1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) 4 * 5 * Amit Bhor, Kanika Nema: Codito Technologies 2004 6 */ 7 8 #include <linux/errno.h> 9 #include <linux/module.h> 10 #include <linux/sched.h> 11 #include <linux/sched/task.h> 12 #include <linux/sched/task_stack.h> 13 14 #include <linux/mm.h> 15 #include <linux/fs.h> 16 #include <linux/unistd.h> 17 #include <linux/ptrace.h> 18 #include <linux/slab.h> 19 #include <linux/syscalls.h> 20 #include <linux/elf.h> 21 #include <linux/tick.h> 22 23 #include <asm/fpu.h> 24 25 SYSCALL_DEFINE1(arc_settls, void *, user_tls_data_ptr) 26 { 27 task_thread_info(current)->thr_ptr = (unsigned int)user_tls_data_ptr; 28 return 0; 29 } 30 31 /* 32 * We return the user space TLS data ptr as sys-call return code 33 * Ideally it should be copy to user. 34 * However we can cheat by the fact that some sys-calls do return 35 * absurdly high values 36 * Since the tls dat aptr is not going to be in range of 0xFFFF_xxxx 37 * it won't be considered a sys-call error 38 * and it will be loads better than copy-to-user, which is a definite 39 * D-TLB Miss 40 */ 41 SYSCALL_DEFINE0(arc_gettls) 42 { 43 return task_thread_info(current)->thr_ptr; 44 } 45 46 SYSCALL_DEFINE3(arc_usr_cmpxchg, int __user *, uaddr, int, expected, int, new) 47 { 48 struct pt_regs *regs = current_pt_regs(); 49 u32 uval; 50 int ret; 51 52 /* 53 * This is only for old cores lacking LLOCK/SCOND, which by definition 54 * can't possibly be SMP. Thus doesn't need to be SMP safe. 55 * And this also helps reduce the overhead for serializing in 56 * the UP case 57 */ 58 WARN_ON_ONCE(IS_ENABLED(CONFIG_SMP)); 59 60 /* Z indicates to userspace if operation succeeded */ 61 regs->status32 &= ~STATUS_Z_MASK; 62 63 ret = access_ok(uaddr, sizeof(*uaddr)); 64 if (!ret) 65 goto fail; 66 67 again: 68 preempt_disable(); 69 70 ret = __get_user(uval, uaddr); 71 if (ret) 72 goto fault; 73 74 if (uval != expected) 75 goto out; 76 77 ret = __put_user(new, uaddr); 78 if (ret) 79 goto fault; 80 81 regs->status32 |= STATUS_Z_MASK; 82 83 out: 84 preempt_enable(); 85 return uval; 86 87 fault: 88 preempt_enable(); 89 90 if (unlikely(ret != -EFAULT)) 91 goto fail; 92 93 mmap_read_lock(current->mm); 94 ret = fixup_user_fault(current->mm, (unsigned long) uaddr, 95 FAULT_FLAG_WRITE, NULL); 96 mmap_read_unlock(current->mm); 97 98 if (likely(!ret)) 99 goto again; 100 101 fail: 102 force_sig(SIGSEGV); 103 return ret; 104 } 105 106 #ifdef CONFIG_ISA_ARCV2 107 108 void arch_cpu_idle(void) 109 { 110 /* Re-enable interrupts <= default irq priority before committing SLEEP */ 111 const unsigned int arg = 0x10 | ARCV2_IRQ_DEF_PRIO; 112 113 __asm__ __volatile__( 114 "sleep %0 \n" 115 : 116 :"I"(arg)); /* can't be "r" has to be embedded const */ 117 118 raw_local_irq_disable(); 119 } 120 121 #else /* ARC700 */ 122 123 void arch_cpu_idle(void) 124 { 125 /* sleep, but enable both set E1/E2 (levels of interrupts) before committing */ 126 __asm__ __volatile__("sleep 0x3 \n"); 127 raw_local_irq_disable(); 128 } 129 130 #endif 131 132 asmlinkage void ret_from_fork(void); 133 134 /* 135 * Copy architecture-specific thread state 136 * 137 * Layout of Child kernel mode stack as setup at the end of this function is 138 * 139 * | ... | 140 * | ... | 141 * | unused | 142 * | | 143 * ------------------ 144 * | r25 | <==== top of Stack (thread.ksp) 145 * ~ ~ 146 * | --to-- | (CALLEE Regs of kernel mode) 147 * | r13 | 148 * ------------------ 149 * | fp | 150 * | blink | @ret_from_fork 151 * ------------------ 152 * | | 153 * ~ ~ 154 * ~ ~ 155 * | | 156 * ------------------ 157 * | r12 | 158 * ~ ~ 159 * | --to-- | (scratch Regs of user mode) 160 * | r0 | 161 * ------------------ 162 * | SP | 163 * | orig_r0 | 164 * | event/ECR | 165 * | user_r25 | 166 * ------------------ <===== END of PAGE 167 */ 168 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) 169 { 170 unsigned long clone_flags = args->flags; 171 unsigned long usp = args->stack; 172 unsigned long tls = args->tls; 173 struct pt_regs *c_regs; /* child's pt_regs */ 174 