get_page_size.c

#include <stdio.h>
#include <fcntl.h>
#include <elf.h>
#include <string.h>
#include <errno.h>
#include <sys/auxv.h>
#include <unistd.h>

// See: https://elixir.bootlin.com/linux/v5.19-rc4/source/fs/binfmt_elf.c#L260
static long get_page_size(void)
{
	Elf64_Off buf[2];
	long page_size;
	int fd;

	fd = open("/proc/self/auxv", O_RDONLY);
	if (fd < 0)
		return -errno;

	while (1) {
		ssize_t ret;

		ret = read(fd, buf, sizeof(buf));
		if (ret < 0) {
			page_size = -errno;
			break;
		}

		if (ret < sizeof(buf)) {
			page_size = -ENOENT;
			break;
		}

		if (buf[0] == AT_PAGESZ) {
			page_size = buf[1];
			break;
		}
	}

	close(fd);
	return page_size;
}

int main(void)
{
	printf("pg = %ld\n", get_page_size());
	return 0;
}