// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright 2022 Google LLC.
 * Author: Suren Baghdasaryan <surenb@google.com>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
/*
 * Fork a child that concurrently modifies address space while the main
 * process is reading /proc/$PID/maps and /proc/$PID/smaps, verifying the
 * results. Address space modifications include:
 *     VMA splitting and merging
 *
 */
#define _GNU_SOURCE
#include "kselftest_harness.h"
#include <errno.h>
#include <fcntl.h>
#include <pthread.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <linux/fs.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>

#define min(a, b) \
        ({ \
                typeof(a) _a = (a); \
                typeof(b) _b = (b); \
                _a < _b ? _a : _b; \
        })

/* /proc/pid/maps parsing routines */
struct page_content {
        char *data;
        ssize_t size;
};

#define LINE_MAX_SIZE           256

struct line_content {
        char text[LINE_MAX_SIZE];
        unsigned long start_addr;
        unsigned long end_addr;
};

enum test_state {
        INIT,
        CHILD_READY,
        PARENT_READY,
        SETUP_READY,
        SETUP_MODIFY_MAPS,
        SETUP_MAPS_MODIFIED,
        SETUP_RESTORE_MAPS,
        SETUP_MAPS_RESTORED,
        TEST_READY,
        TEST_DONE,
};

enum maps_file {
        MAPS,
        SMAPS,
};

struct vma_modifier_info;

FIXTURE(proc_maps_race)
{
        struct vma_modifier_info *mod_info;
        struct page_content page1;
        struct page_content page2;
        struct line_content last_line;
        struct line_content first_line;
        unsigned long duration_sec;
        enum maps_file maps_file;
        int shared_mem_size;
        int skip_pages;
        int page_size;
        int vma_count;
        bool verbose;
        int maps_fd;
        pid_t pid;
};

FIXTURE_VARIANT(proc_maps_race)
{
        const enum maps_file maps_file;
};

FIXTURE_VARIANT_ADD(proc_maps_race, maps) {
        .maps_file = MAPS,
};

FIXTURE_VARIANT_ADD(proc_maps_race, smaps) {
        .maps_file = SMAPS,
};

typedef bool (*vma_modifier_op)(FIXTURE_DATA(proc_maps_race) *self);
typedef bool (*vma_mod_result_check_op)(struct line_content *mod_last_line,
                                        struct line_content *mod_first_line,
                                        struct line_content *restored_last_line,
                                        struct line_content *restored_first_line);

struct vma_modifier_info {
        int vma_count;
        void *addr;
        int prot;
        void *next_addr;
        vma_modifier_op vma_modify;
        vma_modifier_op vma_restore;
        vma_mod_result_check_op vma_mod_check;
        pthread_mutex_t sync_lock;
        pthread_cond_t sync_cond;
        enum test_state curr_state;
        bool exit;
        void *child_mapped_addr[];
};

static bool read_page(FIXTURE_DATA(proc_maps_race) *self,
                      struct page_content *page)
{
        ssize_t  bytes_read;

        bytes_read = read(self->maps_fd, page->data, self->page_size);
        if (bytes_read <= 0)
                return false;

        /* Make sure data always ends with a newline character. */
        if (page->data[bytes_read - 1] != '\n')
                return false;

        page->size = bytes_read;

        return true;
}

static bool parse_vma_line(char *line_start, char *line_end,
                           unsigned long *start, unsigned long *end)
{
        bool found;

        *line_end = '\0'; /* stop sscanf at the EOL */
        found = (sscanf(line_start, "%lx-%lx", start, end) == 2);
        *line_end = '\n';

        return found;
}

static int locate_containing_page(FIXTURE_DATA(proc_maps_race) *self,
                                  unsigned long addr, unsigned long size)
{
        unsigned long start, end;
        int page = 0;

        if (lseek(self->maps_fd, 0, SEEK_SET) < 0)
                return -1;

        while (true) {
                char *curr_pos;
                char *end_pos;

                if (!read_page(self, &self->page1))
                        return -1;

                curr_pos = self->page1.data;
                end_pos = self->page1.data + self->page1.size;
                while (curr_pos < end_pos) {
                        char *line_end;

