1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Architecture specific (PPC64) functions for kexec based crash dumps. 4 * 5 * Copyright (C) 2005, IBM Corp. 6 * 7 * Created by: Haren Myneni 8 */ 9 10 #include <linux/kernel.h> 11 #include <linux/smp.h> 12 #include <linux/reboot.h> 13 #include <linux/kexec.h> 14 #include <linux/export.h> 15 #include <linux/crash_dump.h> 16 #include <linux/delay.h> 17 #include <linux/irq.h> 18 #include <linux/types.h> 19 20 #include <asm/processor.h> 21 #include <asm/machdep.h> 22 #include <asm/kexec.h> 23 #include <asm/prom.h> 24 #include <asm/smp.h> 25 #include <asm/setjmp.h> 26 #include <asm/debug.h> 27 28 /* 29 * The primary CPU waits a while for all secondary CPUs to enter. This is to 30 * avoid sending an IPI if the secondary CPUs are entering 31 * crash_kexec_secondary on their own (eg via a system reset). 32 * 33 * The secondary timeout has to be longer than the primary. Both timeouts are 34 * in milliseconds. 35 */ 36 #define PRIMARY_TIMEOUT 500 37 #define SECONDARY_TIMEOUT 1000 38 39 #define IPI_TIMEOUT 10000 40 #define REAL_MODE_TIMEOUT 10000 41 42 static int time_to_dump; 43 /* 44 * crash_wake_offline should be set to 1 by platforms that intend to wake 45 * up offline cpus prior to jumping to a kdump kernel. Currently powernv 46 * sets it to 1, since we want to avoid things from happening when an 47 * offline CPU wakes up due to something like an HMI (malfunction error), 48 * which propagates to all threads. 49 */ 50 int crash_wake_offline; 51 52 #define CRASH_HANDLER_MAX 3 53 /* List of shutdown handles */ 54 static crash_shutdown_t crash_shutdown_handles[CRASH_HANDLER_MAX]; 55 static DEFINE_SPINLOCK(crash_handlers_lock); 56 57 static unsigned long crash_shutdown_buf[JMP_BUF_LEN]; 58 static int crash_shutdown_cpu = -1; 59 60 static int handle_fault(struct pt_regs *regs) 61 { 62 if (crash_shutdown_cpu == smp_processor_id()) 63 longjmp(crash_shutdown_buf, 1); 64 return 0; 65 } 66 67 #ifdef CONFIG_SMP 68 69 static atomic_t cpus_in_crash; 70 void crash_ipi_callback(struct pt_regs *regs) 71 { 72 static cpumask_t cpus_state_saved = CPU_MASK_NONE; 73 74 int cpu = smp_processor_id(); 75 76 hard_irq_disable(); 77 if (!cpumask_test_cpu(cpu, &cpus_state_saved)) { 78 crash_save_cpu(regs, cpu); 79 cpumask_set_cpu(cpu, &cpus_state_saved); 80 } 81 82 atomic_inc(&cpus_in_crash); 83 smp_mb__after_atomic(); 84 85 /* 86 * Starting the kdump boot. 87 * This barrier is needed to make sure that all CPUs are stopped. 88 */ 89 while (!time_to_dump) 90 cpu_relax(); 91 92 if (ppc_md.kexec_cpu_down) 93 ppc_md.kexec_cpu_down(1, 1); 94 95 #ifdef CONFIG_PPC64 96 kexec_smp_wait(); 97 #else 98 for (;;); /* FIXME */ 99 #endif 100 101 /* NOTREACHED */ 102 } 103 104 static void crash_kexec_prepare_cpus(int cpu) 105 { 106 unsigned int msecs; 107 unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */ 108 int tries = 0; 109 int (*old_handler)(struct pt_regs *regs); 110 111 printk(KERN_EMERG "Sending IPI to other CPUs\n"); 112 113 if (crash_wake_offline) 114 ncpus = num_present_cpus() - 1; 115 116 crash_send_ipi(crash_ipi_callback); 117 smp_wmb(); 118 119 again: 120 /* 121 * FIXME: Until we will have the way to stop other CPUs reliably, 122 * the crash CPU will send an IPI and wait for other CPUs to 123 * respond. 