1/* 2 * PPC64 code to handle Linux booting another kernel. 3 * 4 * Copyright (C) 2004-2005, IBM Corp. 5 * 6 * Created by: Milton D Miller II 7 * 8 * This source code is licensed under the GNU General Public License, 9 * Version 2. See the file COPYING for more details. 10 */ 11 12 13#include <linux/kexec.h> 14#include <linux/smp.h> 15#include <linux/thread_info.h> 16#include <linux/init_task.h> 17#include <linux/errno.h> 18#include <linux/kernel.h> 19#include <linux/cpu.h> 20#include <linux/hardirq.h> 21 22#include <asm/page.h> 23#include <asm/current.h> 24#include <asm/machdep.h> 25#include <asm/cacheflush.h> 26#include <asm/paca.h> 27#include <asm/mmu.h> 28#include <asm/sections.h> /* _end */ 29#include <asm/prom.h> 30#include <asm/smp.h> 31#include <asm/hw_breakpoint.h> 32 33int default_machine_kexec_prepare(struct kimage *image) 34{ 35 int i; 36 unsigned long begin, end; /* limits of segment */ 37 unsigned long low, high; /* limits of blocked memory range */ 38 struct device_node *node; 39 const unsigned long *basep; 40 const unsigned int *sizep; 41 42 if (!ppc_md.hpte_clear_all) 43 return -ENOENT; 44 45 /* 46 * Since we use the kernel fault handlers and paging code to 47 * handle the virtual mode, we must make sure no destination 48 * overlaps kernel static data or bss. 49 */ 50 for (i = 0; i < image->nr_segments; i++) 51 if (image->segment[i].mem < __pa(_end)) 52 return -ETXTBSY; 53 54 /* 55 * For non-LPAR, we absolutely can not overwrite the mmu hash 56 * table, since we are still using the bolted entries in it to 57 * do the copy. Check that here. 58 * 59 * It is safe if the end is below the start of the blocked 60 * region (end <= low), or if the beginning is after the 61 * end of the blocked region (begin >= high). Use the 62 * boolean identity !(a || b) === (!a && !b). 63 */ 64 if (htab_address) { 65 low = __pa(htab_address); 66 high = low + htab_size_bytes; 67 68 for (i = 0; i < image->nr_segments; i++) { 69 begin = image->segment[i].mem; 70 end = begin + image->segment[i].memsz; 71 72 if ((begin < high) && (end > low)) 73 return -ETXTBSY; 74 } 75 } 76 77 /* We also should not overwrite the tce tables */ 78 for_each_node_by_type(node, "pci") { 79 basep = of_get_property(node, "linux,tce-base", NULL); 80 sizep = of_get_property(node, "linux,tce-size", NULL); 81 if (basep == NULL || sizep == NULL) 82 continue; 83 84 low = *basep; 85 high = low + (*sizep); 86 87 for (i = 0; i < image->nr_segments; i++) { 88 begin = image->segment[i].mem; 89 end = begin + image->segment[i].memsz; 90 91 if ((begin < high) && (end > low)) 92 return -ETXTBSY; 93 } 94 } 95 96 return 0; 97} 98 99#define IND_FLAGS (IND_DESTINATION | IND_INDIRECTION | IND_DONE | IND_SOURCE) 100 101static void copy_segments(unsigned long ind) 102{ 103 unsigned long entry; 104 unsigned long *ptr; 105 void *dest; 106 void *addr; 107 108 /* 109 * We rely on kexec_load to create a lists that properly 110 * initializes these pointers before they are used. 111 * We will still crash if the list is wrong, but at least 112 * the compiler will be quiet. 113 */ 114 ptr = NULL; 115 dest = NULL; 116 117 for (entry = ind; !(entry & IND_DONE); entry = *ptr++) { 118 addr = __va(entry & PAGE_MASK); 119 120 switch (entry & IND_FLAGS) { 121 case IND_DESTINATION: 122 dest = addr; 123 break; 124 case IND_INDIRECTION: 125 ptr = addr; 126 break; 127 case IND_SOURCE: 128 copy_page(dest, addr); 129 dest += PAGE_SIZE; 130 } 131 } 132} 133 134void kexec_copy_flush(struct kimage *image) 135{ 136 long i, nr_segments = image->nr_segments; 137 struct kexec_segment ranges[KEXEC_SEGMENT_MAX]; 138 139 /* save the ranges on the stack to efficiently flush the icache */ 140 memcpy(ranges, image->segment, sizeof(ranges)); 141 142 /* 143 * After this call we may not use anything allocated in dynamic 144 * memory, including *image. 145 * 146 * Only globals and the stack are allowed. 