[PATCH v12 07/11] x86/smpboot: Remove early_gdt_descr on 64-bit

Usama Arif
2023-02-26T11:08:59Z

From: Brian Gerst <brgerst@gmail.com>

Build the GDT descriptor on the stack instead.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Tested-by: Usama Arif <usama.arif@bytedance.com>
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
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 ab6e29b32c04..236f2423454d 100644
--- a/arch/x86/kernel/acpi/sleep.c
+++ b/arch/x86/kernel/acpi/sleep.c
@@ -112,8 +112,6 @@ int x86_acpi_suspend_lowlevel(void)
#else /* CONFIG_64BIT */
#ifdef CONFIG_SMP
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 5a2417d788d1..0ccca297e90e 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 62e3bf37f0b8..a22460a07cf8 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1110,10 +1110,10 @@ 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;
--
2.25.1