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authorNicolas Pitre <nico@cam.org>2006-01-14 16:18:08 +0000
committerRussell King <rmk+kernel@arm.linux.org.uk>2006-01-14 16:18:08 +0000
commit2dede2d8e925f4c2cb4e136b14df127685e15dd3 (patch)
tree271b3fb300c5ac143556295d10c6736430ebed85
parentda2b1cd61903c8e9796e76be2d606584f26a78e5 (diff)
[ARM] 3102/1: ARM EABI: stack pointer must be 64-bit aligned after a CPU exception
Patch from Nicolas Pitre The ARM EABI says that the stack pointer has to be 64-bit aligned for reasons already mentioned in patch #3101 when calling C functions. We therefore must verify and adjust sp accordingly when taking an exception from kernel mode since sp might not necessarily be 64-bit aligned if the exception occurs in the middle of a kernel function. If the exception occurs while in user mode then no sp fixup is needed as long as sizeof(struct pt_regs) as well as any additional syscall data stack space remain multiples of 8. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
-rw-r--r--arch/arm/kernel/entry-armv.S17
-rw-r--r--arch/arm/kernel/entry-header.S1
-rw-r--r--include/asm-arm/ptrace.h8
3 files changed, 23 insertions, 3 deletions
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index fb8e7f4c4b3..874e6bb7940 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -105,14 +105,24 @@ common_invalid:
/*
* SVC mode handlers
*/
+
+#if defined(CONFIG_AEABI) && (__LINUX_ARM_ARCH__ >= 5)
+#define SPFIX(code...) code
+#else
+#define SPFIX(code...)
+#endif
+
.macro svc_entry
sub sp, sp, #S_FRAME_SIZE
+ SPFIX( tst sp, #4 )
+ SPFIX( bicne sp, sp, #4 )
stmib sp, {r1 - r12}
ldmia r0, {r1 - r3}
add r5, sp, #S_SP @ here for interlock avoidance
mov r4, #-1 @ "" "" "" ""
add r0, sp, #S_FRAME_SIZE @ "" "" "" ""
+ SPFIX( addne r0, r0, #4 )
str r1, [sp] @ save the "real" r0 copied
@ from the exception stack
@@ -303,7 +313,14 @@ __pabt_svc:
/*
* User mode handlers
+ *
+ * EABI note: sp_svc is always 64-bit aligned here, so should S_FRAME_SIZE
*/
+
+#if defined(CONFIG_AEABI) && (__LINUX_ARM_ARCH__ >= 5) && (S_FRAME_SIZE & 7)
+#error "sizeof(struct pt_regs) must be a multiple of 8"
+#endif
+
.macro usr_entry
sub sp, sp, #S_FRAME_SIZE
stmib sp, {r1 - r12}
diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S
index 648cfff9313..55c99cdab7d 100644
--- a/arch/arm/kernel/entry-header.S
+++ b/arch/arm/kernel/entry-header.S
@@ -19,6 +19,7 @@
@
@ Most of the stack format comes from struct pt_regs, but with
@ the addition of 8 bytes for storing syscall args 5 and 6.
+@ This _must_ remain a multiple of 8 for EABI.
@
#define S_OFF 8
diff --git a/include/asm-arm/ptrace.h b/include/asm-arm/ptrace.h
index 4377e22b7e1..f40948d5444 100644
--- a/include/asm-arm/ptrace.h
+++ b/include/asm-arm/ptrace.h
@@ -60,9 +60,11 @@
#ifndef __ASSEMBLY__
-/* this struct defines the way the registers are stored on the
- stack during a system call. */
-
+/*
+ * This struct defines the way the registers are stored on the
+ * stack during a system call. Note that sizeof(struct pt_regs)
+ * has to be a multiple of 8.
+ */
struct pt_regs {
long uregs[18];
};