# \[PATCH v2 18/27\] x86/xen: Make xen\_cpu\_bringup\_again() a real function

- From: Josh Poimboeuf \<jpoimboe@kernel.org\>
- Date: 2026-09-08 20:34:38 
- List: rust-for-linux
- Page: https://ratatoskr.run/rust-for-linux/2026/09/17533674
- Thread: https://ratatoskr.run/rust-for-linux/2026/09/17533657/t.md

```text
xen_cpu_bringup_again() is SYM_CODE because it switches stacks, but it's
otherwise a callable function from C.

Convert it to STT_FUNC so objtool can detect that it's noreturn and its
entry can be removed from the hard-coded global noreturns list.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 arch/x86/xen/xen-head.S   | 5 +++--
 tools/objtool/noreturns.h | 1 -
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S
index 5dad6c51cdc34..68d769772f309 100644
--- a/arch/x86/xen/xen-head.S
+++ b/arch/x86/xen/xen-head.S
@@ -55,12 +55,13 @@ SYM_CODE_START(asm_cpu_bringup_and_idle)
 	call cpu_bringup_and_idle
 SYM_CODE_END(asm_cpu_bringup_and_idle)
 
-SYM_CODE_START(xen_cpu_bringup_again)
+SYM_FUNC_START(xen_cpu_bringup_again)
 	UNWIND_HINT_FUNC
 	mov	%rdi, %rsp
 	UNWIND_HINT_REGS
 	call	cpu_bringup_and_idle
-SYM_CODE_END(xen_cpu_bringup_again)
+SYM_FUNC_END(xen_cpu_bringup_again)
+STACK_FRAME_NON_STANDARD_FP(xen_cpu_bringup_again)
 .popsection
 #endif
 #endif
diff --git a/tools/objtool/noreturns.h b/tools/objtool/noreturns.h
index ff93e94ee09a0..01c94f20d1818 100644
--- a/tools/objtool/noreturns.h
+++ b/tools/objtool/noreturns.h
@@ -21,5 +21,4 @@ NORETURN(panic)
 NORETURN(vpanic)
 NORETURN(rust_helper_BUG)
 NORETURN(sev_es_terminate)
-NORETURN(xen_cpu_bringup_again)
 NORETURN(xen_start_kernel)
-- 
2.55.0

```