1 /* 2 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License version 2 as 6 * published by the Free Software Foundation. 7 * 8 * Amit Bhor, Kanika Nema: Codito Technologies 2004 9 */ 10 11 #include <linux/errno.h> 12 #include <linux/module.h> 13 #include <linux/sched.h> 14 #include <linux/sched/task.h> 15 #include <linux/sched/task_stack.h> 16 17 #include <linux/mm.h> 18 #include <linux/fs.h> 19 #include <linux/unistd.h> 20 #include <linux/ptrace.h> 21 #include <linux/slab.h> 22 #include <linux/syscalls.h> 23 #include <linux/elf.h> 24 #include <linux/tick.h> 25 26 SYSCALL_DEFINE1(arc_settls, void *, user_tls_data_ptr) 27 { 28 task_thread_info(current)->thr_ptr = (unsigned int)user_tls_data_ptr; 29 return 0; 30 } 31 32 /* 33 * We return the user space TLS data ptr as sys-call return code 34 * Ideally it should be copy to user. 35 * However we can cheat by the fact that some sys-calls do return 36 * absurdly high values 37 * Since the tls dat aptr is not going to be in range of 0xFFFF_xxxx 38 * it won't be considered a sys-call error 39 * and it will be loads better than copy-to-user, which is a definite 40 * D-TLB Miss 41 */ 42 SYSCALL_DEFINE0(arc_gettls) 43 { 44 return task_thread_info(current)->thr_ptr; 45 } 46 47 SYSCALL_DEFINE3(arc_usr_cmpxchg, int *, uaddr, int, expected, int, new) 48 { 49 struct pt_regs *regs = current_pt_regs(); 50 u32 uval; 51 int ret; 52 53 /* 54 * This is only for old cores lacking LLOCK/SCOND, which by defintion 55 * can't possibly be SMP. Thus doesn't need to be SMP safe. 56 * And this also helps reduce the overhead for serializing in 57 * the UP case 58 */ 59 WARN_ON_ONCE(IS_ENABLED(CONFIG_SMP)); 60 61 /* Z indicates to userspace if operation succeded */ 62 regs->status32 &= ~STATUS_Z_MASK; 63 64 ret = access_ok(VERIFY_WRITE, uaddr, sizeof(*uaddr)); 65 if (!ret) 66 goto fail; 67 68 again: 69 preempt_disable(); 70 71 ret = __get_user(uval, uaddr); 72 if (ret) 73 goto fault; 74 75 if (uval != expected) 76 goto out; 77 78 ret = __put_user(new, uaddr); 79 if (ret) 80 goto fault; 81 82 regs->status32 |= STATUS_Z_MASK; 83 84 out: 85 preempt_enable(); 86 return uval; 87 88 fault: 89 preempt_enable(); 90 91 if (unlikely(ret != -EFAULT)) 92 goto fail; 93 94 down_read(¤t->mm->mmap_sem); 95 ret = fixup_user_fault(current, current->mm, (unsigned long) uaddr, 96 FAULT_FLAG_WRITE, NULL); 97 up_read(¤t->mm->mmap_sem); 98 99 if (likely(!ret)) 100 goto again; 101 102 fail: 103 force_sig(SIGSEGV, current); 104 return ret; 105 } 106 107 #ifdef CONFIG_ISA_ARCV2 108 109 void arch_cpu_idle(void) 110 { 111 /* Re-enable interrupts <= default irq priority before commiting SLEEP */ 112 const unsigned int arg = 0x10 | ARCV2_IRQ_DEF_PRIO; 113 114 __asm__ __volatile__( 115 "sleep %0 \n" 116 : 117 :"I"(arg)); /* can't be "r" has to be embedded const */ 118 } 119 120 #elif defined(CONFIG_EZNPS_MTM_EXT) /* ARC700 variant in NPS */ 121 122 void arch_cpu_idle(void) 123 { 124 /* only the calling HW thread needs to sleep */ 125 __asm__ __volatile__( 126 ".word %0 \n" 127 : 128 :"i"(CTOP_INST_HWSCHD_WFT_IE12)); 129 } 130 131 #else /* ARC700 */ 132 133 void arch_cpu_idle(void) 134 { 135 /* sleep, but enable both set E1/E2 (levels of interrutps) before committing */ 136 __asm__ __volatile__("sleep 0x3 \n"); 137 } 138 139 #endif 140 141 asmlinkage void ret_from_fork(void); 142 143 /* 144 * Copy architecture-specific thread state 145 * 146 * Layout of Child kernel mode stack as setup at the end of this function is 147 * 148 * | ... | 149 * | ... | 150 * | unused | 151 * | | 152 * ------------------ 153 * | r25 | <==== top of Stack (thread.ksp) 154 * ~ ~ 155 * | --to-- | (CALLEE Regs of kernel mode) 156 * | r13 | 157 * ------------------ 158 * | fp | 159 * | blink | @ret_from_fork 160 * ------------------ 161 * | | 162 * ~ ~ 163 * ~ ~ 164 * | | 165 * ------------------ 166 * | r12 | 167 * ~ ~ 168 * | --to-- | (scratch