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1/* SPDX-License-Identifier: GPL-2.0-only */2/*3 * Access to user system call parameters and results4 *5 * Copyright (C) 2008-2009 Red Hat, Inc. All rights reserved.6 *7 * This file is a stub providing documentation for what functions8 * asm-ARCH/syscall.h files need to define. Most arch definitions9 * 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 interest13 * cannot return to user mode while we are looking at it.14 */15 16#ifndef _ASM_SYSCALL_H17#define _ASM_SYSCALL_H 118 19struct task_struct;20struct pt_regs;21 22/**23 * syscall_get_nr - find what system call a task is executing24 * @task: task of interest, must be blocked25 * @regs: task_pt_regs() of @task26 *27 * If @task is executing a system call or is at system call28 * tracing about to attempt one, returns the system call number.29 * If @task is not executing a system call, i.e. it's blocked30 * inside the kernel for a fault or signal, returns -1.31 *32 * Note this returns int even on 64-bit machines. Only 32 bits of33 * system call number can be meaningful. If the actual arch value34 * 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 call42 * @task: task of interest, must be in system call exit tracing43 * @regs: task_pt_regs() of @task44 *45 * It's only valid to call this when @task is stopped for system46 * call exit tracing (due to %SYSCALL_WORK_SYSCALL_TRACE or47 * %SYSCALL_WORK_SYSCALL_AUDIT), after ptrace_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 the51 * system call instruction was a no-op. The registers containing52 * the system call number and arguments are as they were before the53 * system call instruction. This may not be the same as what the54 * 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 call60 * @task: task of interest, must be blocked61 * @regs: task_pt_regs() of @task62 *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 exit66 * from a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or67 * %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 call73 * @task: task of interest, must be blocked74 * @regs: task_pt_regs() of @task75 *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 exit80 * from a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or81 * %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 call87 * @task: task of interest, must be blocked88 * @regs: task_pt_regs() of @task89 * @error: negative error code, or zero to indicate success90 * @val: user return value if @error is zero91 *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 a94 * return value of @val. If @error is nonzero, it's a negated errno95 * 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 exit98 * from a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or99 * %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 values106 * @task: task of interest, must be blocked107 * @regs: task_pt_regs() of @task108 * @args: array filled with argument values109 *110 * Fetches 6 arguments to the system call. First argument is stored in111* @args[0], and so on.112 *113 * It's only valid to call this when @task is stopped for tracing on114 * entry to a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or115 * %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 call122 * @task: task of interest, must be blocked123 *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 system127 * call, due to %SYSCALL_WORK_SYSCALL_TRACE, %SYSCALL_WORK_SYSCALL_AUDIT, or128 * %SYSCALL_WORK_SECCOMP.129 *130 * Architectures which permit CONFIG_HAVE_ARCH_SECCOMP_FILTER must131 * provide an implementation of this.132 */133int syscall_get_arch(struct task_struct *task);134#endif /* _ASM_SYSCALL_H */135