arch/arc/kernel/process.c

   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 #ifdef CONFIG_ISA_ARCV2
  83
  84 void arch_cpu_idle(void)
  85 {
  86         /* Re-enable interrupts <= default irq priority before commiting SLEEP */
  87         const unsigned int arg = 0x10 | ARCV2_IRQ_DEF_PRIO;
  88
  89         __asm__ __volatile__(
  90                 "sleep %0       \n"
  91                 :
  92                 :"I"(arg)); /* can't be "r" has to be embedded const */
  93 }
  94
  95 #elif defined(CONFIG_EZNPS_MTM_EXT)     /* ARC700 variant in NPS */
  96
  97 void arch_cpu_idle(void)
  98 {
  99         /* only the calling HW thread needs to sleep */
 100         __asm__ __volatile__(
 101                 ".word %0       \n"
 102                 :
 103                 :"i"(CTOP_INST_HWSCHD_WFT_IE12));
 104 }
 105
 106 #else   /* ARC700 */
 107
 108 void arch_cpu_idle(void)
 109 {
 110         /* sleep, but enable both set E1/E2 (levels of interrutps) before committing */
 111         __asm__ __volatile__("sleep 0x3 \n");
 112 }
 113
 114 #endif
 115
 116 asmlinkage void ret_from_fork(void);
 117
 118 /*
 119  * Copy architecture-specific thread state
 120  *
 121  * Layout of Child kernel mode stack as setup at the end of this function is
 122  *
 123  * |     ...        |
 124  * |     ...        |
 125  * |    unused      |
 126  * |                |
 127  * ------------------
 128  * |     r25        |   <==== top of Stack (thread.ksp)
 129  * ~                ~
 130  * |    --to--      |   (CALLEE Regs of kernel mode)
 131  * |     r13        |
 132  * ------------------
 133  * |     fp         |
 134  * |    blink       |   @ret_from_fork
 135  * ------------------
 136  * |                |
 137  * ~                ~
 138  * ~                ~
 139  * |                |
 140  * ------------------
 141  * |     r12        |
 142  * ~                ~
 143  * |    --to--      |   (scratch Regs of user mode)
 144  * |     r0         |
 145  * ------------------
 146  * |      SP        |
 147  * |    orig_r0     |
 148  * |    event/ECR   |
 149  * |    user_r25    |
 150  * ------------------  <===== END of PAGE
 151  */
 152 int copy_thread(unsigned long clone_flags,
 153                 unsigned long usp, unsigned long kthread_arg,
 154                 struct task_struct *p)
 155 {
 156         struct pt_regs *c_regs;        /* child's pt_regs */
 157         unsigned long *childksp;       /* to unwind out of __switch_to() */
 158         struct callee_regs *c_callee;  /* child's callee regs */
 159         struct callee_regs *parent_callee;  /* paren't callee */
 160         struct pt_regs *regs = current_pt_regs();
 161
 162         /* Mark the specific anchors to begin with (see pic above) */
 163         c_regs = task_pt_regs(p);
 164         childksp = (unsigned long *)c_regs - 2;  /* 2 words for FP/BLINK */
 165         c_callee = ((struct callee_regs *)childksp) - 1;
 166
 167         /*
 168          * __switch_to() uses thread.ksp to start unwinding stack
 169          * For kernel threads we don't need to create callee regs, the
 170          * stack layout nevertheless needs to remain the same.
 171          * Also, since __switch_to anyways unwinds callee regs, we use
 172          * this to populate kernel thread entry-pt/args into callee regs,
 173          * so that ret_from_kernel_thread() becomes simpler.
 174          */
 175         p->thread.ksp = (unsigned long)c_callee;        /* THREAD_KSP */
 176
 177         /* __switch_to expects FP(0), BLINK(return addr) at top */
 178         childksp[0] = 0;                        /* fp */
 179         childksp[1] = (unsigned long)ret_from_fork; /* blink */
 180
 181         if (unlikely(p->flags & PF_KTHREAD)) {
 182                 memset(c_regs, 0, sizeof(struct pt_regs));
 183
 184                 c_callee->r13 = kthread_arg;
 185                 c_callee->r14 = usp;  /* function */
 186
 187                 return 0;
 188         }
 189
 190         /*--------- User Task Only --------------*/
 191
 192         /* __switch_to expects FP(0), BLINK(return addr) at top of stack */
 193         childksp[0] = 0;                                /* for POP fp */
 194         childksp[1] = (unsigned long)ret_from_fork;     /* for POP blink */
 195
 196         /* Copy parents pt regs on child's kernel mode stack */
 197         *c_regs = *regs;
 198
 199         if (usp)
 200                 c_regs->sp = usp;
 201
 202         c_regs->r0 = 0;         /* fork returns 0 in child */
 203
 204         parent_callee = ((struct callee_regs *)regs) - 1;
 205         *c_callee = *parent_callee;
 206
 207         if (unlikely(clone_flags & CLONE_SETTLS)) {
 208                 /*
 209                  * set task's userland tls data ptr from 4th arg
 210                  * clone C-lib call is difft from clone sys-call
 211                  */
 212                 task_thread_info(p)->thr_ptr = regs->r3;
 213         } else {
 214                 /* Normal fork case: set parent's TLS ptr in child */
 215                 task_thread_info(p)->thr_ptr =
 216                 task_thread_info(current)->thr_ptr;
 217         }
 218
 219         return 0;
 220 }
 221
 222 /*
 223  * Do necessary setup to start up a new user task
 224  */
 225 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long usp)
 226 {
 227         regs->sp = usp;
 228         regs->ret = pc;
 229
 230         /*
 231          * [U]ser Mode bit set
 232          * [L] ZOL loop inhibited to begin with - cleared by a LP insn
 233          * Interrupts enabled
 234          */
 235         regs->status32 = STATUS_U_MASK | STATUS_L_MASK | ISA_INIT_STATUS_BITS;
 236
 237 #ifdef CONFIG_EZNPS_MTM_EXT
 238         regs->eflags = 0;
 239 #endif
 240
 241         /* bogus seed values for debugging */
 242         regs->lp_start = 0x10;
 243         regs->lp_end = 0x80;
 244 }
 245
 246 /*
 247  * Some archs flush debug and FPU info here
 248  */
 249 void flush_thread(void)
 250 {
 251 }
 252
 253 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
 254 {
 255         return 0;
 256 }
 257
 258 int elf_check_arch(const struct elf32_hdr *x)
 259 {
 260         unsigned int eflags;
 261
 262         if (x->e_machine != EM_ARC_INUSE) {
 263                 pr_err("ELF not built for %s ISA\n",
 264                         is_isa_arcompact() ? "ARCompact":"ARCv2");
 265                 return 0;
 266         }
 267
 268         eflags = x->e_flags;
 269         if ((eflags & EF_ARC_OSABI_MSK) != EF_ARC_OSABI_CURRENT) {
 270                 pr_err("ABI mismatch - you need newer toolchain\n");
 271                 force_sigsegv(SIGSEGV, current);
 272                 return 0;
 273         }
 274
 275         return 1;
 276 }
 277 EXPORT_SYMBOL(elf_check_arch);