Context Navigation

hal_boot.S @ 35

Last change on this file since 35 was 32, checked in by max@…, 7 years ago
Update. Retrieve and parse the multiboot info, and dump the mmap. Some more sanity checks could probably be added.
File size: 11.7 KB

Rev	Line
[25]	1	/*
	2	* hal_boot.S - Kernel boot entry point
	3	*
[29]	4	* Copyright (c) 2017 Maxime Villard
	5	* This code is inspired a lot from the NetBSD boot procedure, written by
	6	* Maxime Villard too. XXX copyright
[25]	7	*
[29]	8	* This file is part of ALMOS-MKH.
[25]	9	*
[29]	10	* ALMOS-MKH is free software; you can redistribute it and/or modify it
[25]	11	* under the terms of the GNU General Public License as published by
	12	* the Free Software Foundation; version 2.0 of the License.
	13	*
[29]	14	* ALMOS-MKH is distributed in the hope that it will be useful, but
[25]	15	* WITHOUT ANY WARRANTY; without even the implied warranty of
	16	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	17	* General Public License for more details.
	18	*
	19	* You should have received a copy of the GNU General Public License
[29]	20	* along with ALMOS-MKH.; if not, write to the Free Software Foundation,
[25]	21	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
	22	*/
	23
[29]	24	#define x86_ASM
[25]	25	#include <hal_boot.h>
[32]	26	#include <hal_multiboot.h>
[25]	27	#include <hal_register.h>
	28	#include <hal_segmentation.h>
	29
	30	#define MULTIBOOT_HEADER_MAGIC 0x1BADB002
	31	#define MULTIBOOT_HEADER_FLAGS 0x00000000
	32	#define MULTIBOOT_INFO_MAGIC 0x2BADB002
	33	#define CHECKSUM -(MULTIBOOT_HEADER_MAGIC + MULTIBOOT_HEADER_FLAGS)
	34
	35	#if L2_SLOT_KERNBASE > 0
	36	#define TABLE_L2_ENTRIES (2 * (NKL2_KIMG_ENTRIES + 1))
	37	#else
	38	#define TABLE_L2_ENTRIES (NKL2_KIMG_ENTRIES + 1)
	39	#endif
	40
	41	#if L3_SLOT_KERNBASE > 0
	42	#define TABLE_L3_ENTRIES (2 * NKL3_KIMG_ENTRIES)
	43	#else
	44	#define TABLE_L3_ENTRIES NKL3_KIMG_ENTRIES
	45	#endif
	46
	47	#define PROC0_PML4_OFF 0
	48	#define PROC0_STK_OFF (PROC0_PML4_OFF + 1 * PAGE_SIZE)
	49	#define PROC0_PTP3_OFF (PROC0_STK_OFF + STKPAGES * PAGE_SIZE)
	50	#define PROC0_PTP2_OFF (PROC0_PTP3_OFF + NKL4_KIMG_ENTRIES * PAGE_SIZE)
	51	#define PROC0_PTP1_OFF (PROC0_PTP2_OFF + TABLE_L3_ENTRIES * PAGE_SIZE)
	52	#define TABLESIZE \
	53	((NKL4_KIMG_ENTRIES + TABLE_L3_ENTRIES + TABLE_L2_ENTRIES + 1 + STKPAGES) \
	54	* PAGE_SIZE)
	55
	56	/*
	57	* fillkpt - Fill in a kernel page table
	58	* eax = pte (page frame \| control \| status)
	59	* ebx = page table address
	60	* ecx = number of pages to map
	61	*
	62	* Each entry is 8 (PDE_SIZE) bytes long: we must set the 4 upper bytes to 0.
	63	*/
	64	#define fillkpt \
	65	cmpl $0,%ecx ; /* zero-sized? */ \
	66	je 2f ; \
	67	1: movl $0,(PDE_SIZE-4)(%ebx) ; /* upper 32 bits: 0 */ \
	68	movl %eax,(%ebx) ; /* store phys addr */ \
	69	addl $PDE_SIZE,%ebx ; /* next PTE/PDE */ \
	70	addl $PAGE_SIZE,%eax ; /* next phys page */ \
	71	loop 1b ; \
	72	2: ;
	73
	74	/*
	75	* fillkpt_nox - Same as fillkpt, but sets the NX/XD bit.
