linux-kernel - [PATCH] x86/head_64: move parameter close to call function

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Date: Fri, 15 Mar 2024 04:14:20 +0000
From: Wei Yang <richard.weiyang@...il.com>
To: tglx@...utronix.de,
	mingo@...hat.com,
	bp@...en8.de
Cc: x86@...nel.org,
	linux-kernel@...r.kernel.org,
	Wei Yang <richard.weiyang@...il.com>,
	Joerg Roedel <jroedel@...e.de>,
	Michael Roth <michael.roth@....com>,
	Brian Gerst <brgerst@...il.com>,
	Ard Biesheuvel <ardb@...nel.org>
Subject: [PATCH] x86/head_64: move parameter close to call function

startup_64_setup_env is first introduced by 'commit 866b556efa12
("x86/head/64: Install startup GDT")'. Then 'commit 469693d8f622
("x86/head/64: Re-enable stack protection")' insert some code which
leverage %rdi, which is removed by 'commit 8f6be6d870e8 ("x86/smpboot:
Remove initial_gs")'.

This left the parameter of startup_64_setup_env a little far away from
where it is used. Let's move them together for better understanding.

Signed-off-by: Wei Yang <richard.weiyang@...il.com>
CC: Joerg Roedel <jroedel@...e.de>
CC: Michael Roth <michael.roth@....com>
CC: Brian Gerst <brgerst@...il.com>
CC: Ard Biesheuvel <ardb@...nel.org>
---
 arch/x86/kernel/head_64.S | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 3dbd05f93859..5fb8bb7cdabe 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -69,8 +69,6 @@ SYM_CODE_START_NOALIGN(startup_64)
 	/* Set up the stack for verify_cpu() */
 	leaq	(__end_init_task - TOP_OF_KERNEL_STACK_PADDING - PTREGS_SIZE)(%rip), %rsp
 
-	leaq	_text(%rip), %rdi
-
 	/* Setup GSBASE to allow stack canary access for C code */
 	movl	$MSR_GS_BASE, %ecx
 	leaq	INIT_PER_CPU_VAR(fixed_percpu_data)(%rip), %rdx
@@ -78,6 +76,7 @@ SYM_CODE_START_NOALIGN(startup_64)
 	shrq	$32,  %rdx
 	wrmsr
 
+	leaq	_text(%rip), %rdi
 	call	startup_64_setup_env
 
 	/* Now switch to __KERNEL_CS so IRET works reliably */
-- 
2.34.1