Roland McGrath | 828c365 | 2008-07-25 19:45:57 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Access to user system call parameters and results |
| 3 | * |
| 4 | * Copyright (C) 2008 Red Hat, Inc. All rights reserved. |
| 5 | * |
| 6 | * This copyrighted material is made available to anyone wishing to use, |
| 7 | * modify, copy, or redistribute it subject to the terms and conditions |
| 8 | * of the GNU General Public License v.2. |
| 9 | * |
| 10 | * This file is a stub providing documentation for what functions |
| 11 | * asm-ARCH/syscall.h files need to define. Most arch definitions |
| 12 | * will be simple inlines. |
| 13 | * |
| 14 | * All of these functions expect to be called with no locks, |
| 15 | * and only when the caller is sure that the task of interest |
| 16 | * cannot return to user mode while we are looking at it. |
| 17 | */ |
| 18 | |
| 19 | #ifndef _ASM_SYSCALL_H |
| 20 | #define _ASM_SYSCALL_H 1 |
| 21 | |
| 22 | struct task_struct; |
| 23 | struct pt_regs; |
| 24 | |
| 25 | /** |
| 26 | * syscall_get_nr - find what system call a task is executing |
| 27 | * @task: task of interest, must be blocked |
| 28 | * @regs: task_pt_regs() of @task |
| 29 | * |
| 30 | * If @task is executing a system call or is at system call |
| 31 | * tracing about to attempt one, returns the system call number. |
| 32 | * If @task is not executing a system call, i.e. it's blocked |
| 33 | * inside the kernel for a fault or signal, returns -1. |
| 34 | * |
| 35 | * It's only valid to call this when @task is known to be blocked. |
| 36 | */ |
| 37 | long syscall_get_nr(struct task_struct *task, struct pt_regs *regs); |
| 38 | |
| 39 | /** |
| 40 | * syscall_rollback - roll back registers after an aborted system call |
| 41 | * @task: task of interest, must be in system call exit tracing |
| 42 | * @regs: task_pt_regs() of @task |
| 43 | * |
| 44 | * It's only valid to call this when @task is stopped for system |
| 45 | * call exit tracing (due to TIF_SYSCALL_TRACE or TIF_SYSCALL_AUDIT), |
| 46 | * after tracehook_report_syscall_entry() returned nonzero to prevent |
| 47 | * the system call from taking place. |
| 48 | * |
| 49 | * This rolls back the register state in @regs so it's as if the |
| 50 | * system call instruction was a no-op. The registers containing |
| 51 | * the system call number and arguments are as they were before the |
| 52 | * system call instruction. This may not be the same as what the |
| 53 | * register state looked like at system call entry tracing. |
| 54 | */ |
| 55 | void syscall_rollback(struct task_struct *task, struct pt_regs *regs); |
| 56 | |
| 57 | /** |
| 58 | * syscall_get_error - check result of traced system call |
| 59 | * @task: task of interest, must be blocked |
| 60 | * @regs: task_pt_regs() of @task |
| 61 | * |
| 62 | * Returns 0 if the system call succeeded, or -ERRORCODE if it failed. |
| 63 | * |
| 64 | * It's only valid to call this when @task is stopped for tracing on exit |
| 65 | * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT. |
| 66 | */ |
| 67 | long syscall_get_error(struct task_struct *task, struct pt_regs *regs); |
| 68 | |
| 69 | /** |
| 70 | * syscall_get_return_value - get the return value of a traced system call |
| 71 | * @task: task of interest, must be blocked |
| 72 | * @regs: task_pt_regs() of @task |
| 73 | * |
| 74 | * Returns the return value of the successful system call. |
| 75 | * This value is meaningless if syscall_get_error() returned nonzero. |
| 76 | * |
| 77 | * It's only valid to call this when @task is stopped for tracing on exit |
| 78 | * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT. |
| 79 | */ |
| 80 | long syscall_get_return_value(struct task_struct *task, struct pt_regs *regs); |
| 81 | |
| 82 | /** |
| 83 | * syscall_set_return_value - change the return value of a traced system call |
| 84 | * @task: task of interest, must be blocked |
| 85 | * @regs: task_pt_regs() of @task |
| 86 | * @error: negative error code, or zero to indicate success |
| 87 | * @val: user return value if @error is zero |
| 88 | * |
| 89 | * This changes the results of the system call that user mode will see. |
| 90 | * If @error is zero, the user sees a successful system call with a |
| 91 | * return value of @val. If @error is nonzero, it's a negated errno |
| 92 | * code; the user sees a failed system call with this errno code. |
| 93 | * |
| 94 | * It's only valid to call this when @task is stopped for tracing on exit |
| 95 | * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT. |
| 96 | */ |
| 97 | void syscall_set_return_value(struct task_struct *task, struct pt_regs *regs, |
| 98 | int error, long val); |
| 99 | |
| 100 | /** |
| 101 | * syscall_get_arguments - extract system call parameter values |
| 102 | * @task: task of interest, must be blocked |
| 103 | * @regs: task_pt_regs() of @task |
| 104 | * @i: argument index [0,5] |
| 105 | * @n: number of arguments; n+i must be [1,6]. |
| 106 | * @args: array filled with argument values |
| 107 | * |
| 108 | * Fetches @n arguments to the system call starting with the @i'th argument |
| 109 | * (from 0 through 5). Argument @i is stored in @args[0], and so on. |
| 110 | * An arch inline version is probably optimal when @i and @n are constants. |
| 111 | * |
| 112 | * It's only valid to call this when @task is stopped for tracing on |
| 113 | * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT. |
| 114 | * It's invalid to call this with @i + @n > 6; we only support system calls |
| 115 | * taking up to 6 arguments. |
| 116 | */ |
| 117 | void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs, |
| 118 | unsigned int i, unsigned int n, unsigned long *args); |
| 119 | |
| 120 | /** |
| 121 | * syscall_set_arguments - change system call parameter value |
| 122 | * @task: task of interest, must be in system call entry tracing |
| 123 | * @regs: task_pt_regs() of @task |
| 124 | * @i: argument index [0,5] |
| 125 | * @n: number of arguments; n+i must be [1,6]. |
| 126 | * @args: array of argument values to store |
| 127 | * |
| 128 | * Changes @n arguments to the system call starting with the @i'th argument. |
| 129 | * @n'th argument to @val. Argument @i gets value @args[0], and so on. |
| 130 | * An arch inline version is probably optimal when @i and @n are constants. |
| 131 | * |
| 132 | * It's only valid to call this when @task is stopped for tracing on |
| 133 | * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT. |
| 134 | * It's invalid to call this with @i + @n > 6; we only support system calls |
| 135 | * taking up to 6 arguments. |
| 136 | */ |
| 137 | void syscall_set_arguments(struct task_struct *task, struct pt_regs *regs, |
| 138 | unsigned int i, unsigned int n, |
| 139 | const unsigned long *args); |
| 140 | |
| 141 | #endif /* _ASM_SYSCALL_H */ |