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/extmem.h>
7 #include <asm/sections.h>
8 #include <asm/maccess.h>
9 #include <asm/cpu_mf.h>
10 #include <asm/setup.h>
11 #include <asm/kasan.h>
12 #include <asm/kexec.h>
13 #include <asm/sclp.h>
14 #include <asm/diag.h>
15 #include <asm/uv.h>
16 #include <asm/abs_lowcore.h>
17 #include <asm/physmem_info.h>
18 #include "decompressor.h"
19 #include "boot.h"
20 #include "uv.h"
21 
22 struct vm_layout __bootdata_preserved(vm_layout);
23 unsigned long __bootdata_preserved(__abs_lowcore);
24 unsigned long __bootdata_preserved(__memcpy_real_area);
25 pte_t *__bootdata_preserved(memcpy_real_ptep);
26 unsigned long __bootdata_preserved(VMALLOC_START);
27 unsigned long __bootdata_preserved(VMALLOC_END);
28 struct page *__bootdata_preserved(vmemmap);
29 unsigned long __bootdata_preserved(vmemmap_size);
30 unsigned long __bootdata_preserved(MODULES_VADDR);
31 unsigned long __bootdata_preserved(MODULES_END);
32 unsigned long __bootdata_preserved(max_mappable);
33 int __bootdata_preserved(relocate_lowcore);
34 
35 u64 __bootdata_preserved(stfle_fac_list[16]);
36 struct oldmem_data __bootdata_preserved(oldmem_data);
37 
38 struct machine_info machine;
39 
error(char * x)40 void error(char *x)
41 {
42 	boot_printk("\n\n%s\n\n -- System halted", x);
43 	disabled_wait();
44 }
45 
detect_facilities(void)46 static void detect_facilities(void)
47 {
48 	if (test_facility(8)) {
49 		machine.has_edat1 = 1;
50 		local_ctl_set_bit(0, CR0_EDAT_BIT);
51 	}
52 	if (test_facility(78))
53 		machine.has_edat2 = 1;
54 	if (test_facility(130))
55 		machine.has_nx = 1;
56 }
57 
cmma_test_essa(void)58 static int cmma_test_essa(void)
59 {
60 	unsigned long reg1, reg2, tmp = 0;
61 	int rc = 1;
62 	psw_t old;
63 
64 	/* Test ESSA_GET_STATE */
65 	asm volatile(
66 		"	mvc	0(16,%[psw_old]),0(%[psw_pgm])\n"
67 		"	epsw	%[reg1],%[reg2]\n"
68 		"	st	%[reg1],0(%[psw_pgm])\n"
69 		"	st	%[reg2],4(%[psw_pgm])\n"
70 		"	larl	%[reg1],1f\n"
71 		"	stg	%[reg1],8(%[psw_pgm])\n"
72 		"	.insn	rrf,0xb9ab0000,%[tmp],%[tmp],%[cmd],0\n"
73 		"	la	%[rc],0\n"
74 		"1:	mvc	0(16,%[psw_pgm]),0(%[psw_old])\n"
75 		: [reg1] "=&d" (reg1),
76 		  [reg2] "=&a" (reg2),
77 		  [rc] "+&d" (rc),
78 		  [tmp] "=&d" (tmp),
79 		  "+Q" (get_lowcore()->program_new_psw),
80 		  "=Q" (old)
81 		: [psw_old] "a" (&old),
82 		  [psw_pgm] "a" (&get_lowcore()->program_new_psw),
83 		  [cmd] "i" (ESSA_GET_STATE)
84 		: "cc", "memory");
85 	return rc;
86 }
87 
cmma_init(void)88 static void cmma_init(void)
89 {
90 	if (!cmma_flag)
91 		return;
92 	if (cmma_test_essa()) {
93 		cmma_flag = 0;
94 		return;
95 	}
96 	if (test_facility(147))
97 		cmma_flag = 2;
98 }
99 
setup_lpp(void)100 static void setup_lpp(void)
101 {
102 	get_lowcore()->current_pid = 0;
103 	get_lowcore()->lpp = LPP_MAGIC;
104 	if (test_facility(40))
105 		lpp(&get_lowcore()->lpp);
106 }
107 
108 #ifdef CONFIG_KERNEL_UNCOMPRESSED
mem_safe_offset(void)109 static unsigned long mem_safe_offset(void)
110 {
111 	return (unsigned long)_compressed_start;
112 }
113 
deploy_kernel(void * output)114 static void deploy_kernel(void *output)
115 {
116 	void *uncompressed_start = (void *)_compressed_start;
117 
118 	if (output == uncompressed_start)
119 		return;
120 	memmove(output, uncompressed_start, vmlinux.image_size);
