[LTP] [PATCH 01/29] Hugetlb: Migrating libhugetlbfs brk_near_huge
Cyril Hrubis
chrubis@suse.cz
Mon Oct 17 11:30:56 CEST 2022
Hi!
> 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/hugemmap07.c | 163 ++++++++++++++++++
> testcases/kernel/mem/hugetlb/lib/hugetlb.c | 75 ++++++++
> testcases/kernel/mem/hugetlb/lib/hugetlb.h | 5 +
> 5 files changed, 245 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/hugemmap07.c b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap07.c
> new file mode 100644
> index 000000000..06fd0b86c
> --- /dev/null
> +++ b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap07.c
> @@ -0,0 +1,163 @@
> +// SPDX-License-Identifier: LGPL-2.1-or-later
> +/*
> + * Copyright (C) 2005-2006 David Gibson & Adam Litke, IBM Corporation.
> + *
> + * Test Name: brk near hugepage
> + *
> + * 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.
This description has to be in a separate ascii-doc formatted comment
that starts with /*\
> + * HISTORY
> + * Written by David Gibson & Adam Litke
> + *
> + */
> +
> +#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 char *verbose;
> +static int fd = -1;
> +static char hfile[MAXPATHLEN];
> +static long hpage_size;
> +
> +static int arch_has_slice_support(void)
> +{
> +#ifdef __powerpc64__
> + char mmu_type[16];
> + FILE *fp;
> +
> + fp = SAFE_POPEN("cat /proc/cpuinfo | grep MMU | awk '{ print $3}'", "r");
> + if (fscanf(fp, "%s", mmu_type) < 0)
> + tst_brk(TBROK, "Failed to determine MMU type");
> +
> + pclose(fp);
> + return strcmp(mmu_type, "Hash") == 0;
> +#elif defined(__powerpc__) && !defined(PPC_NO_SEGMENTS)
> + return 1;
> +#else
> + return 0;
> +#endif
> +}
> +
> +#ifdef __powerpc64__
> +static void *next_chunk(void *addr)
> +{
> + if (!arch_has_slice_support())
> + return PALIGN(addr, SAFE_READ_MEMINFO("Hugepagesize:")*1024);
> +
> + 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, SAFE_READ_MEMINFO("Hugepagesize:")*1024);
> +}
> +#endif
> +
> +static void run_test(void)
> +{
> + void *brk0, *hugemap_addr, *newbrk;
> + char *p;
> + int err;
> +
> + fd = SAFE_OPEN(hfile, O_RDWR | O_CREAT, 0600);
> + SAFE_UNLINK(hfile);
> + brk0 = sbrk(0);
> + if (verbose)
> + 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, fd, 0);
> + if (p != hugemap_addr) {
> + tst_res(TFAIL, "mmap() at unexpected address %p instead of %p\n", p,
> + hugemap_addr);
> + goto fail;
Can we just do return here instead. The failure has been reported there
is no point in calling tst_brk(TBROK, ...) as well.
> + }
> +
> + err = test_addr_huge((void *)p);
> + if (err != 1) {
> + tst_res(TFAIL, "Mapped address is not hugepage");
> + goto fail;
> + }
I do not get why we even need this check. We map a file located on
hugetlbfs and then we stat it and check that it indeed is on hutetlbfs.
What did we expect to fail here? I would say that the mmap() with right
path is enough to make sure that the file is created on hugetlbfs.
> + 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 iff the new memory is
> + * properly accesible and we don't have a kernel blow up when
> + * we touch it.
> + */
> + memset(brk0, 0, newbrk-brk0);
> + tst_res(TPASS, "Succeding brk is acceptable, as memset confirms that "
> + "new memory is properly accessible without kernel blow up");
> + }
> + SAFE_MUNMAP(p, hpage_size);
> + SAFE_CLOSE(fd);
Shouldn't we brk() back to the original brk0? Does the test work with -i 2?
> + return;
> +fail:
> + tst_brk(TBROK, "Once failed, No point in continuing the test");
> +}
> +
> +static void setup(void)
> +{
> + if (tst_hugepages < 1)
> + tst_brk(TCONF, "Not enough hugepages for testing.");
> +
> + if (!Hopt)
> + Hopt = tst_get_tmpdir();
> + SAFE_MOUNT("none", Hopt, "hugetlbfs", 0, NULL);
> +
> + snprintf(hfile, sizeof(hfile), "%s/ltp_hugetlbfile%d", Hopt, getpid());
> + hpage_size = SAFE_READ_MEMINFO("Hugepagesize:")*1024;
> +}
> +
> +static void cleanup(void)
> +{
> + if (fd >= 0)
> + SAFE_CLOSE(fd);
> + umount2(Hopt, MNT_DETACH);
We whould umount here only if we actually have mounted something.
> +}
> +
> +static struct tst_test test = {
> + .needs_root = 1,
> + .needs_tmpdir = 1,
> + .options = (struct tst_option[]) {
> + {"v", &verbose, "Turns on verbose mode"},
> + {"H:", &Hopt, "Location of hugetlbfs, i.e. -H /var/hugetlbfs"},
> + {"s:", &nr_opt, "Set the number of the been allocated hugepages"},
> + {}
> + },
> + .setup = setup,
> + .cleanup = cleanup,
> + .test_all = run_test,
> + .hugepages = {1, TST_REQUEST},
> +};
> diff --git a/testcases/kernel/mem/hugetlb/lib/hugetlb.c b/testcases/kernel/mem/hugetlb/lib/hugetlb.c
> index 1204f21d2..d215c69dd 100644
> --- a/testcases/kernel/mem/hugetlb/lib/hugetlb.c
> +++ b/testcases/kernel/mem/hugetlb/lib/hugetlb.c
> @@ -29,15 +29,19 @@
> * getipckey()
> * getuserid()
> * rm_shm()
> + * read_maps()
> + * test_addr_huge()
> */
>
> #define TST_NO_DEFAULT_MAIN
> +#define _GNU_SOURCE
> #include <sys/types.h>
> #include <sys/ipc.h>
> #include <sys/shm.h>
> #include <sys/time.h>
> #include <pwd.h>
> #include "hugetlb.h"
> +#include "tst_safe_stdio.h"
>
> key_t shmkey;
>
> @@ -111,3 +115,74 @@ void rm_shm(int shm_id)
> tst_res(TINFO, "id = %d", shm_id);
> }
> }
> +
> +#define MAPS_BUF_SZ 4096
> +#define HUGETLBFS_MAGIC 0x958458f6
> +
> +int read_maps(unsigned long addr, char *buf)
> +{
> + FILE *f;
> + char line[MAPS_BUF_SZ];
> + char *tmp;
> +
> + f = SAFE_FOPEN("/proc/self/maps", "r");
> +
> + while (1) {
> + unsigned long start, end, off, ino;
> + int ret;
> +
> + tmp = fgets(line, MAPS_BUF_SZ, f);
> + if (!tmp)
> + break;
> +
> + buf[0] = '\0';
> + ret = sscanf(line, "%lx-%lx %*s %lx %*s %ld %255s",
> + &start, &end, &off, &ino,
> + buf);
> + if ((ret < 4) || (ret > 5)) {
> + tst_res(TWARN, "Couldn't parse /proc/self/maps line: %s\n",
> + line);
> + SAFE_FCLOSE(f);
> + return -1;
> + }
> +
> + if ((start <= addr) && (addr < end)) {
> + SAFE_FCLOSE(f);
> + return 1;
> + }
> + }
> +
> + SAFE_FCLOSE(f);
> + return 0;
> +}
> +
> +int test_addr_huge(void *p)
> +{
> + char name[256];
> + char *dirend;
> + int ret;
> + struct statfs64 sb;
> +
> + ret = read_maps((unsigned long)p, name);
> + if (ret < 0)
> + return ret;
> + if (ret == 0) {
> + tst_res(TWARN, "Couldn't find address %p in /proc/self/maps\n", p);
> + return -1;
> + }
> +
> + /* looks like a filename? */
> + if (name[0] != '/')
> + return 0;
> +
> + /* Truncate the filename portion */
> + dirend = strrchr(name, '/');
> + if (dirend && dirend > name)
> + *dirend = '\0';
> +
> + ret = statfs64(name, &sb);
> + if (ret)
> + return -1;
> +
> + return (sb.f_type == HUGETLBFS_MAGIC);
> +}
> diff --git a/testcases/kernel/mem/hugetlb/lib/hugetlb.h b/testcases/kernel/mem/hugetlb/lib/hugetlb.h
> index f75109f3e..c522314eb 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)
> @@ -39,5 +42,7 @@ extern key_t shmkey; /* an IPC key generated by ftok() */
> int getipckey(void);
> int getuserid(char *user);
> void rm_shm(int shm_id);
> +int test_addr_huge(void *p);
> +int read_maps(unsigned long addr, char *buf);
>
> #endif /* hugetlb.h */
> --
> 2.31.1
>
>
> --
> Mailing list info: https://lists.linux.it/listinfo/ltp
--
Cyril Hrubis
chrubis@suse.cz
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