Regs of user mode) 169 * | r0 | 170 * ------------------ 171 * | SP | 172 * | orig_r0 | 173 * | event/ECR | 174 * | user_r25 | 175 * ------------------ <===== END of PAGE 176 */ 177 int copy_thread(unsigned long clone_flags, 178 unsigned long usp, unsigned long kthread_arg, 179 struct task_struct *p) 180 { 181 struct pt_regs *c_regs; /* child's pt_regs */ 182 unsigned long *childksp; /* to unwind out of __switch_to() */ 183 struct callee_regs *c_callee; /* child's callee regs */ 184 struct callee_regs *parent_callee; /* paren't callee */ 185 struct pt_regs *regs = current_pt_regs(); 186 187 /* Mark the specific anchors to begin with (see pic above) */ 188 c_regs = task_pt_regs(p); 189 childksp = (unsigned long *)c_regs - 2; /* 2 words for FP/BLINK */ 190 c_callee = ((struct callee_regs *)childksp) - 1; 191 192 /* 193 * __switch_to() uses thread.ksp to start unwinding stack 194 * For kernel threads we don't need to create callee regs, the 195 * stack layout nevertheless needs to remain the same. 196 * Also, since __switch_to anyways unwinds callee regs, we use 197 * this to populate kernel thread entry-pt/args into callee regs, 198 * so that ret_from_kernel_thread() becomes simpler. 199 */ 200 p->thread.ksp = (unsigned long)c_callee; /* THREAD_KSP */ 201 202 /* __switch_to expects FP(0), BLINK(return addr) at top */ 203 childksp[0] = 0; /* fp */ 204 childksp[1] = (unsigned long)ret_from_fork; /* blink */ 205 206 if (unlikely(p->flags & PF_KTHREAD)) { 207 memset(c_regs, 0, sizeof(struct pt_regs)); 208 209 c_callee->r13 = kthread_arg; 210 c_callee->r14 = usp; /* function */ 211 212 return 0; 213 } 214 215 /*--------- User Task Only --------------*/ 216 217 /* __switch_to expects FP(0), BLINK(return addr) at top of stack */ 218 childksp[0] = 0; /* for POP fp */ 219 childksp[1] = (unsigned long)ret_from_fork; /* for POP blink */ 220 221 /* Copy parents pt regs on child's kernel mode stack */ 222 *c_regs = *regs; 223 224 if (usp) 225 c_regs->sp = usp; 226 227 c_regs->r0 = 0; /* fork returns 0 in child */ 228 229 parent_callee = ((struct callee_regs *)regs) - 1; 230 *c_callee = *parent_callee; 231 232 if (unlikely(clone_flags & CLONE_SETTLS)) { 233 /* 234 * set task's userland tls data ptr from 4th arg 235 * clone C-lib call is difft from clone sys-call 236 */ 237 task_thread_info(p)->thr_ptr = regs->r3; 238 } else { 239 /* Normal fork case: set parent's TLS ptr in child */ 240 task_thread_info(p)->thr_ptr = 241 task_thread_info(current)->thr_ptr; 242 } 243 244 245 /* 246 * setup usermode thread pointer #1: 247 * when child is picked by scheduler, __switch_to() uses @c_callee to 248 * populate usermode callee regs: this works (despite being in a kernel 249 * function) since special return path for child @ret_from_fork() 250 * ensures those regs are not clobbered all the way to RTIE to usermode 251 */ 252 c_callee->r25 = task_thread_info(p)->thr_ptr; 253 254 #ifdef CONFIG_ARC_CURR_IN_REG 255 /* 256 * setup usermode thread pointer #2: 257 * however for this special use of r25 in kernel, __switch_to() sets 258 * r25 for kernel needs and only in the final return path is usermode 259 * r25 setup, from pt_regs->user_r25. So set that up as well 260 */ 261 c_regs->user_r25 = c_callee->r25; 262 #endif 263 264 return 0; 265 } 266 267 /* 268 * Do necessary setup to start up a new user task 269 */ 270 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long usp) 271 { 272 regs->sp = usp; 273 regs->ret = pc; 274 275 /* 276 * [U]ser Mode bit set 277 * [L] ZOL loop inhibited to begin with - cleared by a LP insn 278 * Interrupts enabled 279 */ 280 regs->status32 = STATUS_U_MASK | STATUS_L_MASK | ISA_INIT_STATUS_BITS; 281 282 #ifdef CONFIG_EZNPS_MTM_EXT 283 regs->eflags = 0; 284 #endif 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, current); 317 return 0; 318 } 319 320 return 1; 321 } 322 EXPORT_SYMBOL(elf_check_arch); 323