summaryrefslogtreecommitdiffstats
path: root/arch/s390/boot/startup.c
blob: de264a20b132b12aee58b5226082c21e07bd1929 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
// SPDX-License-Identifier: GPL-2.0
#include <linux/string.h>
#include <linux/elf.h>
#include <asm/boot_data.h>
#include <asm/sections.h>
#include <asm/maccess.h>
#include <asm/cpu_mf.h>
#include <asm/setup.h>
#include <asm/kasan.h>
#include <asm/kexec.h>
#include <asm/sclp.h>
#include <asm/diag.h>
#include <asm/uv.h>
#include <asm/abs_lowcore.h>
#include <asm/physmem_info.h>
#include "decompressor.h"
#include "boot.h"
#include "uv.h"

unsigned long __bootdata_preserved(__kaslr_offset);
unsigned long __bootdata_preserved(__abs_lowcore);
unsigned long __bootdata_preserved(__memcpy_real_area);
pte_t *__bootdata_preserved(memcpy_real_ptep);
unsigned long __bootdata_preserved(VMALLOC_START);
unsigned long __bootdata_preserved(VMALLOC_END);
struct page *__bootdata_preserved(vmemmap);
unsigned long __bootdata_preserved(vmemmap_size);
unsigned long __bootdata_preserved(MODULES_VADDR);
unsigned long __bootdata_preserved(MODULES_END);
unsigned long __bootdata(ident_map_size);

u64 __bootdata_preserved(stfle_fac_list[16]);
u64 __bootdata_preserved(alt_stfle_fac_list[16]);
struct oldmem_data __bootdata_preserved(oldmem_data);

struct machine_info machine;

void error(char *x)
{
	sclp_early_printk("\n\n");
	sclp_early_printk(x);
	sclp_early_printk("\n\n -- System halted");

	disabled_wait();
}

static void detect_facilities(void)
{
	if (test_facility(8)) {
		machine.has_edat1 = 1;
		__ctl_set_bit(0, 23);
	}
	if (test_facility(78))
		machine.has_edat2 = 1;
	if (!noexec_disabled && test_facility(130)) {
		machine.has_nx = 1;
		__ctl_set_bit(0, 20);
	}
}

static void setup_lpp(void)
{
	S390_lowcore.current_pid = 0;
	S390_lowcore.lpp = LPP_MAGIC;
	if (test_facility(40))
		lpp(&S390_lowcore.lpp);
}

#ifdef CONFIG_KERNEL_UNCOMPRESSED
unsigned long mem_safe_offset(void)
{
	return vmlinux.default_lma + vmlinux.image_size + vmlinux.bss_size;
}
#endif

static void rescue_initrd(unsigned long min, unsigned long max)
{
	unsigned long old_addr, addr, size;

	if (!IS_ENABLED(CONFIG_BLK_DEV_INITRD))
		return;
	if (!get_physmem_reserved(RR_INITRD, &addr, &size))
		return;
	if (addr >= min && addr + size <= max)
		return;
	old_addr = addr;
	physmem_free(RR_INITRD);
	addr = physmem_alloc_top_down(RR_INITRD, size, 0);
	memmove((void *)addr, (void *)old_addr, size);
}

static void copy_bootdata(void)
{
	if (__boot_data_end - __boot_data_start != vmlinux.bootdata_size)
		error(".boot.data section size mismatch");
	memcpy((void *)vmlinux.bootdata_off, __boot_data_start, vmlinux.bootdata_size);
	if (__boot_data_preserved_end - __boot_data_preserved_start != vmlinux.bootdata_preserved_size)
		error(".boot.preserved.data section size mismatch");
	memcpy((void *)vmlinux.bootdata_preserved_off, __boot_data_preserved_start, vmlinux.bootdata_preserved_size);
}

static void handle_relocs(unsigned long offset)
{
	Elf64_Rela *rela_start, *rela_end, *rela;
	int r_type, r_sym, rc;
	Elf64_Addr loc, val;
	Elf64_Sym *dynsym;