121 	memset(uncompressed_start, 0, vmlinux.image_size);
122 }
123 #endif
124 
rescue_initrd(unsigned long min,unsigned long max)125 static void rescue_initrd(unsigned long min, unsigned long max)
126 {
127 	unsigned long old_addr, addr, size;
128 
129 	if (!IS_ENABLED(CONFIG_BLK_DEV_INITRD))
130 		return;
131 	if (!get_physmem_reserved(RR_INITRD, &addr, &size))
132 		return;
133 	if (addr >= min && addr + size <= max)
134 		return;
135 	old_addr = addr;
136 	physmem_free(RR_INITRD);
137 	addr = physmem_alloc_top_down(RR_INITRD, size, 0);
138 	memmove((void *)addr, (void *)old_addr, size);
139 }
140 
copy_bootdata(void)141 static void copy_bootdata(void)
142 {
143 	if (__boot_data_end - __boot_data_start != vmlinux.bootdata_size)
144 		error(".boot.data section size mismatch");
145 	memcpy((void *)vmlinux.bootdata_off, __boot_data_start, vmlinux.bootdata_size);
146 	if (__boot_data_preserved_end - __boot_data_preserved_start != vmlinux.bootdata_preserved_size)
147 		error(".boot.preserved.data section size mismatch");
148 	memcpy((void *)vmlinux.bootdata_preserved_off, __boot_data_preserved_start, vmlinux.bootdata_preserved_size);
149 }
150 
kaslr_adjust_relocs(unsigned long min_addr,unsigned long max_addr,unsigned long offset,unsigned long phys_offset)151 static void kaslr_adjust_relocs(unsigned long min_addr, unsigned long max_addr,
152 				unsigned long offset, unsigned long phys_offset)
153 {
154 	int *reloc;
155 	long loc;
156 
157 	/* Adjust R_390_64 relocations */
158 	for (reloc = (int *)__vmlinux_relocs_64_start; reloc < (int *)__vmlinux_relocs_64_end; reloc++) {
159 		loc = (long)*reloc + phys_offset;
160 		if (loc < min_addr || loc > max_addr)
161 			error("64-bit relocation outside of kernel!\n");
162 		*(u64 *)loc += offset;
163 	}
164 }
165 
kaslr_adjust_got(unsigned long offset)166 static void kaslr_adjust_got(unsigned long offset)
167 {
168 	u64 *entry;
169 
170 	/*
171 	 * Adjust GOT entries, except for ones for undefined weak symbols
172 	 * that resolved to zero. This also skips the first three reserved
173 	 * entries on s390x that are zero.
174 	 */
175 	for (entry = (u64 *)vmlinux.got_start; entry < (u64 *)vmlinux.got_end; entry++) {
176 		if (*entry)
177 			*entry += offset;
178 	}
179 }
180 
181 /*
182  * Merge information from several sources into a single ident_map_size value.
183  * "ident_map_size" represents the upper limit of physical memory we may ever
184  * reach. It might not be all online memory, but also include standby (offline)
185  * memory. "ident_map_size" could be lower then actual standby or even online
186  * memory present, due to limiting factors. We should never go above this limit.
187  * It is the size of our identity mapping.
188  *
189  * Consider the following factors:
190  * 1. max_physmem_end - end of physical memory online or standby.
191  *    Always >= end of the last online memory range (get_physmem_online_end()).
192  * 2. CONFIG_MAX_PHYSMEM_BITS - the maximum size of physical memory the
193  *    kernel is able to support.
194  * 3. "mem=" kernel command line option which limits physical memory usage.
195  * 4. OLDMEM_BASE which is a kdump memory limit when the kernel is executed as
196  *    crash kernel.
197  * 5. "hsa" size which is a memory limit when the kernel is executed during
198  *    zfcp/nvme dump.