                        line_end = strchr(curr_pos, '\n');
                        if (!line_end)
                                break;

                        if (parse_vma_line(curr_pos, line_end, &start, &end) &&
                            start == addr && end == addr + size)
                                return page;

                        curr_pos = line_end + 1;
                }
                page++;
        }

        return 0;
}

static bool read_two_pages(FIXTURE_DATA(proc_maps_race) *self)
{
        if (lseek(self->maps_fd, 0, SEEK_SET) < 0)
                return false;

        for (int i = 0; i < self->skip_pages; i++)
                if (!read_page(self, &self->page1))
                        return false;

        return read_page(self, &self->page1) && read_page(self, &self->page2);
}

static void copy_line(const char *line_start, const char *line_end,
                      char *buf, size_t buf_size)
{
        size_t len = min(line_end - line_start, buf_size - 1);

        strncpy(buf, line_start, len);
        buf[len] = '\0';
}

static void copy_first_line(struct page_content *page, char *first_line,
                            size_t line_size)
{
        copy_line(page->data, strchr(page->data, '\n'), first_line, line_size);
}

static void copy_last_line(struct page_content *page, char *last_line,
                           size_t line_size)
{
        /* Get the last line in the first page */
        const char *end = page->data + page->size - 1;
        /* skip last newline */
        const char *pos = end - 1;

        /* search previous newline */
        while (pos[-1] != '\n')
                pos--;

        copy_line(pos, end, last_line, line_size);
}

static bool copy_first_entry(struct page_content *page, char *first_line,
                             size_t line_size)
{
        char *start_pos = page->data;

        while (start_pos < page->data + page->size) {
                unsigned long start_addr;
                unsigned long end_addr;
                char *end_pos;

                end_pos = strchr(start_pos, '\n');
                if (!end_pos)
                        break;

                if (parse_vma_line(start_pos, end_pos, &start_addr, &end_addr)) {
                        copy_line(start_pos, end_pos, first_line, line_size);
                        return true;
                }

                start_pos = end_pos + 1;
        }

        return false;
}

static bool copy_last_entry(struct page_content *page, char *last_line,
                            size_t line_size)
{
        char *end_pos = page->data + page->size - 1;
        char *start_pos;

        while (end_pos > page->data) {
                unsigned long start_addr;
                unsigned long end_addr;

                /* skip last newline */
                start_pos = end_pos - 1;
                /* search previous newline */
                while (start_pos > page->data && start_pos[-1] != '\n')
                        start_pos--;
                if (parse_vma_line(start_pos, end_pos, &start_addr, &end_addr)) {
                        copy_line(start_pos, end_pos, last_line, line_size);
                        return true;
                }

                end_pos = start_pos - 1;
        }

        return false;
}

/* Read the last line of the first page and the first line of the second page */
static bool read_boundary_lines(FIXTURE_DATA(proc_maps_race) *self,
                                struct line_content *last_line,
                                struct line_content *first_line)
{
        if (!read_two_pages(self))
                return false;

        if (self->maps_file == MAPS) {
                copy_last_line(&self->page1, last_line->text, LINE_MAX_SIZE);
                copy_first_line(&self->page2, first_line->text, LINE_MAX_SIZE);
        } else if (self->maps_file == SMAPS) {
                if (!copy_last_entry(&self->page1, last_line->text, LINE_MAX_SIZE) ||
                    !copy_first_entry(&self->page2, first_line->text, LINE_MAX_SIZE))
                        return false;
        } else {
                return false;
        }

        return sscanf(last_line->text, "%lx-%lx", &last_line->start_addr,
                      &last_line->end_addr) == 2 &&
               sscanf(first_line->text, "%lx-%lx", &first_line->start_addr,
                      &first_line->end_addr) == 2;
}

