[Bug libc/455] New: ARM profiling fault

["andy dot andystewart at gmail dot com" <sourceware-bugzilla at sources dot redhat dot com>]

A segmentation fault occurs when using the -pg profiling options of gcc for ARM targets.  

The problem is due to how a buffer is allocated for profiling samples.  One allocation is made for 
multiple buffers, and the second buffer is not aligned on a 4 byte boundary.  When _mcount is 
subsequently called, an invalid index is read from the unaligned buffer, and _mcount attempts to store 
the profiling data at an invalid address.

Please include the following patches to gmon/gmon.c, elf/dl-profile.c, and elf/sprof.c in the glibc 
component:

--- glibc-2.3.2/gmon/gmon.c	2004-09-25 10:16:24.000000000 -0700
+++ mod_gmon.c	                2004-09-25 10:09:40.000000000 -0700
@@ -113,7 +113,7 @@
   p->lowpc = ROUNDDOWN(lowpc, HISTFRACTION * sizeof(HISTCOUNTER));
   p->highpc = ROUNDUP(highpc, HISTFRACTION * sizeof(HISTCOUNTER));
   p->textsize = p->highpc - p->lowpc;
-  p->kcountsize = p->textsize / HISTFRACTION;
+  p->kcountsize = ((p->textsize / HISTFRACTION) + 3) & ~3;
   p->hashfraction = HASHFRACTION;
   p->log_hashfraction = -1;
   /* The following test must be kept in sync with the corresponding


--- glibc-2.3.2/elf/dl-profile.c	2004-09-25 11:35:11.000000000 -0700
+++ mod-dl-profile.c	                2004-09-25 11:39:40.000000000 -0700
@@ -238,7 +238,7 @@
     }
   else
     log_hashfraction = -1;
-  tossize = textsize / HASHFRACTION;
+  tossize = ((textsize / HASHFRACTION) + 3) & ~3;
   fromlimit = textsize * ARCDENSITY / 100;
   if (fromlimit < MINARCS)
     fromlimit = MINARCS;


--- glibc-2.3.2/elf/sprof.c	2004-09-25 11:52:41.000000000 -0700
+++ mod-sprof.c	                2004-09-25 11:39:06.000000000 -0700
@@ -452,7 +452,7 @@
     printf ("hashfraction = %d\ndivider = %Zu\n",
 	    result->hashfraction,
 	    result->hashfraction * sizeof (struct here_fromstruct));
-  result->tossize = textsize / HASHFRACTION;
+  result->tossize = ((textsize / HASHFRACTION) + 3) & ~3;
   result->fromlimit = textsize * ARCDENSITY / 100;
   if (result->fromlimit < MINARCS)
     result->fromlimit = MINARCS;

-- 
           Summary: ARM profiling fault
           Product: glibc
           Version: 2.3.2
            Status: NEW
          Severity: critical
          Priority: P1
         Component: libc
        AssignedTo: gotom at debian dot or dot jp
        ReportedBy: andy dot andystewart at gmail dot com
                CC: glibc-bugs at sources dot redhat dot com
 GCC build triplet: Red Hat i386 Linux
  GCC host triplet: ARM Linux
GCC target triplet: ARM Linux


http://sources.redhat.com/bugzilla/show_bug.cgi?id=455

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