199  */
setup_ident_map_size(unsigned long max_physmem_end)200 static void setup_ident_map_size(unsigned long max_physmem_end)
201 {
202 	unsigned long hsa_size;
203 
204 	ident_map_size = max_physmem_end;
205 	if (memory_limit)
206 		ident_map_size = min(ident_map_size, memory_limit);
207 	ident_map_size = min(ident_map_size, 1UL << MAX_PHYSMEM_BITS);
208 
209 #ifdef CONFIG_CRASH_DUMP
210 	if (oldmem_data.start) {
211 		__kaslr_enabled = 0;
212 		ident_map_size = min(ident_map_size, oldmem_data.size);
213 	} else if (ipl_block_valid && is_ipl_block_dump()) {
214 		__kaslr_enabled = 0;
215 		if (!sclp_early_get_hsa_size(&hsa_size) && hsa_size)
216 			ident_map_size = min(ident_map_size, hsa_size);
217 	}
218 #endif
219 }
220 
221 #define FIXMAP_SIZE	round_up(MEMCPY_REAL_SIZE + ABS_LOWCORE_MAP_SIZE, sizeof(struct lowcore))
222 
get_vmem_size(unsigned long identity_size,unsigned long vmemmap_size,unsigned long vmalloc_size,unsigned long rte_size)223 static unsigned long get_vmem_size(unsigned long identity_size,
224 				   unsigned long vmemmap_size,
225 				   unsigned long vmalloc_size,
226 				   unsigned long rte_size)
227 {
228 	unsigned long max_mappable, vsize;
229 
230 	max_mappable = max(identity_size, MAX_DCSS_ADDR);
231 	vsize = round_up(SZ_2G + max_mappable, rte_size) +
232 		round_up(vmemmap_size, rte_size) +
233 		FIXMAP_SIZE + MODULES_LEN + KASLR_LEN;
234 	return size_add(vsize, vmalloc_size);
235 }
236 
setup_kernel_memory_layout(unsigned long kernel_size)237 static unsigned long setup_kernel_memory_layout(unsigned long kernel_size)
238 {
239 	unsigned long vmemmap_start;
240 	unsigned long kernel_start;
241 	unsigned long asce_limit;
242 	unsigned long rte_size;
243 	unsigned long pages;
244 	unsigned long vsize;
245 	unsigned long vmax;
246 
247 	pages = ident_map_size / PAGE_SIZE;
248 	/* vmemmap contains a multiple of PAGES_PER_SECTION struct pages */
249 	vmemmap_size = SECTION_ALIGN_UP(pages) * sizeof(struct page);
250 
251 	/* choose kernel address space layout: 4 or 3 levels. */
252 	BUILD_BUG_ON(!IS_ALIGNED(TEXT_OFFSET, THREAD_SIZE));
253 	BUILD_BUG_ON(!IS_ALIGNED(__NO_KASLR_START_KERNEL, THREAD_SIZE));
254 	BUILD_BUG_ON(__NO_KASLR_END_KERNEL > _REGION1_SIZE);
255 	vsize = get_vmem_size(ident_map_size, vmemmap_size, vmalloc_size, _REGION3_SIZE);
256 	if (IS_ENABLED(CONFIG_KASAN) || __NO_KASLR_END_KERNEL > _REGION2_SIZE ||
257 	    (vsize > _REGION2_SIZE && kaslr_enabled())) {
258 		asce_limit = _REGION1_SIZE;
259 		if (__NO_KASLR_END_KERNEL > _REGION2_SIZE) {
260 			rte_size = _REGION2_SIZE;
261 			vsize = get_vmem_size(ident_map_size, vmemmap_size, vmalloc_size, _REGION2_SIZE);
262 		} else {
263 			rte_size = _REGION3_SIZE;
264 		}
265 	} else {
266 		asce_limit = _REGION2_SIZE;
267 		rte_size = _REGION3_SIZE;
268 	}
269 
270 	/*
271 	 * Forcing modules and vmalloc area under the ultravisor
272 	 * secure storage limit, so that any vmalloc allocation
273 	 * we do could be used to back secure guest storage.
274 	 *
275 	 * Assume the secure storage limit always exceeds _REGION2_SIZE,
276 	 * otherwise asce_limit and rte_size would have been adjusted.
