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Fix tst-pthread-getattr test case

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Get the tst-pthread-getattr fix back with further improvements so that
it does not fail on targets that use the user stack to save
context.
This commit is contained in:
Siddhesh Poyarekar 2012-07-28 13:25:00 +05:30
parent e5abc686ef
commit fc56c5bbc1
2 changed files with 73 additions and 21 deletions
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11
nptl/ChangeLog
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@ -1,3 +1,14 @@
2012-07-28 Siddhesh Poyarekar <siddhesh@redhat.com>
* tst-pthread-getattr.c (MAX_STACK_SIZE): New macro.
(pagesize): New static variable.
(allocate_and_test): Return MEM. Rename parameter to TARGET.
(check_stack_top): New local variables MEM and PAGEMASK. Cap
stack size to MAX_STACK_SIZE. Call allocate_and_test for
halfway up the stack top page. Verify that the top page was
written into.
(do_test): Get pagesize using sysconf.
2012-07-25 Andreas Schwab <schwab@linux-m68k.org>
* sysdeps/unix/sysv/linux/i386/pt-vfork.S: Remove pseudo_end

83
nptl/tst-pthread-getattr.c
View file

@ -21,18 +21,37 @@
#include <stdio.h>
#include <string.h>
#include <sys/resource.h>
#include <sys/param.h>
#include <pthread.h>
#include <alloca.h>
#include <assert.h>
#include <unistd.h>
#include <inttypes.h>
/* Move the stack pointer so that stackaddr is accessible and then check if it
really is accessible. This will segfault if it fails. */
static void
allocate_and_test (void *stackaddr)
/* There is an obscure bug in the kernel due to which RLIMIT_STACK is sometimes
returned as unlimited when it is not, which may cause this test to fail.
There is also the other case where RLIMIT_STACK is intentionally set as
unlimited or very high, which may result in a vma that is too large and again
results in a test case failure. To avoid these problems, we cap the stack
size to one less than 8M. See the following mailing list threads for more
information about this problem:
<http://sourceware.org/ml/libc-alpha/2012-06/msg00599.html>
<http://sourceware.org/ml/libc-alpha/2012-06/msg00713.html>. */
#define MAX_STACK_SIZE (8192 * 1024 - 1)
static size_t pagesize;
/* Check if the page in which TARGET lies is accessible. This will segfault
if it fails. */
static volatile char *
allocate_and_test (char *target)
{
void *mem = &mem;
/* FIXME: The difference will be negative for _STACK_GROWSUP. */
mem = alloca ((size_t) (mem - stackaddr));
*(int *)(mem) = 0;
volatile char *mem = (char *) &mem;
/* FIXME: mem >= target for _STACK_GROWSUP. */
mem = alloca ((size_t) (mem - target));
*mem = 42;
return mem;
}
static int
@ -42,13 +61,13 @@ get_self_pthread_attr (const char *id, void **stackaddr, size_t *stacksize)
int ret;
pthread_t me = pthread_self ();
if ((ret = pthread_getattr_np (me, &attr)))
if ((ret = pthread_getattr_np (me, &attr)) < 0)
{
printf ("%s: pthread_getattr_np failed: %s\n", id, strerror (ret));
return 1;
}
if ((ret = pthread_attr_getstack (&attr, stackaddr, stacksize)))
if ((ret = pthread_attr_getstack (&attr, stackaddr, stacksize)) < 0)
{
printf ("%s: pthread_attr_getstack returned error: %s\n", id,
strerror (ret));
@ -65,8 +84,10 @@ check_stack_top (void)
{
struct rlimit stack_limit;
void *stackaddr;
volatile void *mem;
size_t stacksize = 0;
int ret;
uintptr_t pagemask = ~(pagesize - 1);
puts ("Verifying that stack top is accessible");
@ -77,19 +98,22 @@ check_stack_top (void)
return 1;
}
printf ("current rlimit_stack is %zu\n", (size_t) stack_limit.rlim_cur);
if (get_self_pthread_attr ("check_stack_top", &stackaddr, &stacksize))
return 1;
/* Reduce the rlimit to a page less that what is currently being returned so
that we ensure that pthread_getattr_np uses rlimit. The figure is
intentionally unaligned so to verify that pthread_getattr_np returns an
aligned stacksize that correctly fits into the rlimit. We don't bother
about the case where the stack is limited by the vma below it and not by
the rlimit because the stacksize returned in that case is computed from
the end of that vma and is hence safe. */
stack_limit.rlim_cur = stacksize - 4095;
printf ("Adjusting RLIMIT_STACK to %zu\n", stack_limit.rlim_cur);
if ((ret = setrlimit (RLIMIT_STACK, &stack_limit)))
/* Reduce the rlimit to a page less that what is currently being returned
(subject to a maximum of MAX_STACK_SIZE) so that we ensure that
pthread_getattr_np uses rlimit. The figure is intentionally unaligned so
to verify that pthread_getattr_np returns an aligned stacksize that
correctly fits into the rlimit. We don't bother about the case where the
stack is limited by the vma below it and not by the rlimit because the
stacksize returned in that case is computed from the end of that vma and is
hence safe. */
stack_limit.rlim_cur = MIN (stacksize - pagesize + 1, MAX_STACK_SIZE);
printf ("Adjusting RLIMIT_STACK to %zu\n", (size_t) stack_limit.rlim_cur);
if ((ret = setrlimit (RLIMIT_STACK, &stack_limit)) < 0)
{
perror ("setrlimit failed");
return 1;
@ -100,7 +124,23 @@ check_stack_top (void)
printf ("Adjusted rlimit: stacksize=%zu, stackaddr=%p\n", stacksize,
stackaddr);
allocate_and_test (stackaddr);
/* A lot of targets tend to write stuff on top of the user stack during
context switches, so we cannot possibly safely go up to the very top of
stack and test access there. It is however sufficient to simply check if
the top page is accessible, so we target our access halfway up the top
page. Thanks Chris Metcalf for this idea. */
mem = allocate_and_test (stackaddr + pagesize / 2);
/* Before we celebrate, make sure we actually did test the same page. */
if (((uintptr_t) stackaddr & pagemask) != ((uintptr_t) mem & pagemask))
{
printf ("We successfully wrote into the wrong page.\n"
"Expected %#" PRIxPTR ", but got %#" PRIxPTR "\n",
(uintptr_t) stackaddr & pagemask, (uintptr_t) mem & pagemask);
return 1;
}
puts ("Stack top tests done");
@ -112,6 +152,7 @@ check_stack_top (void)
static int
do_test (void)
{
pagesize = sysconf (_SC_PAGESIZE);
return check_stack_top ();
}