linux-kernel - [PATCH 03/11] x86/head: Mark *_start_kernel() _

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Message-Id: <064f6f3473b39061aad3b9aa09f21b4fe724e5f9.1680912057.git.jpoimboe@kernel.org>
Date:   Fri,  7 Apr 2023 17:09:56 -0700
From:   Josh Poimboeuf <jpoimboe@...nel.org>
To:     x86@...nel.org
Cc:     linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Miroslav Benes <mbenes@...e.cz>, linux-btrfs@...r.kernel.org,
        Mark Rutland <mark.rutland@....com>,
        linux-scsi@...r.kernel.org, linux-hyperv@...r.kernel.org,
        Arnd Bergmann <arnd@...db.de>,
        "Guilherme G . Piccoli" <gpiccoli@...lia.com>,
        Michael Kelley <mikelley@...rosoft.com>
Subject: [PATCH 03/11] x86/head: Mark *_start_kernel() __noreturn

Fixes the following warning:

  vmlinux.o: warning: objtool: resume_play_dead+0x21: unreachable instruction

Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
 arch/x86/include/asm/setup.h | 6 +++---
 arch/x86/kernel/head32.c     | 2 +-
 arch/x86/kernel/head64.c     | 4 ++--
 tools/objtool/check.c        | 2 ++
 4 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h
index f37cbff7354c..f3495623ac99 100644
--- a/arch/x86/include/asm/setup.h
+++ b/arch/x86/include/asm/setup.h
@@ -125,11 +125,11 @@ void clear_bss(void);
 
 #ifdef __i386__
 
-asmlinkage void __init i386_start_kernel(void);
+asmlinkage void __init __noreturn i386_start_kernel(void);
 
 #else
-asmlinkage void __init x86_64_start_kernel(char *real_mode);
-asmlinkage void __init x86_64_start_reservations(char *real_mode_data);
+asmlinkage void __init __noreturn x86_64_start_kernel(char *real_mode);
+asmlinkage void __init __noreturn x86_64_start_reservations(char *real_mode_data);
 
 #endif /* __i386__ */
 #endif /* _SETUP */
diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c
index ec6fefbfd3c0..10c27b4261eb 100644
--- a/arch/x86/kernel/head32.c
+++ b/arch/x86/kernel/head32.c
@@ -29,7 +29,7 @@ static void __init i386_default_early_setup(void)
 	x86_init.mpparse.setup_ioapic_ids = setup_ioapic_ids_from_mpc;
 }
 
-asmlinkage __visible void __init i386_start_kernel(void)
+asmlinkage __visible void __init __noreturn i386_start_kernel(void)
 {
 	/* Make sure IDT is set up before any exception happens */
 	idt_setup_early_handler();
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 387e4b12e823..49f7629b17f7 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -471,7 +471,7 @@ static void __init copy_bootdata(char *real_mode_data)
 	sme_unmap_bootdata(real_mode_data);
 }
 
-asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
+asmlinkage __visible void __init __noreturn x86_64_start_kernel(char * real_mode_data)
 {
 	/*
 	 * Build-time sanity checks on the kernel image and module
@@ -537,7 +537,7 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
 	x86_64_start_reservations(real_mode_data);
 }
 
-void __init x86_64_start_reservations(char *real_mode_data)
+void __init __noreturn x86_64_start_reservations(char *real_mode_data)
 {
 	/* version is always not zero if it is copied */
 	if (!boot_params.hdr.version)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index a6f9a4aeb77b..4e89342dd8fb 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -225,6 +225,8 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
 		"start_kernel",
 		"stop_this_cpu",
 		"usercopy_abort",
+		"x86_64_start_kernel",
+		"x86_64_start_reservations",
 		"xen_cpu_bringup_again",
 		"xen_start_kernel",
 	};
-- 
2.39.2