// SPDX-License-Identifier: GPL-2.0
/*
 * hugepage-madvise:
 *
 * Basic functional testing of madvise MADV_DONTNEED and MADV_REMOVE
 * on hugetlb mappings.
 *
 * Before running this test, make sure the administrator has pre-allocated
 * at least MIN_FREE_PAGES hugetlb pages and they are free.  In addition,
 * the test takes an argument that is the path to a file in a hugetlbfs
 * filesystem.  Therefore, a hugetlbfs filesystem must be mounted on some
 * directory.
 */

#define _GNU_SOURCE
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/mman.h>
#include <fcntl.h>
#include "vm_util.h"
#include "kselftest.h"

#define MIN_FREE_PAGES  20
#define NR_HUGE_PAGES   10      /* common number of pages to map/allocate */

#define validate_free_pages(exp_free)                                   \
        do {                                                            \
                int fhp = get_free_hugepages();                         \
                if (fhp != (exp_free)) {                                \
                        printf("Unexpected number of free huge "        \
                                "pages line %d\n", __LINE__);           \
                        exit(1);                                        \
                }                                                       \
        } while (0)

unsigned long huge_page_size;
unsigned long base_page_size;

void write_fault_pages(void *addr, unsigned long nr_pages)
{
        unsigned long i;

        for (i = 0; i < nr_pages; i++)
                *((unsigned long *)(addr + (i * huge_page_size))) = i;
}

void read_fault_pages(void *addr, unsigned long nr_pages)
{
        force_read_pages(addr, nr_pages, huge_page_size);
}

int main(int argc, char **argv)
{
        unsigned long free_hugepages;
        void *addr, *addr2;
        int fd;
        int ret;

        huge_page_size = default_huge_page_size();
        if (!huge_page_size) {
                printf("Unable to determine huge page size, exiting!\n");
                exit(1);
        }
        base_page_size = sysconf(_SC_PAGE_SIZE);
        if (!huge_page_size) {
                printf("Unable to determine base page size, exiting!\n");
                exit(1);
        }

        free_hugepages = get_free_hugepages();
        if (free_hugepages < MIN_FREE_PAGES) {
                printf("Not enough free huge pages to test, exiting!\n");
                exit(KSFT_SKIP);
        }

        fd = memfd_create(argv[0], MFD_HUGETLB);
        if (fd < 0) {
                perror("memfd_create() failed");
                exit(1);
        }

        /*
         * Test validity of MADV_DONTNEED addr and length arguments.  mmap
         * size is NR_HUGE_PAGES + 2.  One page at the beginning and end of
         * the mapping will be unmapped so we KNOW there is nothing mapped
         * there.
         */
        addr = mmap(NULL, (NR_HUGE_PAGES + 2) * huge_page_size,
                        PROT_READ | PROT_WRITE,
                        MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB,
                        -1, 0);
        if (addr == MAP_FAILED) {
                perror("mmap");
                exit(1);
        }
        if (munmap(addr, huge_page_size) ||
                        munmap(addr + (NR_HUGE_PAGES + 1) * huge_page_size,
                                huge_page_size)) {
                perror("munmap");
                exit(1);
        }
        addr = addr + huge_page_size;

        write_fault_pages(addr, NR_HUGE_PAGES);
        validate_free_pages(free_hugepages - NR_HUGE_PAGES);

        /* addr before mapping should fail */
        ret = madvise(addr - base_page_size, NR_HUGE_PAGES * huge_page_size,
                MADV_DONTNEED);
        if (!ret) {
                printf("Unexpected success of madvise call with invalid addr line %d\n",
                                __LINE__);
                        exit(1);
        }

        /* addr + length after mapping should fail */
        ret = madvise(addr, (NR_HUGE_PAGES * huge_page_size) + base_page_size,
                MADV_DONTNEED);
        if (!ret) {
                printf("Unexpected success of madvise call with invalid length line %d\n",
                                __LINE__);
                        exit(1);
        }

        (void)munmap(addr, NR_HUGE_PAGES * huge_page_size);

