[PATCH] powerpc/watchpoint: Don't call dar_within_range() for Book3S

[PATCH] powerpc/watchpoint: Don't call dar_within_range() for Book3S

[Ravi Bangoria]

DAR is set to the first byte of overlap between actual access and
watched range at DSI on Book3S processor. But actual access range
might or might not be within user asked range. So for Book3S, it
must not call dar_within_range().

This revert portion of commit 39413ae00967 ("powerpc/hw_breakpoints:
Rewrite 8xx breakpoints to allow any address range size.").

Before patch:
  # ./tools/testing/selftests/powerpc/ptrace/perf-hwbreak
  ...
  TESTED: No overlap
  FAILED: Partial overlap: 0 != 2
  TESTED: Partial overlap
  TESTED: No overlap
  FAILED: Full overlap: 0 != 2
  failure: perf_hwbreak

After patch:
  TESTED: No overlap
  TESTED: Partial overlap
  TESTED: Partial overlap
  TESTED: No overlap
  TESTED: Full overlap
  success: perf_hwbreak

Fixes: 39413ae00967 ("powerpc/hw_breakpoints: Rewrite 8xx breakpoints to allow any address range size.")
Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
---
 arch/powerpc/kernel/hw_breakpoint.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c
index 2462cd7c565c..d0854320bb50 100644
--- a/arch/powerpc/kernel/hw_breakpoint.c
+++ b/arch/powerpc/kernel/hw_breakpoint.c
@@ -331,11 +331,13 @@ int hw_breakpoint_handler(struct die_args *args)
 	}
 
 	info->type &= ~HW_BRK_TYPE_EXTRANEOUS_IRQ;
-	if (!dar_within_range(regs->dar, info))
-		info->type |= HW_BRK_TYPE_EXTRANEOUS_IRQ;
-
-	if (!IS_ENABLED(CONFIG_PPC_8xx) && !stepping_handler(regs, bp, info))
-		goto out;
+	if (IS_ENABLED(CONFIG_PPC_8xx)) {
+		if (!dar_within_range(regs->dar, info))
+			info->type |= HW_BRK_TYPE_EXTRANEOUS_IRQ;
+	} else {
+		if (!stepping_handler(regs, bp, info))
+			goto out;
+	}
 
 	/*
 	 * As a policy, the callback is invoked in a 'trigger-after-execute'
-- 
2.21.1

Re: [PATCH] powerpc/watchpoint: Don't call dar_within_range() for Book3S

[Christophe Leroy]

On 02/22/2020 08:20 AM, Ravi Bangoria wrote:
> DAR is set to the first byte of overlap between actual access and
> watched range at DSI on Book3S processor. But actual access range
> might or might not be within user asked range. So for Book3S, it
> must not call dar_within_range().
> 
> This revert portion of commit 39413ae00967 ("powerpc/hw_breakpoints:
> Rewrite 8xx breakpoints to allow any address range size.").
> 
> Before patch:
>    # ./tools/testing/selftests/powerpc/ptrace/perf-hwbreak
>    ...
>    TESTED: No overlap
>    FAILED: Partial overlap: 0 != 2
>    TESTED: Partial overlap
>    TESTED: No overlap
>    FAILED: Full overlap: 0 != 2
>    failure: perf_hwbreak
> 
> After patch:
>    TESTED: No overlap
>    TESTED: Partial overlap
>    TESTED: Partial overlap
>    TESTED: No overlap
>    TESTED: Full overlap
>    success: perf_hwbreak
> 
> Fixes: 39413ae00967 ("powerpc/hw_breakpoints: Rewrite 8xx breakpoints to allow any address range size.")

Oh, this seems to have been introduced by 27985b2a640e 
("powerpc/watchpoint: Don't ignore extraneous exceptions blindly").

I must have lost it through a rebase as we were doing our series 
approximately at the same time, sorry for that.

Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>

> Reported-by: Michael Ellerman <mpe@ellerman.id.au>
> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
> ---
>   arch/powerpc/kernel/hw_breakpoint.c | 12 +++++++-----
>   1 file changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c
> index 2462cd7c565c..d0854320bb50 100644
> --- a/arch/powerpc/kernel/hw_breakpoint.c
> +++ b/arch/powerpc/kernel/hw_breakpoint.c
> @@ -331,11 +331,13 @@ int hw_breakpoint_handler(struct die_args *args)
>   	}
>   
>   	info->type &= ~HW_BRK_TYPE_EXTRANEOUS_IRQ;
> -	if (!dar_within_range(regs->dar, info))
> -		info->type |= HW_BRK_TYPE_EXTRANEOUS_IRQ;
> -
> -	if (!IS_ENABLED(CONFIG_PPC_8xx) && !stepping_handler(regs, bp, info))
> -		goto out;
> +	if (IS_ENABLED(CONFIG_PPC_8xx)) {
> +		if (!dar_within_range(regs->dar, info))
> +			info->type |= HW_BRK_TYPE_EXTRANEOUS_IRQ;
> +	} else {
> +		if (!stepping_handler(regs, bp, info))
> +			goto out;
> +	}
>   
>   	/*
>   	 * As a policy, the callback is invoked in a 'trigger-after-execute'
> 

Re: [PATCH] powerpc/watchpoint: Don't call dar_within_range() for Book3S

[Ravi Bangoria]

On 2/22/20 4:56 PM, Christophe Leroy wrote:
> 
> 
> On 02/22/2020 08:20 AM, Ravi Bangoria wrote:
>> DAR is set to the first byte of overlap between actual access and
>> watched range at DSI on Book3S processor. But actual access range
>> might or might not be within user asked range. So for Book3S, it
>> must not call dar_within_range().
>>
>> This revert portion of commit 39413ae00967 ("powerpc/hw_breakpoints:
>> Rewrite 8xx breakpoints to allow any address range size.").
>>
>> Before patch:
>>    # ./tools/testing/selftests/powerpc/ptrace/perf-hwbreak
>>    ...
>>    TESTED: No overlap
>>    FAILED: Partial overlap: 0 != 2
>>    TESTED: Partial overlap
>>    TESTED: No overlap
>>    FAILED: Full overlap: 0 != 2
>>    failure: perf_hwbreak
>>
>> After patch:
>>    TESTED: No overlap
>>    TESTED: Partial overlap
>>    TESTED: Partial overlap
>>    TESTED: No overlap
>>    TESTED: Full overlap
>>    success: perf_hwbreak
>>
>> Fixes: 39413ae00967 ("powerpc/hw_breakpoints: Rewrite 8xx breakpoints to allow any address range size.")
> 
> Oh, this seems to have been introduced by 27985b2a640e ("powerpc/watchpoint: Don't ignore extraneous exceptions blindly").
> 
> I must have lost it through a rebase as we were doing our series approximately at the same time, sorry for that.
> 
> Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>

No worries. Thanks for the review :)

Ravi

Re: [PATCH] powerpc/watchpoint: Don't call dar_within_range() for Book3S

[Michael Ellerman]

On Sat, 2020-02-22 at 08:20:49 UTC, Ravi Bangoria wrote:
> DAR is set to the first byte of overlap between actual access and
> watched range at DSI on Book3S processor. But actual access range
> might or might not be within user asked range. So for Book3S, it
> must not call dar_within_range().
> 
> This revert portion of commit 39413ae00967 ("powerpc/hw_breakpoints:
> Rewrite 8xx breakpoints to allow any address range size.").
> 
> Before patch:
>   # ./tools/testing/selftests/powerpc/ptrace/perf-hwbreak
>   ...
>   TESTED: No overlap
>   FAILED: Partial overlap: 0 != 2
>   TESTED: Partial overlap
>   TESTED: No overlap
>   FAILED: Full overlap: 0 != 2
>   failure: perf_hwbreak
> 
> After patch:
>   TESTED: No overlap
>   TESTED: Partial overlap
>   TESTED: Partial overlap
>   TESTED: No overlap
>   TESTED: Full overlap
>   success: perf_hwbreak
> 
> Fixes: 39413ae00967 ("powerpc/hw_breakpoints: Rewrite 8xx breakpoints to allow any address range size.")
> Reported-by: Michael Ellerman <mpe@ellerman.id.au>
> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>

Applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/e08658a657f974590809290c62e889f0fd420200

cheers