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
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
|
// SPDX-License-Identifier: GPL-2.0
#include <linux/string.h>
#include <linux/elf.h>
#include <asm/page-states.h>
#include <asm/boot_data.h>
#include <asm/extmem.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"
struct vm_layout __bootdata_preserved(vm_layout);
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_preserved(max_mappable);
u64 __bootdata_preserved(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;
local_ctl_set_bit(0, CR0_EDAT_BIT);
}
if (test_facility(78))
machine.has_edat2 = 1;
if (test_facility(130))
machine.has_nx = 1;
}
static int cmma_test_essa(void)
{
unsigned long reg1, reg2, tmp = 0;
int rc = 1;
psw_t old;
/* Test ESSA_GET_STATE */
asm volatile(
" mvc 0(16,%[psw_old]),0(%[psw_pgm])\n"
" epsw %[reg1],%[reg2]\n"
" st %[reg1],0(%[psw_pgm])\n"
" st %[reg2],4(%[psw_pgm])\n"
" larl %[reg1],1f\n"
" stg %[reg1],8(%[psw_pgm])\n"
" .insn rrf,0xb9ab0000,%[tmp],%[tmp],%[cmd],0\n"
" la %[rc],0\n"
"1: mvc 0(16,%[psw_pgm]),0(%[psw_old])\n"
: [reg1] "=&d" (reg1),
[reg2] "=&a" (reg2),
[rc] "+&d" (rc),
[tmp] "=&d" (tmp),
"+Q" (S390_lowcore.program_new_psw),
"=Q" (old)
: [psw_old] "a" (&old),
[psw_pgm] "a" (&S390_lowcore.program_new_psw),
[cmd] "i" (ESSA_GET_STATE)
: "cc", "memory");
return rc;
}
static void cmma_init(void)
{
if (!cmma_flag)
return;
if (cmma_test_essa()) {
cmma_flag = 0;
return;
}
if (test_facility(147))
cmma_flag = 2;
}
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
static unsigned long mem_safe_offset(void)
{
return (unsigned long)_compressed_start;
}
static void deploy_kernel(void *output)
{
void *uncompressed_start = (void *)_compressed_start;
if (output == uncompressed_start)
return;
memmove(output, uncompressed_start, vmlinux.image_size);
memset(uncompressed_start, 0, vmlinux.image_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 kaslr_adjust_relocs(unsigned long min_addr, unsigned long max_addr,
unsigned long offset, unsigned long phys_offset)
{
int *reloc;
long loc;
/* Adjust R_390_64 relocations */
for (reloc = (int *)__vmlinux_relocs_64_start; reloc < (int *)__vmlinux_relocs_64_end; reloc++) {
loc = (long)*reloc + phys_offset;
if (loc < min_addr || loc > max_addr)
error("64-bit relocation outside of kernel!\n");
*(u64 *)loc += offset - __START_KERNEL;
}
}
static void kaslr_adjust_got(unsigned long offset)
{
u64 *entry;
/*
* Even without -fPIE, Clang still uses a global offset table for some
* reason. Adjust the GOT entries.
*/
for (entry = (u64 *)vmlinux.got_start; entry < (u64 *)vmlinux.got_end; entry++)
*entry += offset - __START_KERNEL;
}
/*
* 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
}
#define FIXMAP_SIZE round_up(MEMCPY_REAL_SIZE + ABS_LOWCORE_MAP_SIZE, sizeof(struct lowcore))
static unsigned long get_vmem_size(unsigned long identity_size,
unsigned long vmemmap_size,
unsigned long vmalloc_size,
unsigned long rte_size)
{
unsigned long max_mappable, vsize;
max_mappable = max(identity_size, MAX_DCSS_ADDR);
vsize = round_up(SZ_2G + max_mappable, rte_size) +
round_up(vmemmap_size, rte_size) +
FIXMAP_SIZE + MODULES_LEN + KASLR_LEN;
return size_add(vsize, vmalloc_size);
}
static unsigned long setup_kernel_memory_layout(unsigned long kernel_size)
{
unsigned long vmemmap_start;
unsigned long kernel_start;
unsigned long asce_limit;
unsigned long rte_size;
unsigned long pages;
unsigned long vsize;
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. */
BUILD_BUG_ON(!IS_ALIGNED(__START_KERNEL, THREAD_SIZE));
BUILD_BUG_ON(!IS_ALIGNED(__NO_KASLR_START_KERNEL, THREAD_SIZE));
BUILD_BUG_ON(__NO_KASLR_END_KERNEL > _REGION1_SIZE);
vsize = get_vmem_size(ident_map_size, vmemmap_size, vmalloc_size, _REGION3_SIZE);
if (IS_ENABLED(CONFIG_KASAN) || __NO_KASLR_END_KERNEL > _REGION2_SIZE ||
(vsize > _REGION2_SIZE && kaslr_enabled())) {
asce_limit = _REGION1_SIZE;
if (__NO_KASLR_END_KERNEL > _REGION2_SIZE) {
rte_size = _REGION2_SIZE;
vsize = get_vmem_size(ident_map_size, vmemmap_size, vmalloc_size, _REGION2_SIZE);
} else {
rte_size = _REGION3_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.
