1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Architecture specific (i386/x86_64) functions for kexec based crash dumps. 4 * 5 * Created by: Hariprasad Nellitheertha (hari@in.ibm.com) 6 * 7 * Copyright (C) IBM Corporation, 2004. All rights reserved. 8 * Copyright (C) Red Hat Inc., 2014. All rights reserved. 9 * Authors: 10 * Vivek Goyal <vgoyal@redhat.com> 11 * 12 */ 13 14 #define pr_fmt(fmt) "kexec: " fmt 15 16 #include <linux/types.h> 17 #include <linux/kernel.h> 18 #include <linux/smp.h> 19 #include <linux/reboot.h> 20 #include <linux/kexec.h> 21 #include <linux/delay.h> 22 #include <linux/elf.h> 23 #include <linux/elfcore.h> 24 #include <linux/export.h> 25 #include <linux/slab.h> 26 #include <linux/vmalloc.h> 27 #include <linux/memblock.h> 28 29 #include <asm/processor.h> 30 #include <asm/hardirq.h> 31 #include <asm/nmi.h> 32 #include <asm/hw_irq.h> 33 #include <asm/apic.h> 34 #include <asm/e820/types.h> 35 #include <asm/io_apic.h> 36 #include <asm/hpet.h> 37 #include <linux/kdebug.h> 38 #include <asm/cpu.h> 39 #include <asm/reboot.h> 40 #include <asm/virtext.h> 41 #include <asm/intel_pt.h> 42 #include <asm/crash.h> 43 #include <asm/cmdline.h> 44 45 /* Used while preparing memory map entries for second kernel */ 46 struct crash_memmap_data { 47 struct boot_params *params; 48 /* Type of memory */ 49 unsigned int type; 50 }; 51 52 /* 53 * This is used to VMCLEAR all VMCSs loaded on the 54 * processor. And when loading kvm_intel module, the 55 * callback function pointer will be assigned. 56 * 57 * protected by rcu. 58 */ 59 crash_vmclear_fn __rcu *crash_vmclear_loaded_vmcss = NULL; 60 EXPORT_SYMBOL_GPL(crash_vmclear_loaded_vmcss); 61 62 static inline void cpu_crash_vmclear_loaded_vmcss(void) 63 { 64 crash_vmclear_fn *do_vmclear_operation = NULL; 65 66 rcu_read_lock(); 67 do_vmclear_operation = rcu_dereference(crash_vmclear_loaded_vmcss); 68 if (do_vmclear_operation) 69 do_vmclear_operation(); 70 rcu_read_unlock(); 71 } 72 73 /* 74 * When the crashkernel option is specified, only use the low 75 * 1M for the real mode trampoline. 76 */ 77 void __init crash_reserve_low_1M(void) 78 { 79 if (cmdline_find_option(boot_command_line, "crashkernel", NULL, 0) < 0) 80 return; 81 82 memblock_reserve(0, 1<<20); 83 pr_info("Reserving the low 1M of memory for crashkernel\n"); 84 } 85 86 #if defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC) 87 88 static void kdump_nmi_callback(int cpu, struct pt_regs *regs) 89 { 90 crash_save_cpu(regs, cpu); 91 92 /* 93 * VMCLEAR VMCSs loaded on all cpus if needed. 94 */ 95 cpu_crash_vmclear_loaded_vmcss(); 96 97 /* Disable VMX or SVM if needed. 98 * 99 * We need to disable virtualization on all CPUs. 100 * Having VMX or SVM enabled on any CPU may break rebooting 101 * after the kdump kernel has finished its task. 102 */ 103 cpu_emergency_vmxoff(); 104 cpu_emergency_svm_disable(); 105 106 /* 107 * Disable Intel PT to stop its logging 108 */ 109 cpu_emergency_stop_pt(); 110 111 disable_local_APIC(); 112 } 113 114 void kdump_nmi_shootdown_cpus(void) 115 { 116 nmi_shootdown_cpus(kdump_nmi_callback); 117 118 disable_local_APIC(); 119 } 120 121 /* Override the weak function in kernel/panic.c */ 122 void crash_smp_send_stop(void) 123 { 124 static int cpus_stopped; 125 126 if (cpus_stopped) 127 return; 128 129 if (smp_ops.crash_stop_other_cpus) 130 smp_ops.crash_stop_other_cpus(); 131 else 132 smp_send_stop(); 133 134 cpus_stopped = 1; 135 } 136 137 #else 138 void crash_smp_send_stop(void) 139 { 140 /* There are no cpus to shootdown */ 141 } 142 #endif 143 144 void native_machine_crash_shutdown(struct pt_regs *regs) 145 { 146 /* This function is only called after the system 147 * has panicked or is otherwise in a critical state. 