syscall.h

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/*
 * Access to user system call parameters and results
 *
 * Copyright (C) 2008-2009 Red Hat, Inc.  All rights reserved.
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU General Public License v.2.
 *
 * See asm-generic/syscall.h for descriptions of what we must do here.
 */

#ifndef _ASM_X86_SYSCALL_H
#define _ASM_X86_SYSCALL_H

#include <linux/audit.h>
#include <linux/sched.h>
#include <linux/err.h>
#include <asm/asm-offsets.h>    /* For NR_syscalls */
#include <asm/thread_info.h>    /* for TS_COMPAT */
#include <asm/unistd.h>

extern const unsigned long sys_call_table[];

/*
 * Only the low 32 bits of orig_ax are meaningful, so we return int.
 * This importantly ignores the high bits on 64-bit, so comparisons
 * sign-extend the low 32 bits.
 */
static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
{
    return regs->orig_ax & __SYSCALL_MASK;
}

static inline void syscall_rollback(struct task_struct *task,
                    struct pt_regs *regs)
{
    regs->ax = regs->orig_ax & __SYSCALL_MASK;
}

static inline long syscall_get_error(struct task_struct *task,
                     struct pt_regs *regs)
{
    unsigned long error = regs->ax;
#ifdef CONFIG_IA32_EMULATION
    /*
     * TS_COMPAT is set for 32-bit syscall entries and then
     * remains set until we return to user mode.
     */
    if (task_thread_info(task)->status & TS_COMPAT)
        /*
         * Sign-extend the value so (int)-EFOO becomes (long)-EFOO
         * and will match correctly in comparisons.
         */
        error = (long) (int) error;
#endif
    return IS_ERR_VALUE(error) ? error : 0;
}

static inline long syscall_get_return_value(struct task_struct *task,
                        struct pt_regs *regs)
{
    return regs->ax;
}

static inline void syscall_set_return_value(struct task_struct *task,
                        struct pt_regs *regs,
                        int error, long val)
{
    regs->ax = (long) error ?: val;
}

#ifdef CONFIG_X86_32

static inline void syscall_get_arguments(struct task_struct *task,
                     struct pt_regs *regs,
                     unsigned int i, unsigned int n,
                     unsigned long *args)
{
    BUG_ON(i + n > 6);
    memcpy(args, &regs->bx + i, n * sizeof(args[0]));
}

static inline void syscall_set_arguments(struct task_struct *task,
                     struct pt_regs *regs,
                     unsigned int i, unsigned int n,
                     const unsigned long *args)
{
    BUG_ON(i + n > 6);
    memcpy(&regs->bx + i, args, n * sizeof(args[0]));
}

static inline int syscall_get_arch(struct task_struct *task,
                   struct pt_regs *regs)
{
    return AUDIT_ARCH_I386;
}

#else    /* CONFIG_X86_64 */

static inline void syscall_get_arguments(struct task_struct *task,
                     struct pt_regs *regs,
                     unsigned int i, unsigned int n,
                     unsigned long *args)
{
# ifdef CONFIG_IA32_EMULATION
    if (task_thread_info(task)->status & TS_COMPAT)
        switch (i) {
        case 0:
            if (!n--) break;
            *args++ = regs->bx;
        case 1:
            if (!n--) break;
            *args++ = regs->cx;
        case 2:
            if (!n--) break;
            *args++ = regs->dx;
        case 3:
            if (!n--) break;
            *args++ = regs->si;
        case 4:
            if (!n--) break;
            *args++ = regs->di;
        case 5:
            if (!n--) break;
            *args++ = regs->bp;
        case 6:
            if (!n--) break;
        default:
            BUG();
            break;
        }
    else
# endif
        switch (i) {
        case 0:
            if (!n--) break;
            *args++ = regs->di;
        case 1:
            if (!n--) break;
            *args++ = regs->si;
        case 2:
            if (!n--) break;
            *args++ = regs->dx;
        case 3:
            if (!n--) break;
            *args++ = regs->r10;
        case 4:
            if (!n--) break;
            *args++ = regs->r8;
        case 5:
            if (!n--) break;
            *args++ = regs->r9;
        case 6:
            if (!n--) break;
        default:
            BUG();
            break;
        }
}

static inline void syscall_set_arguments(struct task_struct *task,
                     struct pt_regs *regs,
                     unsigned int i, unsigned int n,
                     const unsigned long *args)
{
# ifdef CONFIG_IA32_EMULATION
    if (task_thread_info(task)->status & TS_COMPAT)
        switch (i) {
        case 0:
            if (!n--) break;
            regs->bx = *args++;
        case 1:
            if (!n--) break;
            regs->cx = *args++;
        case 2:
            if (!n--) break;
            regs->dx = *args++;
        case 3:
            if (!n--) break;
            regs->si = *args++;
        case 4:
            if (!n--) break;
            regs->di = *args++;
        case 5:
            if (!n--) break;
            regs->bp = *args++;
        case 6:
            if (!n--) break;
        default:
            BUG();
            break;
        }
    else
# endif
        switch (i) {
        case 0:
            if (!n--) break;
            regs->di = *args++;
        case 1:
            if (!n--) break;
            regs->si = *args++;
        case 2:
            if (!n--) break;
            regs->dx = *args++;
        case 3:
            if (!n--) break;
            regs->r10 = *args++;
        case 4:
            if (!n--) break;
            regs->r8 = *args++;
        case 5:
            if (!n--) break;
            regs->r9 = *args++;
        case 6:
            if (!n--) break;
        default:
            BUG();
            break;
        }
}

static inline int syscall_get_arch(struct task_struct *task,
                   struct pt_regs *regs)
{
#ifdef CONFIG_IA32_EMULATION
    /*
     * TS_COMPAT is set for 32-bit syscall entry and then
     * remains set until we return to user mode.
     *
     * TIF_IA32 tasks should always have TS_COMPAT set at
     * system call time.
     *
     * x32 tasks should be considered AUDIT_ARCH_X86_64.
     */
    if (task_thread_info(task)->status & TS_COMPAT)
        return AUDIT_ARCH_I386;
#endif
    /* Both x32 and x86_64 are considered "64-bit". */
    return AUDIT_ARCH_X86_64;
}
#endif  /* CONFIG_X86_32 */

#endif  /* _ASM_X86_SYSCALL_H */