[PATCH 1/2] powerpc: Make stack frame marker upper case

Subsystems: linux for powerpc (32-bit and 64-bit), ptrace support, the rest

STALE1399d LANDED

Landed in mainline as bbd71709087a on 2022-09-28.

4 messages, 3 authors, 2022-10-04 · open the first message on its own page

[PATCH 1/2] powerpc: Make stack frame marker upper case

From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2022-09-27 15:05:31 

Now that the stack frame regs marker is only 32-bits it is not as
obvious in memory dumps and easier to miss, eg:

  c000000004733e40 0000000000000000 0000000000000000  |................|
  c000000004733e50 0000000000000000 0000000000000000  |................|
  c000000004733e60 0000000000000000 0000000000000000  |................|
  c000000004733e70 7367657200000000 0000000000000000  |sger............|
  c000000004733e80 a700000000000000 708897f7ff7f0000  |........p.......|
  c000000004733e90 0073428fff7f0000 208997f7ff7f0000  |.sB..... .......|
  c000000004733ea0 0100000000000000 ffffffffffffffff  |................|
  c000000004733eb0 0000000000000000 0000000000000000  |................|

So make it upper case to make it stand out a bit more:

  c000000004733e70 5347455200000000 0000000000000000  |SGER............|

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
 arch/powerpc/include/asm/ptrace.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h
index 5b496e589d54..6c23d1d25dc7 100644
--- a/arch/powerpc/include/asm/ptrace.h
+++ b/arch/powerpc/include/asm/ptrace.h
@@ -99,7 +99,7 @@ struct pt_regs
 
 #define STACK_FRAME_WITH_PT_REGS (STACK_FRAME_OVERHEAD + sizeof(struct pt_regs))
 
-#define STACK_FRAME_REGS_MARKER	ASM_CONST(0x72656773)
+#define STACK_FRAME_REGS_MARKER	ASM_CONST(0x52454753)
 
 #ifdef __powerpc64__
 
-- 
2.37.3

[PATCH 2/2] powerpc: Reverse stack frame marker on little endian

From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2022-09-27 15:05:01 

On little endian the stack frame marker appears reserved when dumping
memory sequentially, as is typical in xmon or gdb, eg:

  c000000004733e40 0000000000000000 0000000000000000  |................|
  c000000004733e50 0000000000000000 0000000000000000  |................|
  c000000004733e60 0000000000000000 0000000000000000  |................|
  c000000004733e70 5347455200000000 0000000000000000  |SGER............|
  c000000004733e80 a700000000000000 708897f7ff7f0000  |........p.......|
  c000000004733e90 0073428fff7f0000 208997f7ff7f0000  |.sB..... .......|
  c000000004733ea0 0100000000000000 ffffffffffffffff  |................|
  c000000004733eb0 0000000000000000 0000000000000000  |................|

To make it easier to recognise, reverse the value on little endian, so
it always appears as "REGS", eg:

  c000000004733e70 5245475300000000 0000000000000000  |REGS............|

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
 arch/powerpc/include/asm/ptrace.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h
index 6c23d1d25dc7..2efec6d87049 100644
--- a/arch/powerpc/include/asm/ptrace.h
+++ b/arch/powerpc/include/asm/ptrace.h
@@ -99,7 +99,12 @@ struct pt_regs
 
 #define STACK_FRAME_WITH_PT_REGS (STACK_FRAME_OVERHEAD + sizeof(struct pt_regs))
 
+// Always displays as "REGS" in memory dumps
+#ifdef CONFIG_CPU_BIG_ENDIAN
 #define STACK_FRAME_REGS_MARKER	ASM_CONST(0x52454753)
+#else
+#define STACK_FRAME_REGS_MARKER	ASM_CONST(0x53474552)
+#endif
 
 #ifdef __powerpc64__
 
-- 
2.37.3

Re: [PATCH 2/2] powerpc: Reverse stack frame marker on little endian

From: "Nicholas Piggin" <npiggin@gmail.com>
Date: 2022-09-28 03:14:03 

On Wed Sep 28, 2022 at 1:04 AM AEST, Michael Ellerman wrote:
On little endian the stack frame marker appears reserved when dumping
memory sequentially, as is typical in xmon or gdb, eg:

  c000000004733e40 0000000000000000 0000000000000000  |................|
  c000000004733e50 0000000000000000 0000000000000000  |................|
  c000000004733e60 0000000000000000 0000000000000000  |................|
  c000000004733e70 5347455200000000 0000000000000000  |SGER............|
  c000000004733e80 a700000000000000 708897f7ff7f0000  |........p.......|
  c000000004733e90 0073428fff7f0000 208997f7ff7f0000  |.sB..... .......|
  c000000004733ea0 0100000000000000 ffffffffffffffff  |................|
  c000000004733eb0 0000000000000000 0000000000000000  |................|

To make it easier to recognise, reverse the value on little endian, so
it always appears as "REGS", eg:

  c000000004733e70 5245475300000000 0000000000000000  |REGS............|

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Both look fine to me.

Acked-by: Nicholas Piggin <npiggin@gmail.com>
quoted hunk
---
 arch/powerpc/include/asm/ptrace.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h
index 6c23d1d25dc7..2efec6d87049 100644
--- a/arch/powerpc/include/asm/ptrace.h
+++ b/arch/powerpc/include/asm/ptrace.h
@@ -99,7 +99,12 @@ struct pt_regs
 
 #define STACK_FRAME_WITH_PT_REGS (STACK_FRAME_OVERHEAD + sizeof(struct pt_regs))
 
+// Always displays as "REGS" in memory dumps
+#ifdef CONFIG_CPU_BIG_ENDIAN
 #define STACK_FRAME_REGS_MARKER	ASM_CONST(0x52454753)
+#else
+#define STACK_FRAME_REGS_MARKER	ASM_CONST(0x53474552)
+#endif
 
 #ifdef __powerpc64__
 
-- 
2.37.3





  

    
Re: [PATCH 1/2] powerpc: Make stack frame marker upper case

    

      From: Michael Ellerman <hidden>

      Date: 2022-10-04 13:49:15 
    

  

  
On Wed, 28 Sep 2022 01:04:18 +1000, Michael Ellerman wrote:
Now that the stack frame regs marker is only 32-bits it is not as
obvious in memory dumps and easier to miss, eg:

  c000000004733e40 0000000000000000 0000000000000000  |................|
  c000000004733e50 0000000000000000 0000000000000000  |................|
  c000000004733e60 0000000000000000 0000000000000000  |................|
  c000000004733e70 7367657200000000 0000000000000000  |sger............|
  c000000004733e80 a700000000000000 708897f7ff7f0000  |........p.......|
  c000000004733e90 0073428fff7f0000 208997f7ff7f0000  |.sB..... .......|
  c000000004733ea0 0100000000000000 ffffffffffffffff  |................|
  c000000004733eb0 0000000000000000 0000000000000000  |................|

[...]
Applied to powerpc/next.

[1/2] powerpc: Make stack frame marker upper case
      https://git.kernel.org/powerpc/c/bbd71709087a9d486d1da42399eec14e106072f2
[2/2] powerpc: Reverse stack frame marker on little endian
      https://git.kernel.org/powerpc/c/19c95df1277c48e3ef8cc7d9f1d315dce949f203

cheers




    
  

  
    

      

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