linux/include/linux/ptrace.h
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   1#ifndef _LINUX_PTRACE_H
   2#define _LINUX_PTRACE_H
   3
   4#include <linux/compiler.h>             /* For unlikely.  */
   5#include <linux/sched.h>                /* For struct task_struct.  */
   6#include <linux/err.h>                  /* for IS_ERR_VALUE */
   7#include <linux/bug.h>                  /* For BUG_ON.  */
   8#include <uapi/linux/ptrace.h>
   9
  10/*
  11 * Ptrace flags
  12 *
  13 * The owner ship rules for task->ptrace which holds the ptrace
  14 * flags is simple.  When a task is running it owns it's task->ptrace
  15 * flags.  When the a task is stopped the ptracer owns task->ptrace.
  16 */
  17
  18#define PT_SEIZED       0x00010000      /* SEIZE used, enable new behavior */
  19#define PT_PTRACED      0x00000001
  20#define PT_DTRACE       0x00000002      /* delayed trace (used on m68k, i386) */
  21#define PT_PTRACE_CAP   0x00000004      /* ptracer can follow suid-exec */
  22
  23#define PT_OPT_FLAG_SHIFT       3
  24/* PT_TRACE_* event enable flags */
  25#define PT_EVENT_FLAG(event)    (1 << (PT_OPT_FLAG_SHIFT + (event)))
  26#define PT_TRACESYSGOOD         PT_EVENT_FLAG(0)
  27#define PT_TRACE_FORK           PT_EVENT_FLAG(PTRACE_EVENT_FORK)
  28#define PT_TRACE_VFORK          PT_EVENT_FLAG(PTRACE_EVENT_VFORK)
  29#define PT_TRACE_CLONE          PT_EVENT_FLAG(PTRACE_EVENT_CLONE)
  30#define PT_TRACE_EXEC           PT_EVENT_FLAG(PTRACE_EVENT_EXEC)
  31#define PT_TRACE_VFORK_DONE     PT_EVENT_FLAG(PTRACE_EVENT_VFORK_DONE)
  32#define PT_TRACE_EXIT           PT_EVENT_FLAG(PTRACE_EVENT_EXIT)
  33#define PT_TRACE_SECCOMP        PT_EVENT_FLAG(PTRACE_EVENT_SECCOMP)
  34
  35#define PT_EXITKILL             (PTRACE_O_EXITKILL << PT_OPT_FLAG_SHIFT)
  36
  37/* single stepping state bits (used on ARM and PA-RISC) */
  38#define PT_SINGLESTEP_BIT       31
  39#define PT_SINGLESTEP           (1<<PT_SINGLESTEP_BIT)
  40#define PT_BLOCKSTEP_BIT        30
  41#define PT_BLOCKSTEP            (1<<PT_BLOCKSTEP_BIT)
  42
  43extern long arch_ptrace(struct task_struct *child, long request,
  44                        unsigned long addr, unsigned long data);
  45extern int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len);
  46extern int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len);
  47extern void ptrace_disable(struct task_struct *);
  48extern int ptrace_request(struct task_struct *child, long request,
  49                          unsigned long addr, unsigned long data);
  50extern void ptrace_notify(int exit_code);
  51extern void __ptrace_link(struct task_struct *child,
  52                          struct task_struct *new_parent);
  53extern void __ptrace_unlink(struct task_struct *child);
  54extern void exit_ptrace(struct task_struct *tracer);
  55#define PTRACE_MODE_READ        0x01
  56#define PTRACE_MODE_ATTACH      0x02
  57#define PTRACE_MODE_NOAUDIT     0x04
  58/* Returns true on success, false on denial. */
  59extern bool ptrace_may_access(struct task_struct *task, unsigned int mode);
  60
  61static inline int ptrace_reparented(struct task_struct *child)
  62{
  63        return !same_thread_group(child->real_parent, child->parent);
  64}
  65
  66static inline void ptrace_unlink(struct task_struct *child)
  67{
  68        if (unlikely(child->ptrace))
  69                __ptrace_unlink(child);
  70}
  71
  72int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
  73                            unsigned long data);
  74int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
  75                            unsigned long data);
  76
  77/**
  78 * ptrace_parent - return the task that is tracing the given task
  79 * @task: task to consider
  80 *
  81 * Returns %NULL if no one is tracing @task, or the &struct task_struct
  82 * pointer to its tracer.
