1 /* SPDX-License-Identifier: GPL-2.0 */
4 * Copyright (C) 1991, 1992 Linus Torvalds
6 * Enhanced CPU detection and feature setting code by Mike Jagdis
7 * and Martin Mares, November 1997.
11 #include <linux/threads.h>
12 #include <linux/init.h>
13 #include <linux/linkage.h>
14 #include <asm/segment.h>
15 #include <asm/page_types.h>
16 #include <asm/pgtable_types.h>
17 #include <asm/cache.h>
18 #include <asm/thread_info.h>
19 #include <asm/asm-offsets.h>
20 #include <asm/setup.h>
21 #include <asm/processor-flags.h>
22 #include <asm/msr-index.h>
23 #include <asm/cpufeatures.h>
24 #include <asm/percpu.h>
26 #include <asm/bootparam.h>
27 #include <asm/export.h>
28 #include <asm/pgtable_32.h>
30 /* Physical address */
31 #define pa(X) ((X) - __PAGE_OFFSET)
34 * References to members of the new_cpu_data structure.
37 #define X86 new_cpu_data+CPUINFO_x86
38 #define X86_VENDOR new_cpu_data+CPUINFO_x86_vendor
39 #define X86_MODEL new_cpu_data+CPUINFO_x86_model
40 #define X86_STEPPING new_cpu_data+CPUINFO_x86_stepping
41 #define X86_HARD_MATH new_cpu_data+CPUINFO_hard_math
42 #define X86_CPUID new_cpu_data+CPUINFO_cpuid_level
43 #define X86_CAPABILITY new_cpu_data+CPUINFO_x86_capability
44 #define X86_VENDOR_ID new_cpu_data+CPUINFO_x86_vendor_id
47 #define SIZEOF_PTREGS 17*4
50 * Worst-case size of the kernel mapping we need to make:
51 * a relocatable kernel can live anywhere in lowmem, so we need to be able
52 * to map all of lowmem.
54 KERNEL_PAGES = LOWMEM_PAGES
56 INIT_MAP_SIZE = PAGE_TABLE_SIZE(KERNEL_PAGES) * PAGE_SIZE
57 RESERVE_BRK(pagetables, INIT_MAP_SIZE)
60 * 32-bit kernel entrypoint; only used by the boot CPU. On entry,
61 * %esi points to the real-mode code as a 32-bit pointer.
62 * CS and DS must be 4 GB flat segments, but we don't depend on
63 * any particular GDT layout, because we load our own as soon as we
67 SYM_CODE_START(startup_32)
68 movl pa(initial_stack),%ecx
71 * Set segments to known values.
73 lgdt pa(boot_gdt_descr)
74 movl $(__BOOT_DS),%eax
80 leal -__PAGE_OFFSET(%ecx),%esp
83 * Clear BSS first so that there are no surprises...
87 movl $pa(__bss_start),%edi
88 movl $pa(__bss_stop),%ecx
93 * Copy bootup parameters out of the way.
94 * Note: %esi still has the pointer to the real-mode data.
95 * With the kexec as boot loader, parameter segment might be loaded beyond
96 * kernel image and might not even be addressable by early boot page tables.
