[Bug libc/269] New: PPC64 bit longjmp doesn't establish saved TOC properly

["sjmunroe at us dot ibm dot com" <sourceware-bugzilla at sources dot redhat dot com>]

Mark Mendell <mendell@ca.ibm.com> reports:

Hardware Environment:
p690 (actually any 64 bit PPC)

Software Environment:
RHEL 3 QU2 and SLES9 RC5

Steps to Reproduce:
1. t.c:
#include <setjmp.h>

jmp_buf buf1;
jmp_buf buf2;
int *p;
int n_x = 6;

static int g_counter = 0;
#define g(x) \
{		\
  int a[n_x], i;  \
  g_counter++;  \
  p = &a[0];	\
  if( g_counter < 5 ) longjmp(buf1, 2);  \
  else if( g_counter == 5 ) longjmp(buf1, 101);  \
  else { setjmp(buf2); longjmp(buf1, 101); }  \
}

int f(int n)
{
  static int counter = 0;
  int i;


  if( setjmp(buf1) != 101 ) {
    g(6);
  }

  if( counter == 0 ) {
    counter++;
    g(6);
  }

  if( counter == 1 ) {
    counter++;
    longjmp(buf2, 2);
  }

  return n;
}

int main( )
{
  f(6);
}

2. gcc -m64 t.c; a.out

Actual Results:
Segmentation fault

Expected Results:
<none>

Additional Information:

This is a previously seen problem with longjmp on AIX.  It is essential that 
longjmp store gpr2 at 40(sp) before returning to the user program.  This is 
because the call to setjmp is probably followed by a reload of gpr2.  If an
alloca (or VLA in C99) has been done between the setjmp and the longjmp, then
the saved TOC at 40(sp) may not be set.  The easiest fix is to add
'std r2,40(r1)' to the end of longjmp just before returning to the user code.

This was actually seen with a similar program compiled with xlc at -O4, but
I rewrote it for general distribution.

-- 
           Summary: PPC64 bit longjmp doesn't establish saved TOC properly
           Product: glibc
           Version: 2.3.3
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
        AssignedTo: gotom at debian dot or dot jp
        ReportedBy: sjmunroe at us dot ibm dot com
                CC: glibc-bugs at sources dot redhat dot com,sjmunroe at us
                    dot ibm dot com
  GCC host triplet: powerpc64--linux


http://sources.redhat.com/bugzilla/show_bug.cgi?id=269

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