1// SPDX-License-Identifier: GPL-2.0
2#include <linux/string.h>
3#include <linux/elf.h>
4#include <asm/page-states.h>
5#include <asm/boot_data.h>
6#include <asm/sections.h>
7#include <asm/maccess.h>
8#include <asm/cpu_mf.h>
9#include <asm/setup.h>
10#include <asm/kasan.h>
11#include <asm/kexec.h>
12#include <asm/sclp.h>
13#include <asm/diag.h>
14#include <asm/uv.h>
15#include <asm/abs_lowcore.h>
16#include <asm/physmem_info.h>
17#include "decompressor.h"
18#include "boot.h"
19#include "uv.h"
20
21unsigned long __bootdata_preserved(__kaslr_offset);
22unsigned long __bootdata_preserved(__abs_lowcore);
23unsigned long __bootdata_preserved(__memcpy_real_area);
24pte_t *__bootdata_preserved(memcpy_real_ptep);
25unsigned long __bootdata_preserved(VMALLOC_START);
26unsigned long __bootdata_preserved(VMALLOC_END);
27struct page *__bootdata_preserved(vmemmap);
28unsigned long __bootdata_preserved(vmemmap_size);
29unsigned long __bootdata_preserved(MODULES_VADDR);
30unsigned long __bootdata_preserved(MODULES_END);
31unsigned long __bootdata_preserved(max_mappable);
32unsigned long __bootdata(ident_map_size);
33
34u64 __bootdata_preserved(stfle_fac_list[16]);
35u64 __bootdata_preserved(alt_stfle_fac_list[16]);
36struct oldmem_data __bootdata_preserved(oldmem_data);
37
38struct machine_info machine;
39
40void error(char *x)
41{
42 sclp_early_printk("\n\n");
43 sclp_early_printk(x);
44 sclp_early_printk("\n\n -- System halted");
45
46 disabled_wait();
47}
48
49static void detect_facilities(void)
50{
51 if (test_facility(8)) {
52 machine.has_edat1 = 1;
53 local_ctl_set_bit(0, CR0_EDAT_BIT);
54 }
55 if (test_facility(78))
56 machine.has_edat2 = 1;
57 if (test_facility(130))
58 machine.has_nx = 1;
59}
60
61static int cmma_test_essa(void)
62{
63 unsigned long reg1, reg2, tmp = 0;
64 int rc = 1;
65 psw_t old;
66
67 /* Test ESSA_GET_STATE */
68 asm volatile(
69 " mvc 0(16,%[psw_old]),0(%[psw_pgm])\n"
70 " epsw %[reg1],%[reg2]\n"
71 " st %[reg1],0(%[psw_pgm])\n"
72 " st %[reg2],4(%[psw_pgm])\n"
73 " larl %[reg1],1f\n"
74 " stg %[reg1],8(%[psw_pgm])\n"
75 " .insn rrf,0xb9ab0000,%[tmp],%[tmp],%[cmd],0\n"
76 " la %[rc],0\n"
77 "1: mvc 0(16,%[psw_pgm]),0(%[psw_old])\n"
78 : [reg1] "=&d" (reg1),
79 [reg2] "=&a" (reg2),
80 [rc] "+&d" (rc),
81 [tmp] "=&d" (tmp),
82 "+Q" (S390_lowcore.program_new_psw),
83 "=Q" (old)
84 : [psw_old] "a" (&old),
85 [psw_pgm] "a" (&S390_lowcore.program_new_psw),
86 [cmd] "i" (ESSA_GET_STATE)
87 : "cc", "memory");
88 return rc;
89}
90
91static void cmma_init(void)
92{
93 if (!cmma_flag)
94 return;
95 if (cmma_test_essa()) {
96 cmma_flag = 0;
97 return;
98 }
99 if (test_facility(147))
100 cmma_flag = 2;
101}
102
103static void setup_lpp(void)
104{
105 S390_lowcore.current_pid = 0;
106 S390_lowcore.lpp = LPP_MAGIC;
107 if (test_facility(40))
108 lpp(&S390_lowcore.lpp);
109}
110
111#ifdef CONFIG_KERNEL_UNCOMPRESSED
112unsigned long mem_safe_offset(void)
113{
114 return vmlinux.default_lma + vmlinux.image_size + vmlinux.bss_size;
115}
116#endif
117
118static void rescue_initrd(unsigned long min, unsigned long max)
119{
120 unsigned long old_addr, addr, size;
121
122 if (!IS_ENABLED(CONFIG_BLK_DEV_INITRD))