	rela_start = (Elf64_Rela *) vmlinux.rela_dyn_start;
	rela_end = (Elf64_Rela *) vmlinux.rela_dyn_end;
	dynsym = (Elf64_Sym *) vmlinux.dynsym_start;
	for (rela = rela_start; rela < rela_end; rela++) {
		loc = rela->r_offset + offset;
		val = rela->r_addend;
		r_sym = ELF64_R_SYM(rela->r_info);
		if (r_sym) {
			if (dynsym[r_sym].st_shndx != SHN_UNDEF)
				val += dynsym[r_sym].st_value + offset;
		} else {
			/*
			 * 0 == undefined symbol table index (STN_UNDEF),
			 * used for R_390_RELATIVE, only add KASLR offset
			 */
			val += offset;
		}
		r_type = ELF64_R_TYPE(rela->r_info);
		rc = arch_kexec_do_relocs(r_type, (void *) loc, val, 0);
		if (rc)
			error("Unknown relocation type");
	}
}

/*
 * Merge information from several sources into a single ident_map_size value.
 * "ident_map_size" represents the upper limit of physical memory we may ever
 * reach. It might not be all online memory, but also include standby (offline)
 * memory. "ident_map_size" could be lower then actual standby or even online
 * memory present, due to limiting factors. We should never go above this limit.
 * It is the size of our identity mapping.
 *
 * Consider the following factors:
 * 1. max_physmem_end - end of physical memory online or standby.
 *    Always >= end of the last online memory range (get_physmem_online_end()).
 * 2. CONFIG_MAX_PHYSMEM_BITS - the maximum size of physical memory the
 *    kernel is able to support.
 * 3. "mem=" kernel command line option which limits physical memory usage.
 * 4. OLDMEM_BASE which is a kdump memory limit when the kernel is executed as
 *    crash kernel.
 * 5. "hsa" size which is a memory limit when the kernel is executed during
 *    zfcp/nvme dump.
 */
static void setup_ident_map_size(unsigned long max_physmem_end)
{
	unsigned long hsa_size;

	ident_map_size = max_physmem_end;
	if (memory_limit)
		ident_map_size = min(ident_map_size, memory_limit);
	ident_map_size = min(ident_map_size, 1UL << MAX_PHYSMEM_BITS);

#ifdef CONFIG_CRASH_DUMP
	if (oldmem_data.start) {
		__kaslr_enabled = 0;
		ident_map_size = min(ident_map_size, oldmem_data.size);
	} else if (ipl_block_valid && is_ipl_block_dump()) {
		__kaslr_enabled = 0;
		if (!sclp_early_get_hsa_size(&hsa_size) && hsa_size)
			ident_map_size = min(ident_map_size, hsa_size);
	}
#endif
}

static unsigned long setup_kernel_memory_layout(void)
{
	unsigned long vmemmap_start;
	unsigned long asce_limit;
	unsigned long rte_size;
	unsigned long pages;
	unsigned long vmax;

	pages = ident_map_size / PAGE_SIZE;
	/* vmemmap contains a multiple of PAGES_PER_SECTION struct pages */
	vmemmap_size = SECTION_ALIGN_UP(pages) * sizeof(struct page);

