linux-kernel - [PATCH v1 05/14] x86/boot: call puts() from within die()

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Message-ID: <20260120195407.1163051-6-hpa@zytor.com>
Date: Tue, 20 Jan 2026 11:53:57 -0800
From: "H. Peter Anvin" <hpa@...or.com>
To: Thomas Gleixner <tglx@...nel.org>, Ingo Molnar <mingo@...hat.com>,
        Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Uros Bizjak <ubizjak@...il.com>, Petr Mladek <pmladek@...e.com>,
        Andrew Morton <akpm@...ux-foundation.org>, Kees Cook <kees@...nel.org>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Kiryl Shutsemau <kas@...nel.org>,
        Rick Edgecombe <rick.p.edgecombe@...el.com>
Cc: "H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
        linux-coco@...ts.linux.dev, x86@...nel.org
Subject: [PATCH v1 05/14] x86/boot: call puts() from within die()

Every call to die() has a call to puts() in front of it, which adds
unnecessary code bloat. Move the puts() into die() which, being a
noreturn function, is terminal and allows the compiler to not generate
unnecessary code around it.

Signed-off-by: H. Peter Anvin (Intel) <hpa@...or.com>
---
 arch/x86/boot/boot.h   | 2 +-
 arch/x86/boot/header.S | 5 +++--
 arch/x86/boot/main.c   | 6 ++----
 arch/x86/boot/pm.c     | 6 ++----
 4 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/arch/x86/boot/boot.h b/arch/x86/boot/boot.h
index 1f2b7252e387..b4eb8405ba55 100644
--- a/arch/x86/boot/boot.h
+++ b/arch/x86/boot/boot.h
@@ -280,7 +280,7 @@ void console_init(void);
 void query_edd(void);
 
 /* header.S */
-void __noreturn die(void);
+void __noreturn die(const char *msg);
 
 /* memory.c */
 void detect_memory(void);
diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
index 85a21d576f5b..5a54d33e51c2 100644
--- a/arch/x86/boot/header.S
+++ b/arch/x86/boot/header.S
@@ -611,14 +611,15 @@ SETUP_SIGNATURE = 0x5a5aaa55
 # Setup corrupt somehow...
 setup_bad:
 	movl	$setup_corrupt, %eax
-	calll	puts
 	# Fall through...
 
 	.globl	die
 	.type	die, @function
 die:
+	calll	puts
+1:
 	hlt
-	jmp	die
+	jmp	1b
 
 	.size	die, .-die
 
diff --git a/arch/x86/boot/main.c b/arch/x86/boot/main.c
index da01ade4959e..ad8869aad6db 100644
--- a/arch/x86/boot/main.c
+++ b/arch/x86/boot/main.c
@@ -143,10 +143,8 @@ void main(void)
 	init_heap();
 
 	/* Make sure we have all the proper CPU support */
-	if (validate_cpu()) {
-		puts("Unable to boot - please use a kernel appropriate for your CPU.\n");
-		die();
-	}
+	if (validate_cpu())
+		die("Unable to boot - please use a kernel appropriate for your CPU.\n");
 
 	/* Tell the BIOS what CPU mode we intend to run in */
 	set_bios_mode();
diff --git a/arch/x86/boot/pm.c b/arch/x86/boot/pm.c
index 5941f930f6c5..3be89ba4b1b3 100644
--- a/arch/x86/boot/pm.c
+++ b/arch/x86/boot/pm.c
@@ -106,10 +106,8 @@ void go_to_protected_mode(void)
 	realmode_switch_hook();
 
 	/* Enable the A20 gate */
-	if (enable_a20()) {
-		puts("A20 gate not responding, unable to boot...\n");
-		die();
-	}
+	if (enable_a20())
+		die("A20 gate not responding, unable to boot...\n");
 
 	/* Reset coprocessor (IGNNE#) */
 	reset_coprocessor();
-- 
2.52.0