[LTP] [PATCH v5 2/4] Hugetlb: Migrating libhugetlbfs brk_near_huge

[Cyril Hrubis]

Hi!
> --- a/testcases/kernel/mem/hugetlb/hugemmap/Makefile
> +++ b/testcases/kernel/mem/hugetlb/hugemmap/Makefile
> @@ -9,3 +9,8 @@ include $(abs_srcdir)/../Makefile.inc
>  include $(top_srcdir)/include/mk/generic_leaf_target.mk
>  
>  hugemmap06: CFLAGS+=-pthread
> +
> +hugemmap07:
> +ifeq ($(ARCH),ppc)
> +	CPPFLAGS += -DPPC_NO_SEGMENTS
> +endif

I do not think that ARCH is defined in LTP build system. Where does it
come from in the original test?

> diff --git a/testcases/kernel/mem/hugetlb/hugemmap/hugemmap07.c b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap07.c
> new file mode 100644
> index 000000000..73ed4b0d6
> --- /dev/null
> +++ b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap07.c
> @@ -0,0 +1,138 @@
> +// SPDX-License-Identifier: LGPL-2.1-or-later
> +/*
> + * Copyright (C) 2005-2006 David Gibson & Adam Litke, IBM Corporation.
> + * Author: David Gibson & Adam Litke
> + */
> +
> +/*\
> + *
> + * [Description]
> + *
> + * brk() near hugepage:
           ^
	   I would just remove this, it does not render nicely in the
	   asciidoc and it's not useful either.

> + * Certain kernels have a bug where brk() does not perform the same
> + * checks that a MAP_FIXED mmap() will, allowing brk() to create a
> + * normal page VMA in a hugepage only address region. This can lead
> + * to oopses or other badness.
> + */
> +
> +#define _GNU_SOURCE
> +#include <stdio.h>
> +#include <sys/mount.h>
> +#include <limits.h>
> +#include <sys/param.h>
> +#include <sys/types.h>
> +
> +#include "hugetlb.h"
> +#include "tst_safe_stdio.h"
> +
> +#define MNTPOINT "hugetlbfs/"
> +static long hpage_size;
> +static int huge_fd = -1;
> +
> +#ifdef __powerpc64__
> +static int arch_has_slice_support(void)
> +{
> +	char mmu_type[16];
> +	FILE *fp;
> +	int ret;
> +
> +	fp = SAFE_POPEN("cat /proc/cpuinfo | grep MMU | awk '{ print $3}'", "r");
> +	ret = fscanf(fp, "%s", mmu_type);
> +	pclose(fp);
> +
> +	if (ret < 0)
> +		tst_brk(TBROK, "Failed to determine MMU type");
> +
> +	return strcmp(mmu_type, "Hash") == 0;
> +}
> +
> +static void *next_chunk(void *addr)
> +{
> +	if (!arch_has_slice_support())
> +		return PALIGN(addr, hpage_size);
> +
> +	if ((unsigned long)addr < 0x100000000UL)
> +		/* 256M segments below 4G */
> +		return PALIGN(addr, 0x10000000UL);
> +	/* 1TB segments above */
> +	return PALIGN(addr, 0x10000000000UL);
> +}
> +#elif defined(__powerpc__) && !defined(PPC_NO_SEGMENTS)
> +static void *next_chunk(void *addr)
> +{
> +	return PALIGN(addr, 0x10000000UL);
> +}
> +#elif defined(__ia64__)
> +static void *next_chunk(void *addr)
> +{
> +	return PALIGN(addr, 0x8000000000000000UL);
> +}
> +#else
> +static void *next_chunk(void *addr)
> +{
> +	return PALIGN(addr, hpage_size);
> +}
> +#endif
> +
> +static void run_test(void)
> +{
> +	void *brk0, *hugemap_addr, *newbrk;
> +	char *p;
> +	int err;
> +
> +	brk0 = sbrk(0);
> +	tst_res(TINFO, "Initial break at %p", brk0);
> +
> +	hugemap_addr = next_chunk(brk0) + hpage_size;
> +
> +	p = SAFE_MMAP(hugemap_addr, hpage_size, PROT_READ|PROT_WRITE,
> +			MAP_PRIVATE|MAP_FIXED, huge_fd, 0);
> +	if (p != hugemap_addr) {
> +		tst_res(TFAIL, "mmap() at unexpected address %p instead of %p\n", p,
> +		     hugemap_addr);
> +		goto cleanup;
> +	}
> +
> +	newbrk = next_chunk(brk0) + getpagesize();
> +	err = brk((void *)newbrk);
> +	if (err == -1) {
> +		/* Failing the brk() is an acceptable kernel response */
> +		tst_res(TPASS, "Failing the brk is an acceptable response");
> +	} else {
> +		/* Suceeding the brk() is acceptable if the new memory is
> +		 * properly accesible and we don't have a kernel blow up when
> +		 * we touch it.
> +		 */
> +		tst_res(TINFO, "New break at %p", newbrk);
> +		memset(brk0, 0, newbrk-brk0);
> +		tst_res(TPASS, "memory is accessible, hence successful brk() is "
> +				"an acceptable response");
> +	}
> +cleanup:
> +	SAFE_MUNMAP(p, hpage_size);
> +	err = brk(brk0);
> +	if (err == -1)
> +		tst_brk(TBROK, "Failed to set break at the original position");
> +}
> +
> +static void setup(void)
> +{
> +	hpage_size = SAFE_READ_MEMINFO("Hugepagesize:")*1024;
> +	huge_fd = tst_creat_unlinked(MNTPOINT);
> +}
> +
> +static void cleanup(void)
> +{
> +	SAFE_CLOSE(huge_fd);
> +}
> +
> +static struct tst_test test = {
> +	.needs_root = 1,
> +	.mntpoint = MNTPOINT,
> +	.needs_hugetlbfs = 1,
> +	.taint_check = TST_TAINT_D | TST_TAINT_W,
> +	.setup = setup,
> +	.cleanup = cleanup,
> +	.test_all = run_test,
> +	.hugepages = {1, TST_NEEDS},
> +};
> diff --git a/testcases/kernel/mem/hugetlb/lib/hugetlb.h b/testcases/kernel/mem/hugetlb/lib/hugetlb.h
> index f75109f3e..1cfeca95a 100644
> --- a/testcases/kernel/mem/hugetlb/lib/hugetlb.h
> +++ b/testcases/kernel/mem/hugetlb/lib/hugetlb.h
> @@ -20,6 +20,9 @@
>  #include "old_tmpdir.h"
>  #include "mem.h"
>  
> +#define ALIGN(x, a)	(((x) + (a) - 1) & ~((a) - 1))

We do have a LTP_ALIGN() please make use of that one instead.

> +#define PALIGN(p, a) ((void *)ALIGN((unsigned long)(p), (a)))
> +
>  #define SHM_RD	0400
>  #define SHM_WR	0200
>  #define SHM_RW	(SHM_RD|SHM_WR)

Have you run 'make check-hugemmap07' in the respecive directory, did it
report any problems?

-- 
Cyril Hrubis
chrubis@suse.cz