From: Michael Ellerman <mpe@ellerman.id.au>
To: <linuxppc-dev@lists.ozlabs.org>
Cc: npiggin@gmail.com
Subject: [PATCH 2/2] powerpc: Reverse stack frame marker on little endian
Date: Wed, 28 Sep 2022 01:04:19 +1000 [thread overview]
Message-ID: <20220927150419.1503001-2-mpe@ellerman.id.au> (raw)
In-Reply-To: <20220927150419.1503001-1-mpe@ellerman.id.au>
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
next prev parent reply other threads:[~2022-09-27 15:05 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-27 15:04 [PATCH 1/2] powerpc: Make stack frame marker upper case Michael Ellerman
2022-09-27 15:04 ` Michael Ellerman [this message]
2022-09-28 3:13 ` [PATCH 2/2] powerpc: Reverse stack frame marker on little endian Nicholas Piggin
2022-10-04 13:26 ` [PATCH 1/2] powerpc: Make stack frame marker upper case Michael Ellerman
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