diff options
Diffstat (limited to 'arch/x86/kernel/head64.c')
| -rw-r--r-- | arch/x86/kernel/head64.c | 637 |
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); +} |