arch/x86/include/asm/syscall.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * Access to user system call parameters and results
   4  *
   5  * Copyright (C) 2008-2009 Red Hat, Inc.  All rights reserved.
   6  *
   7  * See asm-generic/syscall.h for descriptions of what we must do here.
   8  */
   9
  10 #ifndef _ASM_X86_SYSCALL_H
  11 #define _ASM_X86_SYSCALL_H
  12
  13 #include <uapi/linux/audit.h>
  14 #include <linux/sched.h>
  15 #include <linux/err.h>
  16 #include <asm/asm-offsets.h>    /* For NR_syscalls */
  17 #include <asm/thread_info.h>    /* for TS_COMPAT */
  18 #include <asm/unistd.h>
  19
  20 #ifdef CONFIG_X86_64
  21 typedef asmlinkage long (*sys_call_ptr_t)(const struct pt_regs *);
  22 #else
  23 typedef asmlinkage long (*sys_call_ptr_t)(unsigned long, unsigned long,
  24                                           unsigned long, unsigned long,
  25                                           unsigned long, unsigned long);
  26 #endif /* CONFIG_X86_64 */
  27 extern const sys_call_ptr_t sys_call_table[];
  28
  29 #if defined(CONFIG_X86_32)
  30 #define ia32_sys_call_table sys_call_table
  31 #define __NR_syscall_compat_max __NR_syscall_max
  32 #define IA32_NR_syscalls NR_syscalls
  33 #endif
  34
  35 #if defined(CONFIG_IA32_EMULATION)
  36 extern const sys_call_ptr_t ia32_sys_call_table[];
  37 #endif
  38
  39 #ifdef CONFIG_X86_X32_ABI
  40 extern const sys_call_ptr_t x32_sys_call_table[];
  41 #endif
  42
  43 /*
  44  * Only the low 32 bits of orig_ax are meaningful, so we return int.
  45  * This importantly ignores the high bits on 64-bit, so comparisons
  46  * sign-extend the low 32 bits.
  47  */
  48 static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
  49 {
  50         return regs->orig_ax;
  51 }
  52
  53 static inline void syscall_rollback(struct task_struct *task,
  54                                     struct pt_regs *regs)
  55 {
  56         regs->ax = regs->orig_ax;
  57 }
  58
  59 static inline long syscall_get_error(struct task_struct *task,
  60                                      struct pt_regs *regs)
  61 {
  62         unsigned long error = regs->ax;
  63 #ifdef CONFIG_IA32_EMULATION
  64         /*
  65          * TS_COMPAT is set for 32-bit syscall entries and then
  66          * remains set until we return to user mode.
  67          */
  68         if (task->thread_info.status & (TS_COMPAT|TS_I386_REGS_POKED))
  69                 /*
  70                  * Sign-extend the value so (int)-EFOO becomes (long)-EFOO
  71                  * and will match correctly in comparisons.
  72                  */
  73                 error = (long) (int) error;
  74 #endif
  75         return IS_ERR_VALUE(error) ? error : 0;
  76 }
  77
  78 static inline long syscall_get_return_value(struct task_struct *task,
  79                                             struct pt_regs *regs)
  80 {
  81         return regs->ax;
  82 }
  83
  84 static inline void syscall_set_return_value(struct task_struct *task,
  85                                             struct pt_regs *regs,
  86                                             int error, long val)
  87 {
  88         regs->ax = (long) error ?: val;
  89 }
  90
  91 #ifdef CONFIG_X86_32
  92
  93 static inline void syscall_get_arguments(struct task_struct *task,
  94                                          struct pt_regs *regs,
  95                                          unsigned long *args)
  96 {
  97         memcpy(args, &regs->bx, 6 * sizeof(args[0]));
  98 }
  99
 100 static inline void syscall_set_arguments(struct task_struct *task,
 101                                          struct pt_regs *regs,
 102                                          unsigned int i, unsigned int n,
 103                                          const unsigned long *args)
 104 {
 105         BUG_ON(i + n > 6);
 106         memcpy(&regs->bx + i, args, n * sizeof(args[0]));
 107 }
 108
 109 static inline int syscall_get_arch(struct task_struct *task)
 110 {
 111         return AUDIT_ARCH_I386;
 112 }
 113
 114 #else    /* CONFIG_X86_64 */
 115
 116 static inline void syscall_get_arguments(struct task_struct *task,
 117                                          struct pt_regs *regs,
 118                                          unsigned long *args)
 119 {
 120 # ifdef CONFIG_IA32_EMULATION
 121         if (task->thread_info.status & TS_COMPAT) {
 122                 *args++ = regs->bx;
 123                 *args++ = regs->cx;
 124                 *args++ = regs->dx;
 125                 *args++ = regs->si;
 126                 *args++ = regs->di;
 127                 *args   = regs->bp;
 128         } else
 129 # endif
 130         {
 131                 *args++ = regs->di;
 132                 *args++ = regs->si;
 133                 *args++ = regs->dx;
 134                 *args++ = regs->r10;
 135                 *args++ = regs->r8;
 136                 *args   = regs->r9;
 137         }
 138 }
 139
 140 static inline void syscall_set_arguments(struct task_struct *task,
 141                                          struct pt_regs *regs,
 142                                          const unsigned long *args)
 143 {
 144 # ifdef CONFIG_IA32_EMULATION
 145         if (task->thread_info.status & TS_COMPAT) {
 146                 regs->bx = *args++;
 147                 regs->cx = *args++;
 148                 regs->dx = *args++;
 149                 regs->si = *args++;
 150                 regs->di = *args++;
 151                 regs->bp = *args;
 152         } else
 153 # endif
 154         {
 155                 regs->di = *args++;
 156                 regs->si = *args++;
 157                 regs->dx = *args++;
 158                 regs->r10 = *args++;
 159                 regs->r8 = *args++;
 160                 regs->r9 = *args;
 161         }
 162 }
 163
 164 static inline int syscall_get_arch(struct task_struct *task)
 165 {
 166         /* x32 tasks should be considered AUDIT_ARCH_X86_64. */
 167         return (IS_ENABLED(CONFIG_IA32_EMULATION) &&
 168                 task->thread_info.status & TS_COMPAT)
 169                 ? AUDIT_ARCH_I386 : AUDIT_ARCH_X86_64;
 170 }
 171 #endif  /* CONFIG_X86_32 */
 172
 173 #endif  /* _ASM_X86_SYSCALL_H */