From: Jon Medhurst tixy@yxit.co.uk
The implementation of svc_exit didn't take into account any stack hole created by svc_entry; as happens with the undef handler when kprobes are configured. The fix is to read the saved value of SP rather than trying to calculate it.
Signed-off-by: Jon Medhurst tixy@yxit.co.uk --- arch/arm/kernel/entry-header.S | 12 +++++------- 1 files changed, 5 insertions(+), 7 deletions(-)
diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S index 051166c..83e29ad 100644 --- a/arch/arm/kernel/entry-header.S +++ b/arch/arm/kernel/entry-header.S @@ -121,15 +121,13 @@ .endm #else /* CONFIG_THUMB2_KERNEL */ .macro svc_exit, rpsr + ldr lr, [sp, #S_SP] @ top of the stack + ldrd r0, r1, [sp, #S_LR] @ calling lr and pc clrex @ clear the exclusive monitor - ldr r0, [sp, #S_SP] @ top of the stack - ldr r1, [sp, #S_PC] @ return address - tst r0, #4 @ orig stack 8-byte aligned? - stmdb r0, {r1, \rpsr} @ rfe context + stmdb lr!, {r0, r1, \rpsr} @ calling lr and rfe context ldmia sp, {r0 - r12} - ldr lr, [sp, #S_LR] - addeq sp, sp, #S_FRAME_SIZE - 8 @ aligned - addne sp, sp, #S_FRAME_SIZE - 4 @ not aligned + mov sp, lr + ldr lr, [sp], #4 rfeia sp! .endm