/* Thread synchronization routines */
static void wait_for_state(struct vma_modifier_info *mod_info, enum test_state state)
{
        pthread_mutex_lock(&mod_info->sync_lock);
        while (mod_info->curr_state != state)
                pthread_cond_wait(&mod_info->sync_cond, &mod_info->sync_lock);
        pthread_mutex_unlock(&mod_info->sync_lock);
}

static void signal_state(struct vma_modifier_info *mod_info, enum test_state state)
{
        pthread_mutex_lock(&mod_info->sync_lock);
        mod_info->curr_state = state;
        pthread_cond_signal(&mod_info->sync_cond);
        pthread_mutex_unlock(&mod_info->sync_lock);
}

static void stop_vma_modifier(struct vma_modifier_info *mod_info)
{
        wait_for_state(mod_info, SETUP_READY);
        mod_info->exit = true;
        signal_state(mod_info, SETUP_MODIFY_MAPS);
}

static void print_first_lines(char *text, int nr)
{
        const char *end = text;

        while (nr && (end = strchr(end, '\n')) != NULL) {
                nr--;
                end++;
        }

        if (end) {
                int offs = end - text;

                text[offs] = '\0';
                printf("%s", text);
                text[offs] = '\n';
                printf("\n");
        } else {
                printf("%s", text);
        }
}

static void print_last_lines(char *text, int nr)
{
        const char *start = text + strlen(text);

        nr++; /* to ignore the last newline */
        while (nr) {
                while (start > text && *start != '\n')
                        start--;
                nr--;
                start--;
        }
        printf("%s", start);
}

static void print_boundaries(const char *title, FIXTURE_DATA(proc_maps_race) *self)
{
        if (!self->verbose)
                return;

        printf("%s", title);
        /* Print 3 boundary lines from each page */
        print_last_lines(self->page1.data, 3);
        printf("-----------------page boundary-----------------\n");
        print_first_lines(self->page2.data, 3);
}

static bool print_boundaries_on(bool condition, const char *title,
                                FIXTURE_DATA(proc_maps_race) *self)
{
        if (self->verbose && condition)
                print_boundaries(title, self);

        return condition;
}

static void report_test_start(const char *name, bool verbose)
{
        if (verbose)
                printf("==== %s ====\n", name);
}

static struct timespec print_ts;

static void start_test_loop(struct timespec *ts, bool verbose)
{
        if (verbose)
                print_ts.tv_sec = ts->tv_sec;
}

static void end_test_iteration(struct timespec *ts, bool verbose)
{
        if (!verbose)
                return;

        /* Update every second */
        if (print_ts.tv_sec == ts->tv_sec)
                return;

        printf(".");
        fflush(stdout);
        print_ts.tv_sec = ts->tv_sec;
}

static void end_test_loop(bool verbose)
{
        if (verbose)
                printf("\n");
}

static bool capture_mod_pattern(FIXTURE_DATA(proc_maps_race) *self,
                                struct line_content *mod_last_line,
                                struct line_content *mod_first_line,
                                struct line_content *restored_last_line,
                                struct line_content *restored_first_line)
{
        print_boundaries("Before modification", self);

        signal_state(self->mod_info, SETUP_MODIFY_MAPS);
        wait_for_state(self->mod_info, SETUP_MAPS_MODIFIED);

        /* Copy last line of the first page and first line of the last page */
        if (!read_boundary_lines(self, mod_last_line, mod_first_line))
                return false;

        print_boundaries("After modification", self);

        signal_state(self->mod_info, SETUP_RESTORE_MAPS);
        wait_for_state(self->mod_info, SETUP_MAPS_RESTORED);

        /* Copy last line of the first page and first line of the last page */
        if (!read_boundary_lines(self, restored_last_line, restored_first_line))
                return false;

        print_boundaries("After restore", self);

        if (!self->mod_info->vma_mod_check(mod_last_line, mod_first_line,
                                           restored_last_line, restored_first_line))
                return false;

        /*
         * The content of these lines after modify+resore should be the same
         * as the original.
         */
        return strcmp(restored_last_line->text, self->last_line.text) == 0 &&
               strcmp(restored_first_line->text, self->first_line.text) == 0;
}

static bool query_addr_at(int maps_fd, void *addr,
                          unsigned long *vma_start, unsigned long *vma_end)
{
        struct procmap_query q;

        memset(&q, 0, sizeof(q));
        q.size = sizeof(q);
        /* Find the VMA at the split address */
        q.query_addr = (unsigned long long)addr;
        q.query_flags = 0;
        if (ioctl(maps_fd, PROCMAP_QUERY, &q))
                return false;

