1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 *
4 *  Copyright (C) 1991, 1992  Linus Torvalds
5 *
6 *  Enhanced CPU detection and feature setting code by Mike Jagdis
7 *  and Martin Mares, November 1997.
8 */
9
10.text
11#include <linux/export.h>
12#include <linux/threads.h>
13#include <linux/init.h>
14#include <linux/linkage.h>
15#include <asm/segment.h>
16#include <asm/page_types.h>
17#include <asm/pgtable_types.h>
18#include <asm/cache.h>
19#include <asm/thread_info.h>
20#include <asm/asm-offsets.h>
21#include <asm/setup.h>
22#include <asm/processor-flags.h>
23#include <asm/msr-index.h>
24#include <asm/cpufeatures.h>
25#include <asm/percpu.h>
26#include <asm/nops.h>
27#include <asm/nospec-branch.h>
28#include <asm/bootparam.h>
29#include <asm/pgtable_32.h>
30
31/* Physical address */
32#define pa(X) ((X) - __PAGE_OFFSET)
33
34/*
35 * References to members of the new_cpu_data structure.
36 */
37
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
46
47
48#define SIZEOF_PTREGS 17*4
49
50/*
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.
54 */
55KERNEL_PAGES = LOWMEM_PAGES
56
57INIT_MAP_SIZE = PAGE_TABLE_SIZE(KERNEL_PAGES) * PAGE_SIZE
58RESERVE_BRK(pagetables, INIT_MAP_SIZE)
59
60/*
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
65 * can.
66 */
67__HEAD
68SYM_CODE_START(startup_32)
69	movl pa(initial_stack),%ecx
70
71/*
72 * Set segments to known values.
73 */
74	lgdt pa(boot_gdt_descr)
75	movl $(__BOOT_DS),%eax
76	movl %eax,%ds
77	movl %eax,%es
78	movl %eax,%fs
79	movl %eax,%gs
80	movl %eax,%ss
81	leal -__PAGE_OFFSET(%ecx),%esp
82
83/*
84 * Clear BSS first so that there are no surprises...
85 */
86	cld
87	xorl %eax,%eax
88	movl $pa(__bss_start),%edi
89	movl $pa(__bss_stop),%ecx
90	subl %edi,%ecx
91	shrl $2,%ecx
92	rep ; stosl
93/*
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
99 * page tables.
100 */
101	movl $pa(boot_params),%edi
102	movl $(PARAM_SIZE/4),%ecx
103	cld
104	rep
105	movsl
106	movl pa(boot_params) + NEW_CL_POINTER,%esi
107	andl %esi,%esi
108	jz 1f			# No command line
109	movl $pa(boot_command_line),%edi
110	movl $(COMMAND_LINE_SIZE/4),%ecx
111	rep
112	movsl
1131:
114
115#ifdef CONFIG_OLPC
116	/* save OFW's pgdir table for later use when calling into OFW */
117	movl %cr3, %eax
118	movl %eax, pa(olpc_ofw_pgd)
119#endif
120
121	/* Create early pagetables. */
122	call  mk_early_pgtbl_32
123
124	/* Do early initialization of the fixmap area */
125	movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax
126#ifdef  CONFIG_X86_PAE
127#define KPMDS (((-__PAGE_OFFSET) >> 30) & 3) /* Number of kernel PMDs */
128	movl %eax,pa(initial_pg_pmd+0x1000*KPMDS-8)
129#else
130	movl %eax,pa(initial_page_table+0xffc)
131#endif
132
133	jmp .Ldefault_entry
134SYM_CODE_END(startup_32)
135
136/*
137 * Non-boot CPU entry point; entered from trampoline.S
138 * We can't lgdt here, because lgdt itself uses a data segment, but
139 * we know the trampoline has already loaded the boot_gdt for us.
140 *
141 * If cpu hotplug is not supported then this code can go in init section
142 * which will be freed later
143 */
144SYM_FUNC_START(startup_32_smp)
145	cld
146	movl $(__BOOT_DS),%eax
147	movl %eax,%ds
148	movl %eax,%es
149	movl %eax,%fs
150	movl %eax,%gs
151	movl pa(initial_stack),%ecx
152	movl %eax,%ss
153	leal -__PAGE_OFFSET(%ecx),%esp
154
155.Ldefault_entry:
156	movl $(CR0_STATE & ~X86_CR0_PG),%eax
157	movl %eax,%cr0
158
159/*
160 * We want to start out with EFLAGS unambiguously cleared. Some BIOSes leave
161 * bits like NT set. This would confuse the debugger if this code is traced. So
162 * initialize them properly now before switching to protected mode. That means
163 * DF in particular (even though we have cleared it earlier after copying the
164 * command line) because GCC expects it.