123 return;
124 if (!get_physmem_reserved(RR_INITRD, &addr, &size))
125 return;
126 if (addr >= min && addr + size <= max)
127 return;
128 old_addr = addr;
129 physmem_free(type: RR_INITRD);
130 addr = physmem_alloc_top_down(type: RR_INITRD, size, align: 0);
131 memmove((void *)addr, (void *)old_addr, size);
132}
133
134static void copy_bootdata(void)
135{
136 if (__boot_data_end - __boot_data_start != vmlinux.bootdata_size)
137 error(x: ".boot.data section size mismatch");
138 memcpy((void *)vmlinux.bootdata_off, __boot_data_start, vmlinux.bootdata_size);
139 if (__boot_data_preserved_end - __boot_data_preserved_start != vmlinux.bootdata_preserved_size)
140 error(x: ".boot.preserved.data section size mismatch");
141 memcpy((void *)vmlinux.bootdata_preserved_off, __boot_data_preserved_start, vmlinux.bootdata_preserved_size);
142}
143
144#ifdef CONFIG_PIE_BUILD
145static void kaslr_adjust_relocs(unsigned long min_addr, unsigned long max_addr, unsigned long offset)
146{
147 Elf64_Rela *rela_start, *rela_end, *rela;
148 int r_type, r_sym, rc;
149 Elf64_Addr loc, val;
150 Elf64_Sym *dynsym;
151
152 rela_start = (Elf64_Rela *) vmlinux.rela_dyn_start;
153 rela_end = (Elf64_Rela *) vmlinux.rela_dyn_end;
154 dynsym = (Elf64_Sym *) vmlinux.dynsym_start;
155 for (rela = rela_start; rela < rela_end; rela++) {
156 loc = rela->r_offset + offset;
157 val = rela->r_addend;
158 r_sym = ELF64_R_SYM(rela->r_info);
159 if (r_sym) {
160 if (dynsym[r_sym].st_shndx != SHN_UNDEF)
161 val += dynsym[r_sym].st_value + offset;
162 } else {
163 /*
164 * 0 == undefined symbol table index (STN_UNDEF),
165 * used for R_390_RELATIVE, only add KASLR offset
166 */
167 val += offset;
168 }
169 r_type = ELF64_R_TYPE(rela->r_info);
170 rc = arch_kexec_do_relocs(r_type, (void *) loc, val, 0);
171 if (rc)
172 error("Unknown relocation type");
173 }
174}
175
176static void kaslr_adjust_got(unsigned long offset) {}
177static void rescue_relocs(void) {}
178static void free_relocs(void) {}
179#else
180static int *vmlinux_relocs_64_start;
181static int *vmlinux_relocs_64_end;
182
183static void rescue_relocs(void)
184{
185 unsigned long size = __vmlinux_relocs_64_end - __vmlinux_relocs_64_start;
186
187 vmlinux_relocs_64_start = (void *)physmem_alloc_top_down(RR_RELOC, size, 0);
188 vmlinux_relocs_64_end = (void *)vmlinux_relocs_64_start + size;
189 memmove(vmlinux_relocs_64_start, __vmlinux_relocs_64_start, size);
190}
191
192static void free_relocs(void)
193{
194 physmem_free(type: RR_RELOC);
195}
196
197static void kaslr_adjust_relocs(unsigned long min_addr, unsigned long max_addr, unsigned long offset)
198{
199 int *reloc;
200 long loc;
201
202 /* Adjust R_390_64 relocations */
203 for (reloc = vmlinux_relocs_64_start; reloc < vmlinux_relocs_64_end; reloc++) {
204 loc = (long)*reloc + offset;
205 if (loc < min_addr || loc > max_addr)
206 error(x: "64-bit relocation outside of kernel!\n");
207 *(u64 *)loc += offset;
208 }
209}
210
211static void kaslr_adjust_got(unsigned long offset)
212{
213 u64 *entry;
214
215 /*
216 * Even without -fPIE, Clang still uses a global offset table for some
217 * reason. Adjust the GOT entries.
