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/mm.h> 22 #include <linux/stddef.h> 23 #include <linux/unistd.h> 24 #include <linux/export.h> 25 #include <linux/ptrace.h> 26 #include <linux/mman.h> 27 #include <linux/personality.h> 28 #include <linux/sys.h> 29 #include <linux/completion.h> 30 #include <linux/kallsyms.h> 31 #include <linux/random.h> 32 #include <linux/prctl.h> 33 #include <linux/nmi.h> 34 35 #include <asm/asm.h> 36 #include <asm/bootinfo.h> 37 #include <asm/cpu.h> 38 #include <asm/elf.h> 39 #include <asm/fpu.h> 40 #include <asm/io.h> 41 #include <asm/irq.h> 42 #include <asm/irq_regs.h> 43 #include <asm/loongarch.h> 44 #include <asm/pgtable.h> 45 #include <asm/processor.h> 46 #include <asm/reg.h> 47 #include <asm/unwind.h> 48 #include <asm/vdso.h> 49 50 /* 51 * Idle related variables and functions 52 */ 53 54 unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE; 55 EXPORT_SYMBOL(boot_option_idle_override); 56 57 #ifdef CONFIG_HOTPLUG_CPU 58 void arch_cpu_idle_dead(void) 59 { 60 play_dead(); 61 } 62 #endif 63 64 asmlinkage void ret_from_fork(void); 65 asmlinkage void ret_from_kernel_thread(void); 66 67 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp) 68 { 69 unsigned long crmd; 70 unsigned long prmd; 71 unsigned long euen; 72 73 /* New thread loses kernel privileges. */ 74 crmd = regs->csr_crmd & ~(PLV_MASK); 75 crmd |= PLV_USER; 76 regs->csr_crmd = crmd; 77 78 prmd = regs->csr_prmd & ~(PLV_MASK); 79 prmd |= PLV_USER; 80 regs->csr_prmd = prmd; 81 82 euen = regs->csr_euen & ~(CSR_EUEN_FPEN); 83 regs->csr_euen = euen; 84 lose_fpu(0); 85 86 clear_thread_flag(TIF_LSX_CTX_LIVE); 87 clear_thread_flag(TIF_LASX_CTX_LIVE); 88 clear_used_math(); 89 regs->csr_era = pc; 90 regs->regs[3] = sp; 91 } 92 93 void exit_thread(struct task_struct *tsk) 94 { 95 } 96 97 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) 98 { 99 /* 100 * Save any process state which is live in hardware registers to the 101 * parent context prior to duplication. This prevents the new child 102 * state becoming stale if the parent is preempted before copy_thread() 103 * gets a chance to save the parent's live hardware registers to the 104 * child context. 105 */ 106 preempt_disable(); 107 108 if (is_fpu_owner()) 109 save_fp(current); 110 111 preempt_enable(); 112 113 if (used_math()) 114 memcpy(dst, src, sizeof(struct task_struct)); 115 else 116 memcpy(dst, src, offsetof(struct task_struct, thread.fpu.fpr)); 117 118 return 0; 119 } 120 121 /* 122 * Copy architecture-specific thread state 123 */ 124 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) 125 { 126 unsigned long childksp; 127 unsigned long tls = args->tls; 128 unsigned long usp = args->stack; 129 unsigned long clone_flags = args->flags; 130 struct pt_regs *childregs, *regs = current_pt_regs(); 131 132 childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32; 133 134 /* set up new TSS. */ 135 childregs = (struct pt_regs *) childksp - 1; 136 /* Put the stack after the struct pt_regs. */ 137 childksp = (unsigned long) childregs; 138 p->thread.sched_cfa = 0; 139 p->thread.csr_euen = 0; 140 p->thread.csr_crmd = csr_read32(LOONGARCH_CSR_CRMD); 141 p->thread.csr_prmd = csr_read32(LOONGARCH_CSR_PRMD); 142 p->thread.csr_ecfg = csr_read32(LOONGARCH_CSR_ECFG); 143 if (unlikely(args->fn)) { 144 /* kernel thread */ 145 p->thread.reg03 = childksp; 146 p->thread.reg23 = (unsigned long)args->fn; 147 p->thread.reg24 = (unsigned long)args->fn_arg; 148 p->thread.reg01 = (unsigned long)ret_from_kernel_thread; 149 p->thread.sched_ra = (unsigned long)ret_from_kernel_thread; 150 memset(childregs, 0, sizeof(struct pt_regs)); 151 childregs->csr_euen = p->thread.csr_euen; 152 childregs->csr_crmd = p->thread.csr_crmd; 153 childregs->csr_prmd = p->thread.csr_prmd; 154 childregs->csr_ecfg = p->thread.csr_ecfg; 155 return 0; 156 } 157 158 /* user thread */ 159 *childregs = *regs; 160 childregs->regs[4] = 0; /* Child gets zero as return value */ 161 if (usp) 162 childregs->regs[3] = usp; 163 164 p->thread.reg03 = (unsigned long) childregs; 165 p->thread.reg01 = (unsigned long) ret_from_fork; 166 p->thread.sched_ra = (unsigned long) ret_from_fork; 167 168 /* 169 * New tasks lose permission to use the fpu. This accelerates context 170 * switching for most programs since they don't use the fpu. 171 */ 172 childregs->csr_euen = 0; 173 174 clear_tsk_thread_flag(p, TIF_USEDFPU); 175 clear_tsk_thread_flag(p, TIF_USEDSIMD); 176 clear_tsk_thread_flag(p, TIF_LSX_CTX_LIVE); 177 clear_tsk_thread_flag(p, TIF_LASX_CTX_LIVE); 178 179 if (clone_flags & CLONE_SETTLS) 180 