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-rw-r--r--arch/x86/kernel/head64.c637
1 files changed, 637 insertions, 0 deletions
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
new file mode 100644
index 0000000000..bbc21798df
--- /dev/null
+++ b/arch/x86/kernel/head64.c
@@ -0,0 +1,637 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * prepare to run common code
+ *
+ * Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
+ */
+
+#define DISABLE_BRANCH_PROFILING
+
+/* cpu_feature_enabled() cannot be used this early */
+#define USE_EARLY_PGTABLE_L5
+
+#include <linux/init.h>
+#include <linux/linkage.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/percpu.h>
+#include <linux/start_kernel.h>
+#include <linux/io.h>
+#include <linux/memblock.h>
+#include <linux/cc_platform.h>
+#include <linux/pgtable.h>
+
+#include <asm/processor.h>
+#include <asm/proto.h>
+#include <asm/smp.h>
+#include <asm/setup.h>
+#include <asm/desc.h>
+#include <asm/tlbflush.h>
+#include <asm/sections.h>
+#include <asm/kdebug.h>
+#include <asm/e820/api.h>
+#include <asm/bios_ebda.h>
+#include <asm/bootparam_utils.h>
+#include <asm/microcode.h>
+#include <asm/kasan.h>
+#include <asm/fixmap.h>
+#include <asm/realmode.h>
+#include <asm/extable.h>
+#include <asm/trapnr.h>
+#include <asm/sev.h>
+#include <asm/tdx.h>
+
+/*
+ * Manage page tables very early on.
+ */
+extern pmd_t early_dynamic_pgts[EARLY_DYNAMIC_PAGE_TABLES][PTRS_PER_PMD];
+static unsigned int __initdata next_early_pgt;
+pmdval_t early_pmd_flags = __PAGE_KERNEL_LARGE & ~(_PAGE_GLOBAL | _PAGE_NX);
+
+#ifdef CONFIG_X86_5LEVEL
+unsigned int __pgtable_l5_enabled __ro_after_init;
+unsigned int pgdir_shift __ro_after_init = 39;
+EXPORT_SYMBOL(pgdir_shift);
+unsigned int ptrs_per_p4d __ro_after_init = 1;
+EXPORT_SYMBOL(ptrs_per_p4d);
+#endif
+
+#ifdef CONFIG_DYNAMIC_MEMORY_LAYOUT
+unsigned long page_offset_base __ro_after_init = __PAGE_OFFSET_BASE_L4;
+EXPORT_SYMBOL(page_offset_base);
+unsigned long vmalloc_base __ro_after_init = __VMALLOC_BASE_L4;
+EXPORT_SYMBOL(vmalloc_base);
+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] = {
+ [GDT_ENTRY_KERNEL32_CS] = GDT_ENTRY_INIT(0xc09b, 0, 0xfffff),
+ [GDT_ENTRY_KERNEL_CS] = GDT_ENTRY_INIT(0xa09b, 0, 0xfffff),
+ [GDT_ENTRY_KERNEL_DS] = GDT_ENTRY_INIT(0xc093, 0, 0xfffff),
+};
+
+/*
+ * Address needs to be set at runtime because it references the startup_gdt
+ * while the kernel still uses a direct mapping.
+ */
+static struct desc_ptr startup_gdt_descr = {
+ .size = sizeof(startup_gdt)-1,
+ .address = 0,
+};
+
+#define __head __section(".head.text")
+
+static void __head *fixup_pointer(void *ptr, unsigned long physaddr)
+{
+ return ptr - (void *)_text + (void *)physaddr;
+}
+
+static unsigned long __head *fixup_long(void *ptr, unsigned long physaddr)
+{
+ return fixup_pointer(ptr, physaddr);
+}
+
+#ifdef CONFIG_X86_5LEVEL
+static unsigned int __head *fixup_int(void *ptr, unsigned long physaddr)
+{
+ return fixup_pointer(ptr, physaddr);
+}
+
+static bool __head check_la57_support(unsigned long physaddr)
+{
+ /*
+ * 5-level paging is detected and enabled at kernel decompression
+ * stage. Only check if it has been enabled there.
