[PATCH 5.10 133/148] x86/xen: Fix initialisation in hypercall_page after rethunk

Greg Kroah-Hartman
2022-07-23T10:10:57Z

From: Ben Hutchings <ben@decadent.org.uk>

The hypercall_page is special and the RETs there should not be changed
into rethunk calls (but can have SLS mitigation). Change the initial
instructions to ret + int3 padding, as was done in upstream commit
5b2fc51576ef "x86/ibt,xen: Sprinkle the ENDBR".

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/xen/xen-head.S | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/x86/xen/xen-head.S
+++ b/arch/x86/xen/xen-head.S
@@ -69,9 +69,9 @@ SYM_CODE_END(asm_cpu_bringup_and_idle)
SYM_CODE_START(hypercall_page)
.rept (PAGE_SIZE / 32)
UNWIND_HINT_FUNC
- .skip 31, 0x90
ANNOTATE_UNRET_SAFE
- RET
+ ret
+ .skip 31, 0xcc
.endr

#define HYPERCALL(n) \