From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
commit 64dbc122b20f75183d8822618c24f85144a5a94d upstream.
Somehow the swapgs mitigation entry code patch ended up with a JMPQ
instruction instead of JMP, where only the short jump is needed. Some
assembler versions apparently fail to optimize JMPQ into a two-byte JMP
when possible, instead always using a 7-byte JMP with relocation. For
some reason that makes the entry code explode with a #GP during boot.
Change it back to "JMP" as originally intended.
Fixes: 18ec54fdd6d1 ("x86/speculation: Prepare entry code for Spectre v1 swapgs mitigations")
Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
[bwh: Backported to 4.4: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/entry/entry_64.S | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -567,7 +567,7 @@ END(irq_entries_start)
#ifdef CONFIG_CONTEXT_TRACKING
call enter_from_user_mode
#endif
- jmpq 2f
+ jmp 2f
1:
FENCE_SWAPGS_KERNEL_ENTRY
2:
