/* * * Copyright (C) 1991, 1992 Linus Torvalds * * Enhanced CPU detection and feature setting code by Mike Jagdis * and Martin Mares, November 1997. */ .text #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* 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_MASK new_cpu_data+CPUINFO_x86_mask #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 /* * This is how much memory in addition to the memory covered up to * and including _end we need mapped initially. * We need: * (KERNEL_IMAGE_SIZE/4096) / 1024 pages (worst case, non PAE) * (KERNEL_IMAGE_SIZE/4096) / 512 + 4 pages (worst case for PAE) * * Modulo rounding, each megabyte assigned here requires a kilobyte of * memory, which is currently unreclaimed. * * This should be a multiple of a page. * * KERNEL_IMAGE_SIZE should be greater than pa(_end) * and small than max_low_pfn, otherwise will waste some page table entries */ #if PTRS_PER_PMD > 1 #define PAGE_TABLE_SIZE(pages) (((pages) / PTRS_PER_PMD) + PTRS_PER_PGD) #else #define PAGE_TABLE_SIZE(pages) ((pages) / PTRS_PER_PGD) #endif /* * Number of possible pages in the lowmem region. * * We shift 2 by 31 instead of 1 by 32 to the left in order to avoid a * gas warning about overflowing shift count when gas has been compiled * with only a host target support using a 32-bit type for internal * representation. */ LOWMEM_PAGES = (((2<<31) - __PAGE_OFFSET) >> PAGE_SHIFT) /* Enough space to fit pagetables for the low memory linear map */ MAPPING_BEYOND_END = PAGE_TABLE_SIZE(LOWMEM_PAGES) << PAGE_SHIFT /* * 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 ENTRY(startup_32) movl pa(initial_stack),%ecx /* test KEEP_SEGMENTS flag to see if the bootloader is asking us to not reload segments */ testb $KEEP_SEGMENTS, BP_loadflags(%esi) jnz 2f /* * 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 2: 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 /* * Initialize page tables. This creates a PDE and a set of page * tables, which are located immediately beyond __brk_base. The variable * _brk_end is set up to point to the first "safe" location. * Mappings are created both at virtual address 0 (identity mapping) * and PAGE_OFFSET for up to _end. */ #ifdef CONFIG_X86_PAE /* * In PAE mode initial_page_table is statically defined to contain * enough entries to cover the VMSPLIT option (that is the top 1, 2 or 3 * entries). The identity mapping is handled by pointing two PGD entries * to the first kernel PMD. * * Note the upper half of each PMD or PTE are always zero at this stage. */ #define KPMDS (((-__PAGE_OFFSET) >> 30) & 3) /* Number of kernel PMDs */ xorl %ebx,%ebx /* %ebx is kept at zero */ movl $pa(__brk_base), %edi movl $pa(initial_pg_pmd), %edx movl $PTE_IDENT_ATTR, %eax 10: leal PDE_IDENT_ATTR(%edi),%ecx /* Create PMD entry */ movl %ecx,(%edx) /* Store PMD entry */ /* Upper half already zero */ addl $8,%edx movl $512,%ecx 11: stosl xchgl %eax,%ebx stosl xchgl %eax,%ebx addl $0x1000,%eax loop 11b /* * End condition: we must map up to the end + MAPPING_BEYOND_END. */ movl $pa(_end) + MAPPING_BEYOND_END + PTE_IDENT_ATTR, %ebp cmpl %ebp,%eax jb 10b 1: addl $__PAGE_OFFSET, %edi movl %edi, pa(_brk_end) shrl $12, %eax movl %eax, pa(max_pfn_mapped) /* Do early initialization of the fixmap area */ movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax movl %eax,pa(initial_pg_pmd+0x1000*KPMDS-8) #else /* Not PAE */ page_pde_offset = (__PAGE_OFFSET >> 20); movl $pa(__brk_base), %edi movl $pa(initial_page_table), %edx movl $PTE_IDENT_ATTR, %eax 10: leal PDE_IDENT_ATTR(%edi),%ecx /* Create PDE entry */ movl %ecx,(%edx) /* Store identity PDE entry */ movl %ecx,page_pde_offset(%edx) /* Store kernel PDE entry */ addl $4,%edx movl $1024, %ecx 11: stosl addl $0x1000,%eax loop 11b /* * End condition: we must map up to the end + MAPPING_BEYOND_END. */ movl $pa(_end) + MAPPING_BEYOND_END + PTE_IDENT_ATTR, %ebp cmpl %ebp,%eax jb 10b addl $__PAGE_OFFSET, %edi movl %edi, pa(_brk_end) shrl $12, %eax movl %eax, pa(max_pfn_mapped) /* Do early initialization of the fixmap area */ movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax movl %eax,pa(initial_page_table+0xffc) #endif #ifdef CONFIG_PARAVIRT /* This is can only trip for a broken bootloader... */ cmpw $0x207, pa(boot_params + BP_version) jb .Ldefault_entry /* Paravirt-compatible boot parameters. Look to see what architecture we're booting under. */ movl pa(boot_params + BP_hardware_subarch), %eax cmpl $num_subarch_entries, %eax jae .Lbad_subarch movl pa(subarch_entries)(,%eax,4), %eax subl $__PAGE_OFFSET, %eax jmp *%eax .Lbad_subarch: WEAK(lguest_entry) WEAK(xen_entry) /* Unknown implementation; there's really nothing we can do at this point. */ ud2a __INITDATA subarch_entries: .long .Ldefault_entry /* normal x86/PC */ .long lguest_entry /* lguest hypervisor */ .long xen_entry /* Xen hypervisor */ .long .Ldefault_entry /* Moorestown MID */ num_subarch_entries = (. - subarch_entries) / 4 .previous #else jmp .Ldefault_entry #endif /* CONFIG_PARAVIRT */ #ifdef CONFIG_HOTPLUG_CPU /* * Boot CPU0 entry point. It's called from play_dead(). Everything has been set * up already except stack. We just set up stack here. Then call * start_secondary(). */ ENTRY(start_cpu0) movl initial_stack, %ecx movl %ecx, %esp jmp *(initial_code) ENDPROC(start_cpu0) #endif /* * 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 */ ENTRY(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: #define CR0_STATE (X86_CR0_PE | X86_CR0_MP | X86_CR0_ET | \ X86_CR0_NE | X86_CR0_WP | X86_CR0_AM | \ X86_CR0_PG) 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 /* * start system 32-bit setup. We need to re-do some of the things done * in 16-bit mode for the "real" operations. */ movl setup_once_ref,%eax andl %eax,%eax jz 1f # Did we do this already? call *%eax 1: /* * 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_MASK 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 lidt idt_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 movl $(__KERNEL_STACK_CANARY),%eax movl %eax,%gs xorl %eax,%eax # Clear LDT lldt %ax pushl $0 # fake return address for unwinder jmp *(initial_code) #include "verify_cpu.S" /* * setup_once * * The setup work we only want to run on the BSP. * * Warning: %esi is live across this function. */ __INIT setup_once: /* * Set up a idt with 256 interrupt gates that push zero if there * is no error code and then jump to early_idt_handler_common. * It doesn't actually load the idt - that needs to be done on * each CPU. Interrupts are enabled elsewhere, when we can be * relatively sure everything is ok. */ movl $idt_table,%edi movl $early_idt_handler_array,%eax movl $NUM_EXCEPTION_VECTORS,%ecx 1: movl %eax,(%edi) movl %eax,4(%edi) /* interrupt gate, dpl=0, present */ movl $(0x8E000000 + __KERNEL_CS),2(%edi) addl $EARLY_IDT_HANDLER_SIZE,%eax addl $8,%edi loop 1b movl $256 - NUM_EXCEPTION_VECTORS,%ecx movl $ignore_int,%edx movl $(__KERNEL_CS << 16),%eax movw %dx,%ax /* selector = 0x0010 = cs */ movw $0x8E00,%dx /* interrupt gate - dpl=0, present */ 2: movl %eax,(%edi) movl %edx,4(%edi) addl $8,%edi loop 2b #ifdef CONFIG_CC_STACKPROTECTOR /* * Configure the stack canary. The linker can't handle this by * relocation. Manually set base address in stack canary * segment descriptor. */ movl $gdt_page,%eax movl $stack_canary,%ecx movw %cx, 8 * GDT_ENTRY_STACK_CANARY + 2(%eax) shrl $16, %ecx movb %cl, 8 * GDT_ENTRY_STACK_CANARY + 4(%eax) movb %ch, 8 * GDT_ENTRY_STACK_CANARY + 7(%eax) #endif andl $0,setup_once_ref /* Once is enough, thanks */ ret ENTRY(early_idt_handler_array) # 36(%esp) %eflags # 32(%esp) %cs # 28(%esp) %eip # 24(%rsp) error code i = 0 .rept NUM_EXCEPTION_VECTORS .ifeq (EXCEPTION_ERRCODE_MASK >> i) & 1 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 ENDPROC(early_idt_handler_array) 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 */ movw $0, 2(%esp) /* clear high bits (some CPUs leave garbage) */ pushl %es /* pt_regs->es */ movw $0, 2(%esp) /* clear high bits (some CPUs leave garbage) */ pushl %ds /* pt_regs->ds */ movw $0, 2(%esp) /* clear high bits (some CPUs leave garbage) */ 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 clear high bits */ movw %gs, PT_GS(%esp) movw $0, PT_GS+2(%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 */ popl %es /* pt_regs->es */ popl %fs /* pt_regs->fs */ popl %gs /* pt_regs->gs */ decl %ss:early_recursion_flag addl $4, %esp /* pop pt_regs->orig_ax */ iret ENDPROC(early_idt_handler_common) /* This is the default interrupt "handler" :-) */ ALIGN ignore_int: 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 ENDPROC(ignore_int) __INITDATA .align 4 GLOBAL(early_recursion_flag) .long 0 __REFDATA .align 4 ENTRY(initial_code) .long i386_start_kernel ENTRY(setup_once_ref) .long setup_once /* * BSS section */ __PAGE_ALIGNED_BSS .align PAGE_SIZE #ifdef CONFIG_X86_PAE initial_pg_pmd: .fill 1024*KPMDS,4,0 #else ENTRY(initial_page_table) .fill 1024,4,0 #endif initial_pg_fixmap: .fill 1024,4,0 ENTRY(empty_zero_page) .fill 4096,1,0 ENTRY(swapper_pg_dir) .fill 1024,4,0 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 PAGE_SIZE ENTRY(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 */ #endif .data .balign 4 ENTRY(initial_stack) .long init_thread_union+THREAD_SIZE __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 .globl boot_gdt_descr .globl idt_descr ALIGN # early boot GDT descriptor (must use 1:1 address mapping) .word 0 # 32 bit align gdt_desc.address boot_gdt_descr: .word __BOOT_DS+7 .long boot_gdt - __PAGE_OFFSET .word 0 # 32-bit align idt_desc.address idt_descr: .word IDT_ENTRIES*8-1 # idt contains 256 entries .long idt_table # boot GDT descriptor (later on used by CPU#0): .word 0 # 32 bit align gdt_desc.address ENTRY(early_gdt_descr) .word GDT_ENTRIES*8-1 .long gdt_page /* Overwritten for secondary CPUs */ /* * The boot_gdt must mirror the equivalent in setup.S and is * used only for booting. */ .align L1_CACHE_BYTES ENTRY(boot_gdt) .fill GDT_ENTRY_BOOT_CS,8,0 .quad 0x00cf9a000000ffff /* kernel 4GB code at 0x00000000 */ .quad 0x00cf92000000ffff /* kernel 4GB data at 0x00000000 */