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 int uval = -EFAULT; 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 if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int))) 64 return -EFAULT; 65 66 preempt_disable(); 67 68 if (__get_user(uval, uaddr)) 69 goto done; 70 71 if (uval == expected) { 72 if (!__put_user(new, uaddr)) 73 regs->status32 |= STATUS_Z_MASK; 74 } 75 76 done: 77 preempt_enable(); 78 79 return uval; 80 } 81 82 #ifdef CONFIG_ISA_ARCV2 83 84 void arch_cpu_idle(void) 85 { 86 /* Re-enable interrupts <= default irq priority before commiting SLEEP */ 87 const unsigned int arg = 0x10 | ARCV2_IRQ_DEF_PRIO; 88 89 __asm__ __volatile__( 90 "sleep %0 \n" 91 : 92 :"I"(arg)); /* can't be "r" has to be embedded const */ 93 } 94 95 #else 96 97 void arch_cpu_idle(void) 98 { 99 /* sleep, but enable both set E1/E2 (levels of interrutps) before committing */ 100 __asm__ __volatile__("sleep 0x3 \n"); 101 } 102 103 #endif 104 105 asmlinkage void ret_from_fork(void); 106 107 /* 108 * Copy architecture-specific thread state 109 * 110 * Layout of Child kernel mode stack as setup at the end of this function is 111 * 112 * | ... | 113 * | ... | 114 * | unused | 115 * | | 116 * ------------------ 117 * | r25 | <==== top of Stack (thread.ksp) 118 * ~ ~ 119 * | --to-- | (CALLEE Regs of kernel mode) 120 * | r13 | 121 * ------------------ 122 * | fp | 123 * | blink | @ret_from_fork 124 * ------------------ 125 * | | 126 * ~ ~ 127 * ~ ~ 128 * | | 129 * ------------------ 130 * | r12 | 131 * ~ ~ 132 * | --to-- | (scratch Regs of user mode) 133 * | r0 | 134 * ------------------ 135 * | SP | 136 * | orig_r0 | 137 * | event/ECR | 138 * | user_r25 | 139 * ------------------ <===== END of PAGE 140 */ 141 int copy_thread(unsigned long clone_flags, 142 unsigned long usp, unsigned long kthread_arg, 143 struct task_struct *p) 144 { 145 struct pt_regs *c_regs; /* child's pt_regs */ 146 unsigned long *childksp; /* to unwind out of __switch_to() */ 147 struct callee_regs *c_callee; /* child's callee regs */ 148 struct callee_regs *parent_callee; /* paren't callee */ 149 struct pt_regs *regs = current_pt_regs(); 150 151 /* Mark the specific anchors to begin with (see pic above) */ 152 c_regs = task_pt_regs(p); 153 childksp = (unsigned long *)c_regs - 2; /* 2 words for FP/BLINK */ 154 c_callee = ((struct callee_regs *)childksp) - 1; 155 156 /* 157 * __switch_to() uses thread.ksp to start unwinding stack 158 * For kernel threads we don't need to create callee regs, the 159 * stack layout nevertheless needs to remain the same. 160 * Also, since __switch_to anyways unwinds callee regs, we use 161 * this to populate kernel thread entry-pt/args into callee regs, 162 * so that ret_from_kernel_thread() becomes simpler. 163 */ 164 p->thread.ksp = (unsigned long)c_callee; /* THREAD_KSP */ 165 166 /* __switch_to expects FP(0), BLINK(return addr) at top */ 167 childksp[0] = 0; /* fp */ 168 childksp[1] = (unsigned long)ret_from_fork; /* blink */ 169 170 if (unlikely(p->flags & PF_KTHREAD)) { 171 memset(c_regs, 0, sizeof(struct pt_regs)); 172 173 c_callee->r13 = kthread_arg; 174 c_callee->r14 = usp; /* function */ 175 176 return 0; 177 } 178 179 /*--------- User Task Only --------------*/ 180 181 /* __switch_to expects FP(0), BLINK(return addr) at top of stack */ 182 childksp[0] = 0; /* for POP fp */ 183 childksp[1] = (unsigned long)ret_from_fork; /* for POP blink */ 184 185 /* Copy parents pt regs on child's kernel mode stack */ 186 *c_regs = *regs; 187 188 if (usp) 189 c_regs->sp = usp; 190 191 c_regs->r0 = 0; /* fork returns 0 in child */ 192 193 parent_callee = ((struct callee_regs *)regs) - 1; 194 *c_callee = *parent_callee; 195 196 if (unlikely(clone_flags & CLONE_SETTLS)) { 197 /* 198 * set task's userland tls data ptr from 4th arg 199 * clone C-lib call is difft from clone sys-call 200 */ 201 task_thread_info(p)->thr_ptr = regs->r3; 202 } else { 203 /* Normal fork case: set parent's TLS ptr in child */ 204 task_thread_info(p)->thr_ptr = 205 task_thread_info(current)->thr_ptr; 206 } 207 208 return 0; 209 } 210 211 /* 212 * Do necessary setup to start up a new user task 213 */ 214 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long usp) 215 { 216 regs->sp = usp; 217 regs->ret = pc; 218 219 /* 220 * [U]ser Mode bit set 221 * [L] ZOL loop inhibited to begin with - cleared by a LP insn 222 * Interrupts enabled 223 */ 224 regs->status32 = STATUS_U_MASK | STATUS_L_MASK | ISA_INIT_STATUS_BITS; 225 226 /* bogus seed values for debugging */ 227 regs->lp_start = 0x10; 228 regs->lp_end = 0x80; 229 } 230 231 /* 232 * Some archs flush debug and FPU info here 233 */ 234 void flush_thread(void) 235 { 236 } 237 238 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu) 239 { 240 return 0; 241 } 242 243 int elf_check_arch(const struct elf32_hdr *x) 244 { 245 unsigned int eflags; 246 247 if (x->e_machine != EM_ARC_INUSE) { 248 pr_err("ELF not built for %s ISA\n", 249 is_isa_arcompact() ? "ARCompact":"ARCv2"); 250 return 0; 251 } 252 253 eflags = x->e_flags; 254 if ((eflags & EF_ARC_OSABI_MSK) != EF_ARC_OSABI_CURRENT) { 255 pr_err("ABI mismatch - you need newer toolchain\n"); 256 force_sigsegv(SIGSEGV, current); 257 return 0; 258 } 259 260 return 1; 261 } 262 EXPORT_SYMBOL(elf_check_arch); 263