218 */
219 for (entry = (u64 *)vmlinux.got_start; entry < (u64 *)vmlinux.got_end; entry++)
220 *entry += offset;
221}
222#endif
223
224/*
225 * Merge information from several sources into a single ident_map_size value.
226 * "ident_map_size" represents the upper limit of physical memory we may ever
227 * reach. It might not be all online memory, but also include standby (offline)
228 * memory. "ident_map_size" could be lower then actual standby or even online
229 * memory present, due to limiting factors. We should never go above this limit.
230 * It is the size of our identity mapping.
231 *
232 * Consider the following factors:
233 * 1. max_physmem_end - end of physical memory online or standby.
234 * Always >= end of the last online memory range (get_physmem_online_end()).
235 * 2. CONFIG_MAX_PHYSMEM_BITS - the maximum size of physical memory the
236 * kernel is able to support.
237 * 3. "mem=" kernel command line option which limits physical memory usage.
238 * 4. OLDMEM_BASE which is a kdump memory limit when the kernel is executed as
239 * crash kernel.
240 * 5. "hsa" size which is a memory limit when the kernel is executed during
241 * zfcp/nvme dump.
242 */
243static void setup_ident_map_size(unsigned long max_physmem_end)
244{
245 unsigned long hsa_size;
246
247 ident_map_size = max_physmem_end;
248 if (memory_limit)
249 ident_map_size = min(ident_map_size, memory_limit);
250 ident_map_size = min(ident_map_size, 1UL << MAX_PHYSMEM_BITS);
251
252#ifdef CONFIG_CRASH_DUMP
253 if (oldmem_data.start) {
254 __kaslr_enabled = 0;
255 ident_map_size = min(ident_map_size, oldmem_data.size);
256 } else if (ipl_block_valid && is_ipl_block_dump()) {
257 __kaslr_enabled = 0;
258 if (!sclp_early_get_hsa_size(&hsa_size) && hsa_size)
259 ident_map_size = min(ident_map_size, hsa_size);
260 }
261#endif
262}
263
264static unsigned long setup_kernel_memory_layout(void)
265{
266 unsigned long vmemmap_start;
267 unsigned long asce_limit;
268 unsigned long rte_size;
269 unsigned long pages;
270 unsigned long vsize;
271 unsigned long vmax;
272
273 pages = ident_map_size / PAGE_SIZE;
274 /* vmemmap contains a multiple of PAGES_PER_SECTION struct pages */
275 vmemmap_size = SECTION_ALIGN_UP(pages) * sizeof(struct page);
276
277 /* choose kernel address space layout: 4 or 3 levels. */
278 vsize = round_up(ident_map_size, _REGION3_SIZE) + vmemmap_size +
279 MODULES_LEN + MEMCPY_REAL_SIZE + ABS_LOWCORE_MAP_SIZE;
280 vsize = size_add(addend1: vsize, addend2: vmalloc_size);
281 if (IS_ENABLED(CONFIG_KASAN) || (vsize > _REGION2_SIZE)) {
282 asce_limit = _REGION1_SIZE;
283 rte_size = _REGION2_SIZE;
284 } else {
285 asce_limit = _REGION2_SIZE;
286 rte_size = _REGION3_SIZE;
287 }
288
289 /*
290 * Forcing modules and vmalloc area under the ultravisor
291 * secure storage limit, so that any vmalloc allocation
292 * we do could be used to back secure guest storage.
293 */
294 vmax = adjust_to_uv_max(limit: asce_limit);
295#ifdef CONFIG_KASAN
296 /* force vmalloc and modules below kasan shadow */
297 vmax = min(vmax, KASAN_SHADOW_START);
298#endif
299 __memcpy_real_area = round_down(vmax - MEMCPY_REAL_SIZE, PAGE_SIZE);
300 __abs_lowcore = round_down(__memcpy_real_area - ABS_LOWCORE_MAP_SIZE,
301 sizeof(struct lowcore));
302 MODULES_END = round_down(__abs_lowcore, _SEGMENT_SIZE);
303 MODULES_VADDR = MODULES_END - MODULES_LEN;
304 VMALLOC_END = MODULES_VADDR;
305
306 /* allow vmalloc area to occupy up to about 1/2 of the rest virtual space left */
307 vsize = round_down(VMALLOC_END / 2, _SEGMENT_SIZE);
308 vmalloc_size = min(vmalloc_size, vsize);
309 VMALLOC_START = VMALLOC_END - vmalloc_size;
310
311 /* split remaining virtual space between 1:1 mapping & vmemmap array */
312 pages = VMALLOC_START / (PAGE_SIZE + sizeof(struct page));
313 pages = SECTION_ALIGN_UP(pages);
314 /* keep vmemmap_start aligned to a top level region table entry */
315 vmemmap_start = round_down(VMALLOC_START - pages * sizeof(struct page), rte_size);
316 vmemmap_start = min(vmemmap_start, 1UL << MAX_PHYSMEM_BITS);
317 /* maximum mappable address as seen by arch_get_mappable_range() */
318 max_mappable = vmemmap_start;
319 /* make sure identity map doesn't overlay with vmemmap */
320 ident_map_size = min(ident_map_size, vmemmap_start);
321 vmemmap_size = SECTION_ALIGN_UP(ident_map_size / PAGE_SIZE) * sizeof(struct page);
322 /* make sure vmemmap doesn't overlay with vmalloc area */
323 VMALLOC_START = max(vmemmap_start + vmemmap_size, VMALLOC_START);
324 vmemmap = (struct page *)vmemmap_start;
325
326 return asce_limit;
327}
328
329/*
330 * This function clears the BSS section of the decompressed Linux kernel and NOT the decompressor's.
331 */
332static void clear_bss_section(unsigned long vmlinux_lma)
333{
334 memset((void *)vmlinux_lma + vmlinux.image_size, 0, vmlinux.bss_size);
335}
336
337/*
338 * Set vmalloc area size to an 8th of (potential) physical memory
339 * size, unless size has been set by kernel command line parameter.
340 */
341static void setup_vmalloc_size(void)
342{
343 unsigned long size;
344
345 if (vmalloc_size_set)
346 return;
347 size = round_up(ident_map_size / 8, _SEGMENT_SIZE);
348 vmalloc_size = max(size, vmalloc_size);
349}
350
351static void kaslr_adjust_vmlinux_info(unsigned long offset)
352{
353 *(unsigned long *)(&vmlinux.entry) += offset;
354 vmlinux.bootdata_off += offset;
355 vmlinux.bootdata_preserved_off += offset;
356#ifdef CONFIG_PIE_BUILD
357 vmlinux.rela_dyn_start += offset;
358 vmlinux.rela_dyn_end += offset;
359 vmlinux.dynsym_start += offset;
360#else
361 vmlinux.got_start += offset;
362 vmlinux.got_end += offset;
363#endif
364 vmlinux.init_mm_off += offset;
365 vmlinux.swapper_pg_dir_off += offset;
366 vmlinux.invalid_pg_dir_off += offset;
367#ifdef CONFIG_KASAN
368 vmlinux.kasan_early_shadow_page_off += offset;
369 vmlinux.kasan_early_shadow_pte_off += offset;
370 vmlinux.kasan_early_shadow_pmd_off += offset;
371 vmlinux.kasan_early_shadow_pud_off += offset;
372 vmlinux.kasan_early_shadow_p4d_off += offset;
373#endif
374}
375
376void startup_kernel(void)
377{
378 unsigned long max_physmem_end;
379 unsigned long vmlinux_lma = 0;
380 unsigned long amode31_lma = 0;
381 unsigned long asce_limit;
382 unsigned long safe_addr;
383 void *img;
384 psw_t psw;
385
386 setup_lpp();
387 safe_addr = mem_safe_offset();
388
389 /*
390 * Reserve decompressor memory together with decompression heap, buffer and
391 * memory which might be occupied by uncompressed kernel at default 1Mb
392 * position (if KASLR is off or failed).