  83 *
  84 * Must called under rcu_read_lock().  The pointer returned might be kept
  85 * live only by RCU.  During exec, this may be called with task_lock() held
  86 * on @task, still held from when check_unsafe_exec() was called.
  87 */
  88static inline struct task_struct *ptrace_parent(struct task_struct *task)
  89{
  90        if (unlikely(task->ptrace))
  91                return rcu_dereference(task->parent);
  92        return NULL;
  93}
  94
  95/**
  96 * ptrace_event_enabled - test whether a ptrace event is enabled
  97 * @task: ptracee of interest
  98 * @event: %PTRACE_EVENT_* to test
  99 *
 100 * Test whether @event is enabled for ptracee @task.
 101 *
 102 * Returns %true if @event is enabled, %false otherwise.
 103 */
 104static inline bool ptrace_event_enabled(struct task_struct *task, int event)
 105{
 106        return task->ptrace & PT_EVENT_FLAG(event);
 107}
 108
 109/**
 110 * ptrace_event - possibly stop for a ptrace event notification
 111 * @event:      %PTRACE_EVENT_* value to report
 112 * @message:    value for %PTRACE_GETEVENTMSG to return
 113 *
 114 * Check whether @event is enabled and, if so, report @event and @message
 115 * to the ptrace parent.
 116 *
 117 * Called without locks.
 118 */
 119static inline void ptrace_event(int event, unsigned long message)
 120{
 121        if (unlikely(ptrace_event_enabled(current, event))) {
 122                current->ptrace_message = message;
 123                ptrace_notify((event << 8) | SIGTRAP);
 124        } else if (event == PTRACE_EVENT_EXEC) {
 125                /* legacy EXEC report via SIGTRAP */
 126                if ((current->ptrace & (PT_PTRACED|PT_SEIZED)) == PT_PTRACED)
 127                        send_sig(SIGTRAP, current, 0);
 128        }
 129}
 130
 131/**
 132 * ptrace_init_task - initialize ptrace state for a new child
 133 * @child:              new child task
 134 * @ptrace:             true if child should be ptrace'd by parent's tracer
 135 *
 136 * This is called immediately after adding @child to its parent's children
 137 * list.  @ptrace is false in the normal case, and true to ptrace @child.
 138 *
 139 * Called with current's siglock and write_lock_irq(&tasklist_lock) held.
 140 */
 141static inline void ptrace_init_task(struct task_struct *child, bool ptrace)
 142{
 143        INIT_LIST_HEAD(&child->ptrace_entry);
 144        INIT_LIST_HEAD(&child->ptraced);
 145#ifdef CONFIG_HAVE_HW_BREAKPOINT
 146        atomic_set(&child->ptrace_bp_refcnt, 1);
 147#endif
 148        child->jobctl = 0;
 149        child->ptrace = 0;
 150        child->parent = child->real_parent;
 151
 152        if (unlikely(ptrace) && current->ptrace) {
 153                child->ptrace = current->ptrace;
 154                __ptrace_link(child, current->parent);
 155
 156                if (child->ptrace & PT_SEIZED)
 157                        task_set_jobctl_pending(child, JOBCTL_TRAP_STOP);
 158                else
 159                        sigaddset(&child->pending.signal, SIGSTOP);
 160
 161                set_tsk_thread_flag(child, TIF_SIGPENDING);
 162        }
 163}
 164
 165/**
 166 * ptrace_release_task - final ptrace-related cleanup of a zombie being reaped
 167 * @task:       task in %EXIT_DEAD state
 168 *
 169 * Called with write_lock(&tasklist_lock) held.