165 */
166	pushl $0
167	popfl
168
169/*
170 * New page tables may be in 4Mbyte page mode and may be using the global pages.
171 *
172 * NOTE! If we are on a 486 we may have no cr4 at all! Specifically, cr4 exists
173 * if and only if CPUID exists and has flags other than the FPU flag set.
174 */
175	movl $-1,pa(X86_CPUID)		# preset CPUID level
176	movl $X86_EFLAGS_ID,%ecx
177	pushl %ecx
178	popfl				# set EFLAGS=ID
179	pushfl
180	popl %eax			# get EFLAGS
181	testl $X86_EFLAGS_ID,%eax	# did EFLAGS.ID remained set?
182	jz .Lenable_paging		# hw disallowed setting of ID bit
183					# which means no CPUID and no CR4
184
185	xorl %eax,%eax
186	cpuid
187	movl %eax,pa(X86_CPUID)		# save largest std CPUID function
188
189	movl $1,%eax
190	cpuid
191	andl $~1,%edx			# Ignore CPUID.FPU
192	jz .Lenable_paging		# No flags or only CPUID.FPU = no CR4
193
194	movl pa(mmu_cr4_features),%eax
195	movl %eax,%cr4
196
197	testb $X86_CR4_PAE, %al		# check if PAE is enabled
198	jz .Lenable_paging
199
200	/* Check if extended functions are implemented */
201	movl $0x80000000, %eax
202	cpuid
203	/* Value must be in the range 0x80000001 to 0x8000ffff */
204	subl $0x80000001, %eax
205	cmpl $(0x8000ffff-0x80000001), %eax
206	ja .Lenable_paging
207
208	/* Clear bogus XD_DISABLE bits */
209	call verify_cpu
210
211	mov $0x80000001, %eax
212	cpuid
213	/* Execute Disable bit supported? */
214	btl $(X86_FEATURE_NX & 31), %edx
215	jnc .Lenable_paging
216
217	/* Setup EFER (Extended Feature Enable Register) */
218	movl $MSR_EFER, %ecx
219	rdmsr
220
221	btsl $_EFER_NX, %eax
222	/* Make changes effective */
223	wrmsr
224
225.Lenable_paging:
226
227/*
228 * Enable paging
229 */
230	movl $pa(initial_page_table), %eax
231	movl %eax,%cr3		/* set the page table pointer.. */
232	movl $CR0_STATE,%eax
233	movl %eax,%cr0		/* ..and set paging (PG) bit */
234	ljmp $__BOOT_CS,$1f	/* Clear prefetch and normalize %eip */
2351:
236	/* Shift the stack pointer to a virtual address */
237	addl $__PAGE_OFFSET, %esp
238
239/*
240 * Check if it is 486
241 */
242	movb $4,X86			# at least 486
243	cmpl $-1,X86_CPUID
244	je .Lis486
245
246	/* get vendor info */
247	xorl %eax,%eax			# call CPUID with 0 -> return vendor ID
248	cpuid
249	movl %eax,X86_CPUID		# save CPUID level
250	movl %ebx,X86_VENDOR_ID		# lo 4 chars
251	movl %edx,X86_VENDOR_ID+4	# next 4 chars
252	movl %ecx,X86_VENDOR_ID+8	# last 4 chars
253
254	orl %eax,%eax			# do we have processor info as well?
255	je .Lis486
256
257	movl $1,%eax		# Use the CPUID instruction to get CPU type
258	cpuid
259	movb %al,%cl		# save reg for future use
260	andb $0x0f,%ah		# mask processor family
261	movb %ah,X86
262	andb $0xf0,%al		# mask model
263	shrb $4,%al
264	movb %al,X86_MODEL
265	andb $0x0f,%cl		# mask mask revision
266	movb %cl,X86_STEPPING
267	movl %edx,X86_CAPABILITY
268
269.Lis486:
270	movl $0x50022,%ecx	# set AM, WP, NE and MP
271	movl %cr0,%eax
272	andl $0x80000011,%eax	# Save PG,PE,ET
273	orl %ecx,%eax
274	movl %eax,%cr0
275
276	lgdt early_gdt_descr
277	ljmp $(__KERNEL_CS),$1f
2781:	movl $(__KERNEL_DS),%eax	# reload all the segment registers
279	movl %eax,%ss			# after changing gdt.
