/* SPDX-License-Identifier: GPL-2.0 */ /* * * Copyright (C) 1991, 1992 Linus Torvalds * * Enhanced CPU detection and feature setting code by Mike Jagdis * and Martin Mares, November 1997. */ .text #include <linux/threads.h> #include <linux/init.h> #include <linux/linkage.h> #include <asm/segment.h> #include <asm/page_types.h> #include <asm/pgtable_types.h> #include <asm/cache.h> #include <asm/thread_info.h> #include <asm/asm-offsets.h> #include <asm/setup.h> #include <asm/processor-flags.h> #include <asm/msr-index.h> #include <asm/cpufeatures.h> #include <asm/percpu.h> #include <asm/nops.h> #include <asm/nospec-branch.h> #include <asm/bootparam.h> #include <asm/export.h> #include <asm/pgtable_32.h> /* Physical address */ #define pa(X) ((X) - __PAGE_OFFSET) /* * References to members of the new_cpu_data structure. */ #define X86 new_cpu_data+CPUINFO_x86 #define X86_VENDOR new_cpu_data+CPUINFO_x86_vendor #define X86_MODEL new_cpu_data+CPUINFO_x86_model #define X86_STEPPING new_cpu_data+CPUINFO_x86_stepping #define X86_HARD_MATH new_cpu_data+CPUINFO_hard_math #define X86_CPUID new_cpu_data+CPUINFO_cpuid_level #define X86_CAPABILITY new_cpu_data+CPUINFO_x86_capability #define X86_VENDOR_ID new_cpu_data+CPUINFO_x86_vendor_id #define SIZEOF_PTREGS 17*4 /* * Worst-case size of the kernel mapping we need to make: * a relocatable kernel can live anywhere in lowmem, so we need to be able * to map all of lowmem. */ KERNEL_PAGES = LOWMEM_PAGES INIT_MAP_SIZE = PAGE_TABLE_SIZE(KERNEL_PAGES) * PAGE_SIZE RESERVE_BRK(pagetables, INIT_MAP_SIZE) /* * 32-bit kernel entrypoint; only used by the boot CPU. On entry, * %esi points to the real-mode code as a 32-bit pointer. * CS and DS must be 4 GB flat segments, but we don't depend on * any particular GDT layout, because we load our own as soon as we * can. */ __HEAD SYM_CODE_START(startup_32) movl pa(initial_stack),%ecx /* * Set segments to known values. */ lgdt pa(boot_gdt_descr) movl $(__BOOT_DS),%eax movl %eax,%ds movl %eax,%es movl %eax,%fs movl %eax,%gs movl %eax,%ss leal -__PAGE_OFFSET(%ecx),%esp /* * Clear BSS first so that there are no surprises... */ cld xorl %eax,%eax movl $pa(__bss_start),%edi movl $pa(__bss_stop),%ecx subl %edi,%ecx shrl $2,%ecx rep ; stosl /* * Copy bootup parameters out of the way. * Note: %esi still has the pointer to the real-mode data. * With the kexec as boot loader, parameter segment might be loaded beyond * kernel image and might not even be addressable by early boot page tables. * (kexec on panic case). Hence copy out the parameters before initializing * page tables. */ movl $pa(boot_params),%edi movl $(PARAM_SIZE/4),%ecx cld rep movsl movl pa(boot_params) + NEW_CL_POINTER,%esi andl %esi,%esi jz 1f # No command line movl $pa(boot_command_line),%edi movl $(COMMAND_LINE_SIZE/4),%ecx rep movsl 1: #ifdef CONFIG_OLPC /* save OFW's pgdir table for later use when calling into OFW */ movl %cr3, %eax movl %eax, pa(olpc_ofw_pgd) #endif #ifdef CONFIG_MICROCODE /* Early load ucode on BSP. */ call load_ucode_bsp #endif /* Create early pagetables. */ call mk_early_pgtbl_32 /* Do early initialization of the fixmap area */ movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax #ifdef CONFIG_X86_PAE #define KPMDS (((-__PAGE_OFFSET) >> 30) & 3) /* Number of kernel PMDs */ movl %eax,pa(initial_pg_pmd+0x1000*KPMDS-8) #else movl %eax,pa(initial_page_table+0xffc) #endif jmp .Ldefault_entry SYM_CODE_END(startup_32) /* * Non-boot CPU entry point; entered from trampoline.S * We can't lgdt here, because lgdt itself uses a data segment, but * we know the trampoline has already loaded the boot_gdt for us. * * If cpu hotplug is not supported then this code can go in init section * which will be freed later */ SYM_FUNC_START(startup_32_smp) cld movl $(__BOOT_DS),%eax movl %eax,%ds movl %eax,%es movl %eax,%fs movl %eax,%gs movl pa(initial_stack),%ecx movl %eax,%ss leal -__PAGE_OFFSET(%ecx),%esp #ifdef CONFIG_MICROCODE /* Early load ucode on AP. */ call load_ucode_ap #endif .Ldefault_entry: movl $(CR0_STATE & ~X86_CR0_PG),%eax movl %eax,%cr0 /* * We want to start out with EFLAGS unambiguously cleared. Some BIOSes leave * bits like NT set. This would confuse the debugger if this code is traced. So * initialize them properly now before switching to protected mode. That means * DF in particular (even though we have cleared it earlier after copying the * command line) because GCC expects it. */ pushl $0 popfl /* * New page tables may be in 4Mbyte page mode and may be using the global pages. * * NOTE! If we are on a 486 we may have no cr4 at all! Specifically, cr4 exists * if and only if CPUID exists and has flags other than the FPU flag set. */ movl $-1,pa(X86_CPUID) # preset CPUID level movl $X86_EFLAGS_ID,%ecx pushl %ecx popfl # set EFLAGS=ID pushfl popl %eax # get EFLAGS testl $X86_EFLAGS_ID,%eax # did EFLAGS.ID remained set? jz .Lenable_paging # hw disallowed setting of ID bit # which means no CPUID and no CR4 xorl %eax,%eax cpuid movl %eax,pa(X86_CPUID) # save largest std CPUID function movl $1,%eax cpuid andl $~1,%edx # Ignore CPUID.FPU jz .Lenable_paging # No flags or only CPUID.FPU = no CR4 movl pa(mmu_cr4_features),%eax movl %eax,%cr4 testb $X86_CR4_PAE, %al # check if PAE is enabled jz .Lenable_paging /* Check if extended functions are implemented */ movl $0x80000000, %eax cpuid /* Value must be in the range 0x80000001 to 0x8000ffff */ subl $0x80000001, %eax cmpl $(0x8000ffff-0x80000001), %eax ja .Lenable_paging /* Clear bogus XD_DISABLE bits */ call verify_cpu mov $0x80000001, %eax cpuid /* Execute Disable bit supported? */ btl $(X86_FEATURE_NX & 31), %edx jnc .Lenable_paging /* Setup EFER (Extended Feature Enable Register) */ movl $MSR_EFER, %ecx rdmsr btsl $_EFER_NX, %eax /* Make changes effective */ wrmsr .Lenable_paging: /* * Enable paging */ movl $pa(initial_page_table), %eax movl %eax,%cr3 /* set the page table pointer.. */ movl $CR0_STATE,%eax movl %eax,%cr0 /* ..and set paging (PG) bit */ ljmp $__BOOT_CS,$1f /* Clear prefetch and normalize %eip */ 1: /* Shift the stack pointer to a virtual address */ addl $__PAGE_OFFSET, %esp /* * Check if it is 486 */ movb $4,X86 # at least 486 cmpl $-1,X86_CPUID je .Lis486 /* get vendor info */ xorl %eax,%eax # call CPUID with 0 -> return vendor ID cpuid movl %eax,X86_CPUID # save CPUID level movl %ebx,X86_VENDOR_ID # lo 4 chars movl %edx,X86_VENDOR_ID+4 # next 4 chars movl %ecx,X86_VENDOR_ID+8 # last 4 chars orl %eax,%eax # do we have processor info as well? je .Lis486 movl $1,%eax # Use the CPUID instruction to get CPU type cpuid movb %al,%cl # save reg for future use andb $0x0f,%ah # mask processor family movb %ah,X86 andb $0xf0,%al # mask model shrb $4,%al movb %al,X86_MODEL andb $0x0f,%cl # mask mask revision movb %cl,X86_STEPPING movl %edx,X86_CAPABILITY .Lis486: movl $0x50022,%ecx # set AM, WP, NE and MP movl %cr0,%eax andl $0x80000011,%eax # Save PG,PE,ET orl %ecx,%eax movl %eax,%cr0 lgdt early_gdt_descr ljmp $(__KERNEL_CS),$1f 1: movl $(__KERNEL_DS),%eax # reload all the segment registers movl %eax,%ss # after changing gdt. movl $(__USER_DS),%eax # DS/ES contains default USER segment movl %eax,%ds movl %eax,%es movl $(__KERNEL_PERCPU), %eax movl %eax,%fs # set this cpu's percpu xorl %eax,%eax movl %eax,%gs # clear possible garbage in %gs xorl %eax,%eax # Clear LDT lldt %ax call *(initial_code) 1: jmp 1b SYM_FUNC_END(startup_32_smp) #include "verify_cpu.S" __INIT SYM_FUNC_START(early_idt_handler_array) # 36(%esp) %eflags # 32(%esp) %cs # 28(%esp) %eip # 24(%rsp) error code i = 0 .rept NUM_EXCEPTION_VECTORS .if ((EXCEPTION_ERRCODE_MASK >> i) & 1) == 0 pushl $0 # Dummy error code, to make stack frame uniform .endif pushl $i # 20(%esp) Vector number jmp early_idt_handler_common i = i + 1 .fill early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc .endr SYM_FUNC_END(early_idt_handler_array) SYM_CODE_START_LOCAL(early_idt_handler_common) /* * The stack is the hardware frame, an error code or zero, and the * vector number. */ cld incl %ss:early_recursion_flag /* The vector number is in pt_regs->gs */ cld pushl %fs /* pt_regs->fs (__fsh varies by model) */ pushl %es /* pt_regs->es (__esh varies by model) */ pushl %ds /* pt_regs->ds (__dsh varies by model) */ pushl %eax /* pt_regs->ax */ pushl %ebp /* pt_regs->bp */ pushl %edi /* pt_regs->di */ pushl %esi /* pt_regs->si */ pushl %edx /* pt_regs->dx */ pushl %ecx /* pt_regs->cx */ pushl %ebx /* pt_regs->bx */ /* Fix up DS and ES */ movl $(__KERNEL_DS), %ecx movl %ecx, %ds movl %ecx, %es /* Load the vector number into EDX */ movl PT_GS(%esp), %edx /* Load GS into pt_regs->gs (and maybe clobber __gsh) */ movw %gs, PT_GS(%esp) movl %esp, %eax /* args are pt_regs (EAX), trapnr (EDX) */ call early_fixup_exception popl %ebx /* pt_regs->bx */ popl %ecx /* pt_regs->cx */ popl %edx /* pt_regs->dx */ popl %esi /* pt_regs->si */ popl %edi /* pt_regs->di */ popl %ebp /* pt_regs->bp */ popl %eax /* pt_regs->ax */ popl %ds /* pt_regs->ds (always ignores __dsh) */ popl %es /* pt_regs->es (always ignores __esh) */ popl %fs /* pt_regs->fs (always ignores __fsh) */ popl %gs /* pt_regs->gs (always ignores __gsh) */ decl %ss:early_recursion_flag addl $4, %esp /* pop pt_regs->orig_ax */ iret SYM_CODE_END(early_idt_handler_common) /* This is the default interrupt "handler" :-) */ SYM_FUNC_START(early_ignore_irq) cld #ifdef CONFIG_PRINTK pushl %eax pushl %ecx pushl %edx pushl %es pushl %ds movl $(__KERNEL_DS),%eax movl %eax,%ds movl %eax,%es cmpl $2,early_recursion_flag je hlt_loop incl early_recursion_flag pushl 16(%esp) pushl 24(%esp) pushl 32(%esp) pushl 