        *vma_start = q.vma_start;
        *vma_end = q.vma_end;

        return true;
}

static inline bool split_vma(FIXTURE_DATA(proc_maps_race) *self)
{
        return mmap(self->mod_info->addr, self->page_size, self->mod_info->prot | PROT_EXEC,
                    MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0) != MAP_FAILED;
}

static inline bool merge_vma(FIXTURE_DATA(proc_maps_race) *self)
{
        return mmap(self->mod_info->addr, self->page_size, self->mod_info->prot,
                    MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0) != MAP_FAILED;
}

static inline bool check_split_result(struct line_content *mod_last_line,
                                      struct line_content *mod_first_line,
                                      struct line_content *restored_last_line,
                                      struct line_content *restored_first_line)
{
        /* Make sure vmas at the boundaries are changing */
        return strcmp(mod_last_line->text, restored_last_line->text) != 0 &&
               strcmp(mod_first_line->text, restored_first_line->text) != 0;
}

static inline bool shrink_vma(FIXTURE_DATA(proc_maps_race) *self)
{
        return mremap(self->mod_info->addr, self->page_size * 3,
                      self->page_size, 0) != MAP_FAILED;
}

static inline bool expand_vma(FIXTURE_DATA(proc_maps_race) *self)
{
        return mremap(self->mod_info->addr, self->page_size,
                      self->page_size * 3, 0) != MAP_FAILED;
}

static inline bool check_shrink_result(struct line_content *mod_last_line,
                                       struct line_content *mod_first_line,
                                       struct line_content *restored_last_line,
                                       struct line_content *restored_first_line)
{
        /* Make sure only the last vma of the first page is changing */
        return strcmp(mod_last_line->text, restored_last_line->text) != 0 &&
               strcmp(mod_first_line->text, restored_first_line->text) == 0;
}

static inline bool remap_vma(FIXTURE_DATA(proc_maps_race) *self)
{
        /*
         * Remap the last page of the next vma into the middle of the vma.
         * This splits the current vma and the first and middle parts (the
         * parts at lower addresses) become the last vma objserved in the
         * first page and the first vma observed in the last page.
         */
        return mremap(self->mod_info->next_addr + self->page_size * 2, self->page_size,
                      self->page_size, MREMAP_FIXED | MREMAP_MAYMOVE | MREMAP_DONTUNMAP,
                      self->mod_info->addr + self->page_size) != MAP_FAILED;
}

static inline bool patch_vma(FIXTURE_DATA(proc_maps_race) *self)
{
        return mprotect(self->mod_info->addr + self->page_size, self->page_size,
                        self->mod_info->prot) == 0;
}

static inline bool check_remap_result(struct line_content *mod_last_line,
                                      struct line_content *mod_first_line,
                                      struct line_content *restored_last_line,
                                      struct line_content *restored_first_line)
{
        /* Make sure vmas at the boundaries are changing */
        return strcmp(mod_last_line->text, restored_last_line->text) != 0 &&
               strcmp(mod_first_line->text, restored_first_line->text) != 0;
}

FIXTURE_SETUP(proc_maps_race)
{
        const char *verbose = getenv("VERBOSE");
        const char *duration = getenv("DURATION");
        struct vma_modifier_info *mod_info;
        pthread_mutexattr_t mutex_attr;
        pthread_condattr_t cond_attr;
        unsigned long first_map_addr;
        unsigned long last_map_addr;
        unsigned long duration_sec;
        char fname[32];

        self->page_size = (unsigned long)sysconf(_SC_PAGESIZE);
        self->verbose = verbose && !strncmp(verbose, "1", 1);
        self->maps_file = variant->maps_file;
        duration_sec = duration ? atol(duration) : 0;
        self->duration_sec = duration_sec ? duration_sec : 5UL;

