| Message ID | 1449742961-11432-4-git-send-email-james.morse@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 9a0450344335..8dd009b4cab2 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -93,6 +93,8 @@ and tsk, tsk, #~(THREAD_SIZE - 1) // Ensure MDSCR_EL1.SS is clear, ldr x19, [tsk, #TI_FLAGS] // since we can unmask debug disable_step_tsk x19, x20 // exceptions when scheduling. + + mov x29, xzr // fp pointed to user-space .else add x21, sp, #S_FRAME_SIZE .endif
On entry from el0, we save all the registers on the kernel stack, and restore them before returning. x29 remains unchanged when we call out to C code, which will store x29 as the frame-pointer on the stack. Instead, write 0 into x29 after entry from el0, to avoid any risk of tracing into user space. Signed-off-by: James Morse <james.morse@arm.com> --- arch/arm64/kernel/entry.S | 2 ++ 1 file changed, 2 insertions(+)