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 void arch_cpu_idle(void) 45 { 46 /* sleep, but enable all interrupts before committing */ 47 __asm__("sleep 0x3"); 48 } 49 50 asmlinkage void ret_from_fork(void); 51 52 /* Layout of Child kernel mode stack as setup at the end of this function is 53 * 54 * | ... | 55 * | ... | 56 * | unused | 57 * | | 58 * ------------------ 59 * | r25 | <==== top of Stack (thread.ksp) 60 * ~ ~ 61 * | --to-- | (CALLEE Regs of user mode) 62 * | r13 | 63 * ------------------ 64 * | fp | 65 * | blink | @ret_from_fork 66 * ------------------ 67 * | | 68 * ~ ~ 69 * ~ ~ 70 * | | 71 * ------------------ 72 * | r12 | 73 * ~ ~ 74 * | --to-- | (scratch Regs of user mode) 75 * | r0 | 76 * ------------------ 77 * | SP | 78 * | orig_r0 | 79 * | event/ECR | 80 * | user_r25 | 81 * ------------------ <===== END of PAGE 82 */ 83 int copy_thread(unsigned long clone_flags, 84 unsigned long usp, unsigned long arg, 85 struct task_struct *p) 86 { 87 struct pt_regs *c_regs; /* child's pt_regs */ 88 unsigned long *childksp; /* to unwind out of __switch_to() */ 89 struct callee_regs *c_callee; /* child's callee regs */ 90 struct callee_regs *parent_callee; /* paren't callee */ 91 struct pt_regs *regs = current_pt_regs(); 92 93 /* Mark the specific anchors to begin with (see pic above) */ 94 c_regs = task_pt_regs(p); 95 childksp = (unsigned long *)c_regs - 2; /* 2 words for FP/BLINK */ 96 c_callee = ((struct callee_regs *)childksp) - 1; 97 98 /* 99 * __switch_to() uses thread.ksp to start unwinding stack 100 * For kernel threads we don't need to create callee regs, the 101 * stack layout nevertheless needs to remain the same. 102 * Also, since __switch_to anyways unwinds callee regs, we use 103 * this to populate kernel thread entry-pt/args into callee regs, 104 * so that ret_from_kernel_thread() becomes simpler. 105 */ 106 p->thread.ksp = (unsigned long)c_callee; /* THREAD_KSP */ 107 108 /* __switch_to expects FP(0), BLINK(return addr) at top */ 109 childksp[0] = 0; /* fp */ 110 childksp[1] = (unsigned long)ret_from_fork; /* blink */ 111 112 if (unlikely(p->flags & PF_KTHREAD)) { 113 memset(c_regs, 0, sizeof(struct pt_regs)); 114 115 c_callee->r13 = arg; /* argument to kernel thread */ 116 c_callee->r14 = usp; /* function */ 117 118 return 0; 119 } 120 121 /*--------- User Task Only --------------*/ 122 123 /* __switch_to expects FP(0), BLINK(return addr) at top of stack */ 124 childksp[0] = 0; /* for POP fp */ 125 childksp[1] = (unsigned long)ret_from_fork; /* for POP blink */ 126 127 /* Copy parents pt regs on child's kernel mode stack */ 128 *c_regs = *regs; 129 130 if (usp) 131 c_regs->sp = usp; 132 133 c_regs->r0 = 0; /* fork returns 0 in child */ 134 135 parent_callee = ((struct callee_regs *)regs) - 1; 136 *c_callee = *parent_callee; 137 138 if (unlikely(clone_flags & CLONE_SETTLS)) { 139 /* 140 * set task's userland tls data ptr from 4th arg 141 * clone C-lib call is difft from clone sys-call 142 */ 143 task_thread_info(p)->thr_ptr = regs->r3; 144 } else { 145 /* Normal fork case: set parent's TLS ptr in child */ 146 task_thread_info(p)->thr_ptr = 147 task_thread_info(current)->thr_ptr; 148 } 149 150 return 0; 151 } 152 153 /* 154 * Do necessary setup to start up a new user task 155 */ 156 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long usp) 157 { 158 set_fs(USER_DS); /* user space */ 159 160 regs->sp = usp; 161 regs->ret = pc; 162 163 /* 164 * [U]ser Mode bit set 165 * [L] ZOL loop inhibited to begin with - cleared by a LP insn 166 * Interrupts enabled 167 */ 168 regs->status32 = STATUS_U_MASK | STATUS_L_MASK | 169 STATUS_E1_MASK | STATUS_E2_MASK; 170 171 /* bogus seed values for debugging */ 172 regs->lp_start = 0x10; 173 regs->lp_end = 0x80; 174 } 175 176 /* 177 * Some archs flush debug and FPU info here 178 */ 179 void flush_thread(void) 180 { 181 } 182 183 /* 184 * Free any architecture-specific thread data structures, etc. 185 */ 186 void exit_thread(void) 187 { 188 } 189 190 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu) 191 { 192 return 0; 193 } 194 195 /* 196 * API: expected by schedular Code: If thread is sleeping where is that. 197 * What is this good for? it will be always the scheduler or ret_from_fork. 198 * So we hard code that anyways. 199 */ 200 unsigned long thread_saved_pc(struct task_struct *t) 201 { 202 struct pt_regs *regs = task_pt_regs(t); 203 unsigned long blink = 0; 204 205 /* 206 * If the thread being queried for in not itself calling this, then it 207 * implies it is not executing, which in turn implies it is sleeping, 208 * which in turn implies it got switched OUT by the schedular. 209 * In that case, it's kernel mode blink can reliably retrieved as per 210 * the picture above (right above pt_regs). 211 */ 212 if (t != current && t->state != TASK_RUNNING) 213 blink = *((unsigned int *)regs - 1); 214 215 return blink; 216 } 217 218 int elf_check_arch(const struct elf32_hdr *x) 219 { 220 unsigned int eflags; 221 222 if (x->e_machine != EM_ARCOMPACT) 223 return 0; 224 225 eflags = x->e_flags; 226 if ((eflags & EF_ARC_OSABI_MSK) < EF_ARC_OSABI_CURRENT) { 227 pr_err("ABI mismatch - you need newer toolchain\n"); 228 force_sigsegv(SIGSEGV, current); 229 return 0; 230 } 231 232 return 1; 233 } 234 EXPORT_SYMBOL(elf_check_arch); 235