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/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 int uval = -EFAULT; 48 49 /* 50 * This is only for old cores lacking LLOCK/SCOND, which by defintion 51 * can't possibly be SMP. Thus doesn't need to be SMP safe. 52 * And this also helps reduce the overhead for serializing in 53 * the UP case 54 */ 55 WARN_ON_ONCE(IS_ENABLED(CONFIG_SMP)); 56 57 /* Z indicates to userspace if operation succeded */ 58 regs->status32 &= ~STATUS_Z_MASK; 59 60 if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int))) 61 return -EFAULT; 62 63 preempt_disable(); 64 65 if (__get_user(uval, uaddr)) 66 goto done; 67 68 if (uval == expected) { 69 if (!__put_user(new, uaddr)) 70 regs->status32 |= STATUS_Z_MASK; 71 } 72 73 done: 74 preempt_enable(); 75 76 return uval; 77 } 78 79 void arch_cpu_idle(void) 80 { 81 /* sleep, but enable all interrupts before committing */ 82 __asm__ __volatile__( 83 "sleep %0 \n" 84 : 85 :"I"(ISA_SLEEP_ARG)); /* can't be "r" has to be embedded const */ 86 } 87 88 asmlinkage void ret_from_fork(void); 89 90 /* 91 * Copy architecture-specific thread state 92 * 93 * Layout of Child kernel mode stack as setup at the end of this function is 94 * 95 * | ... | 96 * | ... | 97 * | unused | 98 * | | 99 * ------------------ 100 * | r25 | <==== top of Stack (thread.ksp) 101 * ~ ~ 102 * | --to-- | (CALLEE Regs of kernel mode) 103 * | r13 | 104 * ------------------ 105 * | fp | 106 * | blink | @ret_from_fork 107 * ------------------ 108 * | | 109 * ~ ~ 110 * ~ ~ 111 * | | 112 * ------------------ 113 * | r12 | 114 * ~ ~ 115 * | --to-- | (scratch Regs of user mode) 116 * | r0 | 117 * ------------------ 118 * | SP | 119 * | orig_r0 | 120 * | event/ECR | 121 * | user_r25 | 122 * ------------------ <===== END of PAGE 123 */ 124 int copy_thread(unsigned long clone_flags, 125 unsigned long usp, unsigned long kthread_arg, 126 struct task_struct *p) 127 { 128 struct pt_regs *c_regs; /* child's pt_regs */ 129 unsigned long *childksp; /* to unwind out of __switch_to() */ 130 struct callee_regs *c_callee; /* child's callee regs */ 131 struct callee_regs *parent_callee; /* paren't callee */ 132 struct pt_regs *regs = current_pt_regs(); 133 134 /* Mark the specific anchors to begin with (see pic above) */ 135 c_regs = task_pt_regs(p); 136 childksp = (unsigned long *)c_regs - 2; /* 2 words for FP/BLINK */ 137 c_callee = ((struct callee_regs *)childksp) - 1; 138 139 /* 140 * __switch_to() uses thread.ksp to start unwinding stack 141 * For kernel threads we don't need to create callee regs, the 142 * stack layout nevertheless needs to remain the same. 143 * Also, since __switch_to anyways unwinds callee regs, we use 144 * this to populate kernel thread entry-pt/args into callee regs, 145 * so that ret_from_kernel_thread() becomes simpler. 146 */ 147 p->thread.ksp = (unsigned long)c_callee; /* THREAD_KSP */ 148 149 /* __switch_to expects FP(0), BLINK(return addr) at top */ 150 childksp[0] = 0; /* fp */ 151 childksp[1] = (unsigned long)ret_from_fork; /* blink */ 152 153 if (unlikely(p->flags & PF_KTHREAD)) { 154 memset(c_regs, 0, sizeof(struct pt_regs)); 155 156 c_callee->r13 = kthread_arg; 157 c_callee->r14 = usp; /* function */ 158 159 return 0; 160 } 161 162 /*--------- User Task Only --------------*/ 163 164 /* __switch_to expects FP(0), BLINK(return addr) at top of stack */ 165 childksp[0] = 0; /* for POP fp */ 166 childksp[1] = (unsigned long)ret_from_fork; /* for POP blink */ 167 168 /* Copy parents pt regs on child's kernel mode stack */ 169 *c_regs = *regs; 170 171 if (usp) 172 c_regs->sp = usp; 173 174 c_regs->r0 = 0; /* fork returns 0 in child */ 175 176 parent_callee = ((struct callee_regs *)regs) - 1; 177 *c_callee = *parent_callee; 178 179 if (unlikely(clone_flags & CLONE_SETTLS)) { 180 /* 181 * set task's userland tls data ptr from 4th arg 182 * clone C-lib call is difft from clone sys-call 183 */ 184 task_thread_info(p)->thr_ptr = regs->r3; 185 } else { 186 /* Normal fork case: set parent's TLS ptr in child */ 187 task_thread_info(p)->thr_ptr = 188 task_thread_info(current)->thr_ptr; 189 } 190 191 return 0; 192 } 193 194 /* 195 * Do necessary setup to start up a new user task 196 */ 197 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long usp) 198 { 199 regs->sp = usp; 200 regs->ret = pc; 201 202 /* 203 * [U]ser Mode bit set 204 * [L] ZOL loop inhibited to begin with - cleared by a LP insn 205 * Interrupts enabled 206 */ 207 regs->status32 = STATUS_U_MASK | STATUS_L_MASK | ISA_INIT_STATUS_BITS; 208 209 /* bogus seed values for debugging */ 210 regs->lp_start = 0x10; 211 regs->lp_end = 0x80; 212 } 213 214 /* 215 * Some archs flush debug and FPU info here 216 */ 217 void flush_thread(void) 218 { 219 } 220 221 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu) 222 { 223 return 0; 224 } 225 226 int elf_check_arch(const struct elf32_hdr *x) 227 { 228 unsigned int eflags; 229 230 if (x->e_machine != EM_ARC_INUSE) { 231 pr_err("ELF not built for %s ISA\n", 232 is_isa_arcompact() ? "ARCompact":"ARCv2"); 233 return 0; 234 } 235 236 eflags = x->e_flags; 237 if ((eflags & EF_ARC_OSABI_MSK) != EF_ARC_OSABI_CURRENT) { 238 pr_err("ABI mismatch - you need newer toolchain\n"); 239 force_sigsegv(SIGSEGV, current); 240 return 0; 241 } 242 243 return 1; 244 } 245 EXPORT_SYMBOL(elf_check_arch); 246