LXR linux/arch/nds32/include/asm/syscall.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2// Copyright (C) 2008-2009 Red Hat, Inc.  All rights reserved.
   3// Copyright (C) 2005-2017 Andes Technology Corporation
   4
   5#ifndef _ASM_NDS32_SYSCALL_H
   6#define _ASM_NDS32_SYSCALL_H    1
   7
   8#include <uapi/linux/audit.h>
   9#include <linux/err.h>
  10struct task_struct;
  11struct pt_regs;
  12
  13/**
  14 * syscall_get_nr - find what system call a task is executing
  15 * @task:       task of interest, must be blocked
  16 * @regs:       task_pt_regs() of @task
  17 *
  18 * If @task is executing a system call or is at system call
  19 * tracing about to attempt one, returns the system call number.
  20 * If @task is not executing a system call, i.e. it's blocked
  21 * inside the kernel for a fault or signal, returns -1.
  22 *
  23 * Note this returns int even on 64-bit machines.  Only 32 bits of
  24 * system call number can be meaningful.  If the actual arch value
  25 * is 64 bits, this truncates to 32 bits so 0xffffffff means -1.
  26 *
  27 * It's only valid to call this when @task is known to be blocked.
  28 */
  29static inline int
  30syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
  31{
  32        return regs->syscallno;
  33}
  34
  35/**
  36 * syscall_rollback - roll back registers after an aborted system call
  37 * @task:       task of interest, must be in system call exit tracing
  38 * @regs:       task_pt_regs() of @task
  39 *
  40 * It's only valid to call this when @task is stopped for system
  41 * call exit tracing (due to TIF_SYSCALL_TRACE or TIF_SYSCALL_AUDIT),
  42 * after tracehook_report_syscall_entry() returned nonzero to prevent
  43 * the system call from taking place.
  44 *
  45 * This rolls back the register state in @regs so it's as if the
  46 * system call instruction was a no-op.  The registers containing
  47 * the system call number and arguments are as they were before the
  48 * system call instruction.  This may not be the same as what the
  49 * register state looked like at system call entry tracing.
  50 */
  51static inline void
  52syscall_rollback(struct task_struct *task, struct pt_regs *regs)
  53{
  54        regs->uregs[0] = regs->orig_r0;
  55}
  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 */
  67static inline long
  68syscall_get_error(struct task_struct *task, struct pt_regs *regs)
  69{
  70        unsigned long error = regs->uregs[0];
  71        return IS_ERR_VALUE(error) ? error : 0;
  72}
  73
  74/**
  75 * syscall_get_return_value - get the return value of a traced system call
  76 * @task:       task of interest, must be blocked
  77 * @regs:       task_pt_regs() of @task
  78 *
  79 * Returns the return value of the successful system call.
  80 * This value is meaningless if syscall_get_error() returned nonzero.
  81 *
  82 * It's only valid to call this when @task is stopped for tracing on exit
  83 * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
  84 */
  85static inline long
  86syscall_get_return_value(struct task_struct *task, struct pt_regs *regs)
  87{
  88        return regs->uregs[0];
  89}
  90
  91/**
  92 * syscall_set_return_value - change the return value of a traced system call
  93 * @task:       task of interest, must be blocked
  94 * @regs:       task_pt_regs() of @task
  95 * @error:      negative error code, or zero to indicate success
  96 * @val:        user return value if @error is zero
  97 *
  98 * This changes the results of the system call that user mode will see.
  99 * If @error is zero, the user sees a successful system call with a
 100 * return value of @val.  If @error is nonzero, it's a negated errno
 101 * code; the user sees a failed system call with this errno code.
 102 *
 103 * It's only valid to call this when @task is stopped for tracing on exit
 104 * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
 105 */
 106static inline void
 107syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
 108                         int error, long val)
 109{
 110        regs->uregs[0] = (long)error ? error : val;
 111}
 112
 113/**
 114 * syscall_get_arguments - extract system call parameter values
 115 * @task:       task of interest, must be blocked
 116 * @regs:       task_pt_regs() of @task
 117 * @args:       array filled with argument values
 118 *
 119 * Fetches 6 arguments to the system call (from 0 through 5). The first
 120 * argument is stored in @args[0], and so on.
 121 *
 122 * It's only valid to call this when @task is stopped for tracing on
 123 * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
 124 */
 125#define SYSCALL_MAX_ARGS 6
 126static inline void
 127syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
 128                      unsigned long *args)
 129{
 130        args[0] = regs->orig_r0;
 131        args++;
 132        memcpy(args, &regs->uregs[0] + 1, 5 * sizeof(args[0]));
 133}
 134
 135static inline int
 136syscall_get_arch(struct task_struct *task)
 137{
 138        return IS_ENABLED(CONFIG_CPU_BIG_ENDIAN)
 139                ? AUDIT_ARCH_NDS32BE : AUDIT_ARCH_NDS32;
 140}
 141
 142#endif /* _ASM_NDS32_SYSCALL_H */
 143