/arch/x86/include/asm/syscall.h

  1/*
  2 * Access to user system call parameters and results
  3 *
  4 * Copyright (C) 2008-2009 Red Hat, Inc.  All rights reserved.
  5 *
  6 * This copyrighted material is made available to anyone wishing to use,
  7 * modify, copy, or redistribute it subject to the terms and conditions
  8 * of the GNU General Public License v.2.
  9 *
 10 * See asm-generic/syscall.h for descriptions of what we must do here.
 11 */
 12
 13#ifndef _ASM_X86_SYSCALL_H
 14#define _ASM_X86_SYSCALL_H
 15
 16#include <linux/sched.h>
 17#include <linux/err.h>
 18
 19extern const unsigned long sys_call_table[];
 20
 21/*
 22 * Only the low 32 bits of orig_ax are meaningful, so we return int.
 23 * This importantly ignores the high bits on 64-bit, so comparisons
 24 * sign-extend the low 32 bits.
 25 */
 26static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
 27{
 28	return regs->orig_ax;
 29}
 30
 31static inline void syscall_rollback(struct task_struct *task,
 32				    struct pt_regs *regs)
 33{
 34	regs->ax = regs->orig_ax;
 35}
 36
 37static inline long syscall_get_error(struct task_struct *task,
 38				     struct pt_regs *regs)
 39{
 40	unsigned long error = regs->ax;
 41#ifdef CONFIG_IA32_EMULATION
 42	/*
 43	 * TS_COMPAT is set for 32-bit syscall entries and then
 44	 * remains set until we return to user mode.
 45	 */
 46	if (task_thread_info(task)->status & TS_COMPAT)
 47		/*
 48		 * Sign-extend the value so (int)-EFOO becomes (long)-EFOO
 49		 * and will match correctly in comparisons.
 50		 */
 51		error = (long) (int) error;
 52#endif
 53	return IS_ERR_VALUE(error) ? error : 0;
 54}
 55
 56static inline long syscall_get_return_value(struct task_struct *task,
 57					    struct pt_regs *regs)
 58{
 59	return regs->ax;
 60}
 61
 62static inline void syscall_set_return_value(struct task_struct *task,
 63					    struct pt_regs *regs,
 64					    int error, long val)
 65{
 66	regs->ax = (long) error ?: val;
 67}
 68
 69#ifdef CONFIG_X86_32
 70
 71static inline void syscall_get_arguments(struct task_struct *task,
 72					 struct pt_regs *regs,
 73					 unsigned int i, unsigned int n,
 74					 unsigned long *args)
 75{
 76	BUG_ON(i + n > 6);
 77	memcpy(args, &regs->bx + i, n * sizeof(args[0]));
 78}
 79
 80static inline void syscall_set_arguments(struct task_struct *task,
 81					 struct pt_regs *regs,
 82					 unsigned int i, unsigned int n,
 83					 const unsigned long *args)
 84{
 85	BUG_ON(i + n > 6);
 86	memcpy(&regs->bx + i, args, n * sizeof(args[0]));
 87}
 88
 89#else	 /* CONFIG_X86_64 */
 90
 91static inline void syscall_get_arguments(struct task_struct *task,
 92					 struct pt_regs *regs,
 93					 unsigned int i, unsigned int n,
 94					 unsigned long *args)
 95{
 96# ifdef CONFIG_IA32_EMULATION
 97	if (task_thread_info(task)->status & TS_COMPAT)
 98		switch (i) {
 99		case 0:
100			if (!n--) break;
101			*args++ = regs->bx;
102		case 1:
103			if (!n--) break;
104			*args++ = regs->cx;
105		case 2:
106			if (!n--) break;
107			*args++ = regs->dx;
108		case 3:
109			if (!n--) break;
110			*args++ = regs->si;
111		case 4:
112			if (!n--) break;
113			*args++ = regs->di;
114		case 5:
115			if (!n--) break;
116			*args++ = regs->bp;
117		case 6:
118			if (!n--) break;
119		default:
120			BUG();
121			break;
122		}
123	else
124# endif
125		switch (i) {
126		case 0:
127			if (!n--) break;
128			*args++ = regs->di;
129		case 1:
130			if (!n--) break;
131			*args++ = regs->si;
132		case 2:
133			if (!n--) break;
134			*args++ = regs->dx;
135		case 3:
136			if (!n--) break;
137			*args++ = regs->r10;
138		case 4:
139			if (!n--) break;
140			*args++ = regs->r8;
141		case 5:
142			if (!n--) break;
143			*args++ = regs->r9;
144		case 6:
145			if (!n--) break;
146		default:
147			BUG();
148			break;
149		}
150}
151
152static inline void syscall_set_arguments(struct task_struct *task,
153					 struct pt_regs *regs,
154					 unsigned int i, unsigned int n,
155					 const unsigned long *args)
156{
157# ifdef CONFIG_IA32_EMULATION
158	if (task_thread_info(task)->status & TS_COMPAT)
159		switch (i) {
160		case 0:
161			if (!n--) break;
162			regs->bx = *args++;
163		case 1:
164			if (!n--) break;
165			regs->cx = *args++;
166		case 2:
167			if (!n--) break;
168			regs->dx = *args++;
169		case 3:
170			if (!n--) break;
171			regs->si = *args++;
172		case 4:
173			if (!n--) break;
174			regs->di = *args++;
175		case 5:
176			if (!n--) break;
177			regs->bp = *args++;
178		case 6:
179			if (!n--) break;
180		default:
181			BUG();
182			break;
183		}
184	else
185# endif
186		switch (i) {
187		case 0:
188			if (!n--) break;
189			regs->di = *args++;
190		case 1:
191			if (!n--) break;
192			regs->si = *args++;
193		case 2:
194			if (!n--) break;
195			regs->dx = *args++;
196		case 3:
197			if (!n--) break;
198			regs->r10 = *args++;
199		case 4:
200			if (!n--) break;
201			regs->r8 = *args++;
202		case 5:
203			if (!n--) break;
204			regs->r9 = *args++;
205		case 6:
206			if (!n--) break;
207		default:
208			BUG();
209			break;
210		}
211}
212
213#endif	/* CONFIG_X86_32 */
214
215#endif	/* _ASM_X86_SYSCALL_H */