277 	 */
278 	vmax = adjust_to_uv_max(asce_limit);
279 #ifdef CONFIG_KASAN
280 	BUILD_BUG_ON(__NO_KASLR_END_KERNEL > KASAN_SHADOW_START);
281 	/* force vmalloc and modules below kasan shadow */
282 	vmax = min(vmax, KASAN_SHADOW_START);
283 #endif
284 	vsize = min(vsize, vmax);
285 	if (kaslr_enabled()) {
286 		unsigned long kernel_end, kaslr_len, slots, pos;
287 
288 		kaslr_len = max(KASLR_LEN, vmax - vsize);
289 		slots = DIV_ROUND_UP(kaslr_len - kernel_size, THREAD_SIZE);
290 		if (get_random(slots, &pos))
291 			pos = 0;
292 		kernel_end = vmax - pos * THREAD_SIZE;
293 		kernel_start = round_down(kernel_end - kernel_size, THREAD_SIZE);
294 	} else if (vmax < __NO_KASLR_END_KERNEL || vsize > __NO_KASLR_END_KERNEL) {
295 		kernel_start = round_down(vmax - kernel_size, THREAD_SIZE);
296 		boot_printk("The kernel base address is forced to %lx\n", kernel_start);
297 	} else {
298 		kernel_start = __NO_KASLR_START_KERNEL;
299 	}
300 	__kaslr_offset = kernel_start;
301 
302 	MODULES_END = round_down(kernel_start, _SEGMENT_SIZE);
303 	MODULES_VADDR = MODULES_END - MODULES_LEN;
304 	VMALLOC_END = MODULES_VADDR;
305 	if (IS_ENABLED(CONFIG_KMSAN))
306 		VMALLOC_END -= MODULES_LEN * 2;
307 
308 	/* allow vmalloc area to occupy up to about 1/2 of the rest virtual space left */
309 	vsize = (VMALLOC_END - FIXMAP_SIZE) / 2;
310 	vsize = round_down(vsize, _SEGMENT_SIZE);
311 	vmalloc_size = min(vmalloc_size, vsize);
312 	if (IS_ENABLED(CONFIG_KMSAN)) {
313 		/* take 2/3 of vmalloc area for KMSAN shadow and origins */
314 		vmalloc_size = round_down(vmalloc_size / 3, _SEGMENT_SIZE);
315 		VMALLOC_END -= vmalloc_size * 2;
316 	}
317 	VMALLOC_START = VMALLOC_END - vmalloc_size;
318 
319 	__memcpy_real_area = round_down(VMALLOC_START - MEMCPY_REAL_SIZE, PAGE_SIZE);
320 	__abs_lowcore = round_down(__memcpy_real_area - ABS_LOWCORE_MAP_SIZE,
321 				   sizeof(struct lowcore));
322 
323 	/* split remaining virtual space between 1:1 mapping & vmemmap array */
324 	pages = __abs_lowcore / (PAGE_SIZE + sizeof(struct page));
325 	pages = SECTION_ALIGN_UP(pages);
326 	/* keep vmemmap_start aligned to a top level region table entry */
327 	vmemmap_start = round_down(__abs_lowcore - pages * sizeof(struct page), rte_size);
328 	/* make sure identity map doesn't overlay with vmemmap */
329 	ident_map_size = min(ident_map_size, vmemmap_start);
330 	vmemmap_size = SECTION_ALIGN_UP(ident_map_size / PAGE_SIZE) * sizeof(struct page);
331 	/* make sure vmemmap doesn't overlay with absolute lowcore area */
332 	if (vmemmap_start + vmemmap_size > __abs_lowcore) {
333 		vmemmap_size = SECTION_ALIGN_DOWN(ident_map_size / PAGE_SIZE) * sizeof(struct page);
334 		ident_map_size = vmemmap_size / sizeof(struct page) * PAGE_SIZE;
335 	}
336 	vmemmap = (struct page *)vmemmap_start;
337 	/* maximum address for which linear mapping could be created (DCSS, memory) */
338 	BUILD_BUG_ON(MAX_DCSS_ADDR > (1UL << MAX_PHYSMEM_BITS));
339 	max_mappable = max(ident_map_size, MAX_DCSS_ADDR);
340 	max_mappable = min(max_mappable, vmemmap_start);
341 	if (IS_ENABLED(CONFIG_RANDOMIZE_IDENTITY_BASE))
342 		__identity_base = round_down(vmemmap_start - max_mappable, rte_size);
343 
344 	return asce_limit;
345 }
346 
347 /*
348  * This function clears the BSS section of the decompressed Linux kernel and NOT the decompressor's.
349  */
clear_bss_section(unsigned long kernel_start)350 static void clear_bss_section(unsigned long kernel_start)
351 {
352 	memset((void *)kernel_start + vmlinux.image_size, 0, vmlinux.bss_size);
353 }
354 
355 /*
356  * Set vmalloc area size to an 8th of (potential) physical memory
357  * size, unless size has been set by kernel command line parameter.
358  */
setup_vmalloc_size(void)359 static void setup_vmalloc_size(void)
360 {
361 	unsigned long size;
362 
363 	if (vmalloc_size_set)
364 		return;
365 	size = round_up(ident_map_size / 8, _SEGMENT_SIZE);
366 	vmalloc_size = max(size, vmalloc_size);
367 }
368 
kaslr_adjust_vmlinux_info(long offset)369 static void kaslr_adjust_vmlinux_info(long offset)
370 {
371 	vmlinux.bootdata_off += offset;
372 	vmlinux.bootdata_preserved_off += offset;
373 	vmlinux.got_start += offset;
374 	vmlinux.got_end += offset;
375 	vmlinux.init_mm_off += offset;
376 	vmlinux.swapper_pg_dir_off += offset;
377 	vmlinux.invalid_pg_dir_off += offset;
378 	vmlinux.alt_instructions += offset;
379 	vmlinux.alt_instructions_end += offset;
380 #ifdef CONFIG_KASAN
381 	vmlinux.kasan_early_shadow_page_off += offset;
382 	vmlinux.kasan_early_shadow_pte_off += offset;
383 	vmlinux.kasan_early_shadow_pmd_off += offset;
384 	vmlinux.kasan_early_shadow_pud_off += offset;
385 	vmlinux.kasan_early_shadow_p4d_off += offset;
386 #endif
387 }
388 
startup_kernel(void)389 void startup_kernel(void)
390 {
391 	unsigned long vmlinux_size = vmlinux.image_size + vmlinux.bss_size;
392 	unsigned long nokaslr_text_lma, text_lma = 0, amode31_lma = 0;
393 	unsigned long kernel_size = TEXT_OFFSET + vmlinux_size;
394 	unsigned long kaslr_large_page_offset;
395 	unsigned long max_physmem_end;
396 	unsigned long asce_limit;
397 	unsigned long safe_addr;
398 	psw_t psw;
399 
400 	setup_lpp();
401 
402 	/*
403 	 * Non-randomized kernel physical start address must be _SEGMENT_SIZE
404 	 * aligned (see blow).
405 	 */
406 	nokaslr_text_lma = ALIGN(mem_safe_offset(), _SEGMENT_SIZE);
407 	safe_addr = PAGE_ALIGN(nokaslr_text_lma + vmlinux_size);
408 
409 	/*
410 	 * Reserve decompressor memory together with decompression heap,
411 	 * buffer and memory which might be occupied by uncompressed kernel
412 	 * (if KASLR is off or failed).
413 	 */
414 	physmem_reserve(RR_DECOMPRESSOR, 0, safe_addr);
415 	if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && parmarea.initrd_size)
416 		physmem_reserve(RR_INITRD, parmarea.initrd_start, parmarea.initrd_size);
417 	oldmem_data.start = parmarea.oldmem_base;
418 	oldmem_data.size = parmarea.oldmem_size;
419 
420 	store_ipl_parmblock();
421 	read_ipl_report();
422 	uv_query_info();
423 	sclp_early_read_info();
424 	setup_boot_command_line();
425 	parse_boot_command_line();
426 	detect_facilities();
427 	cmma_init();
428 	sanitize_prot_virt_host();
429 	max_physmem_end = detect_max_physmem_end();
430 	setup_ident_map_size(max_physmem_end);
431 	setup_vmalloc_size();
432 	asce_limit = setup_kernel_memory_layout(kernel_size);
433 	/* got final ident_map_size, physmem allocations could be performed now */
434 	physmem_set_usable_limit(ident_map_size);
435 	detect_physmem_online_ranges(max_physmem_end);
436 	save_ipl_cert_comp_list();
437 	rescue_initrd(safe_addr, ident_map_size);
438 
439 	/*
440 	 * __kaslr_offset_phys must be _SEGMENT_SIZE aligned, so the lower
441 	 * 20 bits (the offset within a large page) are zero. Copy the last
442 	 * 20 bits of __kaslr_offset, which is THREAD_SIZE aligned, to
443 	 * __kaslr_offset_phys.
444 	 *
445 	 * With this the last 20 bits of __kaslr_offset_phys and __kaslr_offset
446 	 * are identical, which is required to allow for large mappings of the
447 	 * kernel image.
448 	 */
449 	kaslr_large_page_offset = __kaslr_offset & ~_SEGMENT_MASK;
450 	if (kaslr_enabled()) {
451 		unsigned long size = vmlinux_size + kaslr_large_page_offset;
452 
453 		text_lma = randomize_within_range(size, _SEGMENT_SIZE, TEXT_OFFSET, ident_map_size);
454 	}
455 	if (!text_lma)
456 		text_lma = nokaslr_text_lma;
457 	text_lma |= kaslr_large_page_offset;
458 
459 	/*
460 	 * [__kaslr_offset_phys..__kaslr_offset_phys + TEXT_OFFSET] region is
461 	 * never accessed via the kernel image mapping as per the linker script:
462 	 *
463 	 *	. = TEXT_OFFSET;
464 	 *
465 	 * Therefore, this region could be used for something else and does
466 	 * not need to be reserved. See how it is skipped in setup_vmem().
467 	 */
468 	__kaslr_offset_phys = text_lma - TEXT_OFFSET;
469 	kaslr_adjust_vmlinux_info(__kaslr_offset_phys);
470 	physmem_reserve(RR_VMLINUX, text_lma, vmlinux_size);
471 	deploy_kernel((void *)text_lma);
472 
473 	/* vmlinux decompression is done, shrink reserved low memory */
474 	physmem_reserve(RR_DECOMPRESSOR, 0, (unsigned long)_decompressor_end);
475 
476 	/*
477 	 * In case KASLR is enabled the randomized location of .amode31
478 	 * section might overlap with .vmlinux.relocs section. To avoid that
479 	 * the below randomize_within_range() could have been called with
480 	 * __vmlinux_relocs_64_end as the lower range address. However,
481 	 * .amode31 section is written to by the decompressed kernel - at
482 	 * that time the contents of .vmlinux.relocs is not needed anymore.
483 	 * Conversly, .vmlinux.relocs is read only by the decompressor, even
484 	 * before the kernel started. Therefore, in case the two sections
485 	 * overlap there is no risk of corrupting any data.
486 	 */
487 	if (kaslr_enabled()) {
488 		unsigned long amode31_min;
489 
490 		amode31_min = (unsigned long)_decompressor_end;
491 		amode31_lma = randomize_within_range(vmlinux.amode31_size, PAGE_SIZE, amode31_min, SZ_2G);
492 	}
493 	if (!amode31_lma)
494 		amode31_lma = text_lma - vmlinux.amode31_size;
495 	physmem_reserve(RR_AMODE31, amode31_lma, vmlinux.amode31_size);
496 
497 	/*
498 	 * The order of the following operations is important:
499 	 *
500 	 * - kaslr_adjust_relocs() must follow clear_bss_section() to establish
501 	 *   static memory references to data in .bss to be used by setup_vmem()
502 	 *   (i.e init_mm.pgd)
503 	 *
504 	 * - setup_vmem() must follow kaslr_adjust_relocs() to be able using
505 	 *   static memory references to data in .bss (i.e init_mm.pgd)
506 	 *
507 	 * - copy_bootdata() must follow setup_vmem() to propagate changes
508 	 *   to bootdata made by setup_vmem()
509 	 */
510 	clear_bss_section(text_lma);
511 	kaslr_adjust_relocs(text_lma, text_lma + vmlinux.image_size,
512 			    __kaslr_offset, __kaslr_offset_phys);
513 	kaslr_adjust_got(__kaslr_offset);
514 	setup_vmem(__kaslr_offset, __kaslr_offset + kernel_size, asce_limit);
515 	copy_bootdata();
516 	__apply_alternatives((struct alt_instr *)_vmlinux_info.alt_instructions,
517 			     (struct alt_instr *)_vmlinux_info.alt_instructions_end,
518 			     ALT_CTX_EARLY);
519 
520 	/*
521 	 * Save KASLR offset for early dumps, before vmcore_info is set.
522 	 * Mark as uneven to distinguish from real vmcore_info pointer.
523 	 */
524 	get_lowcore()->vmcore_info = __kaslr_offset_phys ? __kaslr_offset_phys | 0x1UL : 0;
525 
526 	/*
527 	 * Jump to the decompressed kernel entry point and switch DAT mode on.
528 	 */
529 	psw.addr = __kaslr_offset + vmlinux.entry;
530 	psw.mask = PSW_KERNEL_BITS;
531 	__load_psw(psw);
532 }
533