Commit f7809daf authored by Frederic Weisbecker's avatar Frederic Weisbecker
Browse files

x86: Support for instruction breakpoints 



Instruction breakpoints need to have a specific length of 0 to
be working. Bring this support but also take care the user is not
trying to set an unsupported length, like a range breakpoint for
example.

Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Prasad <prasad@linux.vnet.ibm.com>
Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Jason Wessel <jason.wessel@windriver.com>
parent 0c4519e8

arch/x86/include/asm/hw_breakpoint.h

+1 −1
Original line number Diff line number Diff line
@@ -20,10 +20,10 @@ struct arch_hw_breakpoint { 
#include <linux/list.h>



/* Available HW breakpoint length encodings */

#define X86_BREAKPOINT_LEN_X		0x00

#define X86_BREAKPOINT_LEN_1		0x40

#define X86_BREAKPOINT_LEN_2		0x44

#define X86_BREAKPOINT_LEN_4		0x4c

#define X86_BREAKPOINT_LEN_EXECUTE	0x40



#ifdef CONFIG_X86_64

#define X86_BREAKPOINT_LEN_8		0x48

arch/x86/kernel/hw_breakpoint.c

+29 −15
Original line number Diff line number Diff line
@@ -208,6 +208,9 @@ int arch_bp_generic_fields(int x86_len, int x86_type, 
{

	/* Len */

	switch (x86_len) {

	case X86_BREAKPOINT_LEN_X:

		*gen_len = sizeof(long);

		break;

	case X86_BREAKPOINT_LEN_1:

		*gen_len = HW_BREAKPOINT_LEN_1;

		break;
@@ -251,6 +254,29 @@ static int arch_build_bp_info(struct perf_event *bp) 


	info->address = bp->attr.bp_addr;



	/* Type */

	switch (bp->attr.bp_type) {

	case HW_BREAKPOINT_W:

		info->type = X86_BREAKPOINT_WRITE;

		break;

	case HW_BREAKPOINT_W | HW_BREAKPOINT_R:

		info->type = X86_BREAKPOINT_RW;

		break;

	case HW_BREAKPOINT_X:

		info->type = X86_BREAKPOINT_EXECUTE;

		/*

		 * x86 inst breakpoints need to have a specific undefined len.

		 * But we still need to check userspace is not trying to setup

		 * an unsupported length, to get a range breakpoint for example.

		 */

		if (bp->attr.bp_len == sizeof(long)) {

			info->len = X86_BREAKPOINT_LEN_X;

			return 0;

		}

	default:

		return -EINVAL;

	}



	/* Len */

	switch (bp->attr.bp_len) {

	case HW_BREAKPOINT_LEN_1:
@@ -271,21 +297,6 @@ static int arch_build_bp_info(struct perf_event *bp) 
		return -EINVAL;

	}



	/* Type */

	switch (bp->attr.bp_type) {

	case HW_BREAKPOINT_W:

		info->type = X86_BREAKPOINT_WRITE;

		break;

	case HW_BREAKPOINT_W | HW_BREAKPOINT_R:

		info->type = X86_BREAKPOINT_RW;

		break;

	case HW_BREAKPOINT_X:

		info->type = X86_BREAKPOINT_EXECUTE;

		break;

	default:

		return -EINVAL;

	}



	return 0;

}

/*
@@ -305,6 +316,9 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp) 
	ret = -EINVAL;



	switch (info->len) {

	case X86_BREAKPOINT_LEN_X:

		align = sizeof(long) -1;

		break;

	case X86_BREAKPOINT_LEN_1:

		align = 0;

		break;

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