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/exec.h> 41 #include <asm/fpu.h> 42 #include <asm/lbt.h> 43 #include <asm/io.h> 44 #include <asm/irq.h> 45 #include <asm/irq_regs.h> 46 #include <asm/loongarch.h> 47 #include <asm/pgtable.h> 48 #include <asm/processor.h> 49 #include <asm/reg.h> 50 #include <asm/unwind.h> 51 #include <asm/vdso.h> 52 53 #ifdef CONFIG_STACKPROTECTOR 54 #include <linux/stackprotector.h> 55 unsigned long __stack_chk_guard __read_mostly; 56 EXPORT_SYMBOL(__stack_chk_guard); 57 #endif 58 59 /* 60 * Idle related variables and functions 61 */ 62 63 unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE; 64 EXPORT_SYMBOL(boot_option_idle_override); 65 66 asmlinkage void ret_from_fork(void); 67 asmlinkage void ret_from_kernel_thread(void); 68 69 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp) 70 { 71 unsigned long crmd; 72 unsigned long prmd; 73 unsigned long euen; 74 75 /* New thread loses kernel privileges. */ 76 crmd = regs->csr_crmd & ~(PLV_MASK); 77 crmd |= PLV_USER; 78 regs->csr_crmd = crmd; 79 80 prmd = regs->csr_prmd & ~(PLV_MASK); 81 prmd |= PLV_USER; 82 regs->csr_prmd = prmd; 83 84 euen = regs->csr_euen & ~(CSR_EUEN_FPEN); 85 regs->csr_euen = euen; 86 lose_fpu(0); 87 lose_lbt(0); 88 89 clear_thread_flag(TIF_LSX_CTX_LIVE); 90 clear_thread_flag(TIF_LASX_CTX_LIVE); 91 clear_thread_flag(TIF_LBT_CTX_LIVE); 92 clear_used_math(); 93 regs->csr_era = pc; 94 regs->regs[3] = sp; 95 } 96 97 void flush_thread(void) 98 { 99 flush_ptrace_hw_breakpoint(current); 100 } 101 102 void exit_thread(struct task_struct *tsk) 103 { 104 } 105 106 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) 107 { 108 /* 109 * Save any process state which is live in hardware registers to the 110 * parent context prior to duplication. This prevents the new child 111 * state becoming stale if the parent is preempted before copy_thread() 112 * gets a chance to save the parent's live hardware registers to the 113 * child context. 114 */ 115 preempt_disable(); 116 117 if (is_fpu_owner()) { 118 if (is_lasx_enabled()) 119 save_lasx(current); 120 else if (is_lsx_enabled()) 121 save_lsx(current); 122 else 123 save_fp(current); 124 } 125 126 preempt_enable(); 127 128 if (!used_math()) 129 memcpy(dst, src, offsetof(struct task_struct, thread.fpu.fpr)); 130 else 131 memcpy(dst, src, offsetof(struct task_struct, thread.lbt.scr0)); 132 133 #ifdef CONFIG_CPU_HAS_LBT 134 memcpy(&dst->thread.lbt, &src->thread.lbt, sizeof(struct loongarch_lbt)); 135 #endif 136 137 return 0; 138 } 139 140 /* 141 * Copy architecture-specific thread state 142 */ 143 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) 144 { 145 unsigned long childksp; 146 unsigned long tls = args->tls; 147 unsigned long usp = args->stack; 148 unsigned long clone_flags = args->flags; 149 struct pt_regs *childregs, *regs = current_pt_regs(); 150 151 childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE; 152 153 /* set up new TSS. */ 154 childregs = (struct pt_regs *) childksp - 1; 155 /* Put the stack after the struct