	76	*/
	77	#define fillkpt_nox \
	78	cmpl $0,%ecx ; /* zero-sized? */ \
	79	je 2f ; \
	80	1: movl $PG_NX32,(PDE_SIZE-4)(%ebx); /* upper 32 bits: NX */ \
	81	movl %eax,(%ebx) ; /* store phys addr */ \
	82	addl $PDE_SIZE,%ebx ; /* next PTE/PDE */ \
	83	addl $PAGE_SIZE,%eax ; /* next phys page */ \
	84	loop 1b ; \
	85	2: ;
	86
	87	/*
	88	* fillkpt_blank - Fill in a kernel page table with blank entries
	89	* ebx = page table address
	90	* ecx = number of pages to map
	91	*/
	92	#define fillkpt_blank \
	93	cmpl $0,%ecx ; /* zero-sized? */ \
	94	je 2f ; \
	95	1: movl $0,(PDE_SIZE-4)(%ebx) ; /* upper 32 bits: 0 */ \
	96	movl $0,(%ebx) ; /* lower 32 bits: 0 */ \
	97	addl $PDE_SIZE,%ebx ; /* next PTE/PDE */ \
	98	loop 1b ; \
	99	2: ;
	100
[29]	101	/*
	102	* killkpt - Destroy a kernel page table (long mode)
	103	* rbx = page table address
	104	* rcx = number of pages to destroy
	105	*/
	106	#define killkpt \
	107	1: movq $0,(%rbx) ; \
	108	addq $PDE_SIZE,%rbx ; \
	109	loop 1b ;
	110
[25]	111	/* 32bit version of PG_NX */
	112	#define PG_NX32 0x80000000
	113
	114	#define RELOC(x) ((x) - KERNBASE)
	115
	116	.globl start_x86_64
	117	.globl L4paddr
[29]	118	.globl iom_base
[25]	119
	120	/*
	121	* The multiboot header
	122	*/
	123	.section .boot,"ax",@progbits
	124	multiboot_header:
	125	.align 4
	126	.long MULTIBOOT_HEADER_MAGIC
	127	.long MULTIBOOT_HEADER_FLAGS
	128	.long CHECKSUM
	129
	130	/*
	131	* The variables used in the boot procedure.
	132	*/
	133	.section .data
	134	.align 4
	135
	136	.type L4paddr, @object
	137	L4paddr: .quad 0 /* paddr of L4 */
	138
[29]	139	.type iom_base, @object
	140	iom_base: .quad 0 /* virt. addr. of ISA I/O MEM */
	141
	142
[25]	143	#define GDT64_LIMIT gdt64_end-gdt64_start-1
	144	/* Temporary gdt64, with base address in low memory */
	145	.type gdt64_lo, @object
	146	gdt64_lo:
	147	.word GDT64_LIMIT
	148	.quad RELOC(gdt64_start)
	149	.align 64
	150
	151	/* Temporary gdt64, with base address in high memory */
	152	.type gdt64_hi, @object
	153	gdt64_hi:
	154	.word GDT64_LIMIT
	155	.quad gdt64_start
	156	.align 64
	157	#undef GDT64_LIMIT
	158
	159	.type gdt64_start, @object
	160	gdt64_start:
	161	.quad 0x0000000000000000 /* always empty */
	162	.quad 0x00af9a000000ffff /* kernel CS */
	163	.quad 0x00cf92000000ffff /* kernel DS */
	164	gdt64_end:
	165
	166	.type farjmp64, @object
	167	farjmp64:
	168	.long RELOC(longmode)
[29]	169	.word GDT_FIXED_SEL(GDT_KCODE_SEL, SEL_KPL)
[25]	170	.align 64
	171
	172	/* Space for the temporary stack */
	173	.size tmpstk, tmpstk - .
