1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Author: Huacai Chen <chenhuacai@loongson.cn> 4 * Copyright (C) 2020-2022 Loongson Technology Corporation Limited 5 * 6 * Derived from MIPS: 7 * Copyright (C) 1994 - 1999, 2000 by Ralf Baechle and others. 8 * Copyright (C) 2005, 2006 by Ralf Baechle (ralf@linux-mips.org) 9 * Copyright (C) 1999, 2000 Silicon Graphics, Inc. 10 * Copyright (C) 2004 Thiemo Seufer 11 * Copyright (C) 2013 Imagination Technologies Ltd. 12 */ 13 #include <linux/cpu.h> 14 #include <linux/init.h> 15 #include <linux/kernel.h> 16 #include <linux/errno.h> 17 #include <linux/sched.h> 18 #include <linux/sched/debug.h> 19 #include <linux/sched/task.h> 20 #include <linux/sched/task_stack.h> 21 #include <linux/hw_breakpoint.h> 22 #include <linux/mm.h> 23 #include <linux/stddef.h> 24 #include <linux/unistd.h> 25 #include <linux/export.h> 26 #include <linux/ptrace.h> 27 #include <linux/mman.h> 28 #include <linux/personality.h> 29 #include <linux/sys.h> 30 #include <linux/completion.h> 31 #include <linux/kallsyms.h> 32 #include <linux/random.h> 33 #include <linux/prctl.h> 34 #include <linux/nmi.h> 35 36 #include <asm/asm.h> 37 #include <asm/bootinfo.h> 38 #include <asm/cpu.h> 39 #include <asm/elf.h> 40 #include <asm/fpu.h> 41 #include <asm/io.h> 42 #include <asm/irq.h> 43 #include <asm/irq_regs.h> 44 #include <asm/loongarch.h> 45 #include <asm/pgtable.h> 46 #include <asm/processor.h> 47 #include <asm/reg.h> 48 #include <asm/unwind.h> 49 #include <asm/vdso.h> 50 51 #ifdef CONFIG_STACKPROTECTOR 52 #include <linux/stackprotector.h> 53 unsigned long __stack_chk_guard __read_mostly; 54 EXPORT_SYMBOL(__stack_chk_guard); 55 #endif 56 57 /* 58 * Idle related variables and functions 59 */ 60 61 unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE; 62 EXPORT_SYMBOL(boot_option_idle_override); 63 64 #ifdef CONFIG_HOTPLUG_CPU 65 void __noreturn arch_cpu_idle_dead(void) 66 { 67 play_dead(); 68 } 69 #endif 70 71 asmlinkage void ret_from_fork(void); 72 asmlinkage void ret_from_kernel_thread(void); 73 74 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp) 75 { 76 unsigned long crmd; 77 unsigned long prmd; 78 unsigned long euen; 79 80 /* New thread loses kernel privileges. */ 81 crmd = regs->csr_crmd & ~(PLV_MASK); 82 crmd |= PLV_USER; 83 regs->csr_crmd = crmd; 84 85 prmd = regs->csr_prmd & ~(PLV_MASK); 86 prmd |= PLV_USER; 87 regs->csr_prmd = prmd; 88 89 euen = regs->csr_euen & ~(CSR_EUEN_FPEN); 90 regs->csr_euen = euen; 91 lose_fpu(0); 92 93 clear_thread_flag(TIF_LSX_CTX_LIVE); 94 clear_thread_flag(TIF_LASX_CTX_LIVE); 95 clear_used_math(); 96 regs->csr_era = pc; 97 regs->regs[3] = sp; 98 } 99 100 void flush_thread(void) 101 { 102 flush_ptrace_hw_breakpoint(current); 103 } 104 105 void exit_thread(struct task_struct *tsk) 106 { 107 } 108 109 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) 110 { 111 /* 112 * Save any process state which is live in hardware registers to the 113 * parent context prior to duplication. This prevents the new child 114 * state becoming stale if the parent is preempted before copy_thread() 115 * gets a chance to save the parent's live hardware registers to the 116 * child context. 117 */ 118 preempt_disable(); 119 120 if (is_fpu_owner()) { 121 if (is_lasx_enabled()) 122 save_lasx(current); 123 else if (is_lsx_enabled()) 124 save_lsx(current); 125 else 126 save_fp(current); 127 } 128 129 preempt_enable(); 130 131 if (used_math()) 132 memcpy(dst, src, sizeof(struct task_struct)); 133 else 134 memcpy(dst, src, offsetof(struct task_struct, thread.fpu.fpr)); 135 136 return 0; 137 } 138 139 /* 140 * Copy architecture-specific thread state 141 */ 142 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) 143 { 144 unsigned long childksp; 145 unsigned long tls = args->tls; 146 unsigned long usp = args->stack; 147 unsigned long clone_flags = args->flags; 148 struct pt_regs *childregs, *regs = current_pt_regs(); 149 150 childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE; 151 152 /* set up new TSS. */ 153 childregs = (struct pt_regs *) childksp - 1; 154 /* Put the stack after the struct pt_regs. */ 155 childksp = (unsigned long) childregs; 156 p->thread.sched_cfa = 0; 157 p->thread.csr_euen = 0; 158 p->thread.csr_crmd = csr_read32(LOONGARCH_CSR_CRMD); 159 p->thread.csr_prmd = csr_read32(LOONGARCH_CSR_PRMD); 160 p->thread.csr_ecfg = csr_read32(LOONGARCH_CSR_ECFG); 161 if (unlikely(args->fn)) { 162 /* kernel thread */ 163 p->thread.reg03 = childksp; 164 p->thread.reg23 = (unsigned long)args->fn; 165 p->thread.reg24 = (unsigned long)args->fn_arg; 166 p->thread.reg01 = (unsigned long)ret_from_kernel_thread; 167 p->thread.sched_ra = (unsigned long)ret_from_kernel_thread; 168 memset(childregs, 0, sizeof(struct pt_regs)); 169 childregs->csr_euen = p->thread.csr_euen; 170 childregs->csr_crmd = p->thread.csr_crmd; 171 childregs->csr_prmd = p->thread.csr_prmd; 172 childregs->csr_ecfg = p->thread.csr_ecfg; 173 goto out; 174 } 175 176 /* user thread */ 177 *childregs = *regs; 178 childregs->regs[4] = 0; /* Child gets zero as return value */ 179 if (usp) 180 childregs->regs[3] = usp; 181 182 p->thread.reg03 = (unsigned long) childregs; 183 p->thread.reg01 = (unsigned long) ret_from_fork; 184 p->thread.sched_ra = (unsigned long) ret_from_fork; 185 186 /* 187 * New tasks lose permission to use the fpu. This accelerates context 188 * switching for most programs since they don't use the fpu. 189 */ 190 childregs->csr_euen = 0; 191 192 if (clone_flags & CLONE_SETTLS) 193 childregs->regs[2] = tls; 194 195 out: 196 ptrace_hw_copy_thread(p); 197 clear_tsk_thread_flag(p, TIF_USEDFPU); 198 clear_tsk_thread_flag(p, TIF_USEDSIMD); 199 clear_tsk_thread_flag(p, TIF_LSX_CTX_LIVE); 200 clear_tsk_thread_flag(p, TIF_LASX_CTX_LIVE); 201 202 return 0; 203 } 204 205 unsigned long __get_wchan(struct task_struct *task) 206 { 207 unsigned long pc = 0; 208 struct unwind_state state; 209 210 if (!try_get_task_stack(task)) 211 return 0; 212 213 for (unwind_start(&state, task, NULL); 214 !unwind_done(&state); unwind_next_frame(&state)) { 215 pc = unwind_get_return_address(&state); 216 if (!pc) 217 break; 218 if (in_sched_functions(pc)) 219 continue; 220 break; 221 } 222 223 put_task_stack(task); 224 225 return pc; 226 } 227 228 bool in_irq_stack(unsigned long stack, struct stack_info *info) 229 { 230 unsigned long nextsp; 231 unsigned long begin = (unsigned long)this_cpu_read(irq_stack); 232 unsigned long end = begin + IRQ_STACK_START; 233 234 if (stack < begin || stack >= end) 235 return false; 236 237 nextsp = *(unsigned long *)end; 238 if (nextsp & (SZREG - 1)) 239 return false; 240 241 info->begin = begin; 242 info->end = end; 243 info->next_sp = nextsp; 244 info->type = STACK_TYPE_IRQ; 245 246 