+ */
+ if (!(native_read_cr4() & X86_CR4_LA57))
+ return false;
+
+ *fixup_int(&__pgtable_l5_enabled, physaddr) = 1;
+ *fixup_int(&pgdir_shift, physaddr) = 48;
+ *fixup_int(&ptrs_per_p4d, physaddr) = 512;
+ *fixup_long(&page_offset_base, physaddr) = __PAGE_OFFSET_BASE_L5;
+ *fixup_long(&vmalloc_base, physaddr) = __VMALLOC_BASE_L5;
+ *fixup_long(&vmemmap_base, physaddr) = __VMEMMAP_BASE_L5;
+
+ return true;
+}
+#else
+static bool __head check_la57_support(unsigned long physaddr)
+{
+ return false;
+}
+#endif
+
+static unsigned long __head sme_postprocess_startup(struct boot_params *bp, pmdval_t *pmd)
+{
+ unsigned long vaddr, vaddr_end;
+ int i;
+
+ /* Encrypt the kernel and related (if SME is active) */
+ sme_encrypt_kernel(bp);
+
+ /*
+ * Clear the memory encryption mask from the .bss..decrypted section.
+ * The bss section will be memset to zero later in the initialization so
+ * there is no need to zero it after changing the memory encryption
+ * attribute.
+ */
+ if (sme_get_me_mask()) {
+ vaddr = (unsigned long)__start_bss_decrypted;
+ vaddr_end = (unsigned long)__end_bss_decrypted;
+
+ for (; vaddr < vaddr_end; vaddr += PMD_SIZE) {
+ /*
+ * On SNP, transition the page to shared in the RMP table so that
+ * it is consistent with the page table attribute change.
+ *
+ * __start_bss_decrypted has a virtual address in the high range
+ * mapping (kernel .text). PVALIDATE, by way of
+ * early_snp_set_memory_shared(), requires a valid virtual
+ * address but the kernel is currently running off of the identity
+ * mapping so use __pa() to get a *currently* valid virtual address.
+ */
+ early_snp_set_memory_shared(__pa(vaddr), __pa(vaddr), PTRS_PER_PMD);
+
+ i = pmd_index(vaddr);
+ pmd[i] -= sme_get_me_mask();
+ }
+ }
+
+ /*
+ * Return the SME encryption mask (if SME is active) to be used as a
+ * modifier for the initial pgdir entry programmed into CR3.
+ */
+ return sme_get_me_mask();
+}
+
+/* Code in __startup_64() can be relocated during execution, but the compiler
+ * doesn't have to generate PC-relative relocations when accessing globals from
+ * that function. Clang actually does not generate them, which leads to
+ * boot-time crashes. To work around this problem, every global pointer must
+ * be adjusted using fixup_pointer().
+ */
+unsigned long __head __startup_64(unsigned long physaddr,
+ struct boot_params *bp)
+{
+ unsigned long load_delta, *p;
+ unsigned long pgtable_flags;
+ pgdval_t *pgd;
+ p4dval_t *p4d;
+ pudval_t *pud;
+ pmdval_t *pmd, pmd_entry;
+ pteval_t *mask_ptr;
+ bool la57;
+ int i;
+ unsigned int *next_pgt_ptr;
+
+ la57 = check_la57_support(physaddr);
+
+ /* Is the address too large? */
+ if (physaddr >> MAX_PHYSMEM_BITS)
+ for (;;);
+
+ /*
+ * Compute the delta between the address I am compiled to run at
+ * and the address I am actually running at.