	174	.space 512
	175	tmpstk:
	176
	177	.text
	178
	179	start_x86_64:
	180	.code32
	181
	182	/* Warm boot */
	183	movw $0x1234,0x472
[32]	184	cld
[25]	185
	186	/* Make sure it is a multiboot-compliant bootloader. */
[32]	187	cmpl $MULTIBOOT_INFO_MAGIC,%eax
	188	je 1f
	189	ret /* what to do? */
	190	1:
[25]	191
	192	movl $RELOC(tmpstk),%esp
	193
	194	/* Reset the PSL. */
	195	pushl $PSL_MBO
	196	popfl
	197
[32]	198	/*
	199	* Copy the various multiboot structures
	200	*/
	201	movl %ebx,%esi /* src */
	202	movl $RELOC(mb_info),%edi /* dst */
	203	movl $MULTIBOOT_INFO_SIZE,%ecx /* len */
	204	rep
	205	movsb /* copy esi -> edi */
	206
	207	testl $MULTIBOOT_INFO_HAS_LOADER_NAME,MB_MI_FLAGS(%ebx)
	208	jz 1f
	209	movl MB_MI_LOADER_NAME(%ebx),%esi /* src */
	210	movl $RELOC(mb_loader_name),%edi /* dst */
	211	copy_loop:
	212	cmpb $0,(%esi)
	213	je copy_end
	214	movsb /* copy esi -> edi */
	215	jmp copy_loop
	216	copy_end:
	217	movsb /* copy esi -> edi */
	218	1:
	219
	220	testl $MULTIBOOT_INFO_HAS_MMAP,MB_MI_FLAGS(%ebx)
	221	jz 1f
	222	movl MB_MI_MMAP_ADDR(%ebx),%esi /* src */
	223	movl $RELOC(mb_mmap),%edi /* dst */
	224	movl MB_MI_MMAP_LENGTH(%ebx),%ecx /* len */
	225
	226	rep
	227	movsb /* copy esi -> edi */
	228	1:
	229
[25]	230	/*
	231	* There are four levels of pages in amd64: PML4 -> PDP -> PD -> PT. They will
	232	* be referred to as: L4 -> L3 -> L2 -> L1.
	233	*
	234	* Virtual address space of the kernel:
[32]	235	* +---------------+------+-----------------------------------+-------------+
	236	* \| TEXT + RODATA \| DATA \| L4 -> PROC0 STK -> L3 -> L2 -> L1 \| ISA I/O MEM \|
	237	* +---------------+------+-----------------------------------+-------------+
	238	* (1) (2)
[25]	239	*
	240	* PROC0 STK is obviously not linked as a page level. It just happens to be
	241	* caught between L4 and L3.
	242	*
	243	* (PROC0 STK + L4 + L3 + L2 + L1) is later referred to as BOOTSTRAP TABLES.
	244	*
	245	* ISA I/O MEM has no physical page allocated here, just virtual addresses.
	246	*
	247	* Important note: the kernel segments are properly 4k-aligned
[32]	248	* (see kernel_x86.ld), so there's no need to enforce alignment.
[25]	249	*/
	250
	251	/* Find end of kernel image; brings us on (1). */
	252	movl $RELOC(__kernel_end),%edi
	253
	254	/* Align up for BOOTSTRAP TABLES. */
	255	movl %edi,%esi
	256	addl $PGOFSET,%esi
	257	andl $~PGOFSET,%esi
	258
	259	/* We are on the BOOTSTRAP TABLES. Save L4's physical address. */
	260	movl $RELOC(L4paddr),%ebp
	261	movl %esi,(%ebp)
	262	movl $0,4(%ebp)
	263
	264	/* Now, zero out the BOOTSTRAP TABLES (before filling them in). */
	265	movl %esi,%edi
	266	xorl %eax,%eax
	267	cld
	268	movl $TABLESIZE,%ecx
	269	shrl $2,%ecx
	270	rep
	271	stosl /* copy eax -> edi */
	272
	273	/*
	274	* Build the page tables and levels. We go from L1 to L4, and link the levels
	275	* together. Note: RELOC computes &addr - KERNBASE in 32 bits; the value can't
	276	* be > 4G, or we can't deal with it anyway, since we are in 32bit mode.
	277	*/
	278	/*
	279	* Build L1.