	/* choose kernel address space layout: 4 or 3 levels. */
	vmemmap_start = round_up(ident_map_size, _REGION3_SIZE);
	if (IS_ENABLED(CONFIG_KASAN) ||
	    vmalloc_size > _REGION2_SIZE ||
	    vmemmap_start + vmemmap_size + vmalloc_size + MODULES_LEN >
		    _REGION2_SIZE) {
		asce_limit = _REGION1_SIZE;
		rte_size = _REGION2_SIZE;
	} else {
		asce_limit = _REGION2_SIZE;
		rte_size = _REGION3_SIZE;
	}
	/*
	 * forcing modules and vmalloc area under the ultravisor
	 * secure storage limit, so that any vmalloc allocation
	 * we do could be used to back secure guest storage.
	 */
	vmax = adjust_to_uv_max(asce_limit);
#ifdef CONFIG_KASAN
	/* force vmalloc and modules below kasan shadow */
	vmax = min(vmax, KASAN_SHADOW_START);
#endif
	__memcpy_real_area = round_down(vmax - PAGE_SIZE, PAGE_SIZE);
	__abs_lowcore = round_down(__memcpy_real_area - ABS_LOWCORE_MAP_SIZE,
				   sizeof(struct lowcore));
	MODULES_END = round_down(__abs_lowcore, _SEGMENT_SIZE);
	MODULES_VADDR = MODULES_END - MODULES_LEN;
	VMALLOC_END = MODULES_VADDR;

	/* allow vmalloc area to occupy up to about 1/2 of the rest virtual space left */
	vmalloc_size = min(vmalloc_size, round_down(VMALLOC_END / 2, _REGION3_SIZE));
	VMALLOC_START = VMALLOC_END - vmalloc_size;

	/* split remaining virtual space between 1:1 mapping & vmemmap array */
	pages = VMALLOC_START / (PAGE_SIZE + sizeof(struct page));
	pages = SECTION_ALIGN_UP(pages);
	/* keep vmemmap_start aligned to a top level region table entry */
	vmemmap_start = round_down(VMALLOC_START - pages * sizeof(struct page), rte_size);
	vmemmap_start = min(vmemmap_start, 1UL << MAX_PHYSMEM_BITS);
	/* make sure identity map doesn't overlay with vmemmap */
	ident_map_size = min(ident_map_size, vmemmap_start);
	vmemmap_size = SECTION_ALIGN_UP(ident_map_size / PAGE_SIZE) * sizeof(struct page);
	/* make sure vmemmap doesn't overlay with vmalloc area */
	VMALLOC_START = max(vmemmap_start + vmemmap_size, VMALLOC_START);
	vmemmap = (struct page *)vmemmap_start;

	return asce_limit;
}

/*
 * This function clears the BSS section of the decompressed Linux kernel and NOT the decompressor's.
 */
static void clear_bss_section(unsigned long vmlinux_lma)
{
	memset((void *)vmlinux_lma + vmlinux.image_size, 0, vmlinux.bss_size);
}

/*
 * Set vmalloc area size to an 8th of (potential) physical memory
 * size, unless size has been set by kernel command line parameter.
 */
static void setup_vmalloc_size(void)
{
	unsigned long size;

	if (vmalloc_size_set)
		return;
	size = round_up(ident_map_size / 8, _SEGMENT_SIZE);
	vmalloc_size = max(size, vmalloc_size);
}

static void offset_vmlinux_info(unsigned long offset)
{
	*(unsigned long *)(&vmlinux.entry) += offset;
	vmlinux.bootdata_off += offset;
	vmlinux.bootdata_preserved_off += offset;
	vmlinux.rela_dyn_start += offset;
	vmlinux.rela_dyn_end += offset;
	vmlinux.dynsym_start += offset;
	vmlinux.init_mm_off += offset;
	vmlinux.swapper_pg_dir_off += offset;
	vmlinux.invalid_pg_dir_off += offset;
#ifdef CONFIG_KASAN
	vmlinux.kasan_early_shadow_page_off += offset;
	vmlinux.kasan_early_shadow_pte_off += offset;
	vmlinux.kasan_early_shadow_pmd_off += offset;
	vmlinux.kasan_early_shadow_pud_off += offset;
	vmlinux.kasan_early_shadow_p4d_off += offset;
#endif
}

void startup_kernel(void)
{
	unsigned long max_physmem_end;
	unsigned long vmlinux_lma = 0;
	unsigned long amode31_lma = 0;
	unsigned long asce_limit;
	unsigned long safe_addr;
	void *img;
	psw_t psw;

