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 SYSCALL_DEFINE1(arc_settls, void *, user_tls_data_ptr) 24 { 25 task_thread_info(current)->thr_ptr = (unsigned int)user_tls_data_ptr; 26 return 0; 27 } 28 29 /* 30 * We return the user space TLS data ptr as sys-call return code 31 * Ideally it should be copy to user. 32 * However we can cheat by the fact that some sys-calls do return 33 * absurdly high values 34 * Since the tls dat aptr is not going to be in range of 0xFFFF_xxxx 35 * it won't be considered a sys-call error 36 * and it will be loads better than copy-to-user, which is a definite 37 * D-TLB Miss 38 */ 39 SYSCALL_DEFINE0(arc_gettls) 40 { 41 return task_thread_info(current)->thr_ptr; 42 } 43 44 SYSCALL_DEFINE3(arc_usr_cmpxchg, int *, uaddr, int, expected, int, new) 45 { 46 struct pt_regs *regs = current_pt_regs(); 47 u32 uval; 48 int ret; 49 50 /* 51 * This is only for old cores lacking LLOCK/SCOND, which by defintion 52 * can't possibly be SMP. Thus doesn't need to be SMP safe. 53 * And this also helps reduce the overhead for serializing in 54 * the UP case 55 */ 56 WARN_ON_ONCE(IS_ENABLED(CONFIG_SMP)); 57 58 /* Z indicates to userspace if operation succeded */ 59 regs->status32 &= ~STATUS_Z_MASK; 60 61 ret = access_ok(uaddr, sizeof(*uaddr)); 62 if (!ret) 63 goto fail; 64 65 again: 66 preempt_disable(); 67 68 ret = __get_user(uval, uaddr); 69 if (ret) 70 goto fault; 71 72 if (uval != expected) 73 goto out; 74 75 ret = __put_user(new, uaddr); 76 if (ret) 77 goto fault; 78 79 regs->status32 |= STATUS_Z_MASK; 80 81 out: 82 preempt_enable(); 83 return uval; 84 85 fault: 86 preempt_enable(); 87 88 if (unlikely(ret != -EFAULT)) 89 goto fail; 90 91 down_read(¤t->mm->mmap_sem); 92 ret = fixup_user_fault(current, current->mm, (unsigned long) uaddr, 93 FAULT_FLAG_WRITE, NULL); 94 up_read(¤t->mm->mmap_sem); 95 96 if (likely(!ret)) 97 goto again; 98 99 fail: 100 force_sig(SIGSEGV); 101 return ret; 102 } 103 104 #ifdef CONFIG_ISA_ARCV2 105 106 void arch_cpu_idle(void) 107 { 108 /* Re-enable interrupts <= default irq priority before commiting SLEEP */ 109 const unsigned int arg = 0x10 | ARCV2_IRQ_DEF_PRIO; 110 111 __asm__ __volatile__( 112 "sleep %0 \n" 113 : 114 :"I"(arg)); /* can't be "r" has to be embedded const */ 115 } 116 117 #elif defined(CONFIG_EZNPS_MTM_EXT) /* ARC700 variant in NPS */ 118 119 void arch_cpu_idle(void) 120 { 121 /* only the calling HW thread needs to sleep */ 122 __asm__ __volatile__( 123 ".word %0 \n" 124 : 125 :"i"(CTOP_INST_HWSCHD_WFT_IE12)); 126 } 127 128 #else /* ARC700 */ 129 130 void arch_cpu_idle(void) 131 { 132 /* sleep, but enable both set E1/E2 (levels of interrutps) before committing */ 133 __asm__ __volatile__("sleep 0x3 \n"); 134 } 135 136 #endif 137 138 asmlinkage void ret_from_fork(void); 139 140 /* 141 * Copy architecture-specific thread state 142 * 143 * Layout of Child kernel mode stack as setup at the end of this function is 144 * 145 * | ... | 146 * | ... | 147 * | unused | 148 * | | 149 * ------------------ 150 * | r25 | <==== top of Stack (thread.ksp) 151 * ~ ~ 152 * | --to-- | (CALLEE Regs of kernel mode) 153 * | r13 | 154 * ------------------ 155 * | fp | 156 * | blink | @ret_from_fork 157 * ------------------ 158 * | | 159 * ~ ~ 160 * ~ ~ 161 * | | 162 * ------------------ 163 * | r12 | 164 * ~ ~ 165 * | --to-- | (scratch Regs of user mode) 166 * | r0 | 167 * ------------------ 168 * | SP | 169 * | orig_r0 | 170 * | event/ECR | 171 * | user_r25 | 172 * ------------------ <===== END of PAGE 173 */ 174 int copy_thread_tls(unsigned long clone_flags, unsigned long usp, 175 unsigned long kthread_arg, struct task_struct *p, unsigned long tls) 176 { 177 struct pt_regs *c_regs; /* child's pt_regs */ 178 unsigned long *childksp; /* to unwind out of __switch_to() */ 179 struct callee_regs *c_callee; /* child's callee regs */ 180 struct callee_regs *parent_callee; /* paren't callee */ 181 struct pt_regs *regs = current_pt_regs(); 