pt_regs. */ 156 childksp = (unsigned long) childregs; 157 p->thread.sched_cfa = 0; 158 p->thread.csr_euen = 0; 159 p->thread.csr_crmd = csr_read32(LOONGARCH_CSR_CRMD); 160 p->thread.csr_prmd = csr_read32(LOONGARCH_CSR_PRMD); 161 p->thread.csr_ecfg = csr_read32(LOONGARCH_CSR_ECFG); 162 if (unlikely(args->fn)) { 163 /* kernel thread */ 164 p->thread.reg03 = childksp; 165 p->thread.reg23 = (unsigned long)args->fn; 166 p->thread.reg24 = (unsigned long)args->fn_arg; 167 p->thread.reg01 = (unsigned long)ret_from_kernel_thread; 168 p->thread.sched_ra = (unsigned long)ret_from_kernel_thread; 169 memset(childregs, 0, sizeof(struct pt_regs)); 170 childregs->csr_euen = p->thread.csr_euen; 171 childregs->csr_crmd = p->thread.csr_crmd; 172 childregs->csr_prmd = p->thread.csr_prmd; 173 childregs->csr_ecfg = p->thread.csr_ecfg; 174 goto out; 175 } 176 177 /* user thread */ 178 *childregs = *regs; 179 childregs->regs[4] = 0; /* Child gets zero as return value */ 180 if (usp) 181 childregs->regs[3] = usp; 182 183 p->thread.reg03 = (unsigned long) childregs; 184 p->thread.reg01 = (unsigned long) ret_from_fork; 185 p->thread.sched_ra = (unsigned long) ret_from_fork; 186 187 /* 188 * New tasks lose permission to use the fpu. This accelerates context 189 * switching for most programs since they don't use the fpu. 190 */ 191 childregs->csr_euen = 0; 192 193 if (clone_flags & CLONE_SETTLS) 194 childregs->regs[2] = tls; 195 196 out: 197 ptrace_hw_copy_thread(p); 198 clear_tsk_thread_flag(p, TIF_USEDFPU); 199 clear_tsk_thread_flag(p, TIF_USEDSIMD); 200 clear_tsk_thread_flag(p, TIF_USEDLBT); 201 clear_tsk_thread_flag(p, TIF_LSX_CTX_LIVE); 202 clear_tsk_thread_flag(p, TIF_LASX_CTX_LIVE); 203 clear_tsk_thread_flag(p, TIF_LBT_CTX_LIVE); 204 205 return 0; 206 } 207 208 unsigned long __get_wchan(struct task_struct *task) 209 { 210 unsigned long pc = 0; 211 struct unwind_state state; 212 213 if (!try_get_task_stack(task)) 214 return 0; 215 216 for (unwind_start(&state, task, NULL); 217 !unwind_done(&state); unwind_next_frame(&state)) { 218 pc = unwind_get_return_address(&state); 219 if (!pc) 220 break; 221 if (in_sched_functions(pc)) 222 continue; 223 break; 224 } 225 226 put_task_stack(task); 227 228 return pc; 229 } 230 231 bool in_irq_stack(unsigned long stack, struct stack_info *info) 232 { 233 unsigned long nextsp; 234 unsigned long begin = (unsigned long)this_cpu_read(irq_stack); 235 unsigned long end = begin + IRQ_STACK_START; 236 237 if (stack < begin || stack >= end) 238 return false; 239 240 nextsp = *(unsigned long *)end; 241 if (nextsp & (SZREG - 1)) 242 return false; 243 244 info->begin = begin; 245 info->end = end; 246 info->next_sp = nextsp; 247 info->type = STACK_TYPE_IRQ; 248 249 return true; 250 } 251 252 bool in_task_stack(unsigned long stack, struct task_struct *task, 253 struct stack_info *info) 254 { 255 unsigned long begin = (unsigned long)task_stack_page(task); 256 unsigned long end = begin + THREAD_SIZE; 257 258 if (stack < begin || stack >= end) 259 return false; 260 261 info->begin = begin; 262 info->end = end; 263 info->next_sp = 0; 264 info->type = STACK_TYPE_TASK; 265 266 return true; 267 } 268 269 int get_stack_info(unsigned long stack, struct task_struct *task, 270 struct stack_info *info) 271 { 272 task = task ? : current; 273 274 if (!stack || stack & (SZREG - 1)) 275 goto unknown; 276 277 if (in_task_stack(stack, task, info)) 278 return 0; 279 280 if (task != current) 281 goto unknown; 282 283 if (in_irq_stack(stack, info)) 284 return 0; 285 286 unknown: 287 info->type = STACK_TYPE_UNKNOWN; 288 return -EINVAL; 289 } 290 291 unsigned long stack_top(void) 292 { 293 unsigned long top = TASK_SIZE & PAGE_MASK; 294 295 /* Space for the VDSO & data page */ 296 top -= PAGE_ALIGN(current->thread.vdso->size); 297 top -= VVAR_SIZE; 298 299 /* Space to randomize the VDSO base */ 300 if (current->flags & PF_RANDOMIZE) 301 top -= VDSO_RANDOMIZE_SIZE; 302 303 return top; 304 } 305 306 /* 307 * Don't forget that the stack pointer must be aligned on a 8 bytes 308 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI. 309 */ 310 unsigned long arch_align_stack(unsigned long sp) 311 { 312 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 313 sp -= get_random_u32_below(PAGE_SIZE); 314 315 return sp & STACK_ALIGN; 316 } 317 318 static DEFINE_PER_CPU(call_single_data_t, backtrace_csd); 319 static struct cpumask backtrace_csd_busy; 320 321 static void handle_backtrace(void *info) 322 { 323 nmi_cpu_backtrace(get_irq_regs()); 324 cpumask_clear_cpu(smp_processor_id(), &backtrace_csd_busy); 325 } 326 327 static void raise_backtrace(cpumask_t *mask) 328 { 329 call_single_data_t *csd; 330 int cpu; 331 332 for_each_cpu(cpu, mask) { 333 /* 334 * If we previously sent an IPI to the target CPU & it hasn't 335 * cleared its bit in the busy cpumask then it didn't handle 336 * our previous IPI & it's not safe for us to reuse the 337 * call_single_data_t. 338 */ 339 if (cpumask_test_and_set_cpu(cpu, &backtrace_csd_busy)) { 340 pr_warn("Unable to send backtrace IPI to CPU%u - perhaps it hung?\n", 341 cpu); 342 continue; 343 } 344 345 csd = &per_cpu(backtrace_csd, cpu); 346 csd->func = handle_backtrace; 347 smp_call_function_single_async(cpu, csd); 348 } 349 } 350 351 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu) 352 { 353 nmi_trigger_cpumask_backtrace(mask, exclude_cpu, raise_backtrace); 354 } 355 356 #ifdef CONFIG_64BIT 357 void loongarch_dump_regs64(u64 *uregs, const struct pt_regs *regs) 358 { 359 unsigned int i; 360 361 for (i = LOONGARCH_EF_R1; i <= LOONGARCH_EF_R31; i++) { 362 uregs[i] = regs->regs[i - LOONGARCH_EF_R0]; 363 } 364 365 uregs[LOONGARCH_EF_ORIG_A0] = regs->orig_a0; 366 uregs[LOONGARCH_EF_CSR_ERA] = regs->csr_era; 367 uregs[LOONGARCH_EF_CSR_BADV] = regs->csr_badvaddr; 368 uregs[LOONGARCH_EF_CSR_CRMD] = regs->csr_crmd; 369 uregs[LOONGARCH_EF_CSR_PRMD] = regs->csr_prmd; 370 uregs[LOONGARCH_EF_CSR_EUEN] = regs->csr_euen; 371 uregs[LOONGARCH_EF_CSR_ECFG] = regs->csr_ecfg; 372 uregs[LOONGARCH_EF_CSR_ESTAT] = regs->csr_estat; 373 } 374 #endif /* CONFIG_64BIT */ 375