124 */ 125 msecs = IPI_TIMEOUT; 126 while ((atomic_read(&cpus_in_crash) < ncpus) && (--msecs > 0)) 127 mdelay(1); 128 129 /* Would it be better to replace the trap vector here? */ 130 131 if (atomic_read(&cpus_in_crash) >= ncpus) { 132 printk(KERN_EMERG "IPI complete\n"); 133 return; 134 } 135 136 printk(KERN_EMERG "ERROR: %d cpu(s) not responding\n", 137 ncpus - atomic_read(&cpus_in_crash)); 138 139 /* 140 * If we have a panic timeout set then we can't wait indefinitely 141 * for someone to activate system reset. We also give up on the 142 * second time through if system reset fail to work. 143 */ 144 if ((panic_timeout > 0) || (tries > 0)) 145 return; 146 147 /* 148 * A system reset will cause all CPUs to take an 0x100 exception. 149 * The primary CPU returns here via setjmp, and the secondary 150 * CPUs reexecute the crash_kexec_secondary path. 151 */ 152 old_handler = __debugger; 153 __debugger = handle_fault; 154 crash_shutdown_cpu = smp_processor_id(); 155 156 if (setjmp(crash_shutdown_buf) == 0) { 157 printk(KERN_EMERG "Activate system reset (dumprestart) " 158 "to stop other cpu(s)\n"); 159 160 /* 161 * A system reset will force all CPUs to execute the 162 * crash code again. We need to reset cpus_in_crash so we 163 * wait for everyone to do this. 164 */ 165 atomic_set(&cpus_in_crash, 0); 166 smp_mb(); 167 168 while (atomic_read(&cpus_in_crash) < ncpus) 169 cpu_relax(); 170 } 171 172 crash_shutdown_cpu = -1; 173 __debugger = old_handler; 174 175 tries++; 176 goto again; 177 } 178 179 /* 180 * This function will be called by secondary cpus. 181 */ 182 void crash_kexec_secondary(struct pt_regs *regs) 183 { 184 unsigned long flags; 185 int msecs = SECONDARY_TIMEOUT; 186 187 local_irq_save(flags); 188 189 /* Wait for the primary crash CPU to signal its progress */ 190 while (crashing_cpu < 0) { 191 if (--msecs < 0) { 192 /* No response, kdump image may not have been loaded */ 193 local_irq_restore(flags); 194 return; 195 } 196 197 mdelay(1); 198 } 199 200 crash_ipi_callback(regs); 201 } 202 203 #else /* ! CONFIG_SMP */ 204 205 static void crash_kexec_prepare_cpus(int cpu) 206 { 207 /* 208 * move the secondaries to us so that we can copy 209 * the new kernel 0-0x100 safely 210 * 211 * do this if kexec in setup.c ? 212 */ 213 #ifdef CONFIG_PPC64 214 smp_release_cpus(); 215 #else 216 /* FIXME */ 217 #endif 218 } 219 220 void crash_kexec_secondary(struct pt_regs *regs) 221 { 222 } 223 #endif /* CONFIG_SMP */ 224 225 /* wait for all the CPUs to hit real mode but timeout if they don't come in */ 226 #if defined(CONFIG_SMP) && defined(CONFIG_PPC64) 227 static void __maybe_unused crash_kexec_wait_realmode(int cpu) 228 { 229 unsigned int msecs; 230 int i; 231 232 msecs = REAL_MODE_TIMEOUT; 233 for (i=0; i < nr_cpu_ids && msecs > 0; i++) { 234 if (i == cpu) 235 continue; 236 237 while (paca_ptrs[i]->kexec_state < KEXEC_STATE_REAL_MODE) { 238 barrier(); 239 if (!cpu_possible(i) || !cpu_online(i) || (msecs <= 0)) 240 break; 241 msecs--; 242 mdelay(1); 243 } 244 } 245 mb(); 246 } 247 #else 248 static inline void crash_kexec_wait_realmode(int cpu) {} 249 #endif /* CONFIG_SMP && CONFIG_PPC64 */ 250 251 /* 252 * Register a function to be called on shutdown. Only use this if you 253 * can't reset your device in the second kernel. 