 170 */
 171static inline void ptrace_release_task(struct task_struct *task)
 172{
 173        BUG_ON(!list_empty(&task->ptraced));
 174        ptrace_unlink(task);
 175        BUG_ON(!list_empty(&task->ptrace_entry));
 176}
 177
 178#ifndef force_successful_syscall_return
 179/*
 180 * System call handlers that, upon successful completion, need to return a
 181 * negative value should call force_successful_syscall_return() right before
 182 * returning.  On architectures where the syscall convention provides for a
 183 * separate error flag (e.g., alpha, ia64, ppc{,64}, sparc{,64}, possibly
 184 * others), this macro can be used to ensure that the error flag will not get
 185 * set.  On architectures which do not support a separate error flag, the macro
 186 * is a no-op and the spurious error condition needs to be filtered out by some
 187 * other means (e.g., in user-level, by passing an extra argument to the
 188 * syscall handler, or something along those lines).
 189 */
 190#define force_successful_syscall_return() do { } while (0)
 191#endif
 192
 193#ifndef is_syscall_success
 194/*
 195 * On most systems we can tell if a syscall is a success based on if the retval
 196 * is an error value.  On some systems like ia64 and powerpc they have different
 197 * indicators of success/failure and must define their own.
 198 */
 199#define is_syscall_success(regs) (!IS_ERR_VALUE((unsigned long)(regs_return_value(regs))))
 200#endif
 201
 202/*
 203 * <asm/ptrace.h> should define the following things inside #ifdef __KERNEL__.
 204 *
 205 * These do-nothing inlines are used when the arch does not
 206 * implement single-step.  The kerneldoc comments are here
 207 * to document the interface for all arch definitions.
 208 */
 209
 210#ifndef arch_has_single_step
 211/**
 212 * arch_has_single_step - does this CPU support user-mode single-step?
 213 *
 214 * If this is defined, then there must be function declarations or
 215 * inlines for user_enable_single_step() and user_disable_single_step().
 216 * arch_has_single_step() should evaluate to nonzero iff the machine
 217 * supports instruction single-step for user mode.
 218 * It can be a constant or it can test a CPU feature bit.
 219 */
 220#define arch_has_single_step()          (0)
 221
 222/**
 223 * user_enable_single_step - single-step in user-mode task
 224 * @task: either current or a task stopped in %TASK_TRACED
 225 *
 226 * This can only be called when arch_has_single_step() has returned nonzero.
 227 * Set @task so that when it returns to user mode, it will trap after the
 228 * next single instruction executes.  If arch_has_block_step() is defined,
 229 * this must clear the effects of user_enable_block_step() too.
 230 */
 231static inline void user_enable_single_step(struct task_struct *task)
 232{
 233        BUG();                  /* This can never be called.  */
 234}
 235
 236/**
 237 * user_disable_single_step - cancel user-mode single-step
 238 * @task: either current or a task stopped in %TASK_TRACED
 239 *
 240 * Clear @task of the effects of user_enable_single_step() and
 241 * user_enable_block_step().  This can be called whether or not either
 242 * of those was ever called on @task, and even if arch_has_single_step()
 243 * returned zero.
 244 */
 245static inline void user_disable_single_step(struct task_struct *task)
 246{
 247}
 248#else
 249extern void user_enable_single_step(struct task_struct *);
 250extern void user_disable_single_step(struct task_struct *);
 251#endif  /* arch_has_single_step */
 252
 253#ifndef arch_has_block_step
 254/**
 255 * arch_has_block_step - does this CPU support user-mode block-step?
 256 *
 257 * If this is defined, then there must be a function declaration or inline
 258 * for user_enable_block_step(), and arch_has_single_step() must be defined
 259 * too.  arch_has_block_step() should evaluate to nonzero iff the machine
 260 * supports step-until-branch for user mode.  It can be a constant or it
 261 * can test a CPU feature bit.
 262 */
 263#define arch_has_block_step()           (0)
 264
 265/**
 266 * user_enable_block_step - step until branch in user-mode task
 267 * @task: either current or a task stopped in %TASK_TRACED
 268 *
 269 * This can only be called when arch_has_block_step() has returned nonzero,
 270 * and will never be called when single-instruction stepping is being used.
