TestCases

Kernel Testcases

Math test case

should return 0.0: (hppa floating point error)

#include <stdio.h>
#include <math.h>
int
main (void) {
 double result = exp (-4.3682654441477153e+19);
 printf ("%g\n", result);
 if (result != 0.0)
  return 1;
 return 0;
}

Futex wait failure

No testcase.

Threads and fork on VIPT-WB machines

• Affects #561203.
• Discussed on this thread and this thread

Summary from JDA:

The minifail bug is a "Threads and fork" problem arising from cache corruption. Mainly, copy_user_page is broken when copying memory shared by more than one process. There are also issues in PTE/TLB management on SMP systems. Probably, the vfork/execve bug is caused by the same problem.

Initial patch syscall.S.d.1 from JDA

First testcase minifail.cpp

Build with:

g++ -I/usr/include/qt4 -lQtCore minifail.cpp -o minifail -O0 -g

Fails occasionally with:

$ i=0; while true; do i=$(($i+1)); echo Run $i; ./minifail; done;
$ i=0; while true; do i=$(($i+1)); echo Run $i; ./minifail qt; done;
 

Typical observed failure:

Run 21
Segmentation fault
Run 22
Child OK.
Thread OK.
Run 23
Thread OK.
Segmentation fault
 

• Reduced minifail6.cpp, from this post
• Tentative patch], see this post
• Other version minifail3.c from Helge Deller
• Other version [1] from JDA
• Other version minifail12.cpp from JDA
• Final (?) version minifail_dave.cpp from Helge Deller

---

Other testcase from JDA:

Compile with -static to link with libc.a. Testcase prints incorrect parent pid.:

#!cplusplus
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/types.h>
#include <unistd.h>

#define CALL_EXIT 0

int main (void)
{
  pid_t child;
  pid_t parent;
  char *cmd[] = { "bash", "-c", "echo In child $$;", (char *)0 };
  char *env[] = { "HOME=/tmp", (char *)0 };
  int ret;

  child = vfork();

  if (child == 0)
    {
      ret = execve("/bin/bash", cmd, env);
      // printf ("ret = %d\n", ret);
      _exit(1);
    }
  else
    {
      // printf("child != 0\n");
    }

  parent = getpid();
  printf("parent is %d\n", (unsigned int)parent);
  printf("child is %d\n", (unsigned int)child);

  return 0;
}
 

Patches

• parisc_lock_v2.patch from Helge Deller - Not Applicable (not-upstream)
• entry.S.patch from JDA (not-upstream)
• patch1 from JDA - Superseded by patch2 (not-upstream)
• patch2 from JDA - Included in patch3 (not-upstream)
• bundle patch3 from JDA - Partially split into
  • Call pagefault_disable/pagefault_enable in kmap_atomic/kunmap_atomic (on-buildds)
  • Remove unnecessary macros from entry.S (on-buildds)
  • Delete unnecessary nop's in entry.S (on-buildds)
  • Avoid interruption in critical region in entry.S (on-buildds)
  • LWS fixes for syscall.S (on-buildds)
  • Note: some bits from patch3 have not be separately submitted (futex.h, etc) - Needs review
• pgtable.h patch update, initially found in patch3 from JDA (not-upstream)
• bundle patch4 aka pte.2.d from JDA, updating parts of patch3 (not-upstream)
• patch] from James Bottomley for kmap issues fixing minifail6.cpp (not-upstream)
• bundle patch5 from JDA with a slightly modified version of James' patch (not-upstream)
• bundle patch6 from JDA, with apparently good results both on pa8800 and previous CPUs (not-upstream)
• bundle patch7 from JDA, with reworked pacache.s and cache.c (not-upstream)

vfork/execve

• Affects #558905
• Discussed by Carlos O'Donell in this thread:

I have constructed a vfork test case which shows some of the problems I have using vfork reliably. This fails every time on my PA8700 system running 2.6.32-rc6. It appears as though r28 (ret0) in the parent is being corrupted.

The intent of the testcase is to do the following:

1. vfork
2. Launch "ls -l" in the vfork'd child.
3. Print some information in the parent.

/* vfork.c */
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>

int main (void)
{
  pid_t child;
  char *cmd[] = { "ls", "-l", (char *)0 };
  char *env[] = { "HOME=/tmp", (char *)0 };

  child = vfork();

  if (child == 0)
    {
      execve("/bin/ls", cmd, env);
    }
  else
    {
      printf("child != 0\n");
    }

  printf("child is 0x%x\n", (unsigned int)child);

  return 0;
}
 

Compile this test case twice:

1. gcc -O1 -g -o vfork-O1 vfork.c
2. gcc -O0 -g -o vfork-O0 vfork.c

The return from vfork is corrupted in the parent. This gets worse at -O0.

To remove the C library from the loop I attach a complete vfork implementation as used by glibc. pt-vfork.s

You can compile the test case using: cc -O1 -g -o vfork-O1 vfork.c pt-vfork.s

In summary:

• Test case works on x86.
• Test case fails on hppa.
• Test case works on hppa under strace.

More discussion by Carlos O'Donell in this thread

• Other testcase vforktest.tgz by Carlos O'Donell
• Updated (?) testcase vforktest.tgz by Carlos O'Donell

Patches

• Patch from JDA (not-upstream)
• Patch from Carlos O'Donell - Comments/cleanup (on-buildds)

floating point SIGFPE not trapped

• Affects #559406
• Testcase fputest.c

Patches

• Patch from Helge Deller (in-debian, on-buildds)

GCC TestCases

MMAP

• Affects PR40505.
• Discussed by Carlos O'Donell on this thread.
• Testcase test-mmap.c from Carlos O'Donell

GLIBC TestCases

Segmentation fault in __libc_start_main with -static

Discussed in this thread

Testcase from JDA: Compile with g++ -o xx -static -pthread xx.C

// This test only applies to glibc (NPTL) targets.
// { dg-do run { target *-*-linux* } }
// { dg-options "-pthread" }

#include <pthread.h>
#include <cxxabi.h>
extern "C" int printf (const char *, ...);

int main()
{
  try
    {
      pthread_exit (0);
    }
  catch (abi::__forced_unwind &)
    {
      printf ("caught forced unwind\n");
      throw;
    }
  catch (...)
    {
      printf ("caught ...\n");
      return 1;
    }
}