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- // SPDX-License-Identifier: GPL-2.0
- /*
- * prepare to run common code
- *
- * Copyright (C) 2000 Andrea Arcangeli <[email protected]> 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_PAGE_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 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 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);
- }
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