+ */
+ load_delta = physaddr - (unsigned long)(_text - __START_KERNEL_map);
+
+ /* Is the address not 2M aligned? */
+ if (load_delta & ~PMD_MASK)
+ for (;;);
+
+ /* Include the SME encryption mask in the fixup value */
+ load_delta += sme_get_me_mask();
+
+ /* Fixup the physical addresses in the page table */
+
+ pgd = fixup_pointer(&early_top_pgt, physaddr);
+ p = pgd + pgd_index(__START_KERNEL_map);
+ if (la57)
+ *p = (unsigned long)level4_kernel_pgt;
+ else
+ *p = (unsigned long)level3_kernel_pgt;
+ *p += _PAGE_TABLE_NOENC - __START_KERNEL_map + load_delta;
+
+ if (la57) {
+ p4d = fixup_pointer(&level4_kernel_pgt, physaddr);
+ p4d[511] += load_delta;
+ }
+
+ pud = fixup_pointer(&level3_kernel_pgt, physaddr);
+ pud[510] += load_delta;
+ pud[511] += load_delta;
+
+ pmd = fixup_pointer(level2_fixmap_pgt, physaddr);
+ for (i = FIXMAP_PMD_TOP; i > FIXMAP_PMD_TOP - FIXMAP_PMD_NUM; i--)
+ pmd[i] += load_delta;
+
+ /*
+ * Set up the identity mapping for the switchover. These
+ * entries should *NOT* have the global bit set! This also
+ * creates a bunch of nonsense entries but that is fine --
+ * it avoids problems around wraparound.
+ */
+
+ next_pgt_ptr = fixup_pointer(&next_early_pgt, physaddr);
+ pud = fixup_pointer(early_dynamic_pgts[(*next_pgt_ptr)++], physaddr);
+ pmd = fixup_pointer(early_dynamic_pgts[(*next_pgt_ptr)++], physaddr);
+
+ pgtable_flags = _KERNPG_TABLE_NOENC + sme_get_me_mask();
+
+ if (la57) {
+ p4d = fixup_pointer(early_dynamic_pgts[(*next_pgt_ptr)++],
+ physaddr);
+
+ i = (physaddr >> PGDIR_SHIFT) % PTRS_PER_PGD;
+ pgd[i + 0] = (pgdval_t)p4d + pgtable_flags;
+ pgd[i + 1] = (pgdval_t)p4d + pgtable_flags;
+
+ i = physaddr >> P4D_SHIFT;
+ p4d[(i + 0) % PTRS_PER_P4D] = (pgdval_t)pud + pgtable_flags;
+ p4d[(i + 1) % PTRS_PER_P4D] = (pgdval_t)pud + pgtable_flags;
+ } else {
+ i = (physaddr >> PGDIR_SHIFT) % PTRS_PER_PGD;
+ pgd[i + 0] = (pgdval_t)pud + pgtable_flags;
+ pgd[i + 1] = (pgdval_t)pud + pgtable_flags;
+ }
+
+ i = physaddr >> PUD_SHIFT;
+ pud[(i + 0) % PTRS_PER_PUD] = (pudval_t)pmd + pgtable_flags;
+ pud[(i + 1) % PTRS_PER_PUD] = (pudval_t)pmd + pgtable_flags;
+
+ pmd_entry = __PAGE_KERNEL_LARGE_EXEC & ~_PAGE_GLOBAL;
+ /* Filter out unsupported __PAGE_KERNEL_* bits: */
+ mask_ptr = fixup_pointer(&__supported_pte_mask, physaddr);
+ pmd_entry &= *mask_ptr;
+ pmd_entry += sme_get_me_mask();
+ pmd_entry += physaddr;
+
+ for (i = 0; i < DIV_ROUND_UP(_end - _text, PMD_SIZE); i++) {
+ int idx = i + (physaddr >> PMD_SHIFT);
+
+ pmd[idx % PTRS_PER_PMD] = pmd_entry + i * PMD_SIZE;
+ }
+
+ /*
+ * Fixup the kernel text+data virtual addresses. Note that
+ * we might write invalid pmds, when the kernel is relocated
+ * cleanup_highmap() fixes this up along with the mappings
+ * beyond _end.
+ *
+ * Only the region occupied by the kernel image has so far
+ * been checked against the table of usable memory regions
+ * provided by the firmware, so invalidate pages outside that
+ * region. A page table entry that maps to a reserved area of
+ * memory would allow processor speculation into that area,
+ * and on some hardware (particularly the UV platform) even
+ * speculative access to some reserved areas is caught as an
+ * error, causing the BIOS to halt the system.
