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/vdso.h> 48 49 /* 50 * Idle related variables and functions 51 */ 52 53 unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE; 54 EXPORT_SYMBOL(boot_option_idle_override); 55 56 #ifdef CONFIG_HOTPLUG_CPU 57 void arch_cpu_idle_dead(void) 58 { 59 play_dead(); 60 } 61 #endif 62 63 asmlinkage void ret_from_fork(void); 64 asmlinkage void ret_from_kernel_thread(void); 65 66 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp) 67 { 68 unsigned long crmd; 69 unsigned long prmd; 70 unsigned long euen; 71 72 /* New thread loses kernel privileges. */ 73 crmd = regs->csr_crmd & ~(PLV_MASK); 74 crmd |= PLV_USER; 75 regs->csr_crmd = crmd; 76 77 prmd = regs->csr_prmd & ~(PLV_MASK); 78 prmd |= PLV_USER; 79 regs->csr_prmd = prmd; 80 81 euen = regs->csr_euen & ~(CSR_EUEN_FPEN); 82 regs->csr_euen = euen; 83 lose_fpu(0); 84 85 clear_thread_flag(TIF_LSX_CTX_LIVE); 86 clear_thread_flag(TIF_LASX_CTX_LIVE); 87 clear_used_math(); 88 regs->csr_era = pc; 89 regs->regs[3] = sp; 90 } 91 92 void exit_thread(struct task_struct *tsk) 93 { 94 } 95 96 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) 97 { 98 /* 99 * Save any process state which is live in hardware registers to the 100 * parent context prior to duplication. This prevents the new child 101 * state becoming stale if the parent is preempted before copy_thread() 102 * gets a chance to save the parent's live hardware registers to the 103 * child context. 104 */ 105 preempt_disable(); 106 107 if (is_fpu_owner()) 108 save_fp(current); 109 110 preempt_enable(); 111 112 if (used_math()) 113 memcpy(dst, src, sizeof(struct task_struct)); 114 else 115 memcpy(dst, src, offsetof(struct task_struct, thread.fpu.fpr)); 116 117 return 0; 118 } 119 120 /* 121 * Copy architecture-specific thread state 122 */ 123 int copy_thread(unsigned long clone_flags, unsigned long usp, 124 unsigned long kthread_arg, struct task_struct *p, unsigned long tls) 125 { 126 unsigned long childksp; 127 struct pt_regs *childregs, *regs = current_pt_regs(); 128 129 childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32; 130 131 /* set up new TSS. */ 132 childregs = (struct pt_regs *) childksp - 1; 133 /* Put the stack after the struct pt_regs. */ 134 childksp = (unsigned long) childregs; 135 p->thread.csr_euen = 0; 136 p->thread.csr_crmd = csr_read32(LOONGARCH_CSR_CRMD); 137 p->thread.csr_prmd = csr_read32(LOONGARCH_CSR_PRMD); 138 p->thread.csr_ecfg = csr_read32(LOONGARCH_CSR_ECFG); 139 if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) { 140 /* kernel thread */ 141 p->thread.reg23 = usp; /* fn */ 142 p->thread.reg24 = kthread_arg; 143 p->thread.reg03 = childksp; 144 p->thread.reg01 = (unsigned long) ret_from_kernel_thread; 145 memset(childregs, 0, sizeof(struct pt_regs)); 146 childregs->csr_euen = p->thread.csr_euen; 147 childregs->csr_crmd = p->thread.csr_crmd; 148 childregs->csr_prmd = p->thread.csr_prmd; 149 childregs->csr_ecfg = p->thread.csr_ecfg; 150 return 0; 151 } 152 153 /* user thread */ 154 *childregs = *regs; 155 childregs->regs[4] = 0; /* Child gets zero as return value */ 156 if (usp) 157 childregs->regs[3] = usp; 