process.c

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

#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <signal.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/ptrace.h>
#include <sys/wait.h>
#include <asm/unistd.h>
#include <init.h>
#include <longjmp.h>
#include <os.h>
#include <skas_ptrace.h>

#define ARBITRARY_ADDR -1
#define FAILURE_PID    -1

#define STAT_PATH_LEN sizeof("/proc/#######/stat\0")
#define COMM_SCANF "%*[^)])"

unsigned long os_process_pc(int pid)
{
    char proc_stat[STAT_PATH_LEN], buf[256];
    unsigned long pc = ARBITRARY_ADDR;
    int fd, err;

    sprintf(proc_stat, "/proc/%d/stat", pid);
    fd = open(proc_stat, O_RDONLY, 0);
    if (fd < 0) {
        printk(UM_KERN_ERR "os_process_pc - couldn't open '%s', "
               "errno = %d\n", proc_stat, errno);
        goto out;
    }
    CATCH_EINTR(err = read(fd, buf, sizeof(buf)));
    if (err < 0) {
        printk(UM_KERN_ERR "os_process_pc - couldn't read '%s', "
               "err = %d\n", proc_stat, errno);
        goto out_close;
    }
    os_close_file(fd);
    pc = ARBITRARY_ADDR;
    if (sscanf(buf, "%*d " COMM_SCANF " %*c %*d %*d %*d %*d %*d %*d %*d "
           "%*d %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d "
           "%*d %*d %*d %*d %*d %lu", &pc) != 1)
        printk(UM_KERN_ERR "os_process_pc - couldn't find pc in '%s'\n",
               buf);
 out_close:
    close(fd);
 out:
    return pc;
}

int os_process_parent(int pid)
{
    char stat[STAT_PATH_LEN];
    char data[256];
    int parent = FAILURE_PID, n, fd;

    if (pid == -1)
        return parent;

    snprintf(stat, sizeof(stat), "/proc/%d/stat", pid);
    fd = open(stat, O_RDONLY, 0);
    if (fd < 0) {
        printk(UM_KERN_ERR "Couldn't open '%s', errno = %d\n", stat,
               errno);
        return parent;
    }

    CATCH_EINTR(n = read(fd, data, sizeof(data)));
    close(fd);

    if (n < 0) {
        printk(UM_KERN_ERR "Couldn't read '%s', errno = %d\n", stat,
               errno);
        return parent;
    }

    parent = FAILURE_PID;
    n = sscanf(data, "%*d " COMM_SCANF " %*c %d", &parent);
    if (n != 1)
        printk(UM_KERN_ERR "Failed to scan '%s'\n", data);

    return parent;
}

void os_stop_process(int pid)
{
    kill(pid, SIGSTOP);
}

void os_kill_process(int pid, int reap_child)
{
    kill(pid, SIGKILL);
    if (reap_child)
        CATCH_EINTR(waitpid(pid, NULL, __WALL));
}

/* This is here uniquely to have access to the userspace errno, i.e. the one
 * used by ptrace in case of error.
 */

long os_ptrace_ldt(long pid, long addr, long data)
{
    int ret;

    ret = ptrace(PTRACE_LDT, pid, addr, data);

    if (ret < 0)
        return -errno;
    return ret;
}

/* Kill off a ptraced child by all means available.  kill it normally first,
 * then PTRACE_KILL it, then PTRACE_CONT it in case it's in a run state from
 * which it can't exit directly.
 */

void os_kill_ptraced_process(int pid, int reap_child)
{
    kill(pid, SIGKILL);
    ptrace(PTRACE_KILL, pid);
    ptrace(PTRACE_CONT, pid);
    if (reap_child)
        CATCH_EINTR(waitpid(pid, NULL, __WALL));
}

/* Don't use the glibc version, which caches the result in TLS. It misses some
 * syscalls, and also breaks with clone(), which does not unshare the TLS.
 */

int os_getpid(void)
{
    return syscall(__NR_getpid);
}

int os_getpgrp(void)
{
    return getpgrp();
}

int os_map_memory(void *virt, int fd, unsigned long long off, unsigned long len,
          int r, int w, int x)
{
    void *loc;
    int prot;

    prot = (r ? PROT_READ : 0) | (w ? PROT_WRITE : 0) |
        (x ? PROT_EXEC : 0);

    loc = mmap64((void *) virt, len, prot, MAP_SHARED | MAP_FIXED,
             fd, off);
    if (loc == MAP_FAILED)
        return -errno;
    return 0;
}

int os_protect_memory(void *addr, unsigned long len, int r, int w, int x)
{
    int prot = ((r ? PROT_READ : 0) | (w ? PROT_WRITE : 0) |
            (x ? PROT_EXEC : 0));

    if (mprotect(addr, len, prot) < 0)
        return -errno;

    return 0;
}

int os_unmap_memory(void *addr, int len)
{
    int err;

    err = munmap(addr, len);
    if (err < 0)
        return -errno;
    return 0;
}

#ifndef MADV_REMOVE
#define MADV_REMOVE KERNEL_MADV_REMOVE
#endif

int os_drop_memory(void *addr, int length)
{
    int err;

    err = madvise(addr, length, MADV_REMOVE);
    if (err < 0)
        err = -errno;
    return err;
}

int __init can_drop_memory(void)
{
    void *addr;
    int fd, ok = 0;

    printk(UM_KERN_INFO "Checking host MADV_REMOVE support...");
    fd = create_mem_file(UM_KERN_PAGE_SIZE);
    if (fd < 0) {
        printk(UM_KERN_ERR "Creating test memory file failed, "
               "err = %d\n", -fd);
        goto out;
    }

    addr = mmap64(NULL, UM_KERN_PAGE_SIZE, PROT_READ | PROT_WRITE,
              MAP_SHARED, fd, 0);
    if (addr == MAP_FAILED) {
        printk(UM_KERN_ERR "Mapping test memory file failed, "
               "err = %d\n", -errno);
        goto out_close;
    }

    if (madvise(addr, UM_KERN_PAGE_SIZE, MADV_REMOVE) != 0) {
        printk(UM_KERN_ERR "MADV_REMOVE failed, err = %d\n", -errno);
        goto out_unmap;
    }

    printk(UM_KERN_CONT "OK\n");
    ok = 1;

out_unmap:
    munmap(addr, UM_KERN_PAGE_SIZE);
out_close:
    close(fd);
out:
    return ok;
}

void init_new_thread_signals(void)
{
    set_handler(SIGSEGV);
    set_handler(SIGTRAP);
    set_handler(SIGFPE);
    set_handler(SIGILL);
    set_handler(SIGBUS);
    signal(SIGHUP, SIG_IGN);
    set_handler(SIGIO);
    signal(SIGWINCH, SIG_IGN);
    signal(SIGTERM, SIG_DFL);
}