From: Josh Poimboeuf <[email protected]>
commit 96c64806b4bf35f5edb465cafa6cec490e424a30 upstream.
UNWIND_HINT_FUNC has some limitations: specifically, it doesn't reset
all the registers to undefined. This causes objtool to get confused
about the RBP push in __switch_to_asm(), resulting in bad ORC data.
While __switch_to_asm() does do some stack magic, it's otherwise a
normal callable-from-C function, so just annotate it as a function,
which makes objtool happy and allows it to produces the correct hints
automatically.
Fixes: 8c1f75587a18 ("x86/entry/64: Add unwind hint annotations")
Reviewed-by: Miroslav Benes <[email protected]>
Signed-off-by: Josh Poimboeuf <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Dave Jones <[email protected]>
Cc: Jann Horn <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Vince Weaver <[email protected]>
Link:
https://lore.kernel.org/r/03d0411920d10f7418f2e909210d8e9a3b2ab081.1587808742.git.jpoim...@redhat.com
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
arch/x86/entry/entry_64.S | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -279,8 +279,7 @@ SYM_CODE_END(entry_SYSCALL_64)
* %rdi: prev task
* %rsi: next task
*/
-SYM_CODE_START(__switch_to_asm)
- UNWIND_HINT_FUNC
+SYM_FUNC_START(__switch_to_asm)
/*
* Save callee-saved registers
* This must match the order in inactive_task_frame
@@ -321,7 +320,7 @@ SYM_CODE_START(__switch_to_asm)
popq %rbp
jmp __switch_to
-SYM_CODE_END(__switch_to_asm)
+SYM_FUNC_END(__switch_to_asm)
/*
* A newly forked process directly context switches into this address.
