LXR linux/include/asm-generic/syscall.h

   1/* SPDX-License-Identifier: GPL-2.0-only */
   2/*
   3 * Access to user system call parameters and results
   4 *
   5 * Copyright (C) 2008-2009 Red Hat, Inc.  All rights reserved.
   6 *
   7 * This file is a stub providing documentation for what functions
   8 * asm-ARCH/syscall.h files need to define.  Most arch definitions
   9 * will be simple inlines.
  10 *
  11 * All of these functions expect to be called with no locks,
  12 * and only when the caller is sure that the task of interest
  13 * cannot return to user mode while we are looking at it.
  14 */
  15
  16#ifndef _ASM_SYSCALL_H
  17#define _ASM_SYSCALL_H  1
  18
  19struct task_struct;
  20struct pt_regs;
  21
  22/**
  23 * syscall_get_nr - find what system call a task is executing
  24 * @task:       task of interest, must be blocked
  25 * @regs:       task_pt_regs() of @task
  26 *
  27 * If @task is executing a system call or is at system call
  28 * tracing about to attempt one, returns the system call number.
  29 * If @task is not executing a system call, i.e. it's blocked
  30 * inside the kernel for a fault or signal, returns -1.
  31 *
  32 * Note this returns int even on 64-bit machines.  Only 32 bits of
  33 * system call number can be meaningful.  If the actual arch value
  34 * is 64 bits, this truncates to 32 bits so 0xffffffff means -1.
  35 *
  36 * It's only valid to call this when @task is known to be blocked.
  37 */
  38int syscall_get_nr(struct task_struct *task, struct pt_regs *regs);
  39
  40/**
  41 * syscall_rollback - roll back registers after an aborted system call
  42 * @task:       task of interest, must be in system call exit tracing
  43 * @regs:       task_pt_regs() of @task
  44 *
  45 * It's only valid to call this when @task is stopped for system
  46 * call exit tracing (due to %SYSCALL_WORK_SYSCALL_TRACE or
  47 * %SYSCALL_WORK_SYSCALL_AUDIT), after tracehook_report_syscall_entry()
  48 * returned nonzero to prevent the system call from taking place.
  49 *
  50 * This rolls back the register state in @regs so it's as if the
  51 * system call instruction was a no-op.  The registers containing
  52 * the system call number and arguments are as they were before the
  53 * system call instruction.  This may not be the same as what the
  54 * register state looked like at system call entry tracing.
  55 */
  56void syscall_rollback(struct task_struct *task, struct pt_regs *regs);
  57
  58/**
  59 * syscall_get_error - check result of traced system call
  60 * @task:       task of interest, must be blocked
  61 * @regs:       task_pt_regs() of @task
  62 *
  63 * Returns 0 if the system call succeeded, or -ERRORCODE if it failed.
  64 *
  65 * It's only valid to call this when @task is stopped for tracing on exit
  66 * from a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or
  67 * %SYSCALL_WORK_SYSCALL_AUDIT.
  68 */
  69long syscall_get_error(struct task_struct *task, struct pt_regs *regs);
  70
  71/**
  72 * syscall_get_return_value - get the return value of a traced system call
  73 * @task:       task of interest, must be blocked
  74 * @regs:       task_pt_regs() of @task
  75 *
  76 * Returns the return value of the successful system call.
  77 * This value is meaningless if syscall_get_error() returned nonzero.
  78 *
  79 * It's only valid to call this when @task is stopped for tracing on exit
  80 * from a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or
  81 * %SYSCALL_WORK_SYSCALL_AUDIT.
  82 */
  83long syscall_get_return_value(struct task_struct *task, struct pt_regs *regs);
  84
  85/**
  86 * syscall_set_return_value - change the return value of a traced system call
  87 * @task:       task of interest, must be blocked
  88 * @regs:       task_pt_regs() of @task
  89 * @error:      negative error code, or zero to indicate success
  90 * @val:        user return value if @error is zero
  91 *
  92 * This changes the results of the system call that user mode will see.
  93 * If @error is zero, the user sees a successful system call with a
  94 * return value of @val.  If @error is nonzero, it's a negated errno
  95 * code; the user sees a failed system call with this errno code.
  96 *
  97 * It's only valid to call this when @task is stopped for tracing on exit
  98 * from a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or
  99 * %SYSCALL_WORK_SYSCALL_AUDIT.
 100 */
 101void syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
 102                              int error, long val);
 103
 104/**
 105 * syscall_get_arguments - extract system call parameter values
 106 * @task:       task of interest, must be blocked
 107 * @regs:       task_pt_regs() of @task
 108 * @args:       array filled with argument values
 109 *
 110 * Fetches 6 arguments to the system call.  First argument is stored in
 111*  @args[0], and so on.
 112 *
 113 * It's only valid to call this when @task is stopped for tracing on
 114 * entry to a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or
 115 * %SYSCALL_WORK_SYSCALL_AUDIT.
 116 */
 117void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
 118                           unsigned long *args);
 119
 120/**
 121 * syscall_get_arch - return the AUDIT_ARCH for the current system call
 122 * @task:       task of interest, must be blocked
 123 *
 124 * Returns the AUDIT_ARCH_* based on the system call convention in use.
 125 *
 126 * It's only valid to call this when @task is stopped on entry to a system
 127 * call, due to %SYSCALL_WORK_SYSCALL_TRACE, %SYSCALL_WORK_SYSCALL_AUDIT, or
 128 * %SYSCALL_WORK_SECCOMP.
 129 *
 130 * Architectures which permit CONFIG_HAVE_ARCH_SECCOMP_FILTER must
 131 * provide an implementation of this.
 132 */
 133int syscall_get_arch(struct task_struct *task);
 134#endif  /* _ASM_SYSCALL_H */
 135