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 23SYSCALL_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 */ 39SYSCALL_DEFINE0(arc_gettls) 40{ 41 return task_thread_info(current)->thr_ptr; 42} 43 44void arch_cpu_idle(void) 45{ 46 /* sleep, but enable all interrupts before committing */ 47 __asm__("sleep 0x3"); 48} 49 50asmlinkage 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 */ 83int 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 * Some archs flush debug and FPU info here 155 */ 156void flush_thread(void) 157{ 158} 159 160/* 161 * Free any architecture-specific thread data structures, etc. 162 */ 163void exit_thread(void) 164{ 165} 166 167int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu) 168{ 169 return 0; 170} 171 172/* 173 * API: expected by schedular Code: If thread is sleeping where is that. 174 * What is this good for? it will be always the scheduler or ret_from_fork. 175 * So we hard code that anyways. 176 */ 177unsigned long thread_saved_pc(struct task_struct *t) 178{ 179 struct pt_regs *regs = task_pt_regs(t); 180 unsigned long blink = 0; 181 182 /* 183 * If the thread being queried for in not itself calling this, then it 184 * implies it is not executing, which in turn implies it is sleeping, 185 * which in turn implies it got switched OUT by the schedular. 186 * In that case, it's kernel mode blink can reliably retrieved as per 187 * the picture above (right above pt_regs). 188 */ 189 if (t != current && t->state != TASK_RUNNING) 190 blink = *((unsigned int *)regs - 1); 191 192 return blink; 193} 194 195int elf_check_arch(const struct elf32_hdr *x) 196{ 197 unsigned int eflags; 198 199 if (x->e_machine != EM_ARCOMPACT) 200 return 0; 201 202 eflags = x->e_flags; 203 if ((eflags & EF_ARC_OSABI_MSK) < EF_ARC_OSABI_CURRENT) { 204 pr_err("ABI mismatch - you need newer toolchain\n"); 205 force_sigsegv(SIGSEGV, current); 206 return 0; 207 } 208 209 return 1; 210} 211EXPORT_SYMBOL(elf_check_arch); 212