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 static inline void arch_idle(void) 45 { 46 /* sleep, but enable all interrupts before committing */ 47 __asm__("sleep 0x3"); 48 } 49 50 void cpu_idle(void) 51 { 52 /* Since we SLEEP in idle loop, TIF_POLLING_NRFLAG can't be set */ 53 54 /* endless idle loop with no priority at all */ 55 while (1) { 56 tick_nohz_idle_enter(); 57 rcu_idle_enter(); 58 59 doze: 60 local_irq_disable(); 61 if (!need_resched()) { 62 arch_idle(); 63 goto doze; 64 } else { 65 local_irq_enable(); 66 } 67 68 rcu_idle_exit(); 69 tick_nohz_idle_exit(); 70 71 schedule_preempt_disabled(); 72 } 73 } 74 75 asmlinkage void ret_from_fork(void); 76 77 /* Layout of Child kernel mode stack as setup at the end of this function is 78 * 79 * | ... | 80 * | ... | 81 * | unused | 82 * | | 83 * ------------------ <==== top of Stack (thread.ksp) 84 * | UNUSED 1 word| 85 * ------------------ 86 * | r25 | 87 * ~ ~ 88 * | --to-- | (CALLEE Regs of user mode) 89 * | r13 | 90 * ------------------ 91 * | fp | 92 * | blink | @ret_from_fork 93 * ------------------ 94 * | | 95 * ~ ~ 96 * ~ ~ 97 * | | 98 * ------------------ 99 * | r12 | 100 * ~ ~ 101 * | --to-- | (scratch Regs of user mode) 102 * | r0 | 103 * ------------------ 104 * | UNUSED 1 word| 105 * ------------------ <===== END of PAGE 106 */ 107 int copy_thread(unsigned long clone_flags, 108 unsigned long usp, unsigned long arg, 109 struct task_struct *p) 110 { 111 struct pt_regs *c_regs; /* child's pt_regs */ 112 unsigned long *childksp; /* to unwind out of __switch_to() */ 113 struct callee_regs *c_callee; /* child's callee regs */ 114 struct callee_regs *parent_callee; /* paren't callee */ 115 struct pt_regs *regs = current_pt_regs(); 116 117 /* Mark the specific anchors to begin with (see pic above) */ 118 c_regs = task_pt_regs(p); 119 childksp = (unsigned long *)c_regs - 2; /* 2 words for FP/BLINK */ 120 c_callee = ((struct callee_regs *)childksp) - 1; 121 122 /* 123 * __switch_to() uses thread.ksp to start unwinding stack 124 * For kernel threads we don't need to create callee regs, the 125 * stack layout nevertheless needs to remain the same. 126 * Also, since __switch_to anyways unwinds callee regs, we use 127 * this to populate kernel thread entry-pt/args into callee regs, 128 * so that ret_from_kernel_thread() becomes simpler. 129 */ 130 p->thread.ksp = (unsigned long)c_callee; /* THREAD_KSP */ 131 132 /* __switch_to expects FP(0), BLINK(return addr) at top */ 133 childksp[0] = 0; /* fp */ 134 childksp[1] = (unsigned long)ret_from_fork; /* blink */ 135 136 if (unlikely(p->flags & PF_KTHREAD)) { 137 memset(c_regs, 0, sizeof(struct pt_regs)); 138 139 c_callee->r13 = arg; /* argument to kernel thread */ 140 c_callee->r14 = usp; /* function */ 141 142 return 0; 143 } 144 145 /*--------- User Task Only --------------*/ 146 147 /* __switch_to expects FP(0), BLINK(return addr) at top of stack */ 148 childksp[0] = 0; /* for POP fp */ 149 childksp[1] = (unsigned long)ret_from_fork; /* for POP blink */ 150 151 /* Copy parents pt regs on child's kernel mode stack */ 152 *c_regs = *regs; 153 154 if (usp) 155 c_regs->sp = usp; 156 157 c_regs->r0 = 0; /* fork returns 0 in child */ 158 159 parent_callee = ((struct callee_regs *)regs) - 1; 160 *c_callee = *parent_callee; 161 162 if (unlikely(clone_flags & CLONE_SETTLS)) { 163 /* 164 * set task's userland tls data ptr from 4th arg 165 * clone C-lib call is difft from clone sys-call 166 */ 167 task_thread_info(p)->thr_ptr = regs->r3; 168 } else { 169 /* Normal fork case: set parent's TLS ptr in child */ 170 task_thread_info(p)->thr_ptr = 171 task_thread_info(current)->thr_ptr; 172 } 173 174 return 0; 175 } 176 177 /* 178 * Some archs flush debug and FPU info here 179 */ 180 void flush_thread(void) 181 { 182 } 183 184 /* 185 * Free any architecture-specific thread data structures, etc. 186 */ 187 void exit_thread(void) 188 { 189 } 190 191 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu) 192 { 193 return 0; 194 } 195 196 /* 197 * API: expected by schedular Code: If thread is sleeping where is that. 198 * What is this good for? it will be always the scheduler or ret_from_fork. 199 * So we hard code that anyways. 200 */ 201 unsigned long thread_saved_pc(struct task_struct *t) 202 { 203 struct pt_regs *regs = task_pt_regs(t); 204 unsigned long blink = 0; 205 206 /* 207 * If the thread being queried for in not itself calling this, then it 208 * implies it is not executing, which in turn implies it is sleeping, 209 * which in turn implies it got switched OUT by the schedular. 210 * In that case, it's kernel mode blink can reliably retrieved as per 211 * the picture above (right above pt_regs). 212 */ 213 if (t != current && t->state != TASK_RUNNING) 214 blink = *((unsigned int *)regs - 1); 215 216 return blink; 217 } 218 219 int elf_check_arch(const struct elf32_hdr *x) 220 { 221 unsigned int eflags; 222 223 if (x->e_machine != EM_ARCOMPACT) 224 return 0; 225 226 eflags = x->e_flags; 227 if ((eflags & EF_ARC_OSABI_MSK) < EF_ARC_OSABI_CURRENT) { 228 pr_err("ABI mismatch - you need newer toolchain\n"); 229 force_sigsegv(SIGSEGV, current); 230 return 0; 231 } 232 233 return 1; 234 } 235 EXPORT_SYMBOL(elf_check_arch); 236