[LTP] [PATCH] [PATCH] Add hugemmap37, migrated task-size-overrun.c from libhugetlbfs v2

[Cyril Hrubis]

Hi!
> +/*\
> + *[Descripiton]
> + *
> + * Origin: https://github.com/libhugetlbfs/libhugetlbfs/blob/master/tests/task-size-overrun.c
> + *
> + * This test verifies the behavior of mmap across the TASK_SIZE boundary.
> + * It checks whether mmap with and without MAP_FIXED correctly handles
> + * mappings that straddle the TASK_SIZE boundary.
> + *
> + */
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <sys/mman.h>
> +#include <errno.h>
> +#include <assert.h>
> +
> +#include "hugetlb.h"
> +#include "tst_test.h"
> +#include "tst_safe_stdio.h"
> +#include "tst_safe_macros.h"
> +
> +#define MAPS_BUF_SZ 4096
> +#define _LARGEFILE64_SOURCE
> +#define MNTPOINT "hugetlbfs/"
> +#define ALIGN(x, a) (((x) + (a) - 1) & ~((a) - 1))

We have LTP_ALIGN() macro in the test library.

> +static long hpage_size;
> +static int fd;
> +
> +static unsigned long find_last_mapped(void)
> +{
> +	char line[MAPS_BUF_SZ];
> +	char *tmp;
> +	unsigned long start, end, off, ino;
> +	FILE *f;
> +
> +	f = SAFE_FOPEN("/proc/self/maps", "r");
> +	do {
> +		tmp = fgets(line, MAPS_BUF_SZ, f);
> +	} while (tmp);
> +	SAFE_FCLOSE(f);
> +
> +	tst_res(TINFO, "Last map: %s", line);
> +	SAFE_SSCANF(line, "%lx-%lx %*s %lx %*s %ld %*s", &start, &end, &off, &ino);
> +	tst_res(TINFO, "Last map: at 0x%lx-0x%lx\n", start, end);
> +	return end;
> +}
> +
> +static unsigned long find_task_size(void)
> +{
> +	unsigned long low, high; /* PFNs */
> +	void *p;
> +
> +	low = find_last_mapped();
> +	if (!low || ((low % getpagesize()) != 0))
> +		tst_brk(TBROK, "Bogus stack end address, 0x%lx!?", low);

The last mapping in /proc/self/maps on my systems is [vsyscall] which is
mapped at the end of the address space. I guess that we need to take
last line from the file that is not [vsyscall] (and perhaps there are
other special cases on some architectures but that can be fixed later).

> +	low = low / getpagesize();
> +
> +	/* This sum should get us (2^(wordsize) - 2 pages) */
> +	high = (unsigned long)(-2 * getpagesize()) / tst_get_hugepage_size();

I do not get this at all. We are trying to figure out TASK_SIZE how
exactly do we figure out the upper bound from hugepage size?

> +	tst_res(TINFO, "Binary searching for task size PFNs 0x%lx..0x%lx\n", low, high);
> +
> +	while (high > low + 1) {
> +		unsigned long pfn = (low + high) / 2;
> +		unsigned long addr = pfn * getpagesize();
> +
> +		assert((pfn >= low) && (pfn <= high));

As long as I can tell this assert is never triggered.

> +		p = mmap((void *)addr, getpagesize(), PROT_READ,
> +			   MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, -1, 0);
> +		if (p == MAP_FAILED) {
> +			tst_res(TINFO | TERRNO, "Map failed at 0x%lx", addr);
> +			high = pfn;
> +		} else {
> +			tst_res(TINFO, "Map succeeded at 0x%lx\n", addr);
> +			SAFE_MUNMAP(p, getpagesize());
> +			low = pfn;
> +		}
> +	}
> +
> +	return low * getpagesize();
> +}
> +
> +static void run_test(void)
> +{
> +	void *p;
> +	unsigned long task_size;
> +	unsigned long straddle_addr;
> +
> +	task_size = find_task_size();
> +	tst_res(TINFO, "TASK_SIZE = 0x%lx\n", task_size);
> +
> +	straddle_addr = task_size - hpage_size;
> +	straddle_addr = ALIGN(straddle_addr, hpage_size);
> +
> +	tst_res(TINFO, "Mapping without MAP_FIXED at %lx...", straddle_addr);
> +	errno = 0;
> +	p = mmap((void *)straddle_addr, 2*hpage_size, PROT_READ|PROT_WRITE,
> +		 MAP_SHARED, fd, 0);
> +	if (p == (void *)straddle_addr)
> +		tst_res(TFAIL, "Apparently suceeded in mapping across TASK_SIZE boundary");
> +
> +	tst_res(TINFO, "Mapping with MAP_FIXED at %lx...", straddle_addr);
> +	errno = 0;
> +	p = mmap((void *)straddle_addr, 2*hpage_size, PROT_READ|PROT_WRITE,
> +		 MAP_SHARED|MAP_FIXED, fd, 0);
> +	if (p != MAP_FAILED)
> +		tst_res(TFAIL, "Apparently suceeded in mapping across TASK_SIZE boundary");
> +
> +	tst_res(TPASS, "Test passed!");
> +}
> +
> +static void setup(void)
> +{
> +	hpage_size = getpagesize();
> +	fd = tst_creat_unlinked(MNTPOINT, 0, 0600);
> +}
> +
> +static void cleanup(void)
> +{
> +	if (fd > 0)
> +		SAFE_CLOSE(fd);
> +}
> +
> +static struct tst_test test = {
> +	.needs_root = 1,
> +	.mntpoint = MNTPOINT,
> +	.needs_hugetlbfs = 1,
> +	.setup = setup,
> +	.cleanup = cleanup,
> +	.test_all = run_test,
> +	.hugepages = {3, TST_NEEDS},
> +};
> -- 
> 2.43.5
> 

-- 
Cyril Hrubis
chrubis@suse.cz