linux-kernel - [tip: x86/apic] x86/smpboot: Remove early_gdt

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Date:   Tue, 21 Mar 2023 14:14:15 -0000
From:   "tip-bot2 for Brian Gerst" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Brian Gerst <brgerst@...il.com>,
        David Woodhouse <dwmw@...zon.co.uk>,
        Usama Arif <usama.arif@...edance.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Guilherme G. Piccoli" <gpiccoli@...lia.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: x86/apic] x86/smpboot: Remove early_gdt_descr on 64-bit

The following commit has been merged into the x86/apic branch of tip:

Commit-ID:     c253b64020c7a7c7a1f6adf8922456614be0f665
Gitweb:        https://git.kernel.org/tip/c253b64020c7a7c7a1f6adf8922456614be0f665
Author:        Brian Gerst <brgerst@...il.com>
AuthorDate:    Thu, 16 Mar 2023 22:21:04 
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Tue, 21 Mar 2023 13:35:53 +01:00

x86/smpboot: Remove early_gdt_descr on 64-bit

Build the GDT descriptor on the stack instead.

Signed-off-by: Brian Gerst <brgerst@...il.com>
Signed-off-by: David Woodhouse <dwmw@...zon.co.uk>
Signed-off-by: Usama Arif <usama.arif@...edance.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Tested-by: Usama Arif <usama.arif@...edance.com>
Tested-by: Guilherme G. Piccoli <gpiccoli@...lia.com>
Reviewed-by: David Woodhouse <dwmw@...zon.co.uk>
Link: https://lore.kernel.org/r/20230316222109.1940300-8-usama.arif@bytedance.com

---
 arch/x86/kernel/acpi/sleep.c |  2 --
 arch/x86/kernel/head_64.S    | 11 ++++++-----
 arch/x86/kernel/smpboot.c    |  2 +-
 3 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
index 1b4c43d..de89bb4 100644
--- a/arch/x86/kernel/acpi/sleep.c
+++ b/arch/x86/kernel/acpi/sleep.c
@@ -127,8 +127,6 @@ int x86_acpi_suspend_lowlevel(void)
 	 * value is in the actual %rsp register.
 	 */
 	current->thread.sp = (unsigned long)temp_stack + sizeof(temp_stack);
-	early_gdt_descr.address =
-			(unsigned long)get_cpu_gdt_rw(smp_processor_id());
 	initial_gs = per_cpu_offset(smp_processor_id());
 	smpboot_control = smp_processor_id();
 #endif
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index cc1b145..a5b46c2 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -265,7 +265,12 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL)
 	 * addresses where we're currently running on. We have to do that here
 	 * because in 32bit we couldn't load a 64bit linear address.
 	 */
-	lgdt	early_gdt_descr(%rip)
+	subq	$16, %rsp
+	movw	$(GDT_SIZE-1), (%rsp)
+	leaq	gdt_page(%rdx), %rax
+	movq	%rax, 2(%rsp)
+	lgdt	(%rsp)
+	addq	$16, %rsp
 
 	/* set up data segments */
 	xorl %eax,%eax
@@ -667,10 +672,6 @@ SYM_DATA_END(level1_fixmap_pgt)
 	.data
 	.align 16
 
-SYM_DATA(early_gdt_descr,		.word GDT_ENTRIES*8-1)
-SYM_DATA_LOCAL(early_gdt_descr_base,	.quad INIT_PER_CPU_VAR(gdt_page))
-
-	.align 16
 SYM_DATA(smpboot_control,		.long 0)
 
 	.align 16
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index a1531cc..94e6c54 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1086,10 +1086,10 @@ static int do_boot_cpu(int apicid, int cpu, struct task_struct *idle,
 		start_ip = real_mode_header->trampoline_start64;
 #endif
 	idle->thread.sp = (unsigned long)task_pt_regs(idle);
-	early_gdt_descr.address = (unsigned long)get_cpu_gdt_rw(cpu);
 	initial_code = (unsigned long)start_secondary;
 
 	if (IS_ENABLED(CONFIG_X86_32)) {
+		early_gdt_descr.address = (unsigned long)get_cpu_gdt_rw(cpu);
 		initial_stack  = idle->thread.sp;
 	} else {
 		smpboot_control = cpu;