        /*
         * Have to map enough vmas for /proc/pid/maps to contain more than one
         * page worth of vmas. Assume at least 32 bytes per line in maps output
         */
        self->vma_count = self->page_size / 32 + 1;
        self->shared_mem_size = sizeof(struct vma_modifier_info) + self->vma_count * sizeof(void *);

        /* map shared memory for communication with the child process */
        self->mod_info = (struct vma_modifier_info *)mmap(NULL, self->shared_mem_size,
                                PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0);
        ASSERT_NE(self->mod_info, MAP_FAILED);
        mod_info = self->mod_info;

        /* Initialize shared members */
        pthread_mutexattr_init(&mutex_attr);
        pthread_mutexattr_setpshared(&mutex_attr, PTHREAD_PROCESS_SHARED);
        ASSERT_EQ(pthread_mutex_init(&mod_info->sync_lock, &mutex_attr), 0);
        pthread_condattr_init(&cond_attr);
        pthread_condattr_setpshared(&cond_attr, PTHREAD_PROCESS_SHARED);
        ASSERT_EQ(pthread_cond_init(&mod_info->sync_cond, &cond_attr), 0);
        mod_info->vma_count = self->vma_count;
        mod_info->curr_state = INIT;
        mod_info->exit = false;

        self->pid = fork();
        if (!self->pid) {
                /* Child process modifying the address space */
                int prot = PROT_READ | PROT_WRITE;
                int i;

                for (i = 0; i < mod_info->vma_count; i++) {
                        mod_info->child_mapped_addr[i] = mmap(NULL, self->page_size * 3, prot,
                                        MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
                        ASSERT_NE(mod_info->child_mapped_addr[i], MAP_FAILED);
                        /* change protection in adjacent maps to prevent merging */
                        prot ^= PROT_WRITE;
                }
                signal_state(mod_info, CHILD_READY);
                wait_for_state(mod_info, PARENT_READY);
                while (true) {
                        signal_state(mod_info, SETUP_READY);
                        wait_for_state(mod_info, SETUP_MODIFY_MAPS);
                        if (mod_info->exit)
                                break;

                        ASSERT_TRUE(mod_info->vma_modify(self));
                        signal_state(mod_info, SETUP_MAPS_MODIFIED);
                        wait_for_state(mod_info, SETUP_RESTORE_MAPS);
                        ASSERT_TRUE(mod_info->vma_restore(self));
                        signal_state(mod_info, SETUP_MAPS_RESTORED);

                        wait_for_state(mod_info, TEST_READY);
                        while (mod_info->curr_state != TEST_DONE) {
                                ASSERT_TRUE(mod_info->vma_modify(self));
                                ASSERT_TRUE(mod_info->vma_restore(self));
                        }
                }
                for (i = 0; i < mod_info->vma_count; i++)
                        munmap(mod_info->child_mapped_addr[i], self->page_size * 3);

                exit(0);
        }

        switch (self->maps_file) {
        case MAPS:
                sprintf(fname, "/proc/%d/maps", self->pid);
                break;
        case SMAPS:
                sprintf(fname, "/proc/%d/smaps", self->pid);
                break;
        default:
                ksft_exit_fail();
        }
        self->maps_fd = open(fname, O_RDONLY);
        ASSERT_NE(self->maps_fd, -1);

        /* Wait for the child to map the VMAs */
        wait_for_state(mod_info, CHILD_READY);

        /* Read first two pages */
        self->page1.data = malloc(self->page_size);
        ASSERT_NE(self->page1.data, NULL);
        self->page2.data = malloc(self->page_size);
        ASSERT_NE(self->page2.data, NULL);

        first_map_addr = (unsigned long)mod_info->child_mapped_addr[0];
        last_map_addr = (unsigned long)mod_info->child_mapped_addr[mod_info->vma_count - 1];

        self->skip_pages = locate_containing_page(self,
                                        min(first_map_addr, last_map_addr),
                                        self->page_size * 3);
        ASSERT_NE(self->skip_pages, -1);
        ASSERT_TRUE(read_boundary_lines(self, &self->last_line, &self->first_line));