148 * The minimum amount of code to allow a kexec'd kernel 149 * to run successfully needs to happen here. 150 * 151 * In practice this means shooting down the other cpus in 152 * an SMP system. 153 */ 154 /* The kernel is broken so disable interrupts */ 155 local_irq_disable(); 156 157 crash_smp_send_stop(); 158 159 /* 160 * VMCLEAR VMCSs loaded on this cpu if needed. 161 */ 162 cpu_crash_vmclear_loaded_vmcss(); 163 164 /* Booting kdump kernel with VMX or SVM enabled won't work, 165 * because (among other limitations) we can't disable paging 166 * with the virt flags. 167 */ 168 cpu_emergency_vmxoff(); 169 cpu_emergency_svm_disable(); 170 171 /* 172 * Disable Intel PT to stop its logging 173 */ 174 cpu_emergency_stop_pt(); 175 176 #ifdef CONFIG_X86_IO_APIC 177 /* Prevent crash_kexec() from deadlocking on ioapic_lock. */ 178 ioapic_zap_locks(); 179 clear_IO_APIC(); 180 #endif 181 lapic_shutdown(); 182 restore_boot_irq_mode(); 183 #ifdef CONFIG_HPET_TIMER 184 hpet_disable(); 185 #endif 186 crash_save_cpu(regs, safe_smp_processor_id()); 187 } 188 189 #ifdef CONFIG_KEXEC_FILE 190 191 static int get_nr_ram_ranges_callback(struct resource *res, void *arg) 192 { 193 unsigned int *nr_ranges = arg; 194 195 (*nr_ranges)++; 196 return 0; 197 } 198 199 /* Gather all the required information to prepare elf headers for ram regions */ 200 static struct crash_mem *fill_up_crash_elf_data(void) 201 { 202 unsigned int nr_ranges = 0; 203 struct crash_mem *cmem; 204 205 walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback); 206 if (!nr_ranges) 207 return NULL; 208 209 /* 210 * Exclusion of crash region and/or crashk_low_res may cause 211 * another range split. So add extra two slots here. 212 */ 213 nr_ranges += 2; 214 cmem = vzalloc(struct_size(cmem, ranges, nr_ranges)); 215 if (!cmem) 216 return NULL; 217 218 cmem->max_nr_ranges = nr_ranges; 219 cmem->nr_ranges = 0; 220 221 return cmem; 222 } 223 224 /* 225 * Look for any unwanted ranges between mstart, mend and remove them. This 226 * might lead to split and split ranges are put in cmem->ranges[] array 227 */ 228 static int elf_header_exclude_ranges(struct crash_mem *cmem) 229 { 230 int ret = 0; 231 232 /* Exclude the low 1M because it is always reserved */ 233 ret = crash_exclude_mem_range(cmem, 0, (1<<20)-1); 234 if (ret) 235 return ret; 236 237 /* Exclude crashkernel region */ 238 ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end); 239 if (ret) 240 return ret; 241 242 if (crashk_low_res.end) 243 ret = crash_exclude_mem_range(cmem, crashk_low_res.start, 244 crashk_low_res.end); 245 246 return ret; 247 } 248 249 static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg) 250 { 251 struct crash_mem *cmem = arg; 252 253 cmem->ranges[cmem->nr_ranges].start = res->start; 254 cmem->ranges[cmem->nr_ranges].end = res->end; 255 cmem->nr_ranges++; 256 257 return 0; 258 } 259 260 /* Prepare elf headers. Return addr and size */ 261 static int prepare_elf_headers(struct kimage *image, void **addr, 262 unsigned long *sz) 263 { 264 struct crash_mem *cmem; 265 int ret; 266 267 cmem = fill_up_crash_elf_data(); 268 if (!cmem) 269 return -ENOMEM; 270 271 ret = walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback); 272 if (ret) 273 goto out; 274 275 /* Exclude unwanted mem ranges */ 276 ret = elf_header_exclude_ranges(cmem); 277 if (ret) 278 goto out; 279 280 /* By default prepare 64bit headers */ 281 ret = crash_prepare_elf64_headers(cmem, IS_ENABLED(CONFIG_X86_64), addr, sz); 282 283 out: 284 vfree(cmem); 285 return ret; 286 } 287 288 static int add_e820_entry(struct boot_params *params, struct e820_entry *entry) 289 { 290 unsigned int nr_e820_entries; 291 292 nr_e820_entries = params->e820_entries; 293 if (nr_e820_entries >= E820_MAX_ENTRIES_ZEROPAGE) 294 return 1; 295 296 memcpy(¶ms->e820_table[nr_e820_entries], entry, sizeof(struct