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