158 159 p->thread.reg03 = (unsigned long) childregs; 160 p->thread.reg01 = (unsigned long) ret_from_fork; 161 162 /* 163 * New tasks lose permission to use the fpu. This accelerates context 164 * switching for most programs since they don't use the fpu. 165 */ 166 childregs->csr_euen = 0; 167 168 clear_tsk_thread_flag(p, TIF_USEDFPU); 169 clear_tsk_thread_flag(p, TIF_USEDSIMD); 170 clear_tsk_thread_flag(p, TIF_LSX_CTX_LIVE); 171 clear_tsk_thread_flag(p, TIF_LASX_CTX_LIVE); 172 173 if (clone_flags & CLONE_SETTLS) 174 childregs->regs[2] = tls; 175 176 return 0; 177 } 178 179 unsigned long __get_wchan(struct task_struct *task) 180 { 181 return 0; 182 } 183 184 unsigned long stack_top(void) 185 { 186 unsigned long top = TASK_SIZE & PAGE_MASK; 187 188 /* Space for the VDSO & data page */ 189 top -= PAGE_ALIGN(current->thread.vdso->size); 190 top -= PAGE_SIZE; 191 192 /* Space to randomize the VDSO base */ 193 if (current->flags & PF_RANDOMIZE) 194 top -= VDSO_RANDOMIZE_SIZE; 195 196 return top; 197 } 198 199 /* 200 * Don't forget that the stack pointer must be aligned on a 8 bytes 201 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI. 202 */ 203 unsigned long arch_align_stack(unsigned long sp) 204 { 205 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 206 sp -= get_random_int() & ~PAGE_MASK; 207 208 return sp & STACK_ALIGN; 209 } 210 211 static DEFINE_PER_CPU(call_single_data_t, backtrace_csd); 212 static struct cpumask backtrace_csd_busy; 213 214 static void handle_backtrace(void *info) 215 { 216 nmi_cpu_backtrace(get_irq_regs()); 217 cpumask_clear_cpu(smp_processor_id(), &backtrace_csd_busy); 218 } 219 220 static void raise_backtrace(cpumask_t *mask) 221 { 222 call_single_data_t *csd; 223 int cpu; 224 225 for_each_cpu(cpu, mask) { 226 /* 227 * If we previously sent an IPI to the target CPU & it hasn't 228 * cleared its bit in the busy cpumask then it didn't handle 229 * our previous IPI & it's not safe for us to reuse the 230 * call_single_data_t. 231 */ 232 if (cpumask_test_and_set_cpu(cpu, &backtrace_csd_busy)) { 233 pr_warn("Unable to send backtrace IPI to CPU%u - perhaps it hung?\n", 234 cpu); 235 continue; 236 } 237 238 csd = &per_cpu(backtrace_csd, cpu); 239 csd->func = handle_backtrace; 240 smp_call_function_single_async(cpu, csd); 241 } 242 } 243 244 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self) 245 { 246 nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_backtrace); 247 } 248 249 #ifdef CONFIG_64BIT 250 void loongarch_dump_regs64(u64 *uregs, const struct pt_regs *regs) 251 { 252 unsigned int i; 253 254 for (i = LOONGARCH_EF_R1; i <= LOONGARCH_EF_R31; i++) { 255 uregs[i] = regs->regs[i - LOONGARCH_EF_R0]; 256 } 257 258 uregs[LOONGARCH_EF_ORIG_A0] = regs->orig_a0; 259 uregs[LOONGARCH_EF_CSR_ERA] = regs->csr_era; 260 uregs[LOONGARCH_EF_CSR_BADV] = regs->csr_badvaddr; 261 uregs[LOONGARCH_EF_CSR_CRMD] = regs->csr_crmd; 262 uregs[LOONGARCH_EF_CSR_PRMD] = regs->csr_prmd; 263 uregs[LOONGARCH_EF_CSR_EUEN] = regs->csr_euen; 264 uregs[LOONGARCH_EF_CSR_ECFG] = regs->csr_ecfg; 265 uregs[LOONGARCH_EF_CSR_ESTAT] = regs->csr_estat; 266 } 267 #endif /* CONFIG_64BIT */ 268