[PATCH 06/22] x86/head/64: Annotate start_cpu0() as non-callable

From: Josh Poimboeuf
Date: Sun Jul 14 2019 - 20:37:56 EST


After an objtool improvement, it complains about the fact that
start_cpu0() jumps to code which has an LRET instruction.

arch/x86/kernel/head_64.o: warning: objtool: .head.text+0xe4: unsupported instruction in callable function

Technically, start_cpu0() is callable, but it acts nothing like a
callable function. Prevent objtool from treating it like one by
removing its ELF function annotation.

Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
---
arch/x86/kernel/head_64.S | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index bcd206c8ac90..66b4a7757397 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -253,10 +253,10 @@ END(secondary_startup_64)
* start_secondary() via .Ljump_to_C_code.
*/
ENTRY(start_cpu0)
- movq initial_stack(%rip), %rsp
UNWIND_HINT_EMPTY
+ movq initial_stack(%rip), %rsp
jmp .Ljump_to_C_code
-ENDPROC(start_cpu0)
+END(start_cpu0)
#endif

/* Both SMP bootup and ACPI suspend change these variables */
--
2.20.1