	280	*/
	281	leal (PROC0_PTP1_OFF)(%esi),%ebx
	282
	283	/* Skip the area below the kernel text. */
	284	movl $(KERNTEXTOFF_LO - KERNBASE_LO),%ecx
	285	shrl $PGSHIFT,%ecx
	286	fillkpt_blank
	287
	288	/* Map the kernel code RX. */
	289	movl $(KERNTEXTOFF_LO - KERNBASE_LO),%eax /* start of TEXT */
	290	movl $RELOC(__kernel_data_start),%ecx
	291	subl %eax,%ecx
	292	shrl $PGSHIFT,%ecx
[29]	293	orl $(PG_V\|PG_KR\|PG_G),%eax
[25]	294	fillkpt
	295
	296	/* Map the kernel data RW. */
	297	movl $RELOC(__kernel_data_start),%eax
	298	movl $RELOC(__kernel_end),%ecx
	299	subl %eax,%ecx
	300	shrl $PGSHIFT,%ecx
[29]	301	orl $(PG_V\|PG_KW\|PG_G),%eax
[25]	302	fillkpt_nox
	303
	304	/* Map the BOOTSTRAP TABLES RW. */
	305	movl $RELOC(__kernel_end),%eax /* start of BOOTSTRAP TABLES */
	306	movl $TABLESIZE,%ecx /* length of BOOTSTRAP TABLES */
	307	shrl $PGSHIFT,%ecx
[29]	308	orl $(PG_V\|PG_KW\|PG_G),%eax
[25]	309	fillkpt_nox
	310
	311	/* We are on (2). Map ISA I/O MEM RW. */
	312	movl $IOM_BEGIN,%eax
	313	movl $IOM_SIZE,%ecx /* size of ISA I/O MEM */
	314	shrl $PGSHIFT,%ecx
[29]	315	orl $(PG_V\|PG_KW\|PG_G),%eax
[25]	316	fillkpt_nox
	317
	318	/*
	319	* Build L2. Linked to L1.
	320	*/
	321	leal (PROC0_PTP2_OFF)(%esi),%ebx
	322	leal (PROC0_PTP1_OFF)(%esi),%eax
	323	orl $(PG_V\|PG_KW),%eax
	324	movl $(NKL2_KIMG_ENTRIES+1),%ecx
	325	fillkpt
	326
	327	#if L2_SLOT_KERNBASE > 0
	328	/* If needed, set up level 2 entries for actual kernel mapping */
	329	leal (PROC0_PTP2_OFF + L2_SLOT_KERNBASE * PDE_SIZE)(%esi),%ebx
	330	leal (PROC0_PTP1_OFF)(%esi),%eax
	331	orl $(PG_V\|PG_KW),%eax
	332	movl $(NKL2_KIMG_ENTRIES+1),%ecx
	333	fillkpt
	334	#endif
	335
	336	/*
	337	* Build L3. Linked to L2.
	338	*/
	339	leal (PROC0_PTP3_OFF)(%esi),%ebx
	340	leal (PROC0_PTP2_OFF)(%esi),%eax
	341	orl $(PG_V\|PG_KW),%eax
	342	movl $NKL3_KIMG_ENTRIES,%ecx
	343	fillkpt
	344
	345	#if L3_SLOT_KERNBASE > 0
	346	/* If needed, set up level 3 entries for actual kernel mapping */
	347	leal (PROC0_PTP3_OFF + L3_SLOT_KERNBASE * PDE_SIZE)(%esi),%ebx
	348	leal (PROC0_PTP2_OFF)(%esi),%eax
	349	orl $(PG_V\|PG_KW),%eax
	350	movl $NKL3_KIMG_ENTRIES,%ecx
	351	fillkpt
	352	#endif
	353
	354	/*
	355	* Build L4 for identity mapping. Linked to L3.
	356	*/
	357	leal (PROC0_PML4_OFF)(%esi),%ebx
	358	leal (PROC0_PTP3_OFF)(%esi),%eax
	359	orl $(PG_V\|PG_KW),%eax
	360	movl $NKL4_KIMG_ENTRIES,%ecx
	361	fillkpt
	362
	363	/* Set up L4 entries for actual kernel mapping */
	364	leal (PROC0_PML4_OFF + L4_SLOT_KERNBASE * PDE_SIZE)(%esi),%ebx
	365	leal (PROC0_PTP3_OFF)(%esi),%eax
	366	orl $(PG_V\|PG_KW),%eax
	367	movl $NKL4_KIMG_ENTRIES,%ecx
	368	fillkpt
	369
	370	/* Install recursive top level PDE (one entry) */
	371	leal (PROC0_PML4_OFF + PDIR_SLOT_PTE * PDE_SIZE)(%esi),%ebx
	372	leal (PROC0_PML4_OFF)(%esi),%eax
	373	orl $(PG_V\|PG_KW),%eax
	374	movl $1,%ecx
	375	fillkpt_nox
	376
	377	/*
	378	* Startup checklist:
	379	* 1. Enable PAE (and SSE while here).
