/*
 * Copyright (C) 2013-2018 Canonical, Ltd.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * This code is a complete clean re-write of the stress tool by
 * Colin Ian King <colin.king@canonical.com> and attempts to be
 * backwardly compatible with the stress tool by Amos Waterland
 * <apw@rossby.metr.ou.edu> but has more stress tests and more
 * functionality.
 *
 */
#include "stress-ng.h"

#if defined(__linux__) &&		\
    defined(__NR_process_vm_readv) &&	\
    defined(__NR_process_vm_writev) &&	\
    NEED_GLIBC(2,15,0) &&		\
    defined(HAVE_CLONE)

#include <sys/uio.h>

#define STACK_SIZE	(64 * 1024)

typedef struct {
	const args_t *args;
	size_t sz;
	pid_t pid;
	int pipe_wr[2];
	int pipe_rd[2];
} context_t;

typedef struct {
	void *addr;	/* Buffer to read/write to */
	uint8_t val;	/* Value to check */
} addr_msg_t;

#endif

void stress_set_vm_rw_bytes(const char *opt)
{
	size_t vm_rw_bytes;

	vm_rw_bytes = (size_t)get_uint64_byte_memory(opt, 1);
	check_range_bytes("vm-rw-bytes", vm_rw_bytes,
		MIN_VM_RW_BYTES, MAX_MEM_LIMIT);
	set_setting("vm-rw-bytes", TYPE_ID_SIZE_T, &vm_rw_bytes);
}

#if defined(__linux__) &&		\
    defined(__NR_process_vm_readv) &&	\
    defined(__NR_process_vm_writev) &&	\
    NEED_GLIBC(2,15,0) &&		\
    defined(HAVE_CLONE)

static int stress_vm_child(void *arg)
{
	const context_t *ctxt = (context_t *)arg;
	const args_t *args = ctxt->args;

	uint8_t *buf;
	int ret = EXIT_SUCCESS;
	addr_msg_t msg_rd, msg_wr;

	(void)setpgid(0, g_pgrp);
	stress_parent_died_alarm();

	/* Close unwanted ends */
	(void)close(ctxt->pipe_wr[0]);
	(void)close(ctxt->pipe_rd[1]);

	buf = mmap(NULL, ctxt->sz, PROT_READ | PROT_WRITE,
		MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
	if (buf == MAP_FAILED) {
		ret = exit_status(errno);
		pr_fail_dbg("mmap");
		goto cleanup;
	}

	while (g_keep_stressing_flag) {
		uint8_t *ptr, *end = buf + ctxt->sz;
		int rwret;

		(void)memset(&msg_wr, 0, sizeof(msg_wr));
		msg_wr.addr = buf;
		msg_wr.val = 0;

		/* Send address of buffer to parent */
redo_wr1:
		rwret = write(ctxt->pipe_wr[1], &msg_wr, sizeof(msg_wr));
		if (rwret < 0) {
			if ((errno == EAGAIN) || (errno == EINTR))
				goto redo_wr1;
			if (errno != EBADF)
				pr_fail_dbg("write");
			break;
		}
redo_rd1:
		/* Wait for parent to populate data */
		rwret = read(ctxt->pipe_rd[0], &msg_rd, sizeof(msg_rd));
		if (rwret < 0) {
			if ((errno == EAGAIN) || (errno == EINTR))
				goto redo_rd1;
			pr_fail_dbg("read");
			break;
		}
		if (rwret == 0)
			break;
		if (rwret != sizeof(msg_rd)) {
			pr_fail_dbg("read");
			break;
		}

		if (g_opt_flags & OPT_FLAGS_VERIFY) {
			/* Check memory altered by parent is sane */
			for (ptr = buf; ptr < end; ptr += args->page_size) {
				if (*ptr != msg_rd.val) {
					pr_fail("%s: memory at %p: %d vs %d\n",
						args->name, ptr, *ptr, msg_rd.val);
					goto cleanup;
				}
				*ptr = 0;
			}
		}
	}
cleanup:
	/* Tell parent we're done */
	msg_wr.addr = 0;
	msg_wr.val = 0;
	if (write(ctxt->pipe_wr[1], &msg_wr, sizeof(msg_wr)) <= 0) {
		if (errno != EBADF)
			pr_dbg("%s: failed to write termination message "
				"over pipe: errno=%d (%s)\n",
				args->name, errno, strerror(errno));
	}

	(void)close(ctxt->pipe_wr[1]);
	(void)close(ctxt->pipe_rd[0]);
	(void)munmap(buf, ctxt->sz);
	return ret;
}

static int stress_vm_parent(context_t *ctxt)
{
	/* Parent */
	int status;
	uint8_t val = 0;
	uint8_t *localbuf;
	addr_msg_t msg_rd, msg_wr;
	const args_t *args = ctxt->args;

	(void)setpgid(ctxt->pid, g_pgrp);

	localbuf = mmap(NULL, ctxt->sz, PROT_READ | PROT_WRITE,
			MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
	if (localbuf == MAP_FAILED) {
		(void)close(ctxt->pipe_wr[0]);
		(void)close(ctxt->pipe_wr[1]);
		(void)close(ctxt->pipe_rd[0]);
		(void)close(ctxt->pipe_rd[1]);
		pr_fail_dbg("mmap");
		return EXIT_FAILURE;
	}

	/* Close unwanted ends */
	(void)close(ctxt->pipe_wr[1]);
	(void)close(ctxt->pipe_rd[0]);

	do {
		struct iovec local[1], remote[1];
		uint8_t *ptr, *end = localbuf + ctxt->sz;
		int ret;

