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/nospec-branch.h>
27 #include <asm/bootparam.h>
28 #include <asm/export.h>
29 #include <asm/pgtable_32.h>
31 /* Physical address */
32 #define pa(X) ((X) - __PAGE_OFFSET)
35 * References to members of the new_cpu_data structure.
38 #define X86 new_cpu_data+CPUINFO_x86
39 #define X86_VENDOR new_cpu_data+CPUINFO_x86_vendor
40 #define X86_MODEL new_cpu_data+CPUINFO_x86_model
41 #define X86_STEPPING new_cpu_data+CPUINFO_x86_stepping
42 #define X86_HARD_MATH new_cpu_data+CPUINFO_hard_math
43 #define X86_CPUID new_cpu_data+CPUINFO_cpuid_level
44 #define X86_CAPABILITY new_cpu_data+CPUINFO_x86_capability
45 #define X86_VENDOR_ID new_cpu_data+CPUINFO_x86_vendor_id
48 #define SIZEOF_PTREGS 17*4
51 * Worst-case size of the kernel mapping we need to make:
52 * a relocatable kernel can live anywhere in lowmem, so we need to be able
53 * to map all of lowmem.
55 KERNEL_PAGES = LOWMEM_PAGES
57 INIT_MAP_SIZE = PAGE_TABLE_SIZE(KERNEL_PAGES) * PAGE_SIZE
58 RESERVE_BRK(pagetables, INIT_MAP_SIZE)
61 * 32-bit kernel entrypoint; only used by the boot CPU. On entry,
62 * %esi points to the real-mode code as a 32-bit pointer.
63 * CS and DS must be 4 GB flat segments, but we don't depend on
64 * any particular GDT layout, because we load our own as soon as we
68 SYM_CODE_START(startup_32)
69 movl pa(initial_stack),%ecx
72 * Set segments to known values.
74 lgdt pa(boot_gdt_descr)
75 movl $(__BOOT_DS),%eax
81 leal -__PAGE_OFFSET(%ecx),%esp
84 * Clear BSS first so that there are no surprises...
88 movl $pa(__bss_start),%edi
89 movl $pa(__bss_stop),%ecx
94 * Copy bootup parameters out of the way.
95 * Note: %esi still has the pointer to the real-mode data.
96 * With the kexec as boot loader, parameter segment might be loaded beyond
97 * kernel image and might not even be addressable by early boot page tables.
98 * (kexec on panic case). Hence copy out the parameters before initializing
101 movl $pa(boot_params),%edi
102 movl $(PARAM_SIZE/4),%ecx
106 movl pa(boot_params) + NEW_CL_POINTER,%esi
108 jz 1f # No command line
109 movl $pa(boot_command_line),%edi
110 movl $(COMMAND_LINE_SIZE/4),%ecx
116 /* save OFW's pgdir table for later use when calling into OFW */
118 movl %eax, pa(olpc_ofw_pgd)
121 #ifdef CONFIG_MICROCODE
122 /* Early load ucode on BSP. */
126 /* Create early pagetables. */
127 call mk_early_pgtbl_32
129 /* Do early initialization of the fixmap area */
130 movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax
131 #ifdef CONFIG_X86_PAE
132 #define KPMDS (((-__PAGE_OFFSET) >> 30) & 3) /* Number of kernel PMDs */
133 movl %eax,pa(initial_pg_pmd+0x1000*KPMDS-8)
135 movl %eax,pa(initial_page_table+0xffc)
139 SYM_CODE_END(startup_32)
141 #ifdef CONFIG_HOTPLUG_CPU
143 * Boot CPU0 entry point. It's called from play_dead(). Everything has been set
144 * up already except stack. We just set up stack here. Then call
147 SYM_FUNC_START(start_cpu0)
148 movl initial_stack, %ecx
152 SYM_FUNC_END(start_cpu0)
156 * Non-boot CPU entry point; entered from trampoline.S
157 * We can't lgdt here, because lgdt itself uses a data segment, but
158 * we know the trampoline has already loaded the boot_gdt for us.
160 * If cpu hotplug is not supported then this code can go in init section
161 * which will be freed later
163 SYM_FUNC_START(startup_32_smp)
165 movl $(__BOOT_DS),%eax
170 movl pa(initial_stack),%ecx
172 leal -__PAGE_OFFSET(%ecx),%esp
174 #ifdef CONFIG_MICROCODE
175 /* Early load ucode on AP. */
180 movl $(CR0_STATE & ~X86_CR0_PG),%eax
184 * We want to start out with EFLAGS unambiguously cleared. Some BIOSes leave
185 * bits like NT set. This would confuse the debugger if this code is traced. So
186 * initialize them properly now before switching to protected mode. That means
187 * DF in particular (even though we have cleared it earlier after copying the
188 * command line) because GCC expects it.
194 * New page tables may be in 4Mbyte page mode and may be using the global pages.
196 * NOTE! If we are on a 486 we may have no cr4 at all! Specifically, cr4 exists
197 * if and only if CPUID exists and has flags other than the FPU flag set.
199 movl $-1,pa(X86_CPUID) # preset CPUID level
200 movl $X86_EFLAGS_ID,%ecx
202 popfl # set EFLAGS=ID
204 popl %eax # get EFLAGS
205 testl $X86_EFLAGS_ID,%eax # did EFLAGS.ID remained set?
206 jz .Lenable_paging # hw disallowed setting of ID bit
207 # which means no CPUID and no CR4
211 movl %eax,pa(X86_CPUID) # save largest std CPUID function
215 andl $~1,%edx # Ignore CPUID.FPU
216 jz .Lenable_paging # No flags or only CPUID.FPU = no CR4
218 movl pa(mmu_cr4_features),%eax
221 testb $X86_CR4_PAE, %al # check if PAE is enabled
224 /* Check if extended functions are implemented */
225 movl $0x80000000, %eax
227 /* Value must be in the range 0x80000001 to 0x8000ffff */
228 subl $0x80000001, %eax
229 cmpl $(0x8000ffff-0x80000001), %eax
232 /* Clear bogus XD_DISABLE bits */
235 mov $0x80000001, %eax
237 /* Execute Disable bit supported? */
238 btl $(X86_FEATURE_NX & 31), %edx
241 /* Setup EFER (Extended Feature Enable Register) */
246 /* Make changes effective */
254 movl $pa(initial_page_table), %eax
255 movl %eax,%cr3 /* set the page table pointer.. */
257 movl %eax,%cr0 /* ..and set paging (PG) bit */
258 ljmp $__BOOT_CS,$1f /* Clear prefetch and normalize %eip */
260 /* Shift the stack pointer to a virtual address */
261 addl $__PAGE_OFFSET, %esp
264 * start system 32-bit setup. We need to re-do some of the things done
265 * in 16-bit mode for the "real" operations.
267 movl setup_once_ref,%eax
269 jz 1f # Did we do this already?
276 movb $4,X86 # at least 486
280 /* get vendor info */
281 xorl %eax,%eax # call CPUID with 0 -> return vendor ID
283 movl %eax,X86_CPUID # save CPUID level
284 movl %ebx,X86_VENDOR_ID # lo 4 chars
285 movl %edx,X86_VENDOR_ID+4 # next 4 chars
286 movl %ecx,X86_VENDOR_ID+8 # last 4 chars
288 orl %eax,%eax # do we have processor info as well?
291 movl $1,%eax # Use the CPUID instruction to get CPU type
293 movb %al,%cl # save reg for future use
294 andb $0x0f,%ah # mask processor family
296 andb $0xf0,%al # mask model
299 andb $0x0f,%cl # mask mask revision
300 movb %cl,X86_STEPPING
301 movl %edx,X86_CAPABILITY
304 movl $0x50022,%ecx # set AM, WP, NE and MP
306 andl $0x80000011,%eax # Save PG,PE,ET
311 ljmp $(__KERNEL_CS),$1f
312 1: movl $(__KERNEL_DS),%eax # reload all the segment registers
313 movl %eax,%ss # after changing gdt.
315 movl $(__USER_DS),%eax # DS/ES contains default USER segment
319 movl $(__KERNEL_PERCPU), %eax
320 movl %eax,%fs # set this cpu's percpu
323 movl %eax,%gs # clear possible garbage in %gs
325 xorl %eax,%eax # Clear LDT
330 SYM_FUNC_END(startup_32_smp)
332 #include "verify_cpu.S"
337 * The setup work we only want to run on the BSP.
339 * Warning: %esi is live across this function.
