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x86/boot/64: Load the final kernel GDT during early boot directly, remove startup_gdt[]

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Instead of loading a duplicate GDT just for early boot, load the kernel
GDT from its physical address.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20240226220544.70769-1-brgerst@gmail.com
This commit is contained in:
Brian Gerst 2024-02-26 17:05:44 -05:00 committed by Ingo Molnar
parent 533568e06b
commit 11e36b0f7c
2 changed files with 3 additions and 11 deletions
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1
arch/x86/include/asm/desc.h
View File

@ -46,6 +46,7 @@ struct gdt_page {
} __attribute__((aligned(PAGE_SIZE)));
DECLARE_PER_CPU_PAGE_ALIGNED(struct gdt_page, gdt_page);
DECLARE_INIT_PER_CPU(gdt_page);
/* Provide the original GDT */
static inline struct desc_struct *get_cpu_gdt_rw(unsigned int cpu)

13
arch/x86/kernel/head64.c
View File

@ -68,15 +68,6 @@ unsigned long vmemmap_base __ro_after_init = __VMEMMAP_BASE_L4;
EXPORT_SYMBOL(vmemmap_base);
#endif
/*
* GDT used on the boot CPU before switching to virtual addresses.
*/
static struct desc_struct startup_gdt[GDT_ENTRIES] __initdata = {
[GDT_ENTRY_KERNEL32_CS] = GDT_ENTRY_INIT(DESC_CODE32, 0, 0xfffff),
[GDT_ENTRY_KERNEL_CS] = GDT_ENTRY_INIT(DESC_CODE64, 0, 0xfffff),
[GDT_ENTRY_KERNEL_DS] = GDT_ENTRY_INIT(DESC_DATA64, 0, 0xfffff),
};
#ifdef CONFIG_X86_5LEVEL
static void __head *fixup_pointer(void *ptr, unsigned long physaddr)
{
@ -589,8 +580,8 @@ void __head startup_64_setup_gdt_idt(void)
void *handler = NULL;
struct desc_ptr startup_gdt_descr = {
.address = (unsigned long)&RIP_REL_REF(startup_gdt),
.size = sizeof(startup_gdt) - 1,
.address = (unsigned long)&RIP_REL_REF(init_per_cpu_var(gdt_page.gdt)),
.size = GDT_SIZE - 1,
};
/* Load GDT */