[PATCH] Fix broken mmiotrace due to dr6 by reference change

[PATCH] Fix broken mmiotrace due to dr6 by reference change

[Luca Barbieri]

Commit 62edab9056a6cf0c9207339c8892c923a5217e45 (from June 2009 but merged
in 2.6.33) changes notify_die to pass dr6 by reference.

However, it forgets to fix the check for DR_STEP in kmmio.c, breaking
mmiotrace. It also passes a wrong value to the post handler.

This simple fix makes mmiotrace work again.

Please send to Linus for inclusion in 2.6.33

Signed-off-by: Luca Barbieri <luca@luca-barbieri.com>
---
 arch/x86/mm/kmmio.c |    7 ++++---
 1 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/mm/kmmio.c b/arch/x86/mm/kmmio.c
index c0f6198..536fb68 100644
--- a/arch/x86/mm/kmmio.c
+++ b/arch/x86/mm/kmmio.c
@@ -538,14 +538,15 @@ static int
 kmmio_die_notifier(struct notifier_block *nb, unsigned long val, void *args)
 {
 	struct die_args *arg = args;
+	unsigned long* dr6_p = (unsigned long *)ERR_PTR(arg->err);
 
-	if (val == DIE_DEBUG && (arg->err & DR_STEP))
-		if (post_kmmio_handler(arg->err, arg->regs) == 1) {
+	if (val == DIE_DEBUG && (*dr6_p & DR_STEP))
+		if (post_kmmio_handler(*dr6_p, 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;
+			*dr6_p &= ~DR_STEP;
 			return NOTIFY_STOP;
 		}
 
-- 
1.6.3.3

Re: [PATCH] Fix broken mmiotrace due to dr6 by reference change

[K.Prasad]

On Sat, Jan 16, 2010 at 10:39:30AM +0100, Luca Barbieri wrote:
> Commit 62edab9056a6cf0c9207339c8892c923a5217e45 (from June 2009 but merged
> in 2.6.33) changes notify_die to pass dr6 by reference.
> 
> However, it forgets to fix the check for DR_STEP in kmmio.c, breaking
> mmiotrace. It also passes a wrong value to the post handler.
> 

Yes, looks like I missed it...must have hunted down all those registered
to the die notifier...to propagate the fix.

> This simple fix makes mmiotrace work again.
> 
> Please send to Linus for inclusion in 2.6.33
> 
> Signed-off-by: Luca Barbieri <luca@luca-barbieri.com>
Acked-by: K.Prasad <prasad@linux.vnet.ibm.com>

Thanks,
K.Prasad

> ---
>  arch/x86/mm/kmmio.c |    7 ++++---
>  1 files changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/mm/kmmio.c b/arch/x86/mm/kmmio.c
> index c0f6198..536fb68 100644
> --- a/arch/x86/mm/kmmio.c
> +++ b/arch/x86/mm/kmmio.c
> @@ -538,14 +538,15 @@ static int
>  kmmio_die_notifier(struct notifier_block *nb, unsigned long val, void *args)
>  {
>  	struct die_args *arg = args;
> +	unsigned long* dr6_p = (unsigned long *)ERR_PTR(arg->err);
> 
> -	if (val == DIE_DEBUG && (arg->err & DR_STEP))
> -		if (post_kmmio_handler(arg->err, arg->regs) == 1) {
> +	if (val == DIE_DEBUG && (*dr6_p & DR_STEP))
> +		if (post_kmmio_handler(*dr6_p, 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;
> +			*dr6_p &= ~DR_STEP;
>  			return NOTIFY_STOP;
>  		}
> 
> -- 
> 1.6.3.3
> 

Re: [PATCH] Fix broken mmiotrace due to dr6 by reference change

[Luca Barbieri]

It seems kgdb needs to be fixed too.

[tip:perf/urgent] hw-breakpoints, perf: Fix broken mmiotrace due to dr6 by reference change

[tip-bot for Luca Barbieri]

Commit-ID:  0bb7a95f5455cd87e6a69e5818bc1f509a98d187
Gitweb:     http://git.kernel.org/tip/0bb7a95f5455cd87e6a69e5818bc1f509a98d187
Author:     Luca Barbieri <luca@luca-barbieri.com>
AuthorDate: Sat, 16 Jan 2010 10:39:30 +0100
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Sun, 17 Jan 2010 08:01:44 +0100

hw-breakpoints, perf: Fix broken mmiotrace due to dr6 by reference change

Commit 62edab9056a6cf0c9207339c8892c923a5217e45 (from June 2009
but merged in 2.6.33) changes notify_die to pass dr6 by
reference.

However, it forgets to fix the check for DR_STEP in kmmio.c,
breaking mmiotrace. It also passes a wrong value to the post
handler.

This simple fix makes mmiotrace work again.

Signed-off-by: Luca Barbieri <luca@luca-barbieri.com>
Acked-by: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1263634770-14578-1-git-send-email-luca@luca-barbieri.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 arch/x86/mm/kmmio.c |    7 ++++---
 1 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/mm/kmmio.c b/arch/x86/mm/kmmio.c
index c0f6198..536fb68 100644
--- a/arch/x86/mm/kmmio.c
+++ b/arch/x86/mm/kmmio.c
@@ -538,14 +538,15 @@ static int
 kmmio_die_notifier(struct notifier_block *nb, unsigned long val, void *args)
 {
 	struct die_args *arg = args;
+	unsigned long* dr6_p = (unsigned long *)ERR_PTR(arg->err);
 
-	if (val == DIE_DEBUG && (arg->err & DR_STEP))
-		if (post_kmmio_handler(arg->err, arg->regs) == 1) {
+	if (val == DIE_DEBUG && (*dr6_p & DR_STEP))
+		if (post_kmmio_handler(*dr6_p, 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;
+			*dr6_p &= ~DR_STEP;
 			return NOTIFY_STOP;
 		}