1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/string.h>
3 #include <linux/elf.h>
4 #include <asm/boot_data.h>
5 #include <asm/sections.h>
6 #include <asm/cpu_mf.h>
7 #include <asm/setup.h>
8 #include <asm/kasan.h>
9 #include <asm/kexec.h>
10 #include <asm/sclp.h>
11 #include <asm/diag.h>
12 #include <asm/uv.h>
13 #include "compressed/decompressor.h"
14 #include "boot.h"
15 #include "uv.h"
16
17 unsigned long __bootdata_preserved(__kaslr_offset);
18 unsigned long __bootdata(__amode31_base);
19 unsigned long __bootdata_preserved(VMALLOC_START);
20 unsigned long __bootdata_preserved(VMALLOC_END);
21 struct page *__bootdata_preserved(vmemmap);
22 unsigned long __bootdata_preserved(vmemmap_size);
23 unsigned long __bootdata_preserved(MODULES_VADDR);
24 unsigned long __bootdata_preserved(MODULES_END);
25 unsigned long __bootdata(ident_map_size);
26 int __bootdata(is_full_image) = 1;
27 struct initrd_data __bootdata(initrd_data);
28
29 u64 __bootdata_preserved(stfle_fac_list[16]);
30 u64 __bootdata_preserved(alt_stfle_fac_list[16]);
31 struct oldmem_data __bootdata_preserved(oldmem_data);
32
error(char * x)33 void error(char *x)
34 {
35 sclp_early_printk("\n\n");
36 sclp_early_printk(x);
37 sclp_early_printk("\n\n -- System halted");
38
39 disabled_wait();
40 }
41
setup_lpp(void)42 static void setup_lpp(void)
43 {
44 S390_lowcore.current_pid = 0;
45 S390_lowcore.lpp = LPP_MAGIC;
46 if (test_facility(40))
47 lpp(&S390_lowcore.lpp);
48 }
49
50 #ifdef CONFIG_KERNEL_UNCOMPRESSED
mem_safe_offset(void)51 unsigned long mem_safe_offset(void)
52 {
53 return vmlinux.default_lma + vmlinux.image_size + vmlinux.bss_size;
54 }
55 #endif
56
rescue_initrd(unsigned long addr)57 static void rescue_initrd(unsigned long addr)
58 {
59 if (!IS_ENABLED(CONFIG_BLK_DEV_INITRD))
60 return;
61 if (!initrd_data.start || !initrd_data.size)
62 return;
63 if (addr <= initrd_data.start)
64 return;
65 memmove((void *)addr, (void *)initrd_data.start, initrd_data.size);
66 initrd_data.start = addr;
67 }
68
copy_bootdata(void)69 static void copy_bootdata(void)
70 {
71 if (__boot_data_end - __boot_data_start != vmlinux.bootdata_size)
72 error(".boot.data section size mismatch");
73 memcpy((void *)vmlinux.bootdata_off, __boot_data_start, vmlinux.bootdata_size);
74 if (__boot_data_preserved_end - __boot_data_preserved_start != vmlinux.bootdata_preserved_size)
75 error(".boot.preserved.data section size mismatch");
76 memcpy((void *)vmlinux.bootdata_preserved_off, __boot_data_preserved_start, vmlinux.bootdata_preserved_size);
77 }
78
handle_relocs(unsigned long offset)79 static void handle_relocs(unsigned long offset)
80 {
81 Elf64_Rela *rela_start, *rela_end, *rela;
82 int r_type, r_sym, rc;
83 Elf64_Addr loc, val;
84 Elf64_Sym *dynsym;
85
86 rela_start = (Elf64_Rela *) vmlinux.rela_dyn_start;
87 rela_end = (Elf64_Rela *) vmlinux.rela_dyn_end;
88 dynsym = (Elf64_Sym *) vmlinux.dynsym_start;
89 for (rela = rela_start; rela < rela_end; rela++) {
90 loc = rela->r_offset + offset;
91 val = rela->r_addend;
92 r_sym = ELF64_R_SYM(rela->r_info);
93 if (r_sym) {
94 if (dynsym[r_sym].st_shndx != SHN_UNDEF)
95 val += dynsym[r_sym].st_value + offset;
96 } else {
97 /*
98 * 0 == undefined symbol table index (STN_UNDEF),
99 * used for R_390_RELATIVE, only add KASLR offset
100 */
101 val += offset;
102 }
103 r_type = ELF64_R_TYPE(rela->r_info);
104 rc = arch_kexec_do_relocs(r_type, (void *) loc, val, 0);
105 if (rc)
106 error("Unknown relocation type");
107 }
108 }
109
110 /*
111 * Merge information from several sources into a single ident_map_size value.