        /*
         * Test alignment of MADV_DONTNEED addr and length arguments
         */
        addr = mmap(NULL, NR_HUGE_PAGES * huge_page_size,
                        PROT_READ | PROT_WRITE,
                        MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB,
                        -1, 0);
        if (addr == MAP_FAILED) {
                perror("mmap");
                exit(1);
        }
        write_fault_pages(addr, NR_HUGE_PAGES);
        validate_free_pages(free_hugepages - NR_HUGE_PAGES);

        /* addr is not huge page size aligned and should fail */
        ret = madvise(addr + base_page_size,
                        NR_HUGE_PAGES * huge_page_size - base_page_size,
                        MADV_DONTNEED);
        if (!ret) {
                printf("Unexpected success of madvise call with unaligned start address %d\n",
                                __LINE__);
                        exit(1);
        }

        /* addr + length should be aligned down to huge page size */
        if (madvise(addr,
                        ((NR_HUGE_PAGES - 1) * huge_page_size) + base_page_size,
                        MADV_DONTNEED)) {
                perror("madvise");
                exit(1);
        }

        /* should free all but last page in mapping */
        validate_free_pages(free_hugepages - 1);

        (void)munmap(addr, NR_HUGE_PAGES * huge_page_size);
        validate_free_pages(free_hugepages);

        /*
         * Test MADV_DONTNEED on anonymous private mapping
         */
        addr = mmap(NULL, NR_HUGE_PAGES * huge_page_size,
                        PROT_READ | PROT_WRITE,
                        MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB,
                        -1, 0);
        if (addr == MAP_FAILED) {
                perror("mmap");
                exit(1);
        }
        write_fault_pages(addr, NR_HUGE_PAGES);
        validate_free_pages(free_hugepages - NR_HUGE_PAGES);

        if (madvise(addr, NR_HUGE_PAGES * huge_page_size, MADV_DONTNEED)) {
                perror("madvise");
                exit(1);
        }

        /* should free all pages in mapping */
        validate_free_pages(free_hugepages);

        (void)munmap(addr, NR_HUGE_PAGES * huge_page_size);

        /*
         * Test MADV_DONTNEED on private mapping of hugetlb file
         */
        if (fallocate(fd, 0, 0, NR_HUGE_PAGES * huge_page_size)) {
                perror("fallocate");
                exit(1);
        }
        validate_free_pages(free_hugepages - NR_HUGE_PAGES);

        addr = mmap(NULL, NR_HUGE_PAGES * huge_page_size,
                        PROT_READ | PROT_WRITE,
                        MAP_PRIVATE, fd, 0);
        if (addr == MAP_FAILED) {
                perror("mmap");
                exit(1);
        }

        /* read should not consume any pages */
        read_fault_pages(addr, NR_HUGE_PAGES);
        validate_free_pages(free_hugepages - NR_HUGE_PAGES);

        /* madvise should not free any pages */
        if (madvise(addr, NR_HUGE_PAGES * huge_page_size, MADV_DONTNEED)) {
                perror("madvise");
                exit(1);
        }
        validate_free_pages(free_hugepages - NR_HUGE_PAGES);

        /* writes should allocate private pages */
        write_fault_pages(addr, NR_HUGE_PAGES);
        validate_free_pages(free_hugepages - (2 * NR_HUGE_PAGES));

        /* madvise should free private pages */
        if (madvise(addr, NR_HUGE_PAGES * huge_page_size, MADV_DONTNEED)) {
                perror("madvise");
                exit(1);
        }
        validate_free_pages(free_hugepages - NR_HUGE_PAGES);

        /* writes should allocate private pages */
        write_fault_pages(addr, NR_HUGE_PAGES);
        validate_free_pages(free_hugepages - (2 * NR_HUGE_PAGES));

        /*
         * The fallocate below certainly should free the pages associated
         * with the file.  However, pages in the private mapping are also
         * freed.  This is not the 'correct' behavior, but is expected
         * because this is how it has worked since the initial hugetlb
         * implementation.
         */
        if (fallocate(fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
                                        0, NR_HUGE_PAGES * huge_page_size)) {
                perror("fallocate");
                exit(1);
        }
        validate_free_pages(free_hugepages);

        (void)munmap(addr, NR_HUGE_PAGES * huge_page_size);

