Re: [RFC] MIPS division by zero and libgcj...

[David Daney <ddaney@avtrex.com>]

Maciej W. Rozycki wrote:

>On Thu, 10 Jun 2004, David Daney wrote:
>
>  
>
>>It appears that gcc configured for mipsel-linux will execute a "break 7" 
>>instruction on integer division by zero.
>>
>>This causes the kernel (I am using 2.4.25) to send SIGTRAP.
>>    
>>
>
> It looks like you have a problem in your configuration.  A "break 7"  
>(or "teq <divisor>,$zero,7" -- but that's currently implemented in gas
>only) is indeed emitted and exectuted in the case of division by zero, but
>Linux has the ability to recognize this special break code and sends
>SIGFPE instead.  There are actually two special codes defined, the other
>being "6" for an overflow.  Both are handled by Linux, with si_code in
>struct siginfo being set to FPE_INTDIV or FPE_INTOVF, respectively.  You
>can handle this appropriately in a signal handler.
>
My kernel sources are from linux-mips.org, it is little-endian running on:

# cat /proc/cpuinfo
system type             : ATI-Xilleon
processor               : 0
cpu model               : MIPS 4Kc V0.7
BogoMIPS                : 299.00
wait instruction        : yes
microsecond timers      : yes
tlb_entries             : 16
extra interrupt vector  : yes
hardware watchpoint     : yes
VCED exceptions         : not available
VCEI exceptions         : not available

Could you point me to where in the kernel source this is handled?  I 
will try to see what when wrong.

David Daney.