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 down_read(¤t->mm->mmap_sem); 94 ret = fixup_user_fault(current, current->mm, (unsigned long) uaddr, 95 FAULT_FLAG_WRITE, NULL); 96 up_read(¤t->mm->mmap_sem); 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_tls(unsigned long clone_flags, unsigned long usp, 177 unsigned long kthread_arg, struct task_struct *p, unsigned long tls) 178 { 179 struct pt_regs *c_regs; /* child's pt_regs */ 180 unsigned long *childksp; /* to unwind out of __switch_to() */ 181 struct callee_regs *c_callee; /* child's callee regs */ 182 struct callee_regs *parent_callee; /* paren't callee */ 183 struct pt_regs *regs = current_pt_regs(); 184 185 /* Mark the specific anchors to begin with (see pic above) */ 186 c_regs = task_pt_regs(p); 187 childksp = (unsigned long *)c_regs - 2; /* 2 words for FP/BLINK */ 188 c_callee = ((struct callee_regs *)childksp) - 1; 189 190 /* 191 * __switch_to() uses thread.ksp to start unwinding stack 192 * For kernel threads we don't need to create callee regs, the 193 * stack layout nevertheless needs to remain the same. 194 * Also, since __switch_to anyways unwinds callee regs, we use 195 * this to populate kernel thread entry-pt/args into callee regs, 196 * so that ret_from_kernel_thread() becomes simpler. 197 */ 198 p->thread.ksp = (unsigned long)c_callee; /* THREAD_KSP */ 199 200 /* __switch_to expects FP(0), BLINK(return addr) at top */ 201 childksp[0] = 0; /* fp */ 202 childksp[1] = (unsigned long)ret_from_fork; /* blink */ 203 204 if (unlikely(p->flags & PF_KTHREAD)) { 205 memset(c_regs, 0, sizeof(struct pt_regs)); 206 207 c_callee->r13 = kthread_arg; 208 c_callee->r14 = usp; /* function */ 209 210 return 0; 211 } 212 213 /*--------- User Task Only --------------*/ 214 215 /* __switch_to expects FP(0), BLINK(return addr) at top of stack */ 216 childksp[0] = 0; /* for POP fp */ 217 childksp[1] = (unsigned long)ret_from_fork; /* for POP blink */ 218 219 /* Copy parents pt regs on child's kernel mode stack */ 220 *c_regs = *regs; 221 222 if (usp) 223 c_regs->sp = usp; 224 225 c_regs->r0 = 0; /* fork returns 0 in child */ 226 227 parent_callee = ((struct callee_regs *)regs) - 1; 228 *c_callee = *parent_callee; 229 230 if (unlikely(clone_flags & CLONE_SETTLS)) { 231 /* 232 * set task's userland tls data ptr from 4th arg 233 * clone C-lib call is difft from clone sys-call 234 */ 235 task_thread_info(p)->thr_ptr = tls; 236 } else { 237 /* Normal fork case: set parent's TLS ptr in child */ 238 task_thread_info(p)->thr_ptr = 239 task_thread_info(current)->thr_ptr; 240 } 241 242 243 /* 244 * setup usermode thread pointer #1: 245 * when child is picked by scheduler, __switch_to() uses @c_callee to 246 * populate usermode callee regs: this works (despite being in a kernel 247 * function) since special return path for child @ret_from_fork() 248 * ensures those regs are not clobbered all the way to RTIE to usermode 249 */ 250 c_callee->r25 = task_thread_info(p)->thr_ptr; 251 252 #ifdef CONFIG_ARC_CURR_IN_REG 253 /* 254 * setup usermode thread pointer #2: 255 * however for this special use of r25 in kernel, __switch_to() sets 256 * r25 for kernel needs and only in the final return path is usermode 257 * r25 setup, from pt_regs->user_r25. So set that up as well 258 */ 259 c_regs->user_r25 = c_callee->r25; 260 #endif 261 262 return 0; 263 } 264 265 /* 266 * Do necessary setup to start up a new user task 267 */ 268 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long usp) 269 { 270 regs->sp = usp; 271 regs->ret = pc; 272 273 /* 274 * [U]ser Mode bit set 275 * [L] ZOL loop inhibited to begin with - cleared by a LP insn 276 * Interrupts enabled 277 */ 278 regs->status32 = STATUS_U_MASK | STATUS_L_MASK | ISA_INIT_STATUS_BITS; 279 280 #ifdef CONFIG_EZNPS_MTM_EXT 281 regs->eflags = 0; 282 #endif 283 284 fpu_init_task(regs); 285 286 /* bogus seed values for debugging */ 287 regs->lp_start = 0x10; 288 regs->lp_end = 0x80; 289 } 290 291 /* 292 * Some archs flush debug and FPU info here 293 */ 294 void flush_thread(void) 295 { 296 } 297 298 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu) 299 { 300 return 0; 301 } 302 303 int elf_check_arch(const struct elf32_hdr *x) 304 { 305 unsigned int eflags; 306 307 if (x->e_machine != EM_ARC_INUSE) { 308 pr_err("ELF not built for %s ISA\n", 309 is_isa_arcompact() ? "ARCompact":"ARCv2"); 310 return 0; 311 } 312 313 eflags = x->e_flags; 314 if ((eflags & EF_ARC_OSABI_MSK) != EF_ARC_OSABI_CURRENT) { 315 pr_err("ABI mismatch - you need newer toolchain\n"); 316 force_sigsegv(SIGSEGV); 317 return 0; 318 } 319 320 return 1; 321 } 322 EXPORT_SYMBOL(elf_check_arch); 323