254 */ 255 int crash_shutdown_register(crash_shutdown_t handler) 256 { 257 unsigned int i, rc; 258 259 spin_lock(&crash_handlers_lock); 260 for (i = 0 ; i < CRASH_HANDLER_MAX; i++) 261 if (!crash_shutdown_handles[i]) { 262 /* Insert handle at first empty entry */ 263 crash_shutdown_handles[i] = handler; 264 rc = 0; 265 break; 266 } 267 268 if (i == CRASH_HANDLER_MAX) { 269 printk(KERN_ERR "Crash shutdown handles full, " 270 "not registered.\n"); 271 rc = 1; 272 } 273 274 spin_unlock(&crash_handlers_lock); 275 return rc; 276 } 277 EXPORT_SYMBOL(crash_shutdown_register); 278 279 int crash_shutdown_unregister(crash_shutdown_t handler) 280 { 281 unsigned int i, rc; 282 283 spin_lock(&crash_handlers_lock); 284 for (i = 0 ; i < CRASH_HANDLER_MAX; i++) 285 if (crash_shutdown_handles[i] == handler) 286 break; 287 288 if (i == CRASH_HANDLER_MAX) { 289 printk(KERN_ERR "Crash shutdown handle not found\n"); 290 rc = 1; 291 } else { 292 /* Shift handles down */ 293 for (; i < (CRASH_HANDLER_MAX - 1); i++) 294 crash_shutdown_handles[i] = 295 crash_shutdown_handles[i+1]; 296 /* 297 * Reset last entry to NULL now that it has been shifted down, 298 * this will allow new handles to be added here. 299 */ 300 crash_shutdown_handles[i] = NULL; 301 rc = 0; 302 } 303 304 spin_unlock(&crash_handlers_lock); 305 return rc; 306 } 307 EXPORT_SYMBOL(crash_shutdown_unregister); 308 309 void default_machine_crash_shutdown(struct pt_regs *regs) 310 { 311 unsigned int i; 312 int (*old_handler)(struct pt_regs *regs); 313 314 /* 315 * This function is only called after the system 316 * has panicked or is otherwise in a critical state. 317 * The minimum amount of code to allow a kexec'd kernel 318 * to run successfully needs to happen here. 319 * 320 * In practice this means stopping other cpus in 321 * an SMP system. 322 * The kernel is broken so disable interrupts. 323 */ 324 hard_irq_disable(); 325 326 /* 327 * Make a note of crashing cpu. Will be used in machine_kexec 328 * such that another IPI will not be sent. 329 */ 330 crashing_cpu = smp_processor_id(); 331 332 /* 333 * If we came in via system reset, wait a while for the secondary 334 * CPUs to enter. 335 */ 336 if (TRAP(regs) == 0x100) 337 mdelay(PRIMARY_TIMEOUT); 338 339 crash_kexec_prepare_cpus(crashing_cpu); 340 341 crash_save_cpu(regs, crashing_cpu); 342 343 time_to_dump = 1; 344 345 crash_kexec_wait_realmode(crashing_cpu); 346 347 machine_kexec_mask_interrupts(); 348 349 /* 350 * Call registered shutdown routines safely. Swap out 351 * __debugger_fault_handler, and replace on exit. 352 */ 353 old_handler = __debugger_fault_handler; 354 __debugger_fault_handler = handle_fault; 355 crash_shutdown_cpu = smp_processor_id(); 356 for (i = 0; i < CRASH_HANDLER_MAX && crash_shutdown_handles[i]; i++) { 357 if (setjmp(crash_shutdown_buf) == 0) { 358 /* 359 * Insert syncs and delay to ensure 360 * instructions in the dangerous region don't 361 * leak away from this protected region. 362 */ 363 asm volatile("sync; isync"); 364 /* dangerous region */ 365 crash_shutdown_handles[i](); 366 asm volatile("sync; isync"); 367 } 368 } 369 crash_shutdown_cpu = -1; 370 __debugger_fault_handler = old_handler; 371 372 if (ppc_md.kexec_cpu_down) 373 ppc_md.kexec_cpu_down(1, 0); 374 } 375