147 */ 148 copy_segments(image->head); 149 150 /* 151 * we need to clear the icache for all dest pages sometime, 152 * including ones that were in place on the original copy 153 */ 154 for (i = 0; i < nr_segments; i++) 155 flush_icache_range((unsigned long)__va(ranges[i].mem), 156 (unsigned long)__va(ranges[i].mem + ranges[i].memsz)); 157} 158 159#ifdef CONFIG_SMP 160 161static int kexec_all_irq_disabled = 0; 162 163static void kexec_smp_down(void *arg) 164{ 165 local_irq_disable(); 166 hard_irq_disable(); 167 168 mb(); /* make sure our irqs are disabled before we say they are */ 169 get_paca()->kexec_state = KEXEC_STATE_IRQS_OFF; 170 while(kexec_all_irq_disabled == 0) 171 cpu_relax(); 172 mb(); /* make sure all irqs are disabled before this */ 173 hw_breakpoint_disable(); 174 /* 175 * Now every CPU has IRQs off, we can clear out any pending 176 * IPIs and be sure that no more will come in after this. 177 */ 178 if (ppc_md.kexec_cpu_down) 179 ppc_md.kexec_cpu_down(0, 1); 180 181 kexec_smp_wait(); 182 /* NOTREACHED */ 183} 184 185static void kexec_prepare_cpus_wait(int wait_state) 186{ 187 int my_cpu, i, notified=-1; 188 189 hw_breakpoint_disable(); 190 my_cpu = get_cpu(); 191 /* Make sure each CPU has at least made it to the state we need. 192 * 193 * FIXME: There is a (slim) chance of a problem if not all of the CPUs 194 * are correctly onlined. If somehow we start a CPU on boot with RTAS 195 * start-cpu, but somehow that CPU doesn't write callin_cpu_map[] in 196 * time, the boot CPU will timeout. If it does eventually execute 197 * stuff, the secondary will start up (paca[].cpu_start was written) and 198 * get into a peculiar state. If the platform supports 199 * smp_ops->take_timebase(), the secondary CPU will probably be spinning 200 * in there. If not (i.e. pseries), the secondary will continue on and 201 * try to online itself/idle/etc. If it survives that, we need to find 202 * these possible-but-not-online-but-should-be CPUs and chaperone them 203 * into kexec_smp_wait(). 204 */ 205 for_each_online_cpu(i) { 206 if (i == my_cpu) 207 continue; 208 209 while (paca[i].kexec_state < wait_state) { 210 barrier(); 211 if (i != notified) { 212 printk(KERN_INFO "kexec: waiting for cpu %d " 213 "(physical %d) to enter %i state\n", 214 i, paca[i].hw_cpu_id, wait_state); 215 notified = i; 216 } 217 } 218 } 219 mb(); 220} 221 222/* 223 * We need to make sure each present CPU is online. The next kernel will scan 224 * the device tree and assume primary threads are online and query secondary 225 * threads via RTAS to online them if required. If we don't online primary 226 * threads, they will be stuck. However, we also online secondary threads as we 227 * may be using 'cede offline'. In this case RTAS doesn't see the secondary 228 * threads as offline -- and again, these CPUs will be stuck. 229 * 230 * So, we online all CPUs that should be running, including secondary threads. 231 */ 232static void wake_offline_cpus(void) 233{ 234 int cpu = 0; 235 236 for_each_present_cpu(cpu) { 237 if (!cpu_online(cpu)) { 238 printk(KERN_INFO "kexec: Waking offline cpu %d.\n", 239 cpu); 240 WARN_ON(cpu_up(cpu)); 241 } 242 } 243} 244 245static void kexec_prepare_cpus(void) 246{ 247 wake_offline_cpus(); 248 smp_call_function(kexec_smp_down, NULL, /* wait */0); 249 local_irq_disable(); 250 hard_irq_disable(); 251 252 mb(); /* make sure IRQs are disabled before we say they are */ 253 get_paca()->kexec_state = KEXEC_STATE_IRQS_OFF; 254 255 kexec_prepare_cpus_wait(KEXEC_STATE_IRQS_OFF); 256 /* we are sure every CPU has IRQs off at this point */ 257 kexec_all_irq_disabled = 1; 258 259 /* after we tell the others to go down */ 260 if (ppc_md.kexec_cpu_down) 261 ppc_md.kexec_cpu_down(0, 0); 262 263 /* 264 * Before removing MMU mappings make sure all CPUs have entered real 265 * mode: 266 */ 267 kexec_prepare_cpus_wait(KEXEC_STATE_REAL_MODE); 268 269 put_cpu(); 270} 271 272#else /* ! SMP */ 273 274static void kexec_prepare_cpus(void) 275{ 276 /* 277 * move the secondarys to us so that we can copy 278 * the new kernel 0-0x100 safely 279 * 280 * do this if kexec in setup.c ? 281 * 282 * We need to release the cpus if we are ever going from an 283 * UP to an SMP kernel. 284 */ 285 smp_release_cpus(); 286 if (ppc_md.kexec_cpu_down) 287 ppc_md.kexec_cpu_down(0, 0); 288 local_irq_disable(); 289 hard_irq_disable(); 290} 291 292#endif /* SMP */ 293 294/* 295 * kexec thread structure and stack. 