97 * (kexec on panic case). Hence copy out the parameters before initializing
100 movl $pa(boot_params),%edi
101 movl $(PARAM_SIZE/4),%ecx
105 movl pa(boot_params) + NEW_CL_POINTER,%esi
107 jz 1f # No command line
108 movl $pa(boot_command_line),%edi
109 movl $(COMMAND_LINE_SIZE/4),%ecx
115 /* save OFW's pgdir table for later use when calling into OFW */
117 movl %eax, pa(olpc_ofw_pgd)
120 #ifdef CONFIG_MICROCODE
121 /* Early load ucode on BSP. */
125 /* Create early pagetables. */
126 call mk_early_pgtbl_32
128 /* Do early initialization of the fixmap area */
129 movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax
130 #ifdef CONFIG_X86_PAE
131 #define KPMDS (((-__PAGE_OFFSET) >> 30) & 3) /* Number of kernel PMDs */
132 movl %eax,pa(initial_pg_pmd+0x1000*KPMDS-8)
134 movl %eax,pa(initial_page_table+0xffc)
137 #ifdef CONFIG_PARAVIRT
138 /* This is can only trip for a broken bootloader... */
139 cmpw $0x207, pa(boot_params + BP_version)
142 /* Paravirt-compatible boot parameters. Look to see what architecture
143 we're booting under. */
144 movl pa(boot_params + BP_hardware_subarch), %eax
145 cmpl $num_subarch_entries, %eax
148 movl pa(subarch_entries)(,%eax,4), %eax
149 subl $__PAGE_OFFSET, %eax
153 SYM_INNER_LABEL_ALIGN(xen_entry, SYM_L_WEAK)
154 /* Unknown implementation; there's really
155 nothing we can do at this point. */
161 .long .Ldefault_entry /* normal x86/PC */
162 .long xen_entry /* Xen hypervisor */
163 .long .Ldefault_entry /* Moorestown MID */
164 num_subarch_entries = (. - subarch_entries) / 4
168 #endif /* CONFIG_PARAVIRT */
169 SYM_CODE_END(startup_32)
171 #ifdef CONFIG_HOTPLUG_CPU
173 * Boot CPU0 entry point. It's called from play_dead(). Everything has been set
174 * up already except stack. We just set up stack here. Then call
177 SYM_FUNC_START(start_cpu0)
178 movl initial_stack, %ecx
182 SYM_FUNC_END(start_cpu0)
186 * Non-boot CPU entry point; entered from trampoline.S
187 * We can't lgdt here, because lgdt itself uses a data segment, but
188 * we know the trampoline has already loaded the boot_gdt for us.
190 * If cpu hotplug is not supported then this code can go in init section
191 * which will be freed later
193 SYM_FUNC_START(startup_32_smp)
195 movl $(__BOOT_DS),%eax
200 movl pa(initial_stack),%ecx
202 leal -__PAGE_OFFSET(%ecx),%esp
204 #ifdef CONFIG_MICROCODE
205 /* Early load ucode on AP. */
210 movl $(CR0_STATE & ~X86_CR0_PG),%eax
214 * We want to start out with EFLAGS unambiguously cleared. Some BIOSes leave
215 * bits like NT set. This would confuse the debugger if this code is traced. So
216 * initialize them properly now before switching to protected mode. That means
217 * DF in particular (even though we have cleared it earlier after copying the
218 * command line) because GCC expects it.
224 * New page tables may be in 4Mbyte page mode and may be using the global pages.
226 * NOTE! If we are on a 486 we may have no cr4 at all! Specifically, cr4 exists
227 * if and only if CPUID exists and has flags other than the FPU flag set.
229 movl $-1,pa(X86_CPUID) # preset CPUID level
230 movl $X86_EFLAGS_ID,%ecx
232 popfl # set EFLAGS=ID
234 popl %eax # get EFLAGS
235 testl $X86_EFLAGS_ID,%eax # did EFLAGS.ID remained set?
236 jz .Lenable_paging # hw disallowed setting of ID bit
237 # which means no CPUID and no CR4
241 movl %eax,pa(X86_CPUID) # save largest std CPUID function
245 andl $~1,%edx # Ignore CPUID.FPU
246 jz .Lenable_paging # No flags or only CPUID.FPU = no CR4
248 movl pa(mmu_cr4_features),%eax
251 testb $X86_CR4_PAE, %al # check if PAE is enabled
254 /* Check if extended functions are implemented */
255 movl $0x80000000, %eax
257 /* Value must be in the range 0x80000001 to 0x8000ffff */
258 subl $0x80000001, %eax
259 cmpl $(0x8000ffff-0x80000001), %eax
262 /* Clear bogus XD_DISABLE bits */
265 mov $0x80000001, %eax
267 /* Execute Disable bit supported? */
268 btl $(X86_FEATURE_NX & 31), %edx
271 /* Setup EFER (Extended Feature Enable Register) */
276 /* Make changes effective */
284 movl $pa(initial_page_table), %eax
285 movl %eax,%cr3 /* set the page table pointer.. */
287 movl %eax,%cr0 /* ..and set paging (PG) bit */
288 ljmp $__BOOT_CS,$1f /* Clear prefetch and normalize %eip */
290 /* Shift the stack pointer to a virtual address */
291 addl $__PAGE_OFFSET, %esp
294 * start system 32-bit setup. We need to re-do some of the things done
295 * in 16-bit mode for the "real" operations.
