145 lines
3.3 KiB
C
145 lines
3.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* A test case of using hugepage memory in a user application using the
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* mmap system call with MAP_HUGETLB flag. Before running this program
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* make sure the administrator has allocated enough default sized huge
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* pages to cover the 2 MB allocation.
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*/
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#include <stdlib.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <sys/mman.h>
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#include <fcntl.h>
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#define MAP_LENGTH (2UL * 1024 * 1024)
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#ifndef MAP_HUGETLB
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#define MAP_HUGETLB 0x40000 /* arch specific */
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#endif
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#define PAGE_SIZE 4096
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#define PAGE_COMPOUND_HEAD (1UL << 15)
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#define PAGE_COMPOUND_TAIL (1UL << 16)
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#define PAGE_HUGE (1UL << 17)
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#define HEAD_PAGE_FLAGS (PAGE_COMPOUND_HEAD | PAGE_HUGE)
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#define TAIL_PAGE_FLAGS (PAGE_COMPOUND_TAIL | PAGE_HUGE)
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#define PM_PFRAME_BITS 55
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#define PM_PFRAME_MASK ~((1UL << PM_PFRAME_BITS) - 1)
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/*
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* For ia64 architecture, Linux kernel reserves Region number 4 for hugepages.
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* That means the addresses starting with 0x800000... will need to be
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* specified. Specifying a fixed address is not required on ppc64, i386
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* or x86_64.
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*/
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#ifdef __ia64__
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#define MAP_ADDR (void *)(0x8000000000000000UL)
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#define MAP_FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB | MAP_FIXED)
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#else
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#define MAP_ADDR NULL
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#define MAP_FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB)
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#endif
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static void write_bytes(char *addr, size_t length)
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{
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unsigned long i;
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for (i = 0; i < length; i++)
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*(addr + i) = (char)i;
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}
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static unsigned long virt_to_pfn(void *addr)
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{
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int fd;
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unsigned long pagemap;
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fd = open("/proc/self/pagemap", O_RDONLY);
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if (fd < 0)
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return -1UL;
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lseek(fd, (unsigned long)addr / PAGE_SIZE * sizeof(pagemap), SEEK_SET);
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read(fd, &pagemap, sizeof(pagemap));
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close(fd);
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return pagemap & ~PM_PFRAME_MASK;
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}
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static int check_page_flags(unsigned long pfn)
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{
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int fd, i;
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unsigned long pageflags;
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fd = open("/proc/kpageflags", O_RDONLY);
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if (fd < 0)
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return -1;
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lseek(fd, pfn * sizeof(pageflags), SEEK_SET);
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read(fd, &pageflags, sizeof(pageflags));
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if ((pageflags & HEAD_PAGE_FLAGS) != HEAD_PAGE_FLAGS) {
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close(fd);
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printf("Head page flags (%lx) is invalid\n", pageflags);
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return -1;
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}
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/*
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* pages other than the first page must be tail and shouldn't be head;
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* this also verifies kernel has correctly set the fake page_head to tail
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* while hugetlb_free_vmemmap is enabled.
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*/
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for (i = 1; i < MAP_LENGTH / PAGE_SIZE; i++) {
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read(fd, &pageflags, sizeof(pageflags));
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if ((pageflags & TAIL_PAGE_FLAGS) != TAIL_PAGE_FLAGS ||
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(pageflags & HEAD_PAGE_FLAGS) == HEAD_PAGE_FLAGS) {
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close(fd);
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printf("Tail page flags (%lx) is invalid\n", pageflags);
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return -1;
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}
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}
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close(fd);
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return 0;
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}
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int main(int argc, char **argv)
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{
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void *addr;
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unsigned long pfn;
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addr = mmap(MAP_ADDR, MAP_LENGTH, PROT_READ | PROT_WRITE, MAP_FLAGS, -1, 0);
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if (addr == MAP_FAILED) {
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perror("mmap");
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exit(1);
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}
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/* Trigger allocation of HugeTLB page. */
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write_bytes(addr, MAP_LENGTH);
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pfn = virt_to_pfn(addr);
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if (pfn == -1UL) {
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munmap(addr, MAP_LENGTH);
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perror("virt_to_pfn");
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exit(1);
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}
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printf("Returned address is %p whose pfn is %lx\n", addr, pfn);
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if (check_page_flags(pfn) < 0) {
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munmap(addr, MAP_LENGTH);
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perror("check_page_flags");
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exit(1);
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}
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/* munmap() length of MAP_HUGETLB memory must be hugepage aligned */
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if (munmap(addr, MAP_LENGTH)) {
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perror("munmap");
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exit(1);
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}
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return 0;
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}
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