[PATCH] powerpc: Fix instruction encoding for lis in ppc_function_entry()

'lis r2,N' is 'addis r2,0,N' and the instruction encoding in the macro
LIS_R2 is incorrect (it currently maps to 'addis 0,r2,N'). Fix the same.

Fixes: c71b7eff426fa7 ("powerpc: Add ABIv2 support to ppc_function_entry")
Reported-by: Jiri Olsa <redacted>
Signed-off-by: Naveen N. Rao <redacted>
---
 arch/powerpc/include/asm/code-patching.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/code-patching.h b/arch/powerpc/include/asm/code-patching.h
index eacc9102c2515c..d5b3c3bb95b400 100644
--- a/arch/powerpc/include/asm/code-patching.h
+++ b/arch/powerpc/include/asm/code-patching.h

@@ -73,7 +73,7 @@ void __patch_exception(int exc, unsigned long addr);
 #endif
 
 #define OP_RT_RA_MASK	0xffff0000UL
-#define LIS_R2		0x3c020000UL
+#define LIS_R2		0x3c400000UL
 #define ADDIS_R2_R12	0x3c4c0000UL
 #define ADDI_R2_R2	0x38420000UL
 

base-commit: 91966823812efbd175f904599e5cf2a854b39809
-- 
2.25.1

Le 04/03/2021 à 03:04, Naveen N. Rao a écrit :

That probably goes beyond the scope of this patch, but it would be more readable and less error 
prone to use macros defined in ppc-opcode.h just like kernel/module_64.c does for instance:

#define LIS_R2	(PPC_INST_ADDIS | __PPC_RT(R2))
#define ADDIS_R2_R12	(PPC_INST_ADDIS | __PPC_RT(R2) | __PPC_RA(R12))
#define ADDI_R2_R2	(PPC_INST_ADDI | __PPC_RT(R2) | __PPC_RA(R2))

  

base-commit: 91966823812efbd175f904599e5cf2a854b39809

On Thu, Mar 04, 2021 at 07:34:11AM +0530, Naveen N. Rao wrote:

I tested the new define value with uprobe issue we were dealing with
and now it matches the instruction, so it works for me

thanks a lot for the fix,
jirka

On Thu, Mar 04, 2021 at 07:34:11AM +0530, Naveen N. Rao wrote:

'lis r2,N' is 'addis r2,0,N' and the instruction encoding in the macro
LIS_R2 is incorrect (it currently maps to 'addis 0,r2,N'). Fix the same.

That is written "addis r0,r2,N" even.  Your patch looks fine otherwise,
so with that fix:

Acked-by: Segher Boessenkool <redacted>


Segher

On 2021/03/05 12:37PM, Christophe Leroy wrote:

Le 04/03/2021 à 03:04, Naveen N. Rao a écrit :

quoted

'lis r2,N' is 'addis r2,0,N' and the instruction encoding in the macro
LIS_R2 is incorrect (it currently maps to 'addis 0,r2,N'). Fix the same.

Fixes: c71b7eff426fa7 ("powerpc: Add ABIv2 support to ppc_function_entry")
Reported-by: Jiri Olsa <redacted>
Signed-off-by: Naveen N. Rao <redacted>
---
  arch/powerpc/include/asm/code-patching.h | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/code-patching.h b/arch/powerpc/include/asm/code-patching.h
index eacc9102c2515c..d5b3c3bb95b400 100644
--- a/arch/powerpc/include/asm/code-patching.h
+++ b/arch/powerpc/include/asm/code-patching.h

@@ -73,7 +73,7 @@ void __patch_exception(int exc, unsigned long addr);
  #endif
  #define OP_RT_RA_MASK	0xffff0000UL
-#define LIS_R2		0x3c020000UL
+#define LIS_R2		0x3c400000UL
  #define ADDIS_R2_R12	0x3c4c0000UL
  #define ADDI_R2_R2	0x38420000UL

That probably goes beyond the scope of this patch, but it would be more
readable and less error prone to use macros defined in ppc-opcode.h just
like kernel/module_64.c does for instance:

#define LIS_R2	(PPC_INST_ADDIS | __PPC_RT(R2))
#define ADDIS_R2_R12	(PPC_INST_ADDIS | __PPC_RT(R2) | __PPC_RA(R12))
#define ADDI_R2_R2	(PPC_INST_ADDI | __PPC_RT(R2) | __PPC_RA(R2))

Good point. While that would have made it harder to spot the error, it 
probably would have avoided the error in the first place.

Your change looks good to me.

Thanks,
Naveen

On Thu, 4 Mar 2021 07:34:11 +0530, Naveen N. Rao wrote:

'lis r2,N' is 'addis r2,0,N' and the instruction encoding in the macro
LIS_R2 is incorrect (it currently maps to 'addis 0,r2,N'). Fix the same.

Applied to powerpc/fixes.

[1/1] powerpc/64s: Fix instruction encoding for lis in ppc_function_entry()
      https://git.kernel.org/powerpc/c/cea15316ceee2d4a51dfdecd79e08a438135416c

cheers