e820_entry)); 297 params->e820_entries++; 298 return 0; 299 } 300 301 static int memmap_entry_callback(struct resource *res, void *arg) 302 { 303 struct crash_memmap_data *cmd = arg; 304 struct boot_params *params = cmd->params; 305 struct e820_entry ei; 306 307 ei.addr = res->start; 308 ei.size = resource_size(res); 309 ei.type = cmd->type; 310 add_e820_entry(params, &ei); 311 312 return 0; 313 } 314 315 static int memmap_exclude_ranges(struct kimage *image, struct crash_mem *cmem, 316 unsigned long long mstart, 317 unsigned long long mend) 318 { 319 unsigned long start, end; 320 321 cmem->ranges[0].start = mstart; 322 cmem->ranges[0].end = mend; 323 cmem->nr_ranges = 1; 324 325 /* Exclude elf header region */ 326 start = image->arch.elf_load_addr; 327 end = start + image->arch.elf_headers_sz - 1; 328 return crash_exclude_mem_range(cmem, start, end); 329 } 330 331 /* Prepare memory map for crash dump kernel */ 332 int crash_setup_memmap_entries(struct kimage *image, struct boot_params *params) 333 { 334 int i, ret = 0; 335 unsigned long flags; 336 struct e820_entry ei; 337 struct crash_memmap_data cmd; 338 struct crash_mem *cmem; 339 340 cmem = vzalloc(sizeof(struct crash_mem)); 341 if (!cmem) 342 return -ENOMEM; 343 344 memset(&cmd, 0, sizeof(struct crash_memmap_data)); 345 cmd.params = params; 346 347 /* Add the low 1M */ 348 cmd.type = E820_TYPE_RAM; 349 flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY; 350 walk_iomem_res_desc(IORES_DESC_NONE, flags, 0, (1<<20)-1, &cmd, 351 memmap_entry_callback); 352 353 /* Add ACPI tables */ 354 cmd.type = E820_TYPE_ACPI; 355 flags = IORESOURCE_MEM | IORESOURCE_BUSY; 356 walk_iomem_res_desc(IORES_DESC_ACPI_TABLES, flags, 0, -1, &cmd, 357 memmap_entry_callback); 358 359 /* Add ACPI Non-volatile Storage */ 360 cmd.type = E820_TYPE_NVS; 361 walk_iomem_res_desc(IORES_DESC_ACPI_NV_STORAGE, flags, 0, -1, &cmd, 362 memmap_entry_callback); 363 364 /* Add e820 reserved ranges */ 365 cmd.type = E820_TYPE_RESERVED; 366 flags = IORESOURCE_MEM; 367 walk_iomem_res_desc(IORES_DESC_RESERVED, flags, 0, -1, &cmd, 368 memmap_entry_callback); 369 370 /* Add crashk_low_res region */ 371 if (crashk_low_res.end) { 372 ei.addr = crashk_low_res.start; 373 ei.size = resource_size(&crashk_low_res); 374 ei.type = E820_TYPE_RAM; 375 add_e820_entry(params, &ei); 376 } 377 378 /* Exclude some ranges from crashk_res and add rest to memmap */ 379 ret = memmap_exclude_ranges(image, cmem, crashk_res.start, crashk_res.end); 380 if (ret) 381 goto out; 382 383 for (i = 0; i < cmem->nr_ranges; i++) { 384 ei.size = cmem->ranges[i].end - cmem->ranges[i].start + 1; 385 386 /* If entry is less than a page, skip it */ 387 if (ei.size < PAGE_SIZE) 388 continue; 389 ei.addr = cmem->ranges[i].start; 390 ei.type = E820_TYPE_RAM; 391 add_e820_entry(params, &ei); 392 } 393 394 out: 395 vfree(cmem); 396 return ret; 397 } 398 399 int crash_load_segments(struct kimage *image) 400 { 401 int ret; 402 struct kexec_buf kbuf = { .image = image, .buf_min = 0, 403 .buf_max = ULONG_MAX, .top_down = false }; 404 405 /* Prepare elf headers and add a segment */ 406 ret = prepare_elf_headers(image, &kbuf.buffer, &kbuf.bufsz); 407 if (ret) 408 return ret; 409 410 image->arch.elf_headers = kbuf.buffer; 411 image->arch.elf_headers_sz = kbuf.bufsz; 412 413 kbuf.memsz = kbuf.bufsz; 414 kbuf.buf_align = ELF_CORE_HEADER_ALIGN; 415 kbuf.mem = KEXEC_BUF_MEM_UNKNOWN; 416 ret = kexec_add_buffer(&kbuf); 417 if (ret) { 418 vfree((void *)image->arch.elf_headers); 419 return ret; 420 } 421 image->arch.elf_load_addr = kbuf.mem; 422 pr_debug("Loaded ELF headers at 0x%lx bufsz=0x%lx memsz=0x%lx\n", 423 image->arch.elf_load_addr, kbuf.bufsz, kbuf.bufsz); 424 425 return ret; 426 } 427 #endif /* CONFIG_KEXEC_FILE */ 428