+ */
+
+ pmd = fixup_pointer(level2_kernel_pgt, physaddr);
+
+ /* invalidate pages before the kernel image */
+ for (i = 0; i < pmd_index((unsigned long)_text); i++)
+ pmd[i] &= ~_PAGE_PRESENT;
+
+ /* fixup pages that are part of the kernel image */
+ for (; i <= pmd_index((unsigned long)_end); i++)
+ if (pmd[i] & _PAGE_PRESENT)
+ pmd[i] += load_delta;
+
+ /* invalidate pages after the kernel image */
+ for (; i < PTRS_PER_PMD; i++)
+ pmd[i] &= ~_PAGE_PRESENT;
+
+ /*
+ * Fixup phys_base - remove the memory encryption mask to obtain
+ * the true physical address.
+ */
+ *fixup_long(&phys_base, physaddr) += load_delta - sme_get_me_mask();
+
+ return sme_postprocess_startup(bp, pmd);
+}
+
+/* Wipe all early page tables except for the kernel symbol map */
+static void __init reset_early_page_tables(void)
+{
+ memset(early_top_pgt, 0, sizeof(pgd_t)*(PTRS_PER_PGD-1));
+ next_early_pgt = 0;
+ write_cr3(__sme_pa_nodebug(early_top_pgt));
+}
+
+/* Create a new PMD entry */
+bool __init __early_make_pgtable(unsigned long address, pmdval_t pmd)
+{
+ unsigned long physaddr = address - __PAGE_OFFSET;
+ pgdval_t pgd, *pgd_p;
+ p4dval_t p4d, *p4d_p;
+ pudval_t pud, *pud_p;
+ pmdval_t *pmd_p;
+
+ /* Invalid address or early pgt is done ? */
+ if (physaddr >= MAXMEM || read_cr3_pa() != __pa_nodebug(early_top_pgt))
+ return false;
+
+again:
+ pgd_p = &early_top_pgt[pgd_index(address)].pgd;
+ pgd = *pgd_p;
+
+ /*
+ * The use of __START_KERNEL_map rather than __PAGE_OFFSET here is
+ * critical -- __PAGE_OFFSET would point us back into the dynamic
+ * range and we might end up looping forever...
+ */
+ if (!pgtable_l5_enabled())
+ p4d_p = pgd_p;
+ else if (pgd)
+ p4d_p = (p4dval_t *)((pgd & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
+ else {
+ if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
+ reset_early_page_tables();
+ goto again;
+ }
+
+ p4d_p = (p4dval_t *)early_dynamic_pgts[next_early_pgt++];
+ memset(p4d_p, 0, sizeof(*p4d_p) * PTRS_PER_P4D);
+ *pgd_p = (pgdval_t)p4d_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
+ }
+ p4d_p += p4d_index(address);
+ p4d = *p4d_p;
+
+ if (p4d)
+ pud_p = (pudval_t *)((p4d & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
+ else {
+ if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
+ reset_early_page_tables();
+ goto again;
+ }
+
+ pud_p = (pudval_t *)early_dynamic_pgts[next_early_pgt++];
+ memset(pud_p, 0, sizeof(*pud_p) * PTRS_PER_PUD);
+ *p4d_p = (p4dval_t)pud_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
+ }
+ pud_p += pud_index(address);
+ pud = *pud_p;
+
+ if (pud)
+ pmd_p = (pmdval_t *)((pud & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
+ else {
+ if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
+ reset_early_page_tables();
+ goto again;
+ }
+
+ pmd_p = (pmdval_t *)early_dynamic_pgts[next_early_pgt++];
+ memset(pmd_p, 0, sizeof(*pmd_p) * PTRS_PER_PMD);
+ *pud_p = (pudval_t)pmd_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
+ }
+ pmd_p[pmd_index(address)] = pmd;
+
+ return true;
+}
+
+static bool __init early_make_pgtable(unsigned long address)
+{
+ unsigned long physaddr = address - __PAGE_OFFSET;
+ pmdval_t pmd;
+
+ pmd = (physaddr & PMD_MASK) + early_pmd_flags;
+
+ return __early_make_pgtable(address, pmd);