        /*
         * Test MADV_DONTNEED on shared mapping of hugetlb file
         */
        if (fallocate(fd, 0, 0, NR_HUGE_PAGES * huge_page_size)) {
                perror("fallocate");
                exit(1);
        }
        validate_free_pages(free_hugepages - NR_HUGE_PAGES);

        addr = mmap(NULL, NR_HUGE_PAGES * huge_page_size,
                        PROT_READ | PROT_WRITE,
                        MAP_SHARED, fd, 0);
        if (addr == MAP_FAILED) {
                perror("mmap");
                exit(1);
        }

        /* write should not consume any pages */
        write_fault_pages(addr, NR_HUGE_PAGES);
        validate_free_pages(free_hugepages - NR_HUGE_PAGES);

        /* madvise should not free any pages */
        if (madvise(addr, NR_HUGE_PAGES * huge_page_size, MADV_DONTNEED)) {
                perror("madvise");
                exit(1);
        }
        validate_free_pages(free_hugepages - NR_HUGE_PAGES);

        /*
         * Test MADV_REMOVE on shared mapping of hugetlb file
         *
         * madvise is same as hole punch and should free all pages.
         */
        if (madvise(addr, NR_HUGE_PAGES * huge_page_size, MADV_REMOVE)) {
                perror("madvise");
                exit(1);
        }
        validate_free_pages(free_hugepages);
        (void)munmap(addr, NR_HUGE_PAGES * huge_page_size);

        /*
         * Test MADV_REMOVE on shared and private mapping of hugetlb file
         */
        if (fallocate(fd, 0, 0, NR_HUGE_PAGES * huge_page_size)) {
                perror("fallocate");
                exit(1);
        }
        validate_free_pages(free_hugepages - NR_HUGE_PAGES);

        addr = mmap(NULL, NR_HUGE_PAGES * huge_page_size,
                        PROT_READ | PROT_WRITE,
                        MAP_SHARED, fd, 0);
        if (addr == MAP_FAILED) {
                perror("mmap");
                exit(1);
        }

        /* shared write should not consume any additional pages */
        write_fault_pages(addr, NR_HUGE_PAGES);
        validate_free_pages(free_hugepages - NR_HUGE_PAGES);

        addr2 = mmap(NULL, NR_HUGE_PAGES * huge_page_size,
                        PROT_READ | PROT_WRITE,
                        MAP_PRIVATE, fd, 0);
        if (addr2 == MAP_FAILED) {
                perror("mmap");
                exit(1);
        }

        /* private read should not consume any pages */
        read_fault_pages(addr2, NR_HUGE_PAGES);
        validate_free_pages(free_hugepages - NR_HUGE_PAGES);

        /* private write should consume additional pages */
        write_fault_pages(addr2, NR_HUGE_PAGES);
        validate_free_pages(free_hugepages - (2 * NR_HUGE_PAGES));

        /* madvise of shared mapping should not free any pages */
        if (madvise(addr, NR_HUGE_PAGES * huge_page_size, MADV_DONTNEED)) {
                perror("madvise");
                exit(1);
        }
        validate_free_pages(free_hugepages - (2 * NR_HUGE_PAGES));

        /* madvise of private mapping should free private pages */
        if (madvise(addr2, NR_HUGE_PAGES * huge_page_size, MADV_DONTNEED)) {
                perror("madvise");
                exit(1);
        }
        validate_free_pages(free_hugepages - NR_HUGE_PAGES);

        /* private write should consume additional pages again */
        write_fault_pages(addr2, NR_HUGE_PAGES);
        validate_free_pages(free_hugepages - (2 * NR_HUGE_PAGES));

        /*
         * madvise should free both file and private pages although this is
         * not correct.  private pages should not be freed, but this is
         * expected.  See comment associated with FALLOC_FL_PUNCH_HOLE call.
         */
        if (madvise(addr, NR_HUGE_PAGES * huge_page_size, MADV_REMOVE)) {
                perror("madvise");
                exit(1);
        }
        validate_free_pages(free_hugepages);

        (void)munmap(addr, NR_HUGE_PAGES * huge_page_size);
        (void)munmap(addr2, NR_HUGE_PAGES * huge_page_size);

        close(fd);
        return 0;
}