 271 * Set @task so that when it returns to user mode, it will trap after the
 272 * next branch or trap taken.
 273 */
 274static inline void user_enable_block_step(struct task_struct *task)
 275{
 276        BUG();                  /* This can never be called.  */
 277}
 278#else
 279extern void user_enable_block_step(struct task_struct *);
 280#endif  /* arch_has_block_step */
 281
 282#ifdef ARCH_HAS_USER_SINGLE_STEP_INFO
 283extern void user_single_step_siginfo(struct task_struct *tsk,
 284                                struct pt_regs *regs, siginfo_t *info);
 285#else
 286static inline void user_single_step_siginfo(struct task_struct *tsk,
 287                                struct pt_regs *regs, siginfo_t *info)
 288{
 289        memset(info, 0, sizeof(*info));
 290        info->si_signo = SIGTRAP;
 291}
 292#endif
 293
 294#ifndef arch_ptrace_stop_needed
 295/**
 296 * arch_ptrace_stop_needed - Decide whether arch_ptrace_stop() should be called
 297 * @code:       current->exit_code value ptrace will stop with
 298 * @info:       siginfo_t pointer (or %NULL) for signal ptrace will stop with
 299 *
 300 * This is called with the siglock held, to decide whether or not it's
 301 * necessary to release the siglock and call arch_ptrace_stop() with the
 302 * same @code and @info arguments.  It can be defined to a constant if
 303 * arch_ptrace_stop() is never required, or always is.  On machines where
 304 * this makes sense, it should be defined to a quick test to optimize out
 305 * calling arch_ptrace_stop() when it would be superfluous.  For example,
 306 * if the thread has not been back to user mode since the last stop, the
 307 * thread state might indicate that nothing needs to be done.
 308 */
 309#define arch_ptrace_stop_needed(code, info)     (0)
 310#endif
 311
 312#ifndef arch_ptrace_stop
 313/**
 314 * arch_ptrace_stop - Do machine-specific work before stopping for ptrace
 315 * @code:       current->exit_code value ptrace will stop with
 316 * @info:       siginfo_t pointer (or %NULL) for signal ptrace will stop with
 317 *
 318 * This is called with no locks held when arch_ptrace_stop_needed() has
 319 * just returned nonzero.  It is allowed to block, e.g. for user memory
 320 * access.  The arch can have machine-specific work to be done before
 321 * ptrace stops.  On ia64, register backing store gets written back to user
 322 * memory here.  Since this can be costly (requires dropping the siglock),
 323 * we only do it when the arch requires it for this particular stop, as
 324 * indicated by arch_ptrace_stop_needed().
 325 */
 326#define arch_ptrace_stop(code, info)            do { } while (0)
 327#endif
 328
 329#ifndef current_pt_regs
 330#define current_pt_regs() task_pt_regs(current)
 331#endif
 332
 333#ifndef ptrace_signal_deliver
 334#define ptrace_signal_deliver() ((void)0)
 335#endif
 336
 337/*
 338 * unlike current_pt_regs(), this one is equal to task_pt_regs(current)
 339 * on *all* architectures; the only reason to have a per-arch definition
 340 * is optimisation.
 341 */
 342#ifndef signal_pt_regs
 343#define signal_pt_regs() task_pt_regs(current)
 344#endif
 345
 346#ifndef current_user_stack_pointer
 347#define current_user_stack_pointer() user_stack_pointer(current_pt_regs())
 348#endif
 349
 350extern int task_current_syscall(struct task_struct *target, long *callno,
 351                                unsigned long args[6], unsigned int maxargs,
 352                                unsigned long *sp, unsigned long *pc);
 353
 354#ifdef CONFIG_HAVE_HW_BREAKPOINT
 355extern int ptrace_get_breakpoints(struct task_struct *tsk);
 356extern void ptrace_put_breakpoints(struct task_struct *tsk);
 357#else
 358static inline void ptrace_put_breakpoints(struct task_struct *tsk) { }
 359#endif /* CONFIG_HAVE_HW_BREAKPOINT */
 360
 361#endif
 362
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