I noticed that the LBR fixups were not working anymore
on programs where they used to. I tracked this down to
a recent change to copy_from_user_nmi().
commit db0dc75d6403b6663c0eab4c6ccb672eb9b2ed72
Author: Arun Sharma <[email protected]>
Date: Fri Apr 20 15:41:36 2012 -0700
perf/x86: Check user address explicitly in copy_from_user_nmi()
This commit added a call to __range_not_ok() to the
copy_from_user_nmi() routine. The problem is that the logic
of the test must be reversed. __range_not_ok() returns 0 if the
range is VALID. We want to return early from copy_from_user_nmi()
if the range is NOT valid.
Signed-off-by: Stephane Eranian <[email protected]>
---
diff --git a/arch/x86/lib/usercopy.c b/arch/x86/lib/usercopy.c
index 677b1ed..4f74d94 100644
--- a/arch/x86/lib/usercopy.c
+++ b/arch/x86/lib/usercopy.c
@@ -22,7 +22,7 @@ copy_from_user_nmi(void *to, const void __user *from, unsigned long n)
void *map;
int ret;
- if (__range_not_ok(from, n, TASK_SIZE) == 0)
+ if (__range_not_ok(from, n, TASK_SIZE))
return len;
do {
On Mon, 2012-06-11 at 15:44 +0200, Stephane Eranian wrote:
> I noticed that the LBR fixups were not working anymore
> on programs where they used to. I tracked this down to
> a recent change to copy_from_user_nmi().
>
> commit db0dc75d6403b6663c0eab4c6ccb672eb9b2ed72
> Author: Arun Sharma <[email protected]>
> Date: Fri Apr 20 15:41:36 2012 -0700
>
> perf/x86: Check user address explicitly in copy_from_user_nmi()
>
> This commit added a call to __range_not_ok() to the
> copy_from_user_nmi() routine. The problem is that the logic
> of the test must be reversed. __range_not_ok() returns 0 if the
> range is VALID. We want to return early from copy_from_user_nmi()
> if the range is NOT valid.
D'0h.. Thanks!
On 6/11/12 6:47 AM, Peter Zijlstra wrote:
> On Mon, 2012-06-11 at 15:44 +0200, Stephane Eranian wrote:
>> I noticed that the LBR fixups were not working anymore
>> on programs where they used to. I tracked this down to
>> a recent change to copy_from_user_nmi().
>>
>> commit db0dc75d6403b6663c0eab4c6ccb672eb9b2ed72
>> Author: Arun Sharma<[email protected]>
>> Date: Fri Apr 20 15:41:36 2012 -0700
>>
>> perf/x86: Check user address explicitly in copy_from_user_nmi()
>>
>> This commit added a call to __range_not_ok() to the
>> copy_from_user_nmi() routine. The problem is that the logic
>> of the test must be reversed. __range_not_ok() returns 0 if the
>> range is VALID. We want to return early from copy_from_user_nmi()
>> if the range is NOT valid.
>
> D'0h.. Thanks!
My bad. I was fooled by all the kernel addresses that were unwound
properly. Didn't notice the broken unwinding in user space before I sent
the patch. The fix looks good. Thanks.
-Arun
Commit-ID: 25f42985825dd93f0593efe454e54c2aa13f7830
Gitweb: http://git.kernel.org/tip/25f42985825dd93f0593efe454e54c2aa13f7830
Author: Stephane Eranian <[email protected]>
AuthorDate: Mon, 11 Jun 2012 15:44:26 +0200
Committer: Ingo Molnar <[email protected]>
CommitDate: Wed, 13 Jun 2012 15:00:28 +0200
perf/x86: Fix broken LBR fixup code
I noticed that the LBR fixups were not working anymore
on programs where they used to. I tracked this down to
a recent change to copy_from_user_nmi():
db0dc75d640 ("perf/x86: Check user address explicitly in copy_from_user_nmi()")
This commit added a call to __range_not_ok() to the
copy_from_user_nmi() routine. The problem is that the logic
of the test must be reversed. __range_not_ok() returns 0 if the
range is VALID. We want to return early from copy_from_user_nmi()
if the range is NOT valid.
Signed-off-by: Stephane Eranian <[email protected]>
Signed-off-by: Peter Zijlstra <[email protected]>
Acked-by: Arun Sharma <[email protected]>
Link: http://lkml.kernel.org/r/20120611134426.GA7542@quad
Signed-off-by: Ingo Molnar <[email protected]>
---
arch/x86/lib/usercopy.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/arch/x86/lib/usercopy.c b/arch/x86/lib/usercopy.c
index 677b1ed..4f74d94 100644
--- a/arch/x86/lib/usercopy.c
+++ b/arch/x86/lib/usercopy.c
@@ -22,7 +22,7 @@ copy_from_user_nmi(void *to, const void __user *from, unsigned long n)
void *map;
int ret;
- if (__range_not_ok(from, n, TASK_SIZE) == 0)
+ if (__range_not_ok(from, n, TASK_SIZE))
return len;
do {