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Remove NPTL_GUARD_WITHIN_STACK 

Commit 4b2f65b253 increased the user
space stack by 4x to resolve certain stack overflows.  As such it
no longer makes sense to worry about a single extra page which
might or might not be part of the process stack.  There is now
ample headroom for normal usage.

By eliminating this configure check we are also resolving the
following segfault which intentionally occurs at configure time
and may be logged in dmesg.

  conftest[22156]: segfault at 7fbf18a47e48 ip 00000000004007fe
  sp 00007fbf18a4be50 error 6 in conftest[400000+1000]

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
This commit is contained in:
Brian Behlendorf 2013-01-29 10:35:02 -08:00
parent 9759c60f1a
commit 79c6e4c445
4 changed files with 1 additions and 65 deletions
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56
config/user-nptl_guard_within_stack.m4
View File

@ -1,56 +0,0 @@
dnl #
dnl # Check if the glibc NPTL threading implementation includes the guard area
dnl # within the stack size allocation, rather than allocating extra space at
dnl # the end of the stack, as POSIX.1 requires.
dnl #
AC_DEFUN([ZFS_AC_CONFIG_USER_STACK_GUARD], [
AC_MSG_CHECKING([whether pthread stack includes guard])
saved_CFLAGS="$CFLAGS"
CFLAGS="-fstack-check"
saved_LDFLAGS="$LDFLAGS"
LDFLAGS="-lpthread"
AC_RUN_IFELSE([AC_LANG_PROGRAM(
[
#include <pthread.h>
#include <sys/resource.h>
#include <unistd.h>
#include <bits/local_lim.h>
#define PAGESIZE (sysconf(_SC_PAGESIZE))
#define STACK_SIZE 8192
#define BUFSIZE 4096
void * func(void *arg)
{
char buf[[BUFSIZE]];
}
],
[
pthread_t tid;
pthread_attr_t attr;
struct rlimit l;
l.rlim_cur = 0;
l.rlim_max = 0;
setrlimit(RLIMIT_CORE, &l);
pthread_attr_init(&attr);
pthread_attr_setstacksize(&attr, PTHREAD_STACK_MIN + STACK_SIZE);
pthread_attr_setguardsize(&attr, PAGESIZE);
pthread_create(&tid, &attr, func, NULL);
pthread_join(tid, NULL);
])],
[
AC_MSG_RESULT([no])
],
[
AC_DEFINE([NPTL_GUARD_WITHIN_STACK], 1,
[Define to 1 if NPTL threading implementation includes
guard area in stack allocation])
AC_MSG_RESULT([yes])
])
CFLAGS="$saved_CFLAGS"
LDFLAGS="$saved_LDFLAGS"
])

1
config/user.m4
View File

@ -10,5 +10,4 @@ AC_DEFUN([ZFS_AC_CONFIG_USER], [
ZFS_AC_CONFIG_USER_LIBBLKID ZFS_AC_CONFIG_USER_LIBBLKID
ZFS_AC_CONFIG_USER_LIBSELINUX ZFS_AC_CONFIG_USER_LIBSELINUX
ZFS_AC_CONFIG_USER_FRAME_LARGER_THAN ZFS_AC_CONFIG_USER_FRAME_LARGER_THAN
ZFS_AC_CONFIG_USER_STACK_GUARD
]) ])

6
include/sys/zfs_context.h
View File

@ -190,12 +190,6 @@ extern void vpanic(const char *, __va_list);
#define STACK_SIZE 24576 /* Solaris */ #define STACK_SIZE 24576 /* Solaris */
#endif #endif
#ifdef NPTL_GUARD_WITHIN_STACK
#define EXTRA_GUARD_BYTES PAGESIZE
#else
#define EXTRA_GUARD_BYTES 0
#endif
/* in libzpool, p0 exists only to have its address taken */ /* in libzpool, p0 exists only to have its address taken */
typedef struct proc { typedef struct proc {
uintptr_t this_is_never_used_dont_dereference_it; uintptr_t this_is_never_used_dont_dereference_it;

3
lib/libzpool/kernel.c
View File

@ -175,8 +175,7 @@ zk_thread_create(caddr_t stk, size_t stksize, thread_func_t func, void *arg,
* on Linux. * on Linux.
*/ */
stack = PTHREAD_STACK_MIN + MAX(stksize, STACK_SIZE) * 4 + stack = PTHREAD_STACK_MIN + MAX(stksize, STACK_SIZE) * 4;
EXTRA_GUARD_BYTES;
VERIFY3S(pthread_attr_init(&attr), ==, 0); VERIFY3S(pthread_attr_init(&attr), ==, 0);
VERIFY3S(pthread_attr_setstacksize(&attr, stack), ==, 0); VERIFY3S(pthread_attr_setstacksize(&attr, stack), ==, 0);