280
281	movl $(__USER_DS),%eax		# DS/ES contains default USER segment
282	movl %eax,%ds
283	movl %eax,%es
284
285	movl $(__KERNEL_PERCPU), %eax
286	movl %eax,%fs			# set this cpu's percpu
287
288	xorl %eax,%eax
289	movl %eax,%gs			# clear possible garbage in %gs
290
291	xorl %eax,%eax			# Clear LDT
292	lldt %ax
293
294	call *(initial_code)
2951:	jmp 1b
296SYM_FUNC_END(startup_32_smp)
297
298#include "verify_cpu.S"
299
300__INIT
301SYM_FUNC_START(early_idt_handler_array)
302	# 36(%esp) %eflags
303	# 32(%esp) %cs
304	# 28(%esp) %eip
305	# 24(%rsp) error code
306	i = 0
307	.rept NUM_EXCEPTION_VECTORS
308	.if ((EXCEPTION_ERRCODE_MASK >> i) & 1) == 0
309	pushl $0		# Dummy error code, to make stack frame uniform
310	.endif
311	pushl $i		# 20(%esp) Vector number
312	jmp early_idt_handler_common
313	i = i + 1
314	.fill early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc
315	.endr
316SYM_FUNC_END(early_idt_handler_array)
317
318SYM_CODE_START_LOCAL(early_idt_handler_common)
319	/*
320	 * The stack is the hardware frame, an error code or zero, and the
321	 * vector number.
322	 */
323	cld
324
325	incl %ss:early_recursion_flag
326
327	/* The vector number is in pt_regs->gs */
328
329	cld
330	pushl	%fs		/* pt_regs->fs (__fsh varies by model) */
331	pushl	%es		/* pt_regs->es (__esh varies by model) */
332	pushl	%ds		/* pt_regs->ds (__dsh varies by model) */
333	pushl	%eax		/* pt_regs->ax */
334	pushl	%ebp		/* pt_regs->bp */
335	pushl	%edi		/* pt_regs->di */
336	pushl	%esi		/* pt_regs->si */
337	pushl	%edx		/* pt_regs->dx */
338	pushl	%ecx		/* pt_regs->cx */
339	pushl	%ebx		/* pt_regs->bx */
340
341	/* Fix up DS and ES */
342	movl	$(__KERNEL_DS), %ecx
343	movl	%ecx, %ds
344	movl	%ecx, %es
345
346	/* Load the vector number into EDX */
347	movl	PT_GS(%esp), %edx
348
349	/* Load GS into pt_regs->gs (and maybe clobber __gsh) */
350	movw	%gs, PT_GS(%esp)
351
352	movl	%esp, %eax	/* args are pt_regs (EAX), trapnr (EDX) */
353	call	early_fixup_exception
354
355	popl	%ebx		/* pt_regs->bx */
356	popl	%ecx		/* pt_regs->cx */
357	popl	%edx		/* pt_regs->dx */
358	popl	%esi		/* pt_regs->si */
359	popl	%edi		/* pt_regs->di */
360	popl	%ebp		/* pt_regs->bp */
361	popl	%eax		/* pt_regs->ax */
362	popl	%ds		/* pt_regs->ds (always ignores __dsh) */
363	popl	%es		/* pt_regs->es (always ignores __esh) */
364	popl	%fs		/* pt_regs->fs (always ignores __fsh) */
365	popl	%gs		/* pt_regs->gs (always ignores __gsh) */
366	decl	%ss:early_recursion_flag
367	addl	$4, %esp	/* pop pt_regs->orig_ax */
368	iret
369SYM_CODE_END(early_idt_handler_common)
370
371/* This is the default interrupt "handler" :-) */
372SYM_FUNC_START(early_ignore_irq)
373	cld
374#ifdef CONFIG_PRINTK
375	pushl %eax
376	pushl %ecx
377	pushl %edx
378	pushl %es
379	pushl %ds
380	movl $(__KERNEL_DS),%eax
381	movl %eax,%ds
382	movl %eax,%es
383	cmpl $2,early_recursion_flag
384	je hlt_loop
385	incl early_recursion_flag
386	pushl 16(%esp)
387	pushl 24(%esp)
388	pushl 32(%esp)
389	pushl 40(%esp)
390	pushl $int_msg
391	call _printk
392
393	call dump_stack
394
395	addl $(5*4),%esp
396	popl %ds
397	popl %es
398	popl %edx
399	popl %ecx
400	popl %eax
401#endif
402	iret
403
404hlt_loop:
405	hlt
406	jmp hlt_loop
407SYM_FUNC_END(early_ignore_irq)
408
409__INITDATA
410	.align 4
411SYM_DATA(early_recursion_flag, .long 0)
412
413__REFDATA
414	.align 4
415SYM_DATA(initial_code,		.long i386_start_kernel)
416
417#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
418#define	PGD_ALIGN	(2 * PAGE_SIZE)
419#define PTI_USER_PGD_FILL	1024
420#else
421#define	PGD_ALIGN	(PAGE_SIZE)
422#define PTI_USER_PGD_FILL	0
423#endif
424/*
425 * BSS section
426 */
427__PAGE_ALIGNED_BSS
428	.align PGD_ALIGN
429#ifdef CONFIG_X86_PAE
430.globl initial_pg_pmd
431initial_pg_pmd:
432	.fill 1024*KPMDS,4,0
433#else
434.globl initial_page_table
435initial_page_table:
436	.fill 1024,4,0
437#endif
438	.align PGD_ALIGN
439initial_pg_fixmap:
440	.fill 1024,4,0
441.globl swapper_pg_dir
442	.align PGD_ALIGN
443swapper_pg_dir:
444	.fill 1024,4,0
445	.fill PTI_USER_PGD_FILL,4,0
446.globl empty_zero_page
447empty_zero_page:
448	.fill 4096,1,0
449EXPORT_SYMBOL(empty_zero_page)
450
451/*
452 * This starts the data section.
