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 } 118 119 #else /* ARC700 */ 120 121 void arch_cpu_idle(void) 122 { 123 /* sleep, but enable both set E1/E2 (levels of interrupts) before committing */ 124 __asm__ __volatile__("sleep 0x3 \n"); 125 } 126 127 #endif 128 129 asmlinkage void ret_from_fork(void); 130 131 /* 132 * Copy architecture-specific thread state 133 * 134 * Layout of Child kernel mode stack as setup at the end of this function is 135 * 136 * | ... | 137 * | ... | 138 * | unused | 139 * | | 140 * ------------------ 141 * | r25 | <==== top of Stack (thread.ksp) 142 * ~ ~ 143 * | --to-- | (CALLEE Regs of kernel mode) 144 * | r13 | 145 * ------------------ 146 * | fp | 147 * | blink | @ret_from_fork 148 * ------------------ 149 * | | 150 * ~ ~ 151 * ~ ~ 152 * | | 153 * ------------------ 154 * | r12 | 155 * ~ ~ 156 * | --to-- | (scratch Regs of user mode) 157 * | r0 | 158 * ------------------ 159 * | SP | 160 * | orig_r0 | 161 * | event/ECR | 162 * | user_r25 | 163 * ------------------ <===== END of PAGE 164 */ 165 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) 166 { 167 unsigned long clone_flags = args->flags; 168 unsigned long usp = args->stack; 169 unsigned long tls = args->tls; 170 struct pt_regs *c_regs; /* child's pt_regs */ 171 unsigned long *childksp; /* to unwind out of __switch_to() */ 172 struct callee_regs *c_callee; /* child's callee regs */ 173 struct callee_regs *parent_callee; /* paren't callee */ 174 struct pt_regs *regs = current_pt_regs(); 175 176 /* Mark the specific anchors to begin with (see pic above) */ 177 c_regs = task_pt_regs(p); 178 childksp = (unsigned long *)c_regs - 2; /* 2 words for FP/BLINK */ 179 c_callee = ((struct callee_regs *)childksp) - 1; 180 181 /* 182 * __switch_to() uses thread.ksp to start unwinding stack 183 * For kernel threads we don't need to create callee regs, the 184 * stack layout nevertheless needs to remain the same. 185 * Also, since __switch_to anyways unwinds callee regs, we use 186 * this to populate kernel thread entry-pt/args into callee regs, 187 * so that ret_from_kernel_thread() becomes simpler. 188 */ 189 p->thread.ksp = (unsigned long)c_callee; /* THREAD_KSP */ 190 191 /* __switch_to expects FP(0), BLINK(return addr) at top */ 192 childksp[0] = 0; /* fp */ 193 childksp[1] = (unsigned long)ret_from_fork; /* blink */ 194 195 if (unlikely(args->fn)) { 196 memset(c_regs, 0, sizeof(struct pt_regs)); 197 198 c_callee->r13 = (unsigned long)args->fn_arg; 199 c_callee->r14 = (unsigned long)args->fn; 200 201 return 0; 202 } 203 204 /*--------- User Task Only --------------*/ 205 206 /* __switch_to expects FP(0), BLINK(return addr) at top of stack */ 207 childksp[0] = 0; /* for POP fp */ 208 childksp[1] = (unsigned long)ret_from_fork; /* for POP blink */ 209 210 /* Copy parents pt regs on child's kernel mode stack */ 211 *c_regs = *regs; 212 213 if (usp) 214 c_regs->sp = usp; 215 216 c_regs->r0 = 0; /* fork returns 0 in child */ 217 218 parent_callee = ((struct callee_regs *)regs) - 1; 219 *c_callee = *parent_callee; 220 221 if (unlikely(clone_flags & CLONE_SETTLS)) { 222 /* 223 * set task's userland tls data ptr from 4th arg 224 * clone C-lib call is difft from clone sys-call 225 */ 226 task_thread_info(p)->thr_ptr = tls; 227 } else { 228 /* Normal fork case: set parent's TLS ptr in child */ 229 task_thread_info(p)->thr_ptr = 230 task_thread_info(current)->thr_ptr; 231 } 232 233 234 /* 235 * setup usermode thread pointer #1: 236 * when child is picked by scheduler, __switch_to() uses @c_callee to 237 * populate usermode callee regs: this works (despite being in a kernel 238 * function) since special return path for child @ret_from_fork() 239 * ensures those regs are not clobbered all the way to RTIE to usermode 240 */ 241 c_callee->r25 = task_thread_info(p)->thr_ptr; 242 243 #ifdef CONFIG_ARC_CURR_IN_REG 244 /* 245 * setup usermode thread pointer #2: 246 * however for this special use of r25 in kernel, __switch_to() sets 247 * r25 for kernel needs and only in the final return path is usermode 248 * r25 setup, from pt_regs->user_r25. So set that up as well 249 */ 250 c_regs->user_r25 = c_callee->r25; 251 #endif 252 253 return 0; 254 } 255 256 /* 257 * Do necessary setup to start up a new user task 258 */ 259 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long usp) 260 { 261 regs->sp = usp; 262 regs->ret = pc; 263 264 /* 265 * [U]ser Mode bit set 266 * [L] ZOL loop inhibited to begin with - cleared by a LP insn 267 * Interrupts enabled 268 */ 269 regs->status32 = STATUS_U_MASK | STATUS_L_MASK | ISA_INIT_STATUS_BITS; 270 271 fpu_init_task(regs); 272 273 /* bogus seed values for debugging */ 274 regs->lp_start = 0x10; 275 regs->lp_end = 0x80; 276 } 277 278 /* 279 * Some archs flush debug and FPU info here 280 */ 281 void flush_thread(void) 282 { 283 } 284 285 int elf_check_arch(const struct elf32_hdr *x) 286 { 287 unsigned int eflags; 288 289 if (x->e_machine != EM_ARC_INUSE) { 290 pr_err("ELF not built for %s ISA\n", 291 is_isa_arcompact() ? "ARCompact":"ARCv2"); 292 return 0; 293 } 294 295 eflags = x->e_flags; 296 if ((eflags & EF_ARC_OSABI_MSK) != EF_ARC_OSABI_CURRENT) { 297 pr_err("ABI mismatch - you need newer toolchain\n"); 298 force_fatal_sig(SIGSEGV); 299 return 0; 300 } 301 302 return 1; 303 } 304 EXPORT_SYMBOL(elf_check_arch); 305