unsigned long *childksp; /* to unwind out of __switch_to() */ 175 struct callee_regs *c_callee; /* child's callee regs */ 176 struct callee_regs *parent_callee; /* paren't callee */ 177 struct pt_regs *regs = current_pt_regs(); 178 179 /* Mark the specific anchors to begin with (see pic above) */ 180 c_regs = task_pt_regs(p); 181 childksp = (unsigned long *)c_regs - 2; /* 2 words for FP/BLINK */ 182 c_callee = ((struct callee_regs *)childksp) - 1; 183 184 /* 185 * __switch_to() uses thread.ksp to start unwinding stack 186 * For kernel threads we don't need to create callee regs, the 187 * stack layout nevertheless needs to remain the same. 188 * Also, since __switch_to anyways unwinds callee regs, we use 189 * this to populate kernel thread entry-pt/args into callee regs, 190 * so that ret_from_kernel_thread() becomes simpler. 191 */ 192 p->thread.ksp = (unsigned long)c_callee; /* THREAD_KSP */ 193 194 /* __switch_to expects FP(0), BLINK(return addr) at top */ 195 childksp[0] = 0; /* fp */ 196 childksp[1] = (unsigned long)ret_from_fork; /* blink */ 197 198 if (unlikely(args->fn)) { 199 memset(c_regs, 0, sizeof(struct pt_regs)); 200 201 c_callee->r13 = (unsigned long)args->fn_arg; 202 c_callee->r14 = (unsigned long)args->fn; 203 204 return 0; 205 } 206 207 /*--------- User Task Only --------------*/ 208 209 /* __switch_to expects FP(0), BLINK(return addr) at top of stack */ 210 childksp[0] = 0; /* for POP fp */ 211 childksp[1] = (unsigned long)ret_from_fork; /* for POP blink */ 212 213 /* Copy parents pt regs on child's kernel mode stack */ 214 *c_regs = *regs; 215 216 if (usp) 217 c_regs->sp = usp; 218 219 c_regs->r0 = 0; /* fork returns 0 in child */ 220 221 parent_callee = ((struct callee_regs *)regs) - 1; 222 *c_callee = *parent_callee; 223 224 if (unlikely(clone_flags & CLONE_SETTLS)) { 225 /* 226 * set task's userland tls data ptr from 4th arg 227 * clone C-lib call is difft from clone sys-call 228 */ 229 task_thread_info(p)->thr_ptr = tls; 230 } else { 231 /* Normal fork case: set parent's TLS ptr in child */ 232 task_thread_info(p)->thr_ptr = 233 task_thread_info(current)->thr_ptr; 234 } 235 236 237 /* 238 * setup usermode thread pointer #1: 239 * when child is picked by scheduler, __switch_to() uses @c_callee to 240 * populate usermode callee regs: this works (despite being in a kernel 241 * function) since special return path for child @ret_from_fork() 242 * ensures those regs are not clobbered all the way to RTIE to usermode 243 */ 244 c_callee->r25 = task_thread_info(p)->thr_ptr; 245 246 #ifdef CONFIG_ARC_CURR_IN_REG 247 /* 248 * setup usermode thread pointer #2: 249 * however for this special use of r25 in kernel, __switch_to() sets 250 * r25 for kernel needs and only in the final return path is usermode 251 * r25 setup, from pt_regs->user_r25. So set that up as well 252 */ 253 c_regs->user_r25 = c_callee->r25; 254 #endif 255 256 return 0; 257 } 258 259 /* 260 * Do necessary setup to start up a new user task 261 */ 262 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long usp) 263 { 264 regs->sp = usp; 265 regs->ret = pc; 266 267 /* 268 * [U]ser Mode bit set 269 * [L] ZOL loop inhibited to begin with - cleared by a LP insn 270 * Interrupts enabled 271 */ 272 regs->status32 = STATUS_U_MASK | STATUS_L_MASK | ISA_INIT_STATUS_BITS; 273 274 fpu_init_task(regs); 275 276 /* bogus seed values for debugging */ 277 regs->lp_start = 0x10; 278 regs->lp_end = 0x80; 279 } 280 281 /* 282 * Some archs flush debug and FPU info here 283 */ 284 void flush_thread(void) 285 { 286 } 287 288 int elf_check_arch(const struct elf32_hdr *x) 289 { 290 unsigned int eflags; 291 292 if (x->e_machine != EM_ARC_INUSE) { 293 pr_err("ELF not built for %s ISA\n", 294 is_isa_arcompact() ? "ARCompact":"ARCv2"); 295 return 0; 296 } 297 298 eflags = x->e_flags; 299 if ((eflags & EF_ARC_OSABI_MSK) != EF_ARC_OSABI_CURRENT) { 300 pr_err("ABI mismatch - you need newer toolchain\n"); 301 force_fatal_sig(SIGSEGV); 302 return 0; 303 } 304 305 return 1; 306 } 307 EXPORT_SYMBOL(elf_check_arch); 308