[LTP] [PATCH v3 2/4] Hugetlb: Migrating libhugetlbfs brk_near_huge

[Tarun Sahu]

Migrating the libhugetlbfs/testcases/brk_near_huge.c test

Test Description:
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.

Signed-off-by: Tarun Sahu <tsahu@linux.ibm.com>
---
 runtest/hugetlb                               |   1 +
 testcases/kernel/mem/.gitignore               |   1 +
 .../kernel/mem/hugetlb/hugemmap/Makefile      |   5 +
 .../kernel/mem/hugetlb/hugemmap/hugemmap07.c  | 129 ++++++++++++++++++
 testcases/kernel/mem/hugetlb/lib/hugetlb.h    |   3 +
 5 files changed, 139 insertions(+)
 create mode 100644 testcases/kernel/mem/hugetlb/hugemmap/hugemmap07.c

diff --git a/runtest/hugetlb b/runtest/hugetlb
index f719217ab..f7ff81cb3 100644
--- a/runtest/hugetlb
+++ b/runtest/hugetlb
@@ -3,6 +3,7 @@ hugemmap02 hugemmap02
 hugemmap04 hugemmap04
 hugemmap05 hugemmap05
 hugemmap06 hugemmap06
+hugemmap07 hugemmap07
 hugemmap05_1 hugemmap05 -m
 hugemmap05_2 hugemmap05 -s
 hugemmap05_3 hugemmap05 -s -m
diff --git a/testcases/kernel/mem/.gitignore b/testcases/kernel/mem/.gitignore
index ff2910533..df5256ec8 100644
--- a/testcases/kernel/mem/.gitignore
+++ b/testcases/kernel/mem/.gitignore
@@ -4,6 +4,7 @@
 /hugetlb/hugemmap/hugemmap04
 /hugetlb/hugemmap/hugemmap05
 /hugetlb/hugemmap/hugemmap06
+/hugetlb/hugemmap/hugemmap07
 /hugetlb/hugeshmat/hugeshmat01
 /hugetlb/hugeshmat/hugeshmat02
 /hugetlb/hugeshmat/hugeshmat03
diff --git a/testcases/kernel/mem/hugetlb/hugemmap/Makefile b/testcases/kernel/mem/hugetlb/hugemmap/Makefile
index 2d651b4aa..a368db2b6 100644
--- 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
diff --git a/testcases/kernel/mem/hugetlb/hugemmap/hugemmap07.c b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap07.c
new file mode 100644
index 000000000..5e04cef03
--- /dev/null
+++ b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap07.c
@@ -0,0 +1,129 @@
+// 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:
+ * 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"
+
+static long hpage_size;
+
+#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, tst_hugetlb_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;
+}
+
+static struct tst_test test = {
+	.needs_root = 1,
+	.needs_hugetlbfs = 1,
+	.needs_unlinked_hugetlb_file = 1,
+	.taint_check = TST_TAINT_D | TST_TAINT_W,
+	.setup = setup,
+	.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))
+#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)
-- 
2.31.1