182 183 /* Mark the specific anchors to begin with (see pic above) */ 184 c_regs = task_pt_regs(p); 185 childksp = (unsigned long *)c_regs - 2; /* 2 words for FP/BLINK */ 186 c_callee = ((struct callee_regs *)childksp) - 1; 187 188 /* 189 * __switch_to() uses thread.ksp to start unwinding stack 190 * For kernel threads we don't need to create callee regs, the 191 * stack layout nevertheless needs to remain the same. 192 * Also, since __switch_to anyways unwinds callee regs, we use 193 * this to populate kernel thread entry-pt/args into callee regs, 194 * so that ret_from_kernel_thread() becomes simpler. 195 */ 196 p->thread.ksp = (unsigned long)c_callee; /* THREAD_KSP */ 197 198 /* __switch_to expects FP(0), BLINK(return addr) at top */ 199 childksp[0] = 0; /* fp */ 200 childksp[1] = (unsigned long)ret_from_fork; /* blink */ 201 202 if (unlikely(p->flags & PF_KTHREAD)) { 203 memset(c_regs, 0, sizeof(struct pt_regs)); 204 205 c_callee->r13 = kthread_arg; 206 c_callee->r14 = usp; /* function */ 207 208 return 0; 209 } 210 211 /*--------- User Task Only --------------*/ 212 213 /* __switch_to expects FP(0), BLINK(return addr) at top of stack */ 214 childksp[0] = 0; /* for POP fp */ 215 childksp[1] = (unsigned long)ret_from_fork; /* for POP blink */ 216 217 /* Copy parents pt regs on child's kernel mode stack */ 218 *c_regs = *regs; 219 220 if (usp) 221 c_regs->sp = usp; 222 223 c_regs->r0 = 0; /* fork returns 0 in child */ 224 225 parent_callee = ((struct callee_regs *)regs) - 1; 226 *c_callee = *parent_callee; 227 228 if (unlikely(clone_flags & CLONE_SETTLS)) { 229 /* 230 * set task's userland tls data ptr from 4th arg 231 * clone C-lib call is difft from clone sys-call 232 */ 233 task_thread_info(p)->thr_ptr = tls; 234 } else { 235 /* Normal fork case: set parent's TLS ptr in child */ 236 task_thread_info(p)->thr_ptr = 237 task_thread_info(current)->thr_ptr; 238 } 239 240 241 /* 242 * setup usermode thread pointer #1: 243 * when child is picked by scheduler, __switch_to() uses @c_callee to 244 * populate usermode callee regs: this works (despite being in a kernel 245 * function) since special return path for child @ret_from_fork() 246 * ensures those regs are not clobbered all the way to RTIE to usermode 247 */ 248 c_callee->r25 = task_thread_info(p)->thr_ptr; 249 250 #ifdef CONFIG_ARC_CURR_IN_REG 251 /* 252 * setup usermode thread pointer #2: 253 * however for this special use of r25 in kernel, __switch_to() sets 254 * r25 for kernel needs and only in the final return path is usermode 255 * r25 setup, from pt_regs->user_r25. So set that up as well 256 */ 257 c_regs->user_r25 = c_callee->r25; 258 #endif 259 260 return 0; 261 } 262 263 /* 264 * Do necessary setup to start up a new user task 265 */ 266 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long usp) 267 { 268 regs->sp = usp; 269 regs->ret = pc; 270 271 /* 272 * [U]ser Mode bit set 273 * [L] ZOL loop inhibited to begin with - cleared by a LP insn 274 * Interrupts enabled 275 */ 276 regs->status32 = STATUS_U_MASK | STATUS_L_MASK | ISA_INIT_STATUS_BITS; 277 278 #ifdef CONFIG_EZNPS_MTM_EXT 279 regs->eflags = 0; 280 #endif 281 282 /* bogus seed values for debugging */ 283 regs->lp_start = 0x10; 284 regs->lp_end = 0x80; 285 } 286 287 /* 288 * Some archs flush debug and FPU info here 289 */ 290 void flush_thread(void) 291 { 292 } 293 294 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu) 295 { 296 return 0; 297 } 298 299 int elf_check_arch(const struct elf32_hdr *x) 300 { 301 unsigned int eflags; 302 303 if (x->e_machine != EM_ARC_INUSE) { 304 pr_err("ELF not built for %s ISA\n", 305 is_isa_arcompact() ? "ARCompact":"ARCv2"); 306 return 0; 307 } 308 309 eflags = x->e_flags; 310 if ((eflags & EF_ARC_OSABI_MSK) != EF_ARC_OSABI_CURRENT) { 311 pr_err("ABI mismatch - you need newer toolchain\n"); 312 force_sigsegv(SIGSEGV); 313 return 0; 314 } 315 316 return 1; 317 } 318 EXPORT_SYMBOL(elf_check_arch); 319