453 */
454#ifdef CONFIG_X86_PAE
455__PAGE_ALIGNED_DATA
456	/* Page-aligned for the benefit of paravirt? */
457	.align PGD_ALIGN
458SYM_DATA_START(initial_page_table)
459	.long	pa(initial_pg_pmd+PGD_IDENT_ATTR),0	/* low identity map */
460# if KPMDS == 3
461	.long	pa(initial_pg_pmd+PGD_IDENT_ATTR),0
462	.long	pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0
463	.long	pa(initial_pg_pmd+PGD_IDENT_ATTR+0x2000),0
464# elif KPMDS == 2
465	.long	0,0
466	.long	pa(initial_pg_pmd+PGD_IDENT_ATTR),0
467	.long	pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0
468# elif KPMDS == 1
469	.long	0,0
470	.long	0,0
471	.long	pa(initial_pg_pmd+PGD_IDENT_ATTR),0
472# else
473#  error "Kernel PMDs should be 1, 2 or 3"
474# endif
475	.align PAGE_SIZE		/* needs to be page-sized too */
476
477#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
478	/*
479	 * PTI needs another page so sync_initial_pagetable() works correctly
480	 * and does not scribble over the data which is placed behind the
481	 * actual initial_page_table. See clone_pgd_range().
482	 */
483	.fill 1024, 4, 0
484#endif
485
486SYM_DATA_END(initial_page_table)
487#endif
488
489.data
490.balign 4
491/*
492 * The SIZEOF_PTREGS gap is a convention which helps the in-kernel unwinder
493 * reliably detect the end of the stack.
494 */
495SYM_DATA(initial_stack,
496		.long init_thread_union + THREAD_SIZE -
497		SIZEOF_PTREGS - TOP_OF_KERNEL_STACK_PADDING)
498
499__INITRODATA
500int_msg:
501	.asciz "Unknown interrupt or fault at: %p %p %p\n"
502
503#include "../../x86/xen/xen-head.S"
504
505/*
506 * The IDT and GDT 'descriptors' are a strange 48-bit object
507 * only used by the lidt and lgdt instructions. They are not
508 * like usual segment descriptors - they consist of a 16-bit
509 * segment size, and 32-bit linear address value:
510 */
511
512	.data
513	ALIGN
514# early boot GDT descriptor (must use 1:1 address mapping)
515	.word 0				# 32 bit align gdt_desc.address
516SYM_DATA_START_LOCAL(boot_gdt_descr)
517	.word __BOOT_DS+7
518	.long boot_gdt - __PAGE_OFFSET
519SYM_DATA_END(boot_gdt_descr)
520
521# boot GDT descriptor (later on used by CPU#0):
522	.word 0				# 32 bit align gdt_desc.address
523SYM_DATA_START(early_gdt_descr)
524	.word GDT_ENTRIES*8-1
525	.long gdt_page			/* Overwritten for secondary CPUs */
526SYM_DATA_END(early_gdt_descr)
527
528/*
529 * The boot_gdt must mirror the equivalent in setup.S and is
530 * used only for booting.
531 */
532	.align L1_CACHE_BYTES
533SYM_DATA_START(boot_gdt)
534	.fill GDT_ENTRY_BOOT_CS,8,0
535	.quad 0x00cf9a000000ffff	/* kernel 4GB code at 0x00000000 */
536	.quad 0x00cf92000000ffff	/* kernel 4GB data at 0x00000000 */
537SYM_DATA_END(boot_gdt)
538