From 11e36b0f7c2150a6453872b79555767b43c846d0 Mon Sep 17 00:00:00 2001 From: Brian Gerst Date: Mon, 26 Feb 2024 17:05:44 -0500 Subject: [PATCH] x86/boot/64: Load the final kernel GDT during early boot directly, remove startup_gdt[] Instead of loading a duplicate GDT just for early boot, load the kernel GDT from its physical address. Signed-off-by: Brian Gerst Signed-off-by: Ingo Molnar Acked-by: Ard Biesheuvel Cc: Kees Cook Cc: Andy Lutomirski Cc: Linus Torvalds Cc: "H. Peter Anvin" Cc: Josh Poimboeuf Link: https://lore.kernel.org/r/20240226220544.70769-1-brgerst@gmail.com --- arch/x86/include/asm/desc.h | 1 + arch/x86/kernel/head64.c | 13 ++----------- 2 files changed, 3 insertions(+), 11 deletions(-) diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h index ab97b22ac04a2..52c0150179907 100644 --- a/arch/x86/include/asm/desc.h +++ b/arch/x86/include/asm/desc.h @@ -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) diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index 72351c3121a62..fd77a266f29dd 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -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 */ -- 2.30.2