syscall.h 6.18 KB
Newer Older
1 2 3
/*
 * Access to user system call parameters and results
 *
4
 * Copyright (C) 2008-2009 Red Hat, Inc.  All rights reserved.
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU General Public License v.2.
 *
 * This file is a stub providing documentation for what functions
 * asm-ARCH/syscall.h files need to define.  Most arch definitions
 * will be simple inlines.
 *
 * All of these functions expect to be called with no locks,
 * and only when the caller is sure that the task of interest
 * cannot return to user mode while we are looking at it.
 */

#ifndef _ASM_SYSCALL_H
#define _ASM_SYSCALL_H	1

struct task_struct;
struct pt_regs;

/**
 * syscall_get_nr - find what system call a task is executing
 * @task:	task of interest, must be blocked
 * @regs:	task_pt_regs() of @task
 *
 * If @task is executing a system call or is at system call
 * tracing about to attempt one, returns the system call number.
 * If @task is not executing a system call, i.e. it's blocked
 * inside the kernel for a fault or signal, returns -1.
 *
35 36 37 38
 * Note this returns int even on 64-bit machines.  Only 32 bits of
 * system call number can be meaningful.  If the actual arch value
 * is 64 bits, this truncates to 32 bits so 0xffffffff means -1.
 *
39 40
 * It's only valid to call this when @task is known to be blocked.
 */
41
int syscall_get_nr(struct task_struct *task, struct pt_regs *regs);
42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132

/**
 * syscall_rollback - roll back registers after an aborted system call
 * @task:	task of interest, must be in system call exit tracing
 * @regs:	task_pt_regs() of @task
 *
 * It's only valid to call this when @task is stopped for system
 * call exit tracing (due to TIF_SYSCALL_TRACE or TIF_SYSCALL_AUDIT),
 * after tracehook_report_syscall_entry() returned nonzero to prevent
 * the system call from taking place.
 *
 * This rolls back the register state in @regs so it's as if the
 * system call instruction was a no-op.  The registers containing
 * the system call number and arguments are as they were before the
 * system call instruction.  This may not be the same as what the
 * register state looked like at system call entry tracing.
 */
void syscall_rollback(struct task_struct *task, struct pt_regs *regs);

/**
 * syscall_get_error - check result of traced system call
 * @task:	task of interest, must be blocked
 * @regs:	task_pt_regs() of @task
 *
 * Returns 0 if the system call succeeded, or -ERRORCODE if it failed.
 *
 * It's only valid to call this when @task is stopped for tracing on exit
 * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
 */
long syscall_get_error(struct task_struct *task, struct pt_regs *regs);

/**
 * syscall_get_return_value - get the return value of a traced system call
 * @task:	task of interest, must be blocked
 * @regs:	task_pt_regs() of @task
 *
 * Returns the return value of the successful system call.
 * This value is meaningless if syscall_get_error() returned nonzero.
 *
 * It's only valid to call this when @task is stopped for tracing on exit
 * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
 */
long syscall_get_return_value(struct task_struct *task, struct pt_regs *regs);

/**
 * syscall_set_return_value - change the return value of a traced system call
 * @task:	task of interest, must be blocked
 * @regs:	task_pt_regs() of @task
 * @error:	negative error code, or zero to indicate success
 * @val:	user return value if @error is zero
 *
 * This changes the results of the system call that user mode will see.
 * If @error is zero, the user sees a successful system call with a
 * return value of @val.  If @error is nonzero, it's a negated errno
 * code; the user sees a failed system call with this errno code.
 *
 * It's only valid to call this when @task is stopped for tracing on exit
 * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
 */
void syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
			      int error, long val);

/**
 * syscall_get_arguments - extract system call parameter values
 * @task:	task of interest, must be blocked
 * @regs:	task_pt_regs() of @task
 * @i:		argument index [0,5]
 * @n:		number of arguments; n+i must be [1,6].
 * @args:	array filled with argument values
 *
 * Fetches @n arguments to the system call starting with the @i'th argument
 * (from 0 through 5).  Argument @i is stored in @args[0], and so on.
 * An arch inline version is probably optimal when @i and @n are constants.
 *
 * It's only valid to call this when @task is stopped for tracing on
 * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
 * It's invalid to call this with @i + @n > 6; we only support system calls
 * taking up to 6 arguments.
 */
void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
			   unsigned int i, unsigned int n, unsigned long *args);

/**
 * syscall_set_arguments - change system call parameter value
 * @task:	task of interest, must be in system call entry tracing
 * @regs:	task_pt_regs() of @task
 * @i:		argument index [0,5]
 * @n:		number of arguments; n+i must be [1,6].
 * @args:	array of argument values to store
 *
 * Changes @n arguments to the system call starting with the @i'th argument.
133
 * Argument @i gets value @args[0], and so on.
134 135 136 137 138 139 140 141 142 143 144
 * An arch inline version is probably optimal when @i and @n are constants.
 *
 * It's only valid to call this when @task is stopped for tracing on
 * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
 * It's invalid to call this with @i + @n > 6; we only support system calls
 * taking up to 6 arguments.
 */
void syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
			   unsigned int i, unsigned int n,
			   const unsigned long *args);

145 146 147 148 149
/**
 * syscall_get_arch - return the AUDIT_ARCH for the current system call
 *
 * Returns the AUDIT_ARCH_* based on the system call convention in use.
 *
150
 * It's only valid to call this when current is stopped on entry to a system
151 152 153 154 155
 * call, due to %TIF_SYSCALL_TRACE, %TIF_SYSCALL_AUDIT, or %TIF_SECCOMP.
 *
 * Architectures which permit CONFIG_HAVE_ARCH_SECCOMP_FILTER must
 * provide an implementation of this.
 */
156
int syscall_get_arch(void);
157
#endif	/* _ASM_SYSCALL_H */