		/* Wait for address of child's buffer */
redo_rd2:
		if (!g_keep_stressing_flag)
			break;
		ret = read(ctxt->pipe_wr[0], &msg_rd, sizeof(msg_rd));
		if (ret < 0) {
			if ((errno == EAGAIN) || (errno == EINTR))
				goto redo_rd2;
			pr_fail_dbg("read");
			break;
		}
		if (ret == 0)
			break;
		if (ret != sizeof(msg_rd)) {
			pr_fail_dbg("read");
			break;
		}
		/* Child telling us it's terminating? */
		if (!msg_rd.addr)
			break;

		/* Perform read from child's memory */
		local[0].iov_base = localbuf;
		local[0].iov_len = ctxt->sz;
		remote[0].iov_base = msg_rd.addr;
		remote[0].iov_len = ctxt->sz;
		if (process_vm_readv(ctxt->pid, local, 1, remote, 1, 0) < 0) {
			pr_fail_dbg("process_vm_readv");
			break;
		}

		if (g_opt_flags & OPT_FLAGS_VERIFY) {
			/* Check data is sane */
			for (ptr = localbuf; ptr < end; ptr += args->page_size) {
				if (*ptr) {
					pr_fail("%s: memory at %p: %d vs %d\n",
						args->name, ptr, *ptr, msg_rd.val);
					goto fail;
				}
				*ptr = 0;
			}
			/* Set memory */
			for (ptr = localbuf; ptr < end; ptr += args->page_size)
				*ptr = val;
		}

		/* Write to child's memory */
		msg_wr = msg_rd;
		local[0].iov_base = localbuf;
		local[0].iov_len = ctxt->sz;
		remote[0].iov_base = msg_rd.addr;
		remote[0].iov_len = ctxt->sz;
		if (process_vm_writev(ctxt->pid, local, 1, remote, 1, 0) < 0) {
			pr_fail_dbg("process_vm_writev");
			break;
		}
		msg_wr.val = val;
		val++;
redo_wr2:
		if (!g_keep_stressing_flag)
			break;
		/* Inform child that memory has been changed */
		ret = write(ctxt->pipe_rd[1], &msg_wr, sizeof(msg_wr));
		if (ret < 0) {
			if ((errno == EAGAIN) || (errno == EINTR))
				goto redo_wr2;
			if (errno != EBADF)
				pr_fail_dbg("write");
			break;
		}
		inc_counter(args);
	} while (keep_stressing());
fail:
	/* Tell child we're done */
	msg_wr.addr = NULL;
	msg_wr.val = 0;
	if (write(ctxt->pipe_wr[0], &msg_wr, sizeof(msg_wr)) < 0) {
		if (errno != EBADF)
			pr_dbg("%s: failed to write "
				"termination message "
				"over pipe: errno=%d (%s)\n",
				args->name, errno, strerror(errno));
	}
	(void)close(ctxt->pipe_wr[0]);
	(void)close(ctxt->pipe_rd[1]);
	(void)kill(ctxt->pid, SIGKILL);
	(void)waitpid(ctxt->pid, &status, 0);
	(void)munmap(localbuf, ctxt->sz);

	return EXIT_SUCCESS;
}

/*
 *  stress_vm_rw
 *	stress vm_read_v/vm_write_v
 */
int stress_vm_rw(const args_t *args)
{
	context_t ctxt;
	uint8_t stack[64*1024];
	const ssize_t stack_offset =
		stress_get_stack_direction() * (STACK_SIZE - 64);
	uint8_t *stack_top = stack + stack_offset;
	size_t vm_rw_bytes = DEFAULT_VM_RW_BYTES;

	if (!get_setting("vm-rw-bytes", &vm_rw_bytes)) {
		if (g_opt_flags & OPT_FLAGS_MAXIMIZE)
			vm_rw_bytes = MAX_VM_RW_BYTES;
		if (g_opt_flags & OPT_FLAGS_MINIMIZE)
			vm_rw_bytes = MIN_VM_RW_BYTES;
	}
	vm_rw_bytes /= args->num_instances;
	if (vm_rw_bytes < MIN_VM_RW_BYTES)
		vm_rw_bytes = MIN_VM_RW_BYTES;
	if (vm_rw_bytes < args->page_size)
		vm_rw_bytes = args->page_size;
	ctxt.args = args;
	ctxt.sz = vm_rw_bytes & ~(args->page_size - 1);

	if (pipe(ctxt.pipe_wr) < 0) {
		pr_fail_dbg("pipe");
		return EXIT_NO_RESOURCE;
	}
	if (pipe(ctxt.pipe_rd) < 0) {
		(void)close(ctxt.pipe_wr[0]);
		(void)close(ctxt.pipe_wr[1]);
		pr_fail_dbg("pipe");
		return EXIT_NO_RESOURCE;
	}

again:
	ctxt.pid = clone(stress_vm_child, align_stack(stack_top),
		SIGCHLD | CLONE_VM, &ctxt);
	if (ctxt.pid < 0) {
		if (g_keep_stressing_flag && (errno == EAGAIN))
			goto again;
		(void)close(ctxt.pipe_wr[0]);
		(void)close(ctxt.pipe_wr[1]);
		(void)close(ctxt.pipe_rd[0]);
		(void)close(ctxt.pipe_rd[1]);
		pr_fail_dbg("clone");
		return EXIT_NO_RESOURCE;
	}
	return stress_vm_parent(&ctxt);
}
#else
int stress_vm_rw(const args_t *args)
{
	return stress_not_implemented(args);
}
#endif