childregs->regs[2] = tls; 181 182 return 0; 183 } 184 185 unsigned long __get_wchan(struct task_struct *task) 186 { 187 unsigned long pc; 188 struct unwind_state state; 189 190 if (!try_get_task_stack(task)) 191 return 0; 192 193 unwind_start(&state, task, NULL); 194 state.sp = thread_saved_fp(task); 195 get_stack_info(state.sp, state.task, &state.stack_info); 196 state.pc = thread_saved_ra(task); 197 #ifdef CONFIG_UNWINDER_PROLOGUE 198 state.type = UNWINDER_PROLOGUE; 199 #endif 200 for (; !unwind_done(&state); unwind_next_frame(&state)) { 201 pc = unwind_get_return_address(&state); 202 if (!pc) 203 break; 204 if (in_sched_functions(pc)) 205 continue; 206 break; 207 } 208 209 put_task_stack(task); 210 211 return pc; 212 } 213 214 bool in_irq_stack(unsigned long stack, struct stack_info *info) 215 { 216 unsigned long nextsp; 217 unsigned long begin = (unsigned long)this_cpu_read(irq_stack); 218 unsigned long end = begin + IRQ_STACK_START; 219 220 if (stack < begin || stack >= end) 221 return false; 222 223 nextsp = *(unsigned long *)end; 224 if (nextsp & (SZREG - 1)) 225 return false; 226 227 info->begin = begin; 228 info->end = end; 229 info->next_sp = nextsp; 230 info->type = STACK_TYPE_IRQ; 231 232 return true; 233 } 234 235 bool in_task_stack(unsigned long stack, struct task_struct *task, 236 struct stack_info *info) 237 { 238 unsigned long begin = (unsigned long)task_stack_page(task); 239 unsigned long end = begin + THREAD_SIZE - 32; 240 241 if (stack < begin || stack >= end) 242 return false; 243 244 info->begin = begin; 245 info->end = end; 246 info->next_sp = 0; 247 info->type = STACK_TYPE_TASK; 248 249 return true; 250 } 251 252 int get_stack_info(unsigned long stack, struct task_struct *task, 253 struct stack_info *info) 254 { 255 task = task ? : current; 256 257 if (!stack || stack & (SZREG - 1)) 258 goto unknown; 259 260 if (in_task_stack(stack, task, info)) 261 return 0; 262 263 if (task != current) 264 goto unknown; 265 266 if (in_irq_stack(stack, info)) 267 return 0; 268 269 unknown: 270 info->type = STACK_TYPE_UNKNOWN; 271 return -EINVAL; 272 } 273 274 unsigned long stack_top(void) 275 { 276 unsigned long top = TASK_SIZE & PAGE_MASK; 277 278 /* Space for the VDSO & data page */ 279 top -= PAGE_ALIGN(current->thread.vdso->size); 280 top -= PAGE_SIZE; 281 282 /* Space to randomize the VDSO base */ 283 if (current->flags & PF_RANDOMIZE) 284 top -= VDSO_RANDOMIZE_SIZE; 285 286 return top; 287 } 288 289 /* 290 * Don't forget that the stack pointer must be aligned on a 8 bytes 291 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI. 292 */ 293 unsigned long arch_align_stack(unsigned long sp) 294 { 295 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 296 sp -= prandom_u32_max(PAGE_SIZE); 297 298 return sp & STACK_ALIGN; 299 } 300 301 static DEFINE_PER_CPU(call_single_data_t, backtrace_csd); 302 static struct cpumask backtrace_csd_busy; 303 304 static void handle_backtrace(void *info) 305 { 306 nmi_cpu_backtrace(get_irq_regs()); 307 cpumask_clear_cpu(smp_processor_id(), &backtrace_csd_busy); 308 } 309 310 static void raise_backtrace(cpumask_t *mask) 311 { 312 call_single_data_t *csd; 313 int cpu; 314 315 for_each_cpu(cpu, mask) { 316 /* 317 * If we previously sent an IPI to the target CPU & it hasn't 318 * cleared its bit in the busy cpumask then it didn't handle 319 * our previous IPI & it's not safe for us to reuse the 320 * call_single_data_t. 321 */ 322 if (cpumask_test_and_set_cpu(cpu, &backtrace_csd_busy)) { 323 pr_warn("Unable to send backtrace IPI to CPU%u - perhaps it hung?\n", 324 cpu); 325 continue; 326 } 327 328 csd = &per_cpu(backtrace_csd, cpu); 329 csd->func = handle_backtrace; 330 smp_call_function_single_async(cpu, csd); 331 } 332 } 333 334 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self) 335 { 336 nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_backtrace); 337 } 338 339 #ifdef CONFIG_64BIT 340 void loongarch_dump_regs64(u64 *uregs, const struct pt_regs *regs) 341 { 342 unsigned int i; 343 344 for (i = LOONGARCH_EF_R1; i <= LOONGARCH_EF_R31; i++) { 345 uregs[i] = regs->regs[i - LOONGARCH_EF_R0]; 346 } 347 348 uregs[LOONGARCH_EF_ORIG_A0] = regs->orig_a0; 349 uregs[LOONGARCH_EF_CSR_ERA] = regs->csr_era; 350 uregs[LOONGARCH_EF_CSR_BADV] = regs->csr_badvaddr; 351 uregs[LOONGARCH_EF_CSR_CRMD] = regs->csr_crmd; 352 uregs[LOONGARCH_EF_CSR_PRMD] = regs->csr_prmd; 353 uregs[LOONGARCH_EF_CSR_EUEN] = regs->csr_euen; 354 uregs[LOONGARCH_EF_CSR_ECFG] = regs->csr_ecfg; 355 uregs[LOONGARCH_EF_CSR_ESTAT] = regs->csr_estat; 356 } 357 #endif /* CONFIG_64BIT */ 358