393 */
394 physmem_reserve(RR_DECOMPRESSOR, 0, safe_addr);
395 if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && parmarea.initrd_size)
396 physmem_reserve(RR_INITRD, parmarea.initrd_start, parmarea.initrd_size);
397 oldmem_data.start = parmarea.oldmem_base;
398 oldmem_data.size = parmarea.oldmem_size;
399
400 store_ipl_parmblock();
401 read_ipl_report();
402 uv_query_info();
403 sclp_early_read_info();
404 setup_boot_command_line();
405 parse_boot_command_line();
406 detect_facilities();
407 cmma_init();
408 sanitize_prot_virt_host();
409 max_physmem_end = detect_max_physmem_end();
410 setup_ident_map_size(max_physmem_end);
411 setup_vmalloc_size();
412 asce_limit = setup_kernel_memory_layout();
413 /* got final ident_map_size, physmem allocations could be performed now */
414 physmem_set_usable_limit(ident_map_size);
415 detect_physmem_online_ranges(max_physmem_end);
416 save_ipl_cert_comp_list();
417 rescue_initrd(safe_addr, ident_map_size);
418 rescue_relocs();
419
420 if (kaslr_enabled()) {
421 vmlinux_lma = randomize_within_range(vmlinux.image_size + vmlinux.bss_size,
422 THREAD_SIZE, vmlinux.default_lma,
423 ident_map_size);
424 if (vmlinux_lma) {
425 __kaslr_offset = vmlinux_lma - vmlinux.default_lma;
426 kaslr_adjust_vmlinux_info(__kaslr_offset);
427 }
428 }
429 vmlinux_lma = vmlinux_lma ?: vmlinux.default_lma;
430 physmem_reserve(RR_VMLINUX, vmlinux_lma, vmlinux.image_size + vmlinux.bss_size);
431
432 if (!IS_ENABLED(CONFIG_KERNEL_UNCOMPRESSED)) {
433 img = decompress_kernel();
434 memmove((void *)vmlinux_lma, img, vmlinux.image_size);
435 } else if (__kaslr_offset) {
436 img = (void *)vmlinux.default_lma;
437 memmove((void *)vmlinux_lma, img, vmlinux.image_size);
438 memset(img, 0, vmlinux.image_size);
439 }
440
441 /* vmlinux decompression is done, shrink reserved low memory */
442 physmem_reserve(RR_DECOMPRESSOR, 0, (unsigned long)_decompressor_end);
443 if (kaslr_enabled())
444 amode31_lma = randomize_within_range(vmlinux.amode31_size, PAGE_SIZE, 0, SZ_2G);
445 amode31_lma = amode31_lma ?: vmlinux.default_lma - vmlinux.amode31_size;
446 physmem_reserve(RR_AMODE31, amode31_lma, vmlinux.amode31_size);
447
448 /*
449 * The order of the following operations is important:
450 *
451 * - kaslr_adjust_relocs() must follow clear_bss_section() to establish
452 * static memory references to data in .bss to be used by setup_vmem()
453 * (i.e init_mm.pgd)
454 *
455 * - setup_vmem() must follow kaslr_adjust_relocs() to be able using
456 * static memory references to data in .bss (i.e init_mm.pgd)
457 *
458 * - copy_bootdata() must follow setup_vmem() to propagate changes
459 * to bootdata made by setup_vmem()
460 */
461 clear_bss_section(vmlinux_lma);
462 kaslr_adjust_relocs(vmlinux_lma, vmlinux_lma + vmlinux.image_size, __kaslr_offset);
463 kaslr_adjust_got(__kaslr_offset);
464 free_relocs();
465 setup_vmem(asce_limit);
466 copy_bootdata();
467
468 /*
469 * Save KASLR offset for early dumps, before vmcore_info is set.
470 * Mark as uneven to distinguish from real vmcore_info pointer.
471 */
472 S390_lowcore.vmcore_info = __kaslr_offset ? __kaslr_offset | 0x1UL : 0;
473
474 /*
475 * Jump to the decompressed kernel entry point and switch DAT mode on.
476 */
477 psw.addr = vmlinux.entry;
478 psw.mask = PSW_KERNEL_BITS;
479 __load_psw(psw);
480}
481

source code of linux/arch/s390/boot/startup.c