kmmio_die_notifier(struct notifier_block *nb, unsigned long val, void *args) 
	struct die_args *arg = args;



	if (val == DIE_DEBUG && (arg->err & DR_STEP))

		if (post_kmmio_handler(arg->err, arg->regs) == 1)

		if (post_kmmio_handler(arg->err, arg->regs) == 1) {

			/*

			 * Reset the BS bit in dr6 (pointed by args->err) to

			 * denote completion of processing

			 */

			(*(unsigned long *)ERR_PTR(arg->err)) &= ~DR_STEP;

			return NOTIFY_STOP;

		}



	return NOTIFY_DONE;

}