powerpc/powernv: copy/paste - Mask XERS0 bit in CR

    
NX can set 3rd bit in CR register for XER[SO] (Summation overflow)
which is not related to paste request. The current paste function
returns failure for the successful request when this bit is set.
So mask this bit and check the proper return status.

Fixes: 2392c8c8c045 ("powerpc/powernv/vas: Define copy/paste interfaces")
Cc: stable@vger.kernel.org # v4.14+    
Signed-off-by: Haren Myneni <haren@us.ibm.com>

diff --git a/arch/powerpc/platforms/powernv/copy-paste.h b/arch/powerpc/platforms/powernv/copy-paste.h
index c9a5036..82392e3 100644
--- a/arch/powerpc/platforms/powernv/copy-paste.h
+++ b/arch/powerpc/platforms/powernv/copy-paste.h

@@ -9,7 +9,8 @@
 #include <asm/ppc-opcode.h>
 
 #define CR0_SHIFT	28
-#define CR0_MASK	0xF
+#define CR0_MASK	0xE /* 3rd bit undefined or set for XER[SO] */
+
 /*
  * Copy/paste instructions:
  *

Hi Haren,

Haren Myneni [off-list ref] writes:

Unfortunately this no longer applies to my next branch, because those
macros have been moved out of this header as part of an unrelated patch.

The following patch should work instead, can you please confirm by
testing it?

diff --git a/arch/powerpc/platforms/powernv/copy-paste.h b/arch/powerpc/platforms/powernv/copy-paste.h
index 3fa62de96d9c..c46a326776cf 100644
--- a/arch/powerpc/platforms/powernv/copy-paste.h
+++ b/arch/powerpc/platforms/powernv/copy-paste.h

@@ -41,5 +41,7 @@ static inline int vas_paste(void *paste_address, int offset)
 		: "b" (offset), "b" (paste_address)
 		: "memory", "cr0");
 
-	return (cr >> CR0_SHIFT) & CR0_MASK;
+
+	/* We mask with 0xE to ignore SO */
+	return (cr >> CR0_SHIFT) & 0xE;
 }

cheers

On 06/03/2018 03:48 AM, Michael Ellerman wrote:

Tested with this patch and it works.

Thanks
Haren

cheers

Haren Myneni [off-list ref] writes:

On 06/03/2018 03:48 AM, Michael Ellerman wrote:

quoted

Haren Myneni [off-list ref] writes:

quoted

NX can set 3rd bit in CR register for XER[SO] (Summation overflow)
which is not related to paste request. The current paste function
returns failure for the successful request when this bit is set.
So mask this bit and check the proper return status.

Fixes: 2392c8c8c045 ("powerpc/powernv/vas: Define copy/paste interfaces")
Cc: stable@vger.kernel.org # v4.14+    
Signed-off-by: Haren Myneni <haren@us.ibm.com>

diff --git a/arch/powerpc/platforms/powernv/copy-paste.h b/arch/powerpc/platforms/powernv/copy-paste.h
index c9a5036..82392e3 100644
--- a/arch/powerpc/platforms/powernv/copy-paste.h
+++ b/arch/powerpc/platforms/powernv/copy-paste.h

@@ -9,7 +9,8 @@
 #include <asm/ppc-opcode.h>
 
 #define CR0_SHIFT	28
-#define CR0_MASK	0xF
+#define CR0_MASK	0xE /* 3rd bit undefined or set for XER[SO] */
+
 /*
  * Copy/paste instructions:
  *

Unfortunately this no longer applies to my next branch, because those
macros have been moved out of this header as part of an unrelated patch.

The following patch should work instead, can you please confirm by
testing it?

diff --git a/arch/powerpc/platforms/powernv/copy-paste.h b/arch/powerpc/platforms/powernv/copy-paste.h
index 3fa62de96d9c..c46a326776cf 100644
--- a/arch/powerpc/platforms/powernv/copy-paste.h
+++ b/arch/powerpc/platforms/powernv/copy-paste.h

@@ -41,5 +41,7 @@ static inline int vas_paste(void *paste_address, int offset)
 		: "b" (offset), "b" (paste_address)
 		: "memory", "cr0");

-	return (cr >> CR0_SHIFT) & CR0_MASK;
+
+	/* We mask with 0xE to ignore SO */
+	return (cr >> CR0_SHIFT) & 0xE;
 }

Tested with this patch and it works.

Thanks. I sent a new version to the list and will apply that.

cheers