arch/sh/kernel/ptrace_64.c

   1 /*
   2  * arch/sh/kernel/ptrace_64.c
   3  *
   4  * Copyright (C) 2000, 2001  Paolo Alberelli
   5  * Copyright (C) 2003 - 2007  Paul Mundt
   6  *
   7  * Started from SH3/4 version:
   8  *   SuperH version:   Copyright (C) 1999, 2000  Kaz Kojima & Niibe Yutaka
   9  *
  10  *   Original x86 implementation:
  11  *      By Ross Biro 1/23/92
  12  *      edited by Linus Torvalds
  13  *
  14  * This file is subject to the terms and conditions of the GNU General Public
  15  * License.  See the file "COPYING" in the main directory of this archive
  16  * for more details.
  17  */
  18 #include <linux/kernel.h>
  19 #include <linux/rwsem.h>
  20 #include <linux/sched.h>
  21 #include <linux/mm.h>
  22 #include <linux/smp.h>
  23 #include <linux/smp_lock.h>
  24 #include <linux/errno.h>
  25 #include <linux/ptrace.h>
  26 #include <linux/user.h>
  27 #include <linux/signal.h>
  28 #include <linux/syscalls.h>
  29 #include <linux/audit.h>
  30 #include <linux/seccomp.h>
  31 #include <linux/tracehook.h>
  32 #include <asm/io.h>
  33 #include <asm/uaccess.h>
  34 #include <asm/pgtable.h>
  35 #include <asm/system.h>
  36 #include <asm/processor.h>
  37 #include <asm/mmu_context.h>
  38 #include <asm/syscalls.h>
  39 #include <asm/fpu.h>
  40
  41 /* This mask defines the bits of the SR which the user is not allowed to
  42    change, which are everything except S, Q, M, PR, SZ, FR. */
  43 #define SR_MASK      (0xffff8cfd)
  44
  45 /*
  46  * does not yet catch signals sent when the child dies.
  47  * in exit.c or in signal.c.
  48  */
  49
  50 /*
  51  * This routine will get a word from the user area in the process kernel stack.
  52  */
  53 static inline int get_stack_long(struct task_struct *task, int offset)
  54 {
  55         unsigned char *stack;
  56
  57         stack = (unsigned char *)(task->thread.uregs);
  58         stack += offset;
  59         return (*((int *)stack));
  60 }
  61
  62 static inline unsigned long
  63 get_fpu_long(struct task_struct *task, unsigned long addr)
  64 {
  65         unsigned long tmp;
  66         struct pt_regs *regs;
  67         regs = (struct pt_regs*)((unsigned char *)task + THREAD_SIZE) - 1;
  68
  69         if (!tsk_used_math(task)) {
  70                 if (addr == offsetof(struct user_fpu_struct, fpscr)) {
  71                         tmp = FPSCR_INIT;
  72                 } else {
  73                         tmp = 0xffffffffUL; /* matches initial value in fpu.c */
  74                 }
  75                 return tmp;
  76         }
  77
  78         if (last_task_used_math == task) {
  79                 enable_fpu();
  80                 save_fpu(task, regs);
  81                 disable_fpu();
  82                 last_task_used_math = 0;
  83                 regs->sr |= SR_FD;
  84         }
  85
  86         tmp = ((long *)&task->thread.fpu)[addr / sizeof(unsigned long)];
  87         return tmp;
  88 }
  89
  90 /*
  91  * This routine will put a word into the user area in the process kernel stack.
  92  */
  93 static inline int put_stack_long(struct task_struct *task, int offset,
  94                                  unsigned long data)
  95 {
  96         unsigned char *stack;
  97
  98         stack = (unsigned char *)(task->thread.uregs);
  99         stack += offset;
 100         *(unsigned long *) stack = data;
 101         return 0;
 102 }
 103
 104 static inline int
 105 put_fpu_long(struct task_struct *task, unsigned long addr, unsigned long data)
 106 {
 107         struct pt_regs *regs;
 108
 109         regs = (struct pt_regs*)((unsigned char *)task + THREAD_SIZE) - 1;
 110
 111         if (!tsk_used_math(task)) {
 112                 fpinit(&task->thread.fpu.hard);
 113                 set_stopped_child_used_math(task);
 114         } else if (last_task_used_math == task) {
 115                 enable_fpu();
 116                 save_fpu(task, regs);
 117                 disable_fpu();
 118                 last_task_used_math = 0;
 119                 regs->sr |= SR_FD;
 120         }
 121
 122         ((long *)&task->thread.fpu)[addr / sizeof(unsigned long)] = data;
 123         return 0;
 124 }
 125
 126 void user_enable_single_step(struct task_struct *child)
 127 {
 128         struct pt_regs *regs = child->thread.uregs;
 129
 130         regs->sr |= SR_SSTEP;   /* auto-resetting upon exception */
 131 }
 132
 133 void user_disable_single_step(struct task_struct *child)
 134 {
 135         struct pt_regs *regs = child->thread.uregs;
 136
 137         regs->sr &= ~SR_SSTEP;
 138 }
 139
 140 long arch_ptrace(struct task_struct *child, long request, long addr, long data)
 141 {
 142         int ret;
 143
 144         switch (request) {
 145         /* read the word at location addr in the USER area. */
 146         case PTRACE_PEEKUSR: {
 147                 unsigned long tmp;
 148
 149                 ret = -EIO;
 150                 if ((addr & 3) || addr < 0)
 151                         break;
 152
 153                 if (addr < sizeof(struct pt_regs))
 154                         tmp = get_stack_long(child, addr);
 155                 else if ((addr >= offsetof(struct user, fpu)) &&
 156                          (addr <  offsetof(struct user, u_fpvalid))) {
 157                         tmp = get_fpu_long(child, addr - offsetof(struct user, fpu));
 158                 } else if (addr == offsetof(struct user, u_fpvalid)) {
 159                         tmp = !!tsk_used_math(child);
 160                 } else {
 161                         break;
 162                 }
 163                 ret = put_user(tmp, (unsigned long *)data);
 164                 break;