40(%esp) pushl $int_msg call _printk call dump_stack addl $(5*4),%esp popl %ds popl %es popl %edx popl %ecx popl %eax #endif iret hlt_loop: hlt jmp hlt_loop SYM_FUNC_END(early_ignore_irq) __INITDATA .align 4 SYM_DATA(early_recursion_flag, .long 0) __REFDATA .align 4 SYM_DATA(initial_code, .long i386_start_kernel) #ifdef CONFIG_PAGE_TABLE_ISOLATION #define PGD_ALIGN (2 * PAGE_SIZE) #define PTI_USER_PGD_FILL 1024 #else #define PGD_ALIGN (PAGE_SIZE) #define PTI_USER_PGD_FILL 0 #endif /* * BSS section */ __PAGE_ALIGNED_BSS .align PGD_ALIGN #ifdef CONFIG_X86_PAE .globl initial_pg_pmd initial_pg_pmd: .fill 1024*KPMDS,4,0 #else .globl initial_page_table initial_page_table: .fill 1024,4,0 #endif .align PGD_ALIGN initial_pg_fixmap: .fill 1024,4,0 .globl swapper_pg_dir .align PGD_ALIGN swapper_pg_dir: .fill 1024,4,0 .fill PTI_USER_PGD_FILL,4,0 .globl empty_zero_page empty_zero_page: .fill 4096,1,0 EXPORT_SYMBOL(empty_zero_page) /* * This starts the data section. */ #ifdef CONFIG_X86_PAE __PAGE_ALIGNED_DATA /* Page-aligned for the benefit of paravirt? */ .align PGD_ALIGN SYM_DATA_START(initial_page_table) .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 /* low identity map */ # if KPMDS == 3 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x2000),0 # elif KPMDS == 2 .long 0,0 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0 # elif KPMDS == 1 .long 0,0 .long 0,0 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 # else # error "Kernel PMDs should be 1, 2 or 3" # endif .align PAGE_SIZE /* needs to be page-sized too */ #ifdef CONFIG_PAGE_TABLE_ISOLATION /* * PTI needs another page so sync_initial_pagetable() works correctly * and does not scribble over the data which is placed behind the * actual initial_page_table. See clone_pgd_range(). */ .fill 1024, 4, 0 #endif SYM_DATA_END(initial_page_table) #endif .data .balign 4 /* * The SIZEOF_PTREGS gap is a convention which helps the in-kernel unwinder * reliably detect the end of the stack. */ SYM_DATA(initial_stack, .long init_thread_union + THREAD_SIZE - SIZEOF_PTREGS - TOP_OF_KERNEL_STACK_PADDING) __INITRODATA int_msg: .asciz "Unknown interrupt or fault at: %p %p %p\n" #include "../../x86/xen/xen-head.S" /* * The IDT and GDT 'descriptors' are a strange 48-bit object * only used by the lidt and lgdt instructions. They are not * like usual segment descriptors - they consist of a 16-bit * segment size, and 32-bit linear address value: */ .data ALIGN # early boot GDT descriptor (must use 1:1 address mapping) .word 0 # 32 bit align gdt_desc.address SYM_DATA_START_LOCAL(boot_gdt_descr) .word __BOOT_DS+7 .long boot_gdt - __PAGE_OFFSET SYM_DATA_END(boot_gdt_descr) # boot GDT descriptor (later on used by CPU#0): .word 0 # 32 bit align gdt_desc.address SYM_DATA_START(early_gdt_descr) .word GDT_ENTRIES*8-1 .long gdt_page /* Overwritten for secondary CPUs */ SYM_DATA_END(early_gdt_descr) /* * The boot_gdt must mirror the equivalent in setup.S and is * used only for booting. */ .align L1_CACHE_BYTES SYM_DATA_START(boot_gdt) .fill GDT_ENTRY_BOOT_CS,8,0 .quad 0x00cf9a000000ffff /* kernel 4GB code at 0x00000000 */ .quad 0x00cf92000000ffff /* kernel 4GB data at 0x00000000 */ SYM_DATA_END(boot_gdt)