343 andl $0,setup_once_ref /* Once is enough, thanks */
346 SYM_FUNC_START(early_idt_handler_array)
350 # 24(%rsp) error code
352 .rept NUM_EXCEPTION_VECTORS
353 .if ((EXCEPTION_ERRCODE_MASK >> i) & 1) == 0
354 pushl $0 # Dummy error code, to make stack frame uniform
356 pushl $i # 20(%esp) Vector number
357 jmp early_idt_handler_common
359 .fill early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc
361 SYM_FUNC_END(early_idt_handler_array)
363 SYM_CODE_START_LOCAL(early_idt_handler_common)
365 * The stack is the hardware frame, an error code or zero, and the
370 incl %ss:early_recursion_flag
372 /* The vector number is in pt_regs->gs */
375 pushl %fs /* pt_regs->fs (__fsh varies by model) */
376 pushl %es /* pt_regs->es (__esh varies by model) */
377 pushl %ds /* pt_regs->ds (__dsh varies by model) */
378 pushl %eax /* pt_regs->ax */
379 pushl %ebp /* pt_regs->bp */
380 pushl %edi /* pt_regs->di */
381 pushl %esi /* pt_regs->si */
382 pushl %edx /* pt_regs->dx */
383 pushl %ecx /* pt_regs->cx */
384 pushl %ebx /* pt_regs->bx */
386 /* Fix up DS and ES */
387 movl $(__KERNEL_DS), %ecx
391 /* Load the vector number into EDX */
392 movl PT_GS(%esp), %edx
394 /* Load GS into pt_regs->gs (and maybe clobber __gsh) */
395 movw %gs, PT_GS(%esp)
397 movl %esp, %eax /* args are pt_regs (EAX), trapnr (EDX) */
398 call early_fixup_exception
400 popl %ebx /* pt_regs->bx */
401 popl %ecx /* pt_regs->cx */
402 popl %edx /* pt_regs->dx */
403 popl %esi /* pt_regs->si */
404 popl %edi /* pt_regs->di */
405 popl %ebp /* pt_regs->bp */
406 popl %eax /* pt_regs->ax */
407 popl %ds /* pt_regs->ds (always ignores __dsh) */
408 popl %es /* pt_regs->es (always ignores __esh) */
409 popl %fs /* pt_regs->fs (always ignores __fsh) */
410 popl %gs /* pt_regs->gs (always ignores __gsh) */
411 decl %ss:early_recursion_flag
412 addl $4, %esp /* pop pt_regs->orig_ax */
414 SYM_CODE_END(early_idt_handler_common)
416 /* This is the default interrupt "handler" :-) */
417 SYM_FUNC_START(early_ignore_irq)
425 movl $(__KERNEL_DS),%eax
428 cmpl $2,early_recursion_flag
430 incl early_recursion_flag
452 SYM_FUNC_END(early_ignore_irq)
456 SYM_DATA(early_recursion_flag, .long 0)
460 SYM_DATA(initial_code, .long i386_start_kernel)
461 SYM_DATA(setup_once_ref, .long setup_once)
463 #ifdef CONFIG_PAGE_TABLE_ISOLATION
464 #define PGD_ALIGN (2 * PAGE_SIZE)
465 #define PTI_USER_PGD_FILL 1024
467 #define PGD_ALIGN (PAGE_SIZE)
468 #define PTI_USER_PGD_FILL 0
475 #ifdef CONFIG_X86_PAE
476 .globl initial_pg_pmd
480 .globl initial_page_table
487 .globl swapper_pg_dir
491 .fill PTI_USER_PGD_FILL,4,0
492 .globl empty_zero_page
495 EXPORT_SYMBOL(empty_zero_page)
498 * This starts the data section.
500 #ifdef CONFIG_X86_PAE
502 /* Page-aligned for the benefit of paravirt? */
504 SYM_DATA_START(initial_page_table)
505 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 /* low identity map */
507 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0
508 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0
509 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x2000),0
512 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0
513 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0
517 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0
519 # error "Kernel PMDs should be 1, 2 or 3"
521 .align PAGE_SIZE /* needs to be page-sized too */
523 #ifdef CONFIG_PAGE_TABLE_ISOLATION
525 * PTI needs another page so sync_initial_pagetable() works correctly
526 * and does not scribble over the data which is placed behind the
527 * actual initial_page_table. See clone_pgd_range().
532 SYM_DATA_END(initial_page_table)
538 * The SIZEOF_PTREGS gap is a convention which helps the in-kernel unwinder
539 * reliably detect the end of the stack.
541 SYM_DATA(initial_stack,
542 .long init_thread_union + THREAD_SIZE -
543 SIZEOF_PTREGS - TOP_OF_KERNEL_STACK_PADDING)
547 .asciz "Unknown interrupt or fault at: %p %p %p\n"
549 #include "../../x86/xen/xen-head.S"
552 * The IDT and GDT 'descriptors' are a strange 48-bit object
553 * only used by the lidt and lgdt instructions. They are not
554 * like usual segment descriptors - they consist of a 16-bit
555 * segment size, and 32-bit linear address value:
560 # early boot GDT descriptor (must use 1:1 address mapping)
561 .word 0 # 32 bit align gdt_desc.address
562 SYM_DATA_START_LOCAL(boot_gdt_descr)
564 .long boot_gdt - __PAGE_OFFSET
565 SYM_DATA_END(boot_gdt_descr)
567 # boot GDT descriptor (later on used by CPU#0):
568 .word 0 # 32 bit align gdt_desc.address
569 SYM_DATA_START(early_gdt_descr)
570 .word GDT_ENTRIES*8-1
571 .long gdt_page /* Overwritten for secondary CPUs */
572 SYM_DATA_END(early_gdt_descr)
575 * The boot_gdt must mirror the equivalent in setup.S and is
576 * used only for booting.
578 .align L1_CACHE_BYTES
579 SYM_DATA_START(boot_gdt)
580 .fill GDT_ENTRY_BOOT_CS,8,0
581 .quad 0x00cf9a000000ffff /* kernel 4GB code at 0x00000000 */
582 .quad 0x00cf92000000ffff /* kernel 4GB data at 0x00000000 */
583 SYM_DATA_END(boot_gdt)