*
* Assume the secure storage limit always exceeds _REGION2_SIZE,
* otherwise asce_limit and rte_size would have been adjusted.
*/
vmax = adjust_to_uv_max(asce_limit);
#ifdef CONFIG_KASAN
BUILD_BUG_ON(__NO_KASLR_END_KERNEL > KASAN_SHADOW_START);
/* force vmalloc and modules below kasan shadow */
vmax = min(vmax, KASAN_SHADOW_START);
#endif
vsize = min(vsize, vmax);
if (kaslr_enabled()) {
unsigned long kernel_end, kaslr_len, slots, pos;
kaslr_len = max(KASLR_LEN, vmax - vsize);
slots = DIV_ROUND_UP(kaslr_len - kernel_size, THREAD_SIZE);
if (get_random(slots, &pos))
pos = 0;
kernel_end = vmax - pos * THREAD_SIZE;
kernel_start = round_down(kernel_end - kernel_size, THREAD_SIZE);
} else if (vmax < __NO_KASLR_END_KERNEL || vsize > __NO_KASLR_END_KERNEL) {
kernel_start = round_down(vmax - kernel_size, THREAD_SIZE);
decompressor_printk("The kernel base address is forced to %lx\n", kernel_start);
} else {
kernel_start = __NO_KASLR_START_KERNEL;
}
__kaslr_offset = kernel_start;
MODULES_END = round_down(kernel_start, _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 */
vsize = (VMALLOC_END - FIXMAP_SIZE) / 2;
vsize = round_down(vsize, _SEGMENT_SIZE);
vmalloc_size = min(vmalloc_size, vsize);
VMALLOC_START = VMALLOC_END - vmalloc_size;
__memcpy_real_area = round_down(VMALLOC_START - MEMCPY_REAL_SIZE, PAGE_SIZE);
__abs_lowcore = round_down(__memcpy_real_area - ABS_LOWCORE_MAP_SIZE,
sizeof(struct lowcore));
/* split remaining virtual space between 1:1 mapping & vmemmap array */
pages = __abs_lowcore / (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(__abs_lowcore - pages * sizeof(struct page), rte_size);
/* 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 absolute lowcore area */
if (vmemmap_start + vmemmap_size > __abs_lowcore) {
vmemmap_size = SECTION_ALIGN_DOWN(ident_map_size / PAGE_SIZE) * sizeof(struct page);
ident_map_size = vmemmap_size / sizeof(struct page) * PAGE_SIZE;
}
vmemmap = (struct page *)vmemmap_start;
/* maximum address for which linear mapping could be created (DCSS, memory) */
BUILD_BUG_ON(MAX_DCSS_ADDR > (1UL << MAX_PHYSMEM_BITS));
max_mappable = max(ident_map_size, MAX_DCSS_ADDR);
max_mappable = min(max_mappable, vmemmap_start);
__identity_base = round_down(vmemmap_start - max_mappable, rte_size);
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 kernel_start)
{
memset((void *)kernel_start + 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 kaslr_adjust_vmlinux_info(long offset)
{
vmlinux.bootdata_off += offset;
vmlinux.bootdata_preserved_off += offset;
vmlinux.got_start += offset;
vmlinux.got_end += 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
}
static void fixup_vmlinux_info(void)
{
vmlinux.entry -= __START_KERNEL;
kaslr_adjust_vmlinux_info(-__START_KERNEL);
}
void startup_kernel(void)
{
unsigned long kernel_size = vmlinux.image_size + vmlinux.bss_size;
unsigned long nokaslr_offset_phys, kaslr_large_page_offset;
unsigned long amode31_lma = 0;
unsigned long max_physmem_end;
unsigned long asce_limit;
unsigned long safe_addr;
psw_t psw;
fixup_vmlinux_info();
setup_lpp();
/*
* Non-randomized kernel physical start address must be _SEGMENT_SIZE
* aligned (see blow).
