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