+}
+
+void __init do_early_exception(struct pt_regs *regs, int trapnr)
+{
+ if (trapnr == X86_TRAP_PF &&
+ early_make_pgtable(native_read_cr2()))
+ return;
+
+ if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT) &&
+ trapnr == X86_TRAP_VC && handle_vc_boot_ghcb(regs))
+ return;
+
+ if (trapnr == X86_TRAP_VE && tdx_early_handle_ve(regs))
+ return;
+
+ early_fixup_exception(regs, trapnr);
+}
+
+/* Don't add a printk in there. printk relies on the PDA which is not initialized
+ yet. */
+void __init clear_bss(void)
+{
+ memset(__bss_start, 0,
+ (unsigned long) __bss_stop - (unsigned long) __bss_start);
+ memset(__brk_base, 0,
+ (unsigned long) __brk_limit - (unsigned long) __brk_base);
+}
+
+static unsigned long get_cmd_line_ptr(void)
+{
+ unsigned long cmd_line_ptr = boot_params.hdr.cmd_line_ptr;
+
+ cmd_line_ptr |= (u64)boot_params.ext_cmd_line_ptr << 32;
+
+ return cmd_line_ptr;
+}
+
+static void __init copy_bootdata(char *real_mode_data)
+{
+ char * command_line;
+ unsigned long cmd_line_ptr;
+
+ /*
+ * If SME is active, this will create decrypted mappings of the
+ * boot data in advance of the copy operations.
+ */
+ sme_map_bootdata(real_mode_data);
+
+ memcpy(&boot_params, real_mode_data, sizeof(boot_params));
+ sanitize_boot_params(&boot_params);
+ cmd_line_ptr = get_cmd_line_ptr();
+ if (cmd_line_ptr) {
+ command_line = __va(cmd_line_ptr);
+ memcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
+ }
+
+ /*
+ * The old boot data is no longer needed and won't be reserved,
+ * freeing up that memory for use by the system. If SME is active,
+ * we need to remove the mappings that were created so that the
+ * memory doesn't remain mapped as decrypted.
+ */
+ sme_unmap_bootdata(real_mode_data);
+}
+
+asmlinkage __visible void __init __noreturn x86_64_start_kernel(char * real_mode_data)
+{
+ /*
+ * Build-time sanity checks on the kernel image and module
+ * area mappings. (these are purely build-time and produce no code)
+ */
+ BUILD_BUG_ON(MODULES_VADDR < __START_KERNEL_map);
+ BUILD_BUG_ON(MODULES_VADDR - __START_KERNEL_map < KERNEL_IMAGE_SIZE);
+ BUILD_BUG_ON(MODULES_LEN + KERNEL_IMAGE_SIZE > 2*PUD_SIZE);
+ BUILD_BUG_ON((__START_KERNEL_map & ~PMD_MASK) != 0);
+ BUILD_BUG_ON((MODULES_VADDR & ~PMD_MASK) != 0);
+ BUILD_BUG_ON(!(MODULES_VADDR > __START_KERNEL));
+ MAYBE_BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) ==
+ (__START_KERNEL & PGDIR_MASK)));
+ BUILD_BUG_ON(__fix_to_virt(__end_of_fixed_addresses) <= MODULES_END);
+
+ cr4_init_shadow();
+
+ /* Kill off the identity-map trampoline */
+ reset_early_page_tables();
+
+ clear_bss();
+
+ /*
+ * This needs to happen *before* kasan_early_init() because latter maps stuff
+ * into that page.
+ */
+ clear_page(init_top_pgt);
+
+ /*
+ * SME support may update early_pmd_flags to include the memory
+ * encryption mask, so it needs to be called before anything
+ * that may generate a page fault.
+ */
+ sme_early_init();
+
+ kasan_early_init();
+
+ /*
+ * Flush global TLB entries which could be left over from the trampoline page
+ * table.
+ *
+ * This needs to happen *after* kasan_early_init() as KASAN-enabled .configs
+ * instrument native_write_cr4() so KASAN must be initialized for that
+ * instrumentation to work.
