// SPDX-License-Identifier: GPL-2.0

  /*

   * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)

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

   */

  #include <stdio.h>

  #include <stdlib.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>

  
  #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
  ", 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
  ", 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'
  ",
  		       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
  ", 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
  ", 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'
  ", data);

  	return parent;

  }

  void os_alarm_process(int pid)
  {
  	kill(pid, SIGALRM);
  }

  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));

  }
  
  /* 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
  ", -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
  ", -errno);

  		goto out_close;

  	}

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

  		goto out_unmap;

  	}

  	printk(UM_KERN_CONT "OK
  ");

  	ok = 1;
  
  out_unmap:
  	munmap(addr, UM_KERN_PAGE_SIZE);
  out_close:
  	close(fd);
  out:
  	return ok;

  }

  static int os_page_mincore(void *addr)
  {
  	char vec[2];
  	int ret;
  
  	ret = mincore(addr, UM_KERN_PAGE_SIZE, vec);
  	if (ret < 0) {
  		if (errno == ENOMEM || errno == EINVAL)
  			return 0;
  		else
  			return -errno;
  	}
  
  	return vec[0] & 1;
  }
  
  int os_mincore(void *addr, unsigned long len)
  {
  	char *vec;
  	int ret, i;
  
  	if (len <= UM_KERN_PAGE_SIZE)
  		return os_page_mincore(addr);
  
  	vec = calloc(1, (len + UM_KERN_PAGE_SIZE - 1) / UM_KERN_PAGE_SIZE);
  	if (!vec)
  		return -ENOMEM;
  
  	ret = mincore(addr, UM_KERN_PAGE_SIZE, vec);
  	if (ret < 0) {
  		if (errno == ENOMEM || errno == EINVAL)
  			ret = 0;
  		else
  			ret = -errno;
  
  		goto out;
  	}
  
  	for (i = 0; i < ((len + UM_KERN_PAGE_SIZE - 1) / UM_KERN_PAGE_SIZE); i++) {
  		if (!(vec[i] & 1)) {
  			ret = 0;
  			goto out;
  		}
  	}
  
  	ret = 1;
  out:
  	free(vec);
  	return ret;
  }

  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);

  }