        /*
         * Find the addresses corresponding to the last line in the first page
         * and the first line in the last page.
         */
        mod_info->addr = NULL;
        mod_info->next_addr = NULL;
        for (int i = 0; i < mod_info->vma_count; i++) {
                if (mod_info->child_mapped_addr[i] == (void *)self->last_line.start_addr) {
                        mod_info->addr = mod_info->child_mapped_addr[i];
                        mod_info->prot = PROT_READ;
                        /* Even VMAs have write permission */
                        if ((i % 2) == 0)
                                mod_info->prot |= PROT_WRITE;
                } else if (mod_info->child_mapped_addr[i] == (void *)self->first_line.start_addr) {
                        mod_info->next_addr = mod_info->child_mapped_addr[i];
                }

                if (mod_info->addr && mod_info->next_addr)
                        break;
        }
        ASSERT_TRUE(mod_info->addr && mod_info->next_addr);

        signal_state(mod_info, PARENT_READY);
}

FIXTURE_TEARDOWN(proc_maps_race)
{
        int status;

        stop_vma_modifier(self->mod_info);

        free(self->page2.data);
        free(self->page1.data);

        for (int i = 0; i < self->vma_count; i++)
                munmap(self->mod_info->child_mapped_addr[i], self->page_size);
        close(self->maps_fd);
        waitpid(self->pid, &status, 0);
        munmap(self->mod_info, self->shared_mem_size);
}

TEST_F(proc_maps_race, test_maps_tearing_from_split)
{
        struct vma_modifier_info *mod_info = self->mod_info;

        struct line_content split_last_line;
        struct line_content split_first_line;
        struct line_content restored_last_line;
        struct line_content restored_first_line;

        wait_for_state(mod_info, SETUP_READY);

        /* re-read the file to avoid using stale data from previous test */
        ASSERT_TRUE(read_boundary_lines(self, &self->last_line, &self->first_line));

        mod_info->vma_modify = split_vma;
        mod_info->vma_restore = merge_vma;
        mod_info->vma_mod_check = check_split_result;

        report_test_start("Tearing from split", self->verbose);
        ASSERT_TRUE(capture_mod_pattern(self, &split_last_line, &split_first_line,
                                        &restored_last_line, &restored_first_line));

        /* Now start concurrent modifications for self->duration_sec */
        signal_state(mod_info, TEST_READY);

        struct line_content new_last_line;
        struct line_content new_first_line;
        struct timespec start_ts, end_ts;

        clock_gettime(CLOCK_MONOTONIC_COARSE, &start_ts);
        start_test_loop(&start_ts, self->verbose);
        do {
                bool last_line_changed;
                bool first_line_changed;
                unsigned long vma_start;
                unsigned long vma_end;

                ASSERT_TRUE(read_boundary_lines(self, &new_last_line, &new_first_line));

                /* Check if we read vmas after split */
                if (!strcmp(new_last_line.text, split_last_line.text)) {
                        /*
                         * The vmas should be consistent with split results,
                         * however if vma was concurrently restored after a
                         * split, it can be reported twice (first the original
                         * split one, then the same vma but extended after the
                         * merge) because we found it as the next vma again.
                         * In that case new first line will be the same as the
                         * last restored line.
                         */
                        ASSERT_FALSE(print_boundaries_on(
                                        strcmp(new_first_line.text, split_first_line.text) &&
                                        strcmp(new_first_line.text, restored_last_line.text),
                                        "Split result invalid", self));
                } else {
                        /* The vmas should be consistent with merge results */
                        ASSERT_FALSE(print_boundaries_on(
                                        strcmp(new_last_line.text, restored_last_line.text),
                                        "Merge result invalid", self));
                        ASSERT_FALSE(print_boundaries_on(
                                        strcmp(new_first_line.text, restored_first_line.text),
                                        "Merge result invalid", self));
                }
                /*
                 * First and last lines should change in unison. If the last
                 * line changed then the first line should change as well and
                 * vice versa.
                 */
                last_line_changed = strcmp(new_last_line.text, self->last_line.text) != 0;
                first_line_changed = strcmp(new_first_line.text, self->first_line.text) != 0;
                ASSERT_EQ(last_line_changed, first_line_changed);
                if (self->maps_file == MAPS) {
                        /* Check if PROCMAP_QUERY ioclt() finds the right VMA */
                        ASSERT_TRUE(query_addr_at(self->maps_fd, mod_info->addr + self->page_size,
                                                  &vma_start, &vma_end));
                        /*
                         * The vma at the split address can be either the same as
                         * original one (if read before the split) or the same as the
                         * first line in the second page (if read after the split).
                         */
                        ASSERT_TRUE((vma_start == self->last_line.start_addr &&
                                     vma_end == self->last_line.end_addr) ||
                                    (vma_start == split_first_line.start_addr &&
                                     vma_end == split_first_line.end_addr));
                }
                clock_gettime(CLOCK_MONOTONIC_COARSE, &end_ts);
                end_test_iteration(&end_ts, self->verbose);
        } while (end_ts.tv_sec - start_ts.tv_sec < self->duration_sec);
        end_test_loop(self->verbose);