296 * 297 * We need to make sure that this is 16384-byte aligned due to the 298 * way process stacks are handled. It also must be statically allocated 299 * or allocated as part of the kimage, because everything else may be 300 * overwritten when we copy the kexec image. We piggyback on the 301 * "init_task" linker section here to statically allocate a stack. 302 * 303 * We could use a smaller stack if we don't care about anything using 304 * current, but that audit has not been performed. 305 */ 306static union thread_union kexec_stack __init_task_data = 307 { }; 308 309/* 310 * For similar reasons to the stack above, the kexecing CPU needs to be on a 311 * static PACA; we switch to kexec_paca. 312 */ 313struct paca_struct kexec_paca; 314 315/* Our assembly helper, in misc_64.S */ 316extern void kexec_sequence(void *newstack, unsigned long start, 317 void *image, void *control, 318 void (*clear_all)(void)) __noreturn; 319 320/* too late to fail here */ 321void default_machine_kexec(struct kimage *image) 322{ 323 /* prepare control code if any */ 324 325 /* 326 * If the kexec boot is the normal one, need to shutdown other cpus 327 * into our wait loop and quiesce interrupts. 328 * Otherwise, in the case of crashed mode (crashing_cpu >= 0), 329 * stopping other CPUs and collecting their pt_regs is done before 330 * using debugger IPI. 331 */ 332 333 if (crashing_cpu == -1) 334 kexec_prepare_cpus(); 335 336 pr_debug("kexec: Starting switchover sequence.\n"); 337 338 /* switch to a staticly allocated stack. Based on irq stack code. 339 * We setup preempt_count to avoid using VMX in memcpy. 340 * XXX: the task struct will likely be invalid once we do the copy! 341 */ 342 kexec_stack.thread_info.task = current_thread_info()->task; 343 kexec_stack.thread_info.flags = 0; 344 kexec_stack.thread_info.preempt_count = HARDIRQ_OFFSET; 345 kexec_stack.thread_info.cpu = current_thread_info()->cpu; 346 347 /* We need a static PACA, too; copy this CPU's PACA over and switch to 348 * it. Also poison per_cpu_offset to catch anyone using non-static 349 * data. 350 */ 351 memcpy(&kexec_paca, get_paca(), sizeof(struct paca_struct)); 352 kexec_paca.data_offset = 0xedeaddeadeeeeeeeUL; 353 paca = (struct paca_struct *)RELOC_HIDE(&kexec_paca, 0) - 354 kexec_paca.paca_index; 355 setup_paca(&kexec_paca); 356 357 /* XXX: If anyone does 'dynamic lppacas' this will also need to be 358 * switched to a static version! 359 */ 360 361 /* Some things are best done in assembly. Finding globals with 362 * a toc is easier in C, so pass in what we can. 363 */ 364 kexec_sequence(&kexec_stack, image->start, image, 365 page_address(image->control_code_page), 366 ppc_md.hpte_clear_all); 367 /* NOTREACHED */ 368} 369 370/* Values we need to export to the second kernel via the device tree. */ 371static unsigned long htab_base; 372static unsigned long htab_size; 373 374static struct property htab_base_prop = { 375 .name = "linux,htab-base", 376 .length = sizeof(unsigned long), 377 .value = &htab_base, 378}; 379 380static struct property htab_size_prop = { 381 .name = "linux,htab-size", 382 .length = sizeof(unsigned long), 383 .value = &htab_size, 384}; 385 386static int __init export_htab_values(void) 387{ 388 struct device_node *node; 389 struct property *prop; 390 391 /* On machines with no htab htab_address is NULL */ 392 if (!htab_address) 393 return -ENODEV; 394 395 node = of_find_node_by_path("/chosen"); 396 if (!node) 397 return -ENODEV; 398 399 /* remove any stale propertys so ours can be found */ 400 prop = of_find_property(node, htab_base_prop.name, NULL); 401 if (prop) 402 of_remove_property(node, prop); 403 prop = of_find_property(node, htab_size_prop.name, NULL); 404 if (prop) 405 of_remove_property(node, prop); 406 407 htab_base = cpu_to_be64(__pa(htab_address)); 408 of_add_property(node, &htab_base_prop); 409 htab_size = cpu_to_be64(htab_size_bytes); 410 of_add_property(node, &htab_size_prop); 411 412 of_node_put(node); 413 return 0; 414} 415late_initcall(export_htab_values); 416