297 movl setup_once_ref,%eax
299 jz 1f # Did we do this already?
306 movb $4,X86 # at least 486
310 /* get vendor info */
311 xorl %eax,%eax # call CPUID with 0 -> return vendor ID
313 movl %eax,X86_CPUID # save CPUID level
314 movl %ebx,X86_VENDOR_ID # lo 4 chars
315 movl %edx,X86_VENDOR_ID+4 # next 4 chars
316 movl %ecx,X86_VENDOR_ID+8 # last 4 chars
318 orl %eax,%eax # do we have processor info as well?
321 movl $1,%eax # Use the CPUID instruction to get CPU type
323 movb %al,%cl # save reg for future use
324 andb $0x0f,%ah # mask processor family
326 andb $0xf0,%al # mask model
329 andb $0x0f,%cl # mask mask revision
330 movb %cl,X86_STEPPING
331 movl %edx,X86_CAPABILITY
334 movl $0x50022,%ecx # set AM, WP, NE and MP
336 andl $0x80000011,%eax # Save PG,PE,ET
341 ljmp $(__KERNEL_CS),$1f
342 1: movl $(__KERNEL_DS),%eax # reload all the segment registers
343 movl %eax,%ss # after changing gdt.
345 movl $(__USER_DS),%eax # DS/ES contains default USER segment
349 movl $(__KERNEL_PERCPU), %eax
350 movl %eax,%fs # set this cpu's percpu
352 movl $(__KERNEL_STACK_CANARY),%eax
355 xorl %eax,%eax # Clear LDT
360 SYM_FUNC_END(startup_32_smp)
362 #include "verify_cpu.S"
367 * The setup work we only want to run on the BSP.
369 * Warning: %esi is live across this function.
373 #ifdef CONFIG_STACKPROTECTOR
375 * Configure the stack canary. The linker can't handle this by
376 * relocation. Manually set base address in stack canary
377 * segment descriptor.
380 movl $stack_canary,%ecx
381 movw %cx, 8 * GDT_ENTRY_STACK_CANARY + 2(%eax)
383 movb %cl, 8 * GDT_ENTRY_STACK_CANARY + 4(%eax)
384 movb %ch, 8 * GDT_ENTRY_STACK_CANARY + 7(%eax)
387 andl $0,setup_once_ref /* Once is enough, thanks */
390 SYM_FUNC_START(early_idt_handler_array)
394 # 24(%rsp) error code
396 .rept NUM_EXCEPTION_VECTORS
397 .if ((EXCEPTION_ERRCODE_MASK >> i) & 1) == 0
398 pushl $0 # Dummy error code, to make stack frame uniform
400 pushl $i # 20(%esp) Vector number
401 jmp early_idt_handler_common
403 .fill early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc
405 SYM_FUNC_END(early_idt_handler_array)
407 SYM_CODE_START_LOCAL(early_idt_handler_common)
409 * The stack is the hardware frame, an error code or zero, and the
414 incl %ss:early_recursion_flag
416 /* The vector number is in pt_regs->gs */
419 pushl %fs /* pt_regs->fs (__fsh varies by model) */
420 pushl %es /* pt_regs->es (__esh varies by model) */
421 pushl %ds /* pt_regs->ds (__dsh varies by model) */
422 pushl %eax /* pt_regs->ax */
423 pushl %ebp /* pt_regs->bp */
424 pushl %edi /* pt_regs->di */
425 pushl %esi /* pt_regs->si */
426 pushl %edx /* pt_regs->dx */
427 pushl %ecx /* pt_regs->cx */
428 pushl %ebx /* pt_regs->bx */
430 /* Fix up DS and ES */
431 movl $(__KERNEL_DS), %ecx
435 /* Load the vector number into EDX */
436 movl PT_GS(%esp), %edx
438 /* Load GS into pt_regs->gs (and maybe clobber __gsh) */
439 movw %gs, PT_GS(%esp)
441 movl %esp, %eax /* args are pt_regs (EAX), trapnr (EDX) */
442 call early_fixup_exception
444 popl %ebx /* pt_regs->bx */
445 popl %ecx /* pt_regs->cx */
446 popl %edx /* pt_regs->dx */
447 popl %esi /* pt_regs->si */
448 popl %edi /* pt_regs->di */
449 popl %ebp /* pt_regs->bp */
450 popl %eax /* pt_regs->ax */
451 popl %ds /* pt_regs->ds (always ignores __dsh) */
452 popl %es /* pt_regs->es (always ignores __esh) */