+ */
+ __native_tlb_flush_global(this_cpu_read(cpu_tlbstate.cr4));
+
+ idt_setup_early_handler();
+
+ /* Needed before cc_platform_has() can be used for TDX */
+ tdx_early_init();
+
+ copy_bootdata(__va(real_mode_data));
+
+ /*
+ * Load microcode early on BSP.
+ */
+ load_ucode_bsp();
+
+ /* set init_top_pgt kernel high mapping*/
+ init_top_pgt[511] = early_top_pgt[511];
+
+ x86_64_start_reservations(real_mode_data);
+}
+
+void __init __noreturn x86_64_start_reservations(char *real_mode_data)
+{
+ /* version is always not zero if it is copied */
+ if (!boot_params.hdr.version)
+ copy_bootdata(__va(real_mode_data));
+
+ x86_early_init_platform_quirks();
+
+ switch (boot_params.hdr.hardware_subarch) {
+ case X86_SUBARCH_INTEL_MID:
+ x86_intel_mid_early_setup();
+ break;
+ default:
+ break;
+ }
+
+ start_kernel();
+}
+
+/*
+ * Data structures and code used for IDT setup in head_64.S. The bringup-IDT is
+ * used until the idt_table takes over. On the boot CPU this happens in
+ * x86_64_start_kernel(), on secondary CPUs in start_secondary(). In both cases
+ * this happens in the functions called from head_64.S.
+ *
+ * The idt_table can't be used that early because all the code modifying it is
+ * in idt.c and can be instrumented by tracing or KASAN, which both don't work
+ * during early CPU bringup. Also the idt_table has the runtime vectors
+ * configured which require certain CPU state to be setup already (like TSS),
+ * which also hasn't happened yet in early CPU bringup.
+ */
+static gate_desc bringup_idt_table[NUM_EXCEPTION_VECTORS] __page_aligned_data;
+
+static struct desc_ptr bringup_idt_descr = {
+ .size = (NUM_EXCEPTION_VECTORS * sizeof(gate_desc)) - 1,
+ .address = 0, /* Set at runtime */
+};
+
+static void set_bringup_idt_handler(gate_desc *idt, int n, void *handler)
+{
+#ifdef CONFIG_AMD_MEM_ENCRYPT
+ struct idt_data data;
+ gate_desc desc;
+
+ init_idt_data(&data, n, handler);
+ idt_init_desc(&desc, &data);
+ native_write_idt_entry(idt, n, &desc);
+#endif
+}
+
+/* This runs while still in the direct mapping */
+static void startup_64_load_idt(unsigned long physbase)
+{
+ struct desc_ptr *desc = fixup_pointer(&bringup_idt_descr, physbase);
+ gate_desc *idt = fixup_pointer(bringup_idt_table, physbase);
+
+
+ if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) {
+ void *handler;
+
+ /* VMM Communication Exception */
+ handler = fixup_pointer(vc_no_ghcb, physbase);
+ set_bringup_idt_handler(idt, X86_TRAP_VC, handler);
+ }
+
+ desc->address = (unsigned long)idt;
+ native_load_idt(desc);
+}
+
+/* This is used when running on kernel addresses */
+void early_setup_idt(void)
+{
+ /* VMM Communication Exception */
+ if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) {
+ setup_ghcb();
+ set_bringup_idt_handler(bringup_idt_table, X86_TRAP_VC, vc_boot_ghcb);
+ }
+
+ bringup_idt_descr.address = (unsigned long)bringup_idt_table;
+ native_load_idt(&bringup_idt_descr);
+}
+
+/*
+ * Setup boot CPU state needed before kernel switches to virtual addresses.
+ */
+void __head startup_64_setup_env(unsigned long physbase)
+{
+ /* Load GDT */
+ startup_gdt_descr.address = (unsigned long)fixup_pointer(startup_gdt, physbase);
+ native_load_gdt(&startup_gdt_descr);
+
+ /* New GDT is live - reload data segment registers */
+ asm volatile("movl %%eax, %%ds\n"
+ "movl %%eax, %%ss\n"
+ "movl %%eax, %%es\n" : : "a"(__KERNEL_DS) : "memory");
+
+ startup_64_load_idt(physbase);
+}