 165         }
 166
 167         case PTRACE_POKEUSR:
 168                 /* write the word at location addr in the USER area. We must
 169                    disallow any changes to certain SR bits or u_fpvalid, since
 170                    this could crash the kernel or result in a security
 171                    loophole. */
 172                 ret = -EIO;
 173                 if ((addr & 3) || addr < 0)
 174                         break;
 175
 176                 if (addr < sizeof(struct pt_regs)) {
 177                         /* Ignore change of top 32 bits of SR */
 178                         if (addr == offsetof (struct pt_regs, sr)+4)
 179                         {
 180                                 ret = 0;
 181                                 break;
 182                         }
 183                         /* If lower 32 bits of SR, ignore non-user bits */
 184                         if (addr == offsetof (struct pt_regs, sr))
 185                         {
 186                                 long cursr = get_stack_long(child, addr);
 187                                 data &= ~(SR_MASK);
 188                                 data |= (cursr & SR_MASK);
 189                         }
 190                         ret = put_stack_long(child, addr, data);
 191                 }
 192                 else if ((addr >= offsetof(struct user, fpu)) &&
 193                          (addr <  offsetof(struct user, u_fpvalid))) {
 194                         ret = put_fpu_long(child, addr - offsetof(struct user, fpu), data);
 195                 }
 196                 break;
 197
 198         default:
 199                 ret = ptrace_request(child, request, addr, data);
 200                 break;
 201         }
 202         return ret;
 203 }
 204
 205 asmlinkage int sh64_ptrace(long request, long pid, long addr, long data)
 206 {
 207 #define WPC_DBRMODE 0x0d104008
 208         static int first_call = 1;
 209
 210         lock_kernel();
 211         if (first_call) {
 212                 /* Set WPC.DBRMODE to 0.  This makes all debug events get
 213                  * delivered through RESVEC, i.e. into the handlers in entry.S.
 214                  * (If the kernel was downloaded using a remote gdb, WPC.DBRMODE
 215                  * would normally be left set to 1, which makes debug events get
 216                  * delivered through DBRVEC, i.e. into the remote gdb's
 217                  * handlers.  This prevents ptrace getting them, and confuses
 218                  * the remote gdb.) */
 219                 printk("DBRMODE set to 0 to permit native debugging\n");
 220                 poke_real_address_q(WPC_DBRMODE, 0);
 221                 first_call = 0;
 222         }
 223         unlock_kernel();
 224
 225         return sys_ptrace(request, pid, addr, data);
 226 }
 227
 228 static inline int audit_arch(void)
 229 {
 230         int arch = EM_SH;
 231
 232 #ifdef CONFIG_64BIT
 233         arch |= __AUDIT_ARCH_64BIT;
 234 #endif
 235 #ifdef CONFIG_CPU_LITTLE_ENDIAN
 236         arch |= __AUDIT_ARCH_LE;
 237 #endif
 238
 239         return arch;
 240 }
 241
 242 asmlinkage long long do_syscall_trace_enter(struct pt_regs *regs)
 243 {
 244         long long ret = 0;
 245
 246         secure_computing(regs->regs[9]);
 247
 248         if (test_thread_flag(TIF_SYSCALL_TRACE) &&
 249             tracehook_report_syscall_entry(regs))
 250                 /*
 251                  * Tracing decided this syscall should not happen.
 252                  * We'll return a bogus call number to get an ENOSYS
 253                  * error, but leave the original number in regs->regs[0].
 254                  */
 255                 ret = -1LL;
 256
 257         if (unlikely(current->audit_context))
 258                 audit_syscall_entry(audit_arch(), regs->regs[1],
 259                                     regs->regs[2], regs->regs[3],
 260                                     regs->regs[4], regs->regs[5]);
 261
 262         return ret ?: regs->regs[9];
 263 }
 264
 265 asmlinkage void do_syscall_trace_leave(struct pt_regs *regs)
 266 {
 267         if (unlikely(current->audit_context))
 268                 audit_syscall_exit(AUDITSC_RESULT(regs->regs[9]),
 269                                    regs->regs[9]);
 270
 271         if (test_thread_flag(TIF_SYSCALL_TRACE))
 272                 tracehook_report_syscall_exit(regs, 0);
 273 }
 274
 275 /* Called with interrupts disabled */
 276 asmlinkage void do_single_step(unsigned long long vec, struct pt_regs *regs)
 277 {
 278         /* This is called after a single step exception (DEBUGSS).
 279            There is no need to change the PC, as it is a post-execution
 280            exception, as entry.S does not do anything to the PC for DEBUGSS.
 281            We need to clear the Single Step setting in SR to avoid
 282            continually stepping. */
 283         local_irq_enable();
 284         regs->sr &= ~SR_SSTEP;
 285         force_sig(SIGTRAP, current);
 286 }
 287
 288 /* Called with interrupts disabled */
 289 asmlinkage void do_software_break_point(unsigned long long vec,
 290                                         struct pt_regs *regs)
 291 {
 292         /* We need to forward step the PC, to counteract the backstep done
 293            in signal.c. */
 294         local_irq_enable();
 295         force_sig(SIGTRAP, current);
 296         regs->pc += 4;
 297 }
 298
 299 /*
 300  * Called by kernel/ptrace.c when detaching..
 301  *
 302  * Make sure single step bits etc are not set.
 303  */
 304 void ptrace_disable(struct task_struct *child)
 305 {
 306         user_disable_single_step(child);
 307 }