        /* Signal the modifyer thread to stop and wait until it exits */
        signal_state(mod_info, TEST_DONE);
}

TEST_F(proc_maps_race, test_maps_tearing_from_resize)
{
        struct vma_modifier_info *mod_info = self->mod_info;

        struct line_content shrunk_last_line;
        struct line_content shrunk_first_line;
        struct line_content restored_last_line;
        struct line_content restored_first_line;

        wait_for_state(mod_info, SETUP_READY);

        /* re-read the file to avoid using stale data from previous test */
        ASSERT_TRUE(read_boundary_lines(self, &self->last_line, &self->first_line));

        mod_info->vma_modify = shrink_vma;
        mod_info->vma_restore = expand_vma;
        mod_info->vma_mod_check = check_shrink_result;

        report_test_start("Tearing from resize", self->verbose);
        ASSERT_TRUE(capture_mod_pattern(self, &shrunk_last_line, &shrunk_first_line,
                                        &restored_last_line, &restored_first_line));

        /* Now start concurrent modifications for self->duration_sec */
        signal_state(mod_info, TEST_READY);

        struct line_content new_last_line;
        struct line_content new_first_line;
        struct timespec start_ts, end_ts;

        clock_gettime(CLOCK_MONOTONIC_COARSE, &start_ts);
        start_test_loop(&start_ts, self->verbose);
        do {
                unsigned long vma_start;
                unsigned long vma_end;

                ASSERT_TRUE(read_boundary_lines(self, &new_last_line, &new_first_line));

                /* Check if we read vmas after shrinking it */
                if (!strcmp(new_last_line.text, shrunk_last_line.text)) {
                        /*
                         * The vmas should be consistent with shrunk results,
                         * however if the vma was concurrently restored, it
                         * can be reported twice (first as shrunk one, then
                         * as restored one) because we found it as the next vma
                         * again. In that case new first line will be the same
                         * as the last restored line.
                         */
                        ASSERT_FALSE(print_boundaries_on(
                                        strcmp(new_first_line.text, shrunk_first_line.text) &&
                                        strcmp(new_first_line.text, restored_last_line.text),
                                        "Shrink result invalid", self));
                } else {
                        /* The vmas should be consistent with the original/resored state */
                        ASSERT_FALSE(print_boundaries_on(
                                        strcmp(new_last_line.text, restored_last_line.text),
                                        "Expand result invalid", self));
                        ASSERT_FALSE(print_boundaries_on(
                                        strcmp(new_first_line.text, restored_first_line.text),
                                        "Expand result invalid", self));
                }
                if (self->maps_file == MAPS) {
                        /* Check if PROCMAP_QUERY ioclt() finds the right VMA */
                        ASSERT_TRUE(query_addr_at(self->maps_fd, mod_info->addr,
                                                  &vma_start, &vma_end));
                        /*
                         * The vma should stay at the same address and have either the
                         * original size of 3 pages or 1 page if read after shrinking.
                         */
                        ASSERT_TRUE(vma_start == self->last_line.start_addr &&
                                    (vma_end - vma_start == self->page_size * 3 ||
                                     vma_end - vma_start == self->page_size));
                }
                clock_gettime(CLOCK_MONOTONIC_COARSE, &end_ts);
                end_test_iteration(&end_ts, self->verbose);
        } while (end_ts.tv_sec - start_ts.tv_sec < self->duration_sec);
        end_test_loop(self->verbose);