*/
nokaslr_offset_phys = ALIGN(mem_safe_offset(), _SEGMENT_SIZE);
safe_addr = PAGE_ALIGN(nokaslr_offset_phys + kernel_size);
/*
* Reserve decompressor memory together with decompression heap,
* buffer and memory which might be occupied by uncompressed kernel
* (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();
cmma_init();
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(kernel_size);
/* 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);
/*
* __kaslr_offset_phys must be _SEGMENT_SIZE aligned, so the lower
* 20 bits (the offset within a large page) are zero. Copy the last
* 20 bits of __kaslr_offset, which is THREAD_SIZE aligned, to
* __kaslr_offset_phys.
*
* With this the last 20 bits of __kaslr_offset_phys and __kaslr_offset
* are identical, which is required to allow for large mappings of the
* kernel image.
*/
kaslr_large_page_offset = __kaslr_offset & ~_SEGMENT_MASK;
if (kaslr_enabled()) {
unsigned long end = ident_map_size - kaslr_large_page_offset;
__kaslr_offset_phys = randomize_within_range(kernel_size, _SEGMENT_SIZE, 0, end);
}
if (!__kaslr_offset_phys)
__kaslr_offset_phys = nokaslr_offset_phys;
__kaslr_offset_phys |= kaslr_large_page_offset;
kaslr_adjust_vmlinux_info(__kaslr_offset_phys);
physmem_reserve(RR_VMLINUX, __kaslr_offset_phys, kernel_size);
deploy_kernel((void *)__kaslr_offset_phys);
/* vmlinux decompression is done, shrink reserved low memory */
physmem_reserve(RR_DECOMPRESSOR, 0, (unsigned long)_decompressor_end);
/*
* In case KASLR is enabled the randomized location of .amode31
* section might overlap with .vmlinux.relocs section. To avoid that
* the below randomize_within_range() could have been called with
* __vmlinux_relocs_64_end as the lower range address. However,
* .amode31 section is written to by the decompressed kernel - at
* that time the contents of .vmlinux.relocs is not needed anymore.
* Conversly, .vmlinux.relocs is read only by the decompressor, even
* before the kernel started. Therefore, in case the two sections
* overlap there is no risk of corrupting any data.
*/
if (kaslr_enabled())
amode31_lma = randomize_within_range(vmlinux.amode31_size, PAGE_SIZE, 0, SZ_2G);
if (!amode31_lma)
amode31_lma = __kaslr_offset_phys - vmlinux.amode31_size;
physmem_reserve(RR_AMODE31, amode31_lma, vmlinux.amode31_size);
/*
* The order of the following operations is important:
*
* - kaslr_adjust_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 kaslr_adjust_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(__kaslr_offset_phys);
kaslr_adjust_relocs(__kaslr_offset_phys, __kaslr_offset_phys + vmlinux.image_size,
__kaslr_offset, __kaslr_offset_phys);
kaslr_adjust_got(__kaslr_offset);
setup_vmem(__kaslr_offset, __kaslr_offset + kernel_size, 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_phys ? __kaslr_offset_phys | 0x1UL : 0;
/*
* Jump to the decompressed kernel entry point and switch DAT mode on.
*/
psw.addr = __kaslr_offset + vmlinux.entry;
psw.mask = PSW_KERNEL_BITS;
__load_psw(psw);
}
|