From: Josh Poimboeuf jpoimboe@redhat.com
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 mbenes@suse.cz Signed-off-by: Josh Poimboeuf jpoimboe@redhat.com Signed-off-by: Ingo Molnar mingo@kernel.org Cc: Andy Lutomirski luto@kernel.org Cc: Dave Jones dsj@fb.com Cc: Jann Horn jannh@google.com Cc: Peter Zijlstra peterz@infradead.org Cc: Thomas Gleixner tglx@linutronix.de Cc: Vince Weaver vincent.weaver@maine.edu Link: https://lore.kernel.org/r/03d0411920d10f7418f2e909210d8e9a3b2ab081.158780874... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- 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.