/* * Access to user system call parameters and results * * Copyright (C) 2008-2009 Red Hat, Inc. All rights reserved. * * 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. * * 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. * * It's only valid to call this when @task is known to be blocked. */ int syscall_get_nr(struct task_struct *task, struct pt_regs *regs); /** * 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. * Argument @i gets value @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_set_arguments(struct task_struct *task, struct pt_regs *regs, unsigned int i, unsigned int n, const unsigned long *args); /** * syscall_get_arch - return the AUDIT_ARCH for the current system call * * Returns the AUDIT_ARCH_* based on the system call convention in use. * * It's only valid to call this when current is stopped on entry to a system * 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. */ int syscall_get_arch(void); #endif /* _ASM_SYSCALL_H */