Re: mips64 assembler

[David Daney <ddaney@caviumnetworks.com>]

On 10/15/2010 10:11 AM, Camm Maguire wrote:
> Greetings!  What is wrong with this stub attempting a jump to contents
> of register $t0?
>
> (gdb) p/x *(ul *)0x109413c@4
> $3 = {0x3c080077, /*lui t0,0x77*/
>        0x2508a170, