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