	380	*/
	381	movl %cr4,%eax
[29]	382	orl $(CR4_PAE\|CR4_OSFXSR\|CR4_OSXMMEXCPT\|CR4_PGE),%eax
[25]	383	movl %eax,%cr4
	384
	385	/*
	386	* 2. Set Long Mode Enable in EFER. Also enable the syscall extensions,
	387	* and NOX.
	388	*/
	389	movl $MSR_EFER,%ecx
	390	rdmsr
	391	xorl %eax,%eax /* XXX */
	392	orl $(EFER_LME\|EFER_SCE\|EFER_NXE),%eax
	393	wrmsr
	394
	395	/*
	396	* 3. Load %cr3 with pointer to PML4.
	397	*/
	398	movl %esi,%eax
	399	movl %eax,%cr3
	400
	401	/*
	402	* 4. Enable paging and the rest of it.
	403	*/
	404	movl %cr0,%eax
	405	orl $(CR0_PE\|CR0_PG\|CR0_NE\|CR0_TS\|CR0_MP\|CR0_WP\|CR0_AM),%eax
	406	movl %eax,%cr0
	407	jmp compat
	408	compat:
	409
	410	/*
	411	* 5. Not quite done yet, we're now in a compatibility segment, in
	412	* legacy mode. We must jump to a long mode segment. Need to set up
	413	* a temporary GDT with a long mode segment in it to do that.
	414	*/
	415	movl $RELOC(gdt64_lo),%eax
	416	lgdt (%eax)
	417	movl $RELOC(farjmp64),%eax
	418	ljmp *(%eax)
	419
	420	.code64
	421	longmode:
	422	/*
	423	* 6. Finally, we're in long mode. However, we're still in the identity
	424	* mapped area (could not jump out of that earlier because it would
	425	* have been a > 32bit jump). We can do that now, so here we go.
	426	*/
	427	movabsq $longmode_hi,%rax
[29]	428	jmp *%rax
[25]	429
	430	longmode_hi:
	431	/*
	432	* We left the identity mapped area. Base address of
	433	* the temporary gdt64 should now be in high memory.
	434	*/
	435	movq $RELOC(gdt64_hi),%rax
	436	lgdt (%rax)
	437
	438	/*
	439	* We have arrived. There's no need anymore for the identity mapping in
	440	* low memory, remove it.
	441	*/
	442	movq $KERNBASE,%r8
	443
[29]	444	#if L2_SLOT_KERNBASE > 0
	445	movq $(NKL2_KIMG_ENTRIES+1),%rcx
	446	leaq (PROC0_PTP2_OFF)(%rsi),%rbx /* old, phys address */
	447	addq %r8,%rbx /* new, virt address */
	448	killkpt
	449	#endif
[25]	450
[29]	451	#if L3_SLOT_KERNBASE > 0
	452	movq $NKL3_KIMG_ENTRIES,%rcx
	453	leaq (PROC0_PTP3_OFF)(%rsi),%rbx /* old, phys address */
	454	addq %r8,%rbx /* new, virt address */
	455	killkpt
	456	#endif
[25]	457
[29]	458	movq $NKL4_KIMG_ENTRIES,%rcx
	459	leaq (PROC0_PML4_OFF)(%rsi),%rbx /* old, phys address of PML4 */
	460	addq %r8,%rbx /* new, virt address of PML4 */
	461	killkpt
[25]	462
[32]	463	/* Save the virtual address of ISA I/O MEM. */
[29]	464	movq $(TABLESIZE+KERNBASE),%rdx
	465	addq %rsi,%rdx
	466	movq %rdx,iom_base(%rip)
[25]	467
[29]	468	/* Set up bootstrap stack. */
	469	leaq (PROC0_STK_OFF)(%rsi),%rax
	470	addq %r8,%rax
	471	leaq (STKSIZE)(%rax),%rsp
	472	xorq %rbp,%rbp /* mark end of frames */
	473
	474	xorw %ax,%ax
	475	movw %ax,%gs
	476	movw %ax,%fs
	477
	478	/* The first physical page available. */
	479	leaq (TABLESIZE)(%rsi),%rdi
	480
	481	call init_x86_64
	482

Note: See TracBrowser for help on using the repository browser.

Download in other formats:

Original Format