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>
  10 struct task_struct;
  11 struct 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  */
  29 static inline int
  30 syscall_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  */
  51 static inline void
  52 syscall_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  */
  67 static inline long
  68 syscall_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  */
  85 static inline long
  86 syscall_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  */
 106 static inline void
 107 syscall_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
 126 static inline void
 127 syscall_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
 135 /**
 136  * syscall_set_arguments - change system call parameter value
 137  * @task:       task of interest, must be in system call entry tracing
 138  * @regs:       task_pt_regs() of @task
 139  * @args:       array of argument values to store
 140  *
 141  * Changes 6 arguments to the system call. The first argument gets value
 142  * @args[0], and so on.
 143  *
 144  * It's only valid to call this when @task is stopped for tracing on
 145  * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
 146  */
 147 static inline void
 148 syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
 149                       const unsigned long *args)
 150 {
 151         regs->orig_r0 = args[0];
 152         args++;
 153
 154         memcpy(&regs->uregs[0] + 1, args, 5 * sizeof(args[0]));
 155 }
 156
 157 static inline int
 158 syscall_get_arch(struct task_struct *task)
 159 {
 160         return IS_ENABLED(CONFIG_CPU_BIG_ENDIAN)
 161                 ? AUDIT_ARCH_NDS32BE : AUDIT_ARCH_NDS32;
 162 }
 163
 164 #endif /* _ASM_NDS32_SYSCALL_H */