return true; 247 } 248 249 bool in_task_stack(unsigned long stack, struct task_struct *task, 250 struct stack_info *info) 251 { 252 unsigned long begin = (unsigned long)task_stack_page(task); 253 unsigned long end = begin + THREAD_SIZE; 254 255 if (stack < begin || stack >= end) 256 return false; 257 258 info->begin = begin; 259 info->end = end; 260 info->next_sp = 0; 261 info->type = STACK_TYPE_TASK; 262 263 return true; 264 } 265 266 int get_stack_info(unsigned long stack, struct task_struct *task, 267 struct stack_info *info) 268 { 269 task = task ? : current; 270 271 if (!stack || stack & (SZREG - 1)) 272 goto unknown; 273 274 if (in_task_stack(stack, task, info)) 275 return 0; 276 277 if (task != current) 278 goto unknown; 279 280 if (in_irq_stack(stack, info)) 281 return 0; 282 283 unknown: 284 info->type = STACK_TYPE_UNKNOWN; 285 return -EINVAL; 286 } 287 288 unsigned long stack_top(void) 289 { 290 unsigned long top = TASK_SIZE & PAGE_MASK; 291 292 /* Space for the VDSO & data page */ 293 top -= PAGE_ALIGN(current->thread.vdso->size); 294 top -= VVAR_SIZE; 295 296 /* Space to randomize the VDSO base */ 297 if (current->flags & PF_RANDOMIZE) 298 top -= VDSO_RANDOMIZE_SIZE; 299 300 return top; 301 } 302 303 /* 304 * Don't forget that the stack pointer must be aligned on a 8 bytes 305 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI. 306 */ 307 unsigned long arch_align_stack(unsigned long sp) 308 { 309 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 310 sp -= get_random_u32_below(PAGE_SIZE); 311 312 return sp & STACK_ALIGN; 313 } 314 315 static DEFINE_PER_CPU(call_single_data_t, backtrace_csd); 316 static struct cpumask backtrace_csd_busy; 317 318 static void handle_backtrace(void *info) 319 { 320 nmi_cpu_backtrace(get_irq_regs()); 321 cpumask_clear_cpu(smp_processor_id(), &backtrace_csd_busy); 322 } 323 324 static void raise_backtrace(cpumask_t *mask) 325 { 326 call_single_data_t *csd; 327 int cpu; 328 329 for_each_cpu(cpu, mask) { 330 /* 331 * If we previously sent an IPI to the target CPU & it hasn't 332 * cleared its bit in the busy cpumask then it didn't handle 333 * our previous IPI & it's not safe for us to reuse the 334 * call_single_data_t. 335 */ 336 if (cpumask_test_and_set_cpu(cpu, &backtrace_csd_busy)) { 337 pr_warn("Unable to send backtrace IPI to CPU%u - perhaps it hung?\n", 338 cpu); 339 continue; 340 } 341 342 csd = &per_cpu(backtrace_csd, cpu); 343 csd->func = handle_backtrace; 344 smp_call_function_single_async(cpu, csd); 345 } 346 } 347 348 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self) 349 { 350 nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_backtrace); 351 } 352 353 #ifdef CONFIG_64BIT 354 void loongarch_dump_regs64(u64 *uregs, const struct pt_regs *regs) 355 { 356 unsigned int i; 357 358 for (i = LOONGARCH_EF_R1; i <= LOONGARCH_EF_R31; i++) { 359 uregs[i] = regs->regs[i - LOONGARCH_EF_R0]; 360 } 361 362 uregs[LOONGARCH_EF_ORIG_A0] = regs->orig_a0; 363 uregs[LOONGARCH_EF_CSR_ERA] = regs->csr_era; 364 uregs[LOONGARCH_EF_CSR_BADV] = regs->csr_badvaddr; 365 uregs[LOONGARCH_EF_CSR_CRMD] = regs->csr_crmd; 366 uregs[LOONGARCH_EF_CSR_PRMD] = regs->csr_prmd; 367 uregs[LOONGARCH_EF_CSR_EUEN] = regs->csr_euen; 368 uregs[LOONGARCH_EF_CSR_ECFG] = regs->csr_ecfg; 369 uregs[LOONGARCH_EF_CSR_ESTAT] = regs->csr_estat; 370 } 371 #endif /* CONFIG_64BIT */ 372