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 *, 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 defintion 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 succeded */ 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, 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 commiting 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 #elif defined(CONFIG_EZNPS_MTM_EXT) /* ARC700 variant in NPS */ 120 121 void arch_cpu_idle(void) 122 { 123 /* only the calling HW thread needs to sleep */ 124 __asm__ __volatile__( 125 ".word %0 \n" 126 : 127 :"i"(CTOP_INST_HWSCHD_WFT_IE12)); 128 } 129 130 #else /* ARC700 */ 131 132 void arch_cpu_idle(void) 133 { 134 /* sleep, but enable both set E1/E2 (levels of interrutps) before committing */ 135 __asm__ __volatile__("sleep 0x3 \n"); 136 } 137 138 #endif 139 140 asmlinkage void ret_from_fork(void); 141 142 /* 143 * Copy architecture-specific thread state 144 * 145 * Layout of Child kernel mode stack as setup at the end of this function is 146 * 147 * | ... | 148 * | ... | 149 * | unused | 150 * | | 151 * ------------------ 152 * | r25 | <==== top of Stack (thread.ksp) 153 * ~ ~ 154 * | --to-- | (CALLEE Regs of kernel mode) 155 * | r13 | 156 * ------------------ 157 * | fp | 158 * | blink | @ret_from_fork 159 * ------------------ 160 * | | 161 * ~ ~ 162 * ~ ~ 163 * | | 164 * ------------------ 165 * | r12 | 166 * ~ ~ 167 * | --to-- | (scratch Regs of user mode) 168 * | r0 | 169 * ------------------ 170 * | SP | 171 * | orig_r0 | 172 * | event/ECR | 173 * | user_r25 | 174 * ------------------ <===== END of PAGE 175 */ 176 int copy_thread(unsigned long clone_flags, unsigned long usp, 177 unsigned long kthread_arg, struct task_struct *p, 178 unsigned long tls) 179 { 180 struct pt_regs *c_regs; /* child's pt_regs */ 181 unsigned long *childksp; /* to unwind out of __switch_to() */ 182 struct callee_regs *c_callee; /* child's callee regs */ 183 struct callee_regs *parent_callee; /* paren't callee */ 184 struct pt_regs *regs = current_pt_regs(); 185 186 /* Mark the specific anchors to begin with (see pic above) */ 187 c_regs = task_pt_regs(p); 188 childksp = (unsigned long *)c_regs - 2; /* 2 words for FP/BLINK */ 189 c_callee = ((struct callee_regs *)childksp) - 1; 190 191 /* 192 * __switch_to() uses thread.ksp to start unwinding stack 193 * For kernel threads we don't need to create callee regs, the 194 * stack layout nevertheless needs to remain the same. 195 * Also, since __switch_to anyways unwinds callee regs, we use 196 * this to populate kernel thread entry-pt/args into callee regs, 197 * so that ret_from_kernel_thread() becomes simpler. 198 */ 199 p->thread.ksp = (unsigned long)c_callee; /* THREAD_KSP */ 200 201 /* __switch_to expects FP(0), BLINK(return addr) at top */ 202 childksp[0] = 0; /* fp */ 203 childksp[1] = (unsigned long)ret_from_fork; /* blink */ 204 205 if (unlikely(p->flags & PF_KTHREAD)) { 206 memset(c_regs, 0, sizeof(struct pt_regs)); 207 208 c_callee->r13 = kthread_arg; 209 c_callee->r14 = usp; /* function */ 210 211 return 0; 212 } 213 214 /*--------- User Task Only --------------*/ 215 216 /* __switch_to expects FP(0), BLINK(return addr) at top of stack */ 217 childksp[0] = 0; /* for POP fp */ 218 childksp[1] = (unsigned long)ret_from_fork; /* for POP blink */ 219 220 /* Copy parents pt regs on child's kernel mode stack */ 221 *c_regs = *regs; 222 223 if (usp) 224 c_regs->sp = usp; 225 226 c_regs->r0 = 0; /* fork returns 0 in child */ 227 228 parent_callee = ((struct callee_regs *)regs) - 1; 229 *c_callee = *parent_callee; 230 231 if (unlikely(clone_flags & CLONE_SETTLS)) { 232 /* 233 * set task's userland tls data ptr from 4th arg 234 * clone C-lib call is difft from clone sys-call 235 */ 236 task_thread_info(p)->thr_ptr = tls; 237 } else { 238 /* Normal fork case: set parent's TLS ptr in child */ 239 task_thread_info(p)->thr_ptr = 240 task_thread_info(current)->thr_ptr; 241 } 242 243 244 /* 245 * setup usermode thread pointer #1: 246 * when child is picked by scheduler, __switch_to() uses @c_callee to 247 * populate usermode callee regs: this works (despite being in a kernel 248 * function) since special return path for child @ret_from_fork() 249 * ensures those regs are not clobbered all the way to RTIE to usermode 250 */ 251 c_callee->r25 = task_thread_info(p)->thr_ptr; 252 253 #ifdef CONFIG_ARC_CURR_IN_REG 254 /* 255 * setup usermode thread pointer #2: 256 * however for this special use of r25 in kernel, __switch_to() sets 257 * r25 for kernel needs and only in the final return path is usermode 258 * r25 setup, from pt_regs->user_r25. So set that up as well 259 */ 260 c_regs->user_r25 = c_callee->r25; 261 #endif 262 263 return 0; 264 } 265 266 /* 267 * Do necessary setup to start up a new user task 268 */ 269 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long usp) 270 { 271 regs->sp = usp; 272 regs->ret = pc; 273 274 /* 275 * [U]ser Mode bit set 276 * [L] ZOL loop inhibited to begin with - cleared by a LP insn 277 * Interrupts enabled 278 */ 279 regs->status32 = STATUS_U_MASK | STATUS_L_MASK | ISA_INIT_STATUS_BITS; 280 281 #ifdef CONFIG_EZNPS_MTM_EXT 282 regs->eflags = 0; 283 #endif 284 285 fpu_init_task(regs); 286 287 /* bogus seed values for debugging */ 288 regs->lp_start = 0x10; 289 regs->lp_end = 0x80; 290 } 291 292 /* 293 * Some archs flush debug and FPU info here 294 */ 295 void flush_thread(void) 296 { 297 } 298 299 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu) 300 { 301 return 0; 302 } 303 304 int elf_check_arch(const struct elf32_hdr *x) 305 { 306 unsigned int eflags; 307 308 if (x->e_machine != EM_ARC_INUSE) { 309 pr_err("ELF not built for %s ISA\n", 310 is_isa_arcompact() ? "ARCompact":"ARCv2"); 311 return 0; 312 } 313 314 eflags = x->e_flags; 315 if ((eflags & EF_ARC_OSABI_MSK) != EF_ARC_OSABI_CURRENT) { 316 pr_err("ABI mismatch - you need newer toolchain\n"); 317 force_sigsegv(SIGSEGV); 318 return 0; 319 } 320 321 return 1; 322 } 323 EXPORT_SYMBOL(elf_check_arch); 324