	setup_lpp();
	safe_addr = mem_safe_offset();
	/*
	 * reserve decompressor memory together with decompression heap, buffer and
	 * memory which might be occupied by uncompressed kernel at default 1Mb
	 * position (if KASLR is off or failed).
	 */
	physmem_reserve(RR_DECOMPRESSOR, 0, safe_addr);
	if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && parmarea.initrd_size)
		physmem_reserve(RR_INITRD, parmarea.initrd_start, parmarea.initrd_size);
	oldmem_data.start = parmarea.oldmem_base;
	oldmem_data.size = parmarea.oldmem_size;

	store_ipl_parmblock();
	read_ipl_report();
	uv_query_info();
	sclp_early_read_info();
	setup_boot_command_line();
	parse_boot_command_line();
	detect_facilities();
	sanitize_prot_virt_host();
	max_physmem_end = detect_max_physmem_end();
	setup_ident_map_size(max_physmem_end);
	setup_vmalloc_size();
	asce_limit = setup_kernel_memory_layout();
	/* got final ident_map_size, physmem allocations could be performed now */
	physmem_set_usable_limit(ident_map_size);
	detect_physmem_online_ranges(max_physmem_end);
	save_ipl_cert_comp_list();
	rescue_initrd(safe_addr, ident_map_size);

	if (kaslr_enabled()) {
		vmlinux_lma = randomize_within_range(vmlinux.image_size + vmlinux.bss_size,
						     THREAD_SIZE, vmlinux.default_lma,
						     ident_map_size);
		if (vmlinux_lma) {
			__kaslr_offset = vmlinux_lma - vmlinux.default_lma;
			offset_vmlinux_info(__kaslr_offset);
		}
	}
	vmlinux_lma = vmlinux_lma ?: vmlinux.default_lma;
	physmem_reserve(RR_VMLINUX, vmlinux_lma, vmlinux.image_size + vmlinux.bss_size);

	if (!IS_ENABLED(CONFIG_KERNEL_UNCOMPRESSED)) {
		img = decompress_kernel();
		memmove((void *)vmlinux_lma, img, vmlinux.image_size);
	} else if (__kaslr_offset) {
		img = (void *)vmlinux.default_lma;
		memmove((void *)vmlinux_lma, img, vmlinux.image_size);
		memset(img, 0, vmlinux.image_size);
	}

	/* vmlinux decompression is done, shrink reserved low memory */
	physmem_reserve(RR_DECOMPRESSOR, 0, (unsigned long)_decompressor_end);
	if (kaslr_enabled())
		amode31_lma = randomize_within_range(vmlinux.amode31_size, PAGE_SIZE, 0, SZ_2G);
	amode31_lma = amode31_lma ?: vmlinux.default_lma - vmlinux.amode31_size;
	physmem_reserve(RR_AMODE31, amode31_lma, vmlinux.amode31_size);

	/*
	 * The order of the following operations is important:
	 *
	 * - handle_relocs() must follow clear_bss_section() to establish static
	 *   memory references to data in .bss to be used by setup_vmem()
	 *   (i.e init_mm.pgd)
	 *
	 * - setup_vmem() must follow handle_relocs() to be able using
	 *   static memory references to data in .bss (i.e init_mm.pgd)
	 *
	 * - copy_bootdata() must follow setup_vmem() to propagate changes to
	 *   bootdata made by setup_vmem()
	 */
	clear_bss_section(vmlinux_lma);
	handle_relocs(__kaslr_offset);
	setup_vmem(asce_limit);
	copy_bootdata();

	/*
	 * Save KASLR offset for early dumps, before vmcore_info is set.
	 * Mark as uneven to distinguish from real vmcore_info pointer.
	 */
	S390_lowcore.vmcore_info = __kaslr_offset ? __kaslr_offset | 0x1UL : 0;

	/*
	 * Jump to the decompressed kernel entry point and switch DAT mode on.
	 */
	psw.addr = vmlinux.entry;
	psw.mask = PSW_KERNEL_BITS;
	__load_psw(psw);
}