453 popl %fs /* pt_regs->fs (always ignores __fsh) */
454 popl %gs /* pt_regs->gs (always ignores __gsh) */
455 decl %ss:early_recursion_flag
456 addl $4, %esp /* pop pt_regs->orig_ax */
458 SYM_CODE_END(early_idt_handler_common)
460 /* This is the default interrupt "handler" :-) */
461 SYM_FUNC_START(early_ignore_irq)
469 movl $(__KERNEL_DS),%eax
472 cmpl $2,early_recursion_flag
474 incl early_recursion_flag
496 SYM_FUNC_END(early_ignore_irq)
500 SYM_DATA(early_recursion_flag, .long 0)
504 SYM_DATA(initial_code, .long i386_start_kernel)
505 SYM_DATA(setup_once_ref, .long setup_once)
507 #ifdef CONFIG_PAGE_TABLE_ISOLATION
508 #define PGD_ALIGN (2 * PAGE_SIZE)
509 #define PTI_USER_PGD_FILL 1024
511 #define PGD_ALIGN (PAGE_SIZE)
512 #define PTI_USER_PGD_FILL 0
519 #ifdef CONFIG_X86_PAE
520 .globl initial_pg_pmd
524 .globl initial_page_table
531 .globl swapper_pg_dir
535 .fill PTI_USER_PGD_FILL,4,0
536 .globl empty_zero_page
539 EXPORT_SYMBOL(empty_zero_page)
542 * This starts the data section.
544 #ifdef CONFIG_X86_PAE
546 /* Page-aligned for the benefit of paravirt? */
548 SYM_DATA_START(initial_page_table)
549 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 /* low identity map */
551 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0
552 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0
553 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x2000),0
556 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0
557 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0
561 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0
563 # error "Kernel PMDs should be 1, 2 or 3"
565 .align PAGE_SIZE /* needs to be page-sized too */
567 #ifdef CONFIG_PAGE_TABLE_ISOLATION
569 * PTI needs another page so sync_initial_pagetable() works correctly
570 * and does not scribble over the data which is placed behind the
571 * actual initial_page_table. See clone_pgd_range().
576 SYM_DATA_END(initial_page_table)
582 * The SIZEOF_PTREGS gap is a convention which helps the in-kernel unwinder
583 * reliably detect the end of the stack.
585 SYM_DATA(initial_stack,
586 .long init_thread_union + THREAD_SIZE -
587 SIZEOF_PTREGS - TOP_OF_KERNEL_STACK_PADDING)
591 .asciz "Unknown interrupt or fault at: %p %p %p\n"
593 #include "../../x86/xen/xen-head.S"
596 * The IDT and GDT 'descriptors' are a strange 48-bit object
597 * only used by the lidt and lgdt instructions. They are not
598 * like usual segment descriptors - they consist of a 16-bit
599 * segment size, and 32-bit linear address value:
604 # early boot GDT descriptor (must use 1:1 address mapping)
605 .word 0 # 32 bit align gdt_desc.address
606 SYM_DATA_START_LOCAL(boot_gdt_descr)
608 .long boot_gdt - __PAGE_OFFSET
609 SYM_DATA_END(boot_gdt_descr)
611 # boot GDT descriptor (later on used by CPU#0):
612 .word 0 # 32 bit align gdt_desc.address
613 SYM_DATA_START(early_gdt_descr)
614 .word GDT_ENTRIES*8-1
615 .long gdt_page /* Overwritten for secondary CPUs */
616 SYM_DATA_END(early_gdt_descr)
619 * The boot_gdt must mirror the equivalent in setup.S and is
620 * used only for booting.
622 .align L1_CACHE_BYTES
623 SYM_DATA_START(boot_gdt)
624 .fill GDT_ENTRY_BOOT_CS,8,0
625 .quad 0x00cf9a000000ffff /* kernel 4GB code at 0x00000000 */
626 .quad 0x00cf92000000ffff /* kernel 4GB data at 0x00000000 */
627 SYM_DATA_END(boot_gdt)