        /* Signal the modifyer thread to stop and wait until it exits */
        signal_state(mod_info, TEST_DONE);
}

TEST_F(proc_maps_race, test_maps_tearing_from_remap)
{
        struct vma_modifier_info *mod_info = self->mod_info;

        struct line_content remapped_last_line;
        struct line_content remapped_first_line;
        struct line_content restored_last_line;
        struct line_content restored_first_line;

        wait_for_state(mod_info, SETUP_READY);

        /* re-read the file to avoid using stale data from previous test */
        ASSERT_TRUE(read_boundary_lines(self, &self->last_line, &self->first_line));

        mod_info->vma_modify = remap_vma;
        mod_info->vma_restore = patch_vma;
        mod_info->vma_mod_check = check_remap_result;

        report_test_start("Tearing from remap", self->verbose);
        ASSERT_TRUE(capture_mod_pattern(self, &remapped_last_line, &remapped_first_line,
                                        &restored_last_line, &restored_first_line));

        /* Now start concurrent modifications for self->duration_sec */
        signal_state(mod_info, TEST_READY);

        struct line_content new_last_line;
        struct line_content new_first_line;
        struct timespec start_ts, end_ts;

        clock_gettime(CLOCK_MONOTONIC_COARSE, &start_ts);
        start_test_loop(&start_ts, self->verbose);
        do {
                unsigned long vma_start;
                unsigned long vma_end;

                ASSERT_TRUE(read_boundary_lines(self, &new_last_line, &new_first_line));

                /* Check if we read vmas after remapping it */
                if (!strcmp(new_last_line.text, remapped_last_line.text)) {
                        /*
                         * The vmas should be consistent with remap results,
                         * however if the vma was concurrently restored, it
                         * can be reported twice (first as split one, then
                         * as restored one) because we found it as the next vma
                         * again. In that case new first line will be the same
                         * as the last restored line.
                         */
                        ASSERT_FALSE(print_boundaries_on(
                                        strcmp(new_first_line.text, remapped_first_line.text) &&
                                        strcmp(new_first_line.text, restored_last_line.text),
                                        "Remap result invalid", self));
                } else {
                        /* The vmas should be consistent with the original/resored state */
                        ASSERT_FALSE(print_boundaries_on(
                                        strcmp(new_last_line.text, restored_last_line.text),
                                        "Remap restore result invalid", self));
                        ASSERT_FALSE(print_boundaries_on(
                                        strcmp(new_first_line.text, restored_first_line.text),
                                        "Remap restore result invalid", self));
                }
                if (self->maps_file == MAPS) {
                        /* Check if PROCMAP_QUERY ioclt() finds the right VMA */
                        ASSERT_TRUE(query_addr_at(self->maps_fd, mod_info->addr + self->page_size,
                                                  &vma_start, &vma_end));
                        /*
                         * The vma should either stay at the same address and have the
                         * original size of 3 pages or we should find the remapped vma
                         * at the remap destination address with size of 1 page.
                         */
                        ASSERT_TRUE((vma_start == self->last_line.start_addr &&
                                     vma_end - vma_start == self->page_size * 3) ||
                                    (vma_start == self->last_line.start_addr + self->page_size &&
                                     vma_end - vma_start == self->page_size));
                }
                clock_gettime(CLOCK_MONOTONIC_COARSE, &end_ts);
                end_test_iteration(&end_ts, self->verbose);
        } while (end_ts.tv_sec - start_ts.tv_sec < self->duration_sec);
        end_test_loop(self->verbose);

        /* Signal the modifyer thread to stop and wait until it exits */
        signal_state(mod_info, TEST_DONE);
}

TEST_HARNESS_MAIN