112 * "ident_map_size" represents the upper limit of physical memory we may ever
113 * reach. It might not be all online memory, but also include standby (offline)
114 * memory. "ident_map_size" could be lower then actual standby or even online
115 * memory present, due to limiting factors. We should never go above this limit.
116 * It is the size of our identity mapping.
117 *
118 * Consider the following factors:
119 * 1. max_physmem_end - end of physical memory online or standby.
120 * Always <= end of the last online memory block (get_mem_detect_end()).
121 * 2. CONFIG_MAX_PHYSMEM_BITS - the maximum size of physical memory the
122 * kernel is able to support.
123 * 3. "mem=" kernel command line option which limits physical memory usage.
124 * 4. OLDMEM_BASE which is a kdump memory limit when the kernel is executed as
125 * crash kernel.
126 * 5. "hsa" size which is a memory limit when the kernel is executed during
127 * zfcp/nvme dump.
128 */
setup_ident_map_size(unsigned long max_physmem_end)129 static void setup_ident_map_size(unsigned long max_physmem_end)
130 {
131 unsigned long hsa_size;
132
133 ident_map_size = max_physmem_end;
134 if (memory_limit)
135 ident_map_size = min(ident_map_size, memory_limit);
136 ident_map_size = min(ident_map_size, 1UL << MAX_PHYSMEM_BITS);
137
138 #ifdef CONFIG_CRASH_DUMP
139 if (oldmem_data.start) {
140 kaslr_enabled = 0;
141 ident_map_size = min(ident_map_size, oldmem_data.size);
142 } else if (ipl_block_valid && is_ipl_block_dump()) {
143 kaslr_enabled = 0;
144 if (!sclp_early_get_hsa_size(&hsa_size) && hsa_size)
145 ident_map_size = min(ident_map_size, hsa_size);
146 }
147 #endif
148 }
149
setup_kernel_memory_layout(void)150 static void setup_kernel_memory_layout(void)
151 {
152 unsigned long vmemmap_start;
153 unsigned long rte_size;
154 unsigned long pages;
155
156 pages = ident_map_size / PAGE_SIZE;
157 /* vmemmap contains a multiple of PAGES_PER_SECTION struct pages */
158 vmemmap_size = SECTION_ALIGN_UP(pages) * sizeof(struct page);
159
160 /* choose kernel address space layout: 4 or 3 levels. */
161 vmemmap_start = round_up(ident_map_size, _REGION3_SIZE);
162 if (IS_ENABLED(CONFIG_KASAN) ||
163 vmalloc_size > _REGION2_SIZE ||
164 vmemmap_start + vmemmap_size + vmalloc_size + MODULES_LEN >
165 _REGION2_SIZE) {
166 MODULES_END = _REGION1_SIZE;
167 rte_size = _REGION2_SIZE;
168 } else {
169 MODULES_END = _REGION2_SIZE;
170 rte_size = _REGION3_SIZE;
171 }
172 /*
173 * forcing modules and vmalloc area under the ultravisor
174 * secure storage limit, so that any vmalloc allocation
175 * we do could be used to back secure guest storage.
176 */
177 adjust_to_uv_max(&MODULES_END);
178 #ifdef CONFIG_KASAN
179 /* force vmalloc and modules below kasan shadow */
180 MODULES_END = min(MODULES_END, KASAN_SHADOW_START);
181 #endif
182 MODULES_VADDR = MODULES_END - MODULES_LEN;
183 VMALLOC_END = MODULES_VADDR;
184
185 /* allow vmalloc area to occupy up to about 1/2 of the rest virtual space left */
186 vmalloc_size = min(vmalloc_size, round_down(VMALLOC_END / 2, _REGION3_SIZE));
187 VMALLOC_START = VMALLOC_END - vmalloc_size;
188
189 /* split remaining virtual space between 1:1 mapping & vmemmap array */
190 pages = VMALLOC_START / (PAGE_SIZE + sizeof(struct page));
191 pages = SECTION_ALIGN_UP(pages);
192 /* keep vmemmap_start aligned to a top level region table entry */
193 vmemmap_start = round_down(VMALLOC_START - pages * sizeof(struct page), rte_size);
194 /* vmemmap_start is the future VMEM_MAX_PHYS, make sure it is within MAX_PHYSMEM */
195 vmemmap_start = min(vmemmap_start, 1UL << MAX_PHYSMEM_BITS);
196 /* make sure identity map doesn't overlay with vmemmap */
197 ident_map_size = min(ident_map_size, vmemmap_start);
198 vmemmap_size = SECTION_ALIGN_UP(ident_map_size / PAGE_SIZE) * sizeof(struct page);
199 /* make sure vmemmap doesn't overlay with vmalloc area */
200 VMALLOC_START = max(vmemmap_start + vmemmap_size, VMALLOC_START);
201 vmemmap = (struct page *)vmemmap_start;
202 }
203
204 /*
205 * This function clears the BSS section of the decompressed Linux kernel and NOT the decompressor's.
206 */
clear_bss_section(void)207 static void clear_bss_section(void)
208 {
209 memset((void *)vmlinux.default_lma + vmlinux.image_size, 0, vmlinux.bss_size);
210 }
211
212 /*
213 * Set vmalloc area size to an 8th of (potential) physical memory
214 * size, unless size has been set by kernel command line parameter.
215 */
setup_vmalloc_size(void)216 static void setup_vmalloc_size(void)
217 {
218 unsigned long size;
219
220 if (vmalloc_size_set)
221 return;
222 size = round_up(ident_map_size / 8, _SEGMENT_SIZE);
223 vmalloc_size = max(size, vmalloc_size);
224 }
225
offset_vmlinux_info(unsigned long offset)226 static void offset_vmlinux_info(unsigned long offset)
227 {
228 vmlinux.default_lma += offset;
229 *(unsigned long *)(&vmlinux.entry) += offset;
230 vmlinux.bootdata_off += offset;
231 vmlinux.bootdata_preserved_off += offset;
232 vmlinux.rela_dyn_start += offset;
233 vmlinux.rela_dyn_end += offset;
234 vmlinux.dynsym_start += offset;
235 }
236
reserve_amode31(unsigned long safe_addr)237 static unsigned long reserve_amode31(unsigned long safe_addr)
238 {
239 __amode31_base = PAGE_ALIGN(safe_addr);
240 return safe_addr + vmlinux.amode31_size;
241 }
242
startup_kernel(void)243 void startup_kernel(void)
244 {
245 unsigned long random_lma;
246 unsigned long safe_addr;
247 void *img;
248
249 initrd_data.start = parmarea.initrd_start;
250 initrd_data.size = parmarea.initrd_size;
251 oldmem_data.start = parmarea.oldmem_base;
252 oldmem_data.size = parmarea.oldmem_size;
253
254 setup_lpp();
255 store_ipl_parmblock();
256 safe_addr = mem_safe_offset();
257 safe_addr = reserve_amode31(safe_addr);
258 safe_addr = read_ipl_report(safe_addr);
259 uv_query_info();
260 rescue_initrd(safe_addr);
261 sclp_early_read_info();
262 setup_boot_command_line();
263 parse_boot_command_line();
264 sanitize_prot_virt_host();
265 setup_ident_map_size(detect_memory());
266 setup_vmalloc_size();
267 setup_kernel_memory_layout();
268
269 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && kaslr_enabled) {
270 random_lma = get_random_base(safe_addr);
271 if (random_lma) {
272 __kaslr_offset = random_lma - vmlinux.default_lma;
273 img = (void *)vmlinux.default_lma;
274 offset_vmlinux_info(__kaslr_offset);
275 }
276 }
277
278 if (!IS_ENABLED(CONFIG_KERNEL_UNCOMPRESSED)) {
279 img = decompress_kernel();
280 memmove((void *)vmlinux.default_lma, img, vmlinux.image_size);
281 } else if (__kaslr_offset)
282 memcpy((void *)vmlinux.default_lma, img, vmlinux.image_size);
283
284 clear_bss_section();
285 copy_bootdata();
286 if (IS_ENABLED(CONFIG_RELOCATABLE))
287 handle_relocs(__kaslr_offset);
288
289 if (__kaslr_offset) {
290 /*
291 * Save KASLR offset for early dumps, before vmcore_info is set.
292 * Mark as uneven to distinguish from real vmcore_info pointer.
293 */
294 S390_lowcore.vmcore_info = __kaslr_offset | 0x1UL;
295 /* Clear non-relocated kernel */
296 if (IS_ENABLED(CONFIG_KERNEL_UNCOMPRESSED))
297 memset(img, 0, vmlinux.image_size);
298 }
299 vmlinux.entry();
300 }
301