syscall.c

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/*
 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Licensed under the GPL
 */

#include <linux/kernel.h>
#include <linux/ptrace.h>
#include <kern_util.h>
#include <sysdep/ptrace.h>
#include <sysdep/syscalls.h>

extern int syscall_table_size;
#define NR_SYSCALLS (syscall_table_size / sizeof(void *))

void handle_syscall(struct uml_pt_regs *r)
{
    struct pt_regs *regs = container_of(r, struct pt_regs, regs);
    long result;
    int syscall;

    syscall_trace_enter(regs);

    /*
     * This should go in the declaration of syscall, but when I do that,
     * strace -f -c bash -c 'ls ; ls' breaks, sometimes not tracing
     * children at all, sometimes hanging when bash doesn't see the first
     * ls exit.
     * The assembly looks functionally the same to me.  This is
     *     gcc version 4.0.1 20050727 (Red Hat 4.0.1-5)
     * in case it's a compiler bug.
     */
    syscall = UPT_SYSCALL_NR(r);
    if ((syscall >= NR_SYSCALLS) || (syscall < 0))
        result = -ENOSYS;
    else result = EXECUTE_SYSCALL(syscall, regs);

    PT_REGS_SET_SYSCALL_RETURN(regs, result);

    syscall_trace_leave(regs);
}