diff options
| author | James Morse <[email protected]> | 2015-12-10 10:22:41 +0000 |
|---|---|---|
| committer | Will Deacon <[email protected]> | 2015-12-10 12:08:09 +0000 |
| commit | 49003a8d6b35e128ef5e51433e60e783a46fbe5f (patch) | |
| tree | 5e60d93b6b55bfaf31a7b7d2e1b9bde9021ef893 | |
| parent | 1ffe199b1c9b72a8e752a9ae2a7af10128ab2ca1 (diff) | |
arm64: don't call C code with el0's fp register
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 <[email protected]>
Signed-off-by: Will Deacon <[email protected]>
| -rw-r--r-- | arch/arm64/kernel/entry.S | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index e394f8c9595a..2284c296e3f7 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 |