weird SIGSEGV si_code

[Kevin Tew <tewk at cs dot utah dot edu>]

I'm using a SIGSEGV signal handler to handle mprotect violations for a 
generational garbage collector.

I'm getting weird random SIGSEGV signals where si_code is 0 and si_addr 
is 0x3e80000270f.
0x3e80000270f is not mapped according to /proc/PID/maps

libc code tends to make me think that si->si_code should always be   
SEGV_MAPERR = 1 SEGV_ACCERR=2

Any ideas what could cause this or what 0x3e80000xxxx memory addresses mean?

Kevin Tew


void fault_handler(int sn, struct siginfo *si, void *ctx)
{
 void *p = si->si_addr;
 int c = si->si_code;
printf("%p %i %i\n", p, sn, c);
...
}

p = 0x3e80000270f
sn = 11
si_code = 0

x86_64 Ubuntu Linux 9.10

# uname -a
Linux tan 2.6.31-16-generic #52-Ubuntu SMP Thu Dec 3 22:07:16 UTC 2009 
x86_64 GNU/Linux

$ gcc -v
Using built-in specs.
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 
4.4.1-4ubuntu8' --with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs 
--enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr 
--enable-shared --enable-multiarch --enable-linker-build-id 
--with-system-zlib --libexecdir=/usr/lib --without-included-gettext 
--enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.4 
--program-suffix=-4.4 --enable-nls --enable-clocale=gnu 
--enable-libstdcxx-debug --enable-objc-gc --disable-werror 
--with-arch-32=i486 --with-tune=generic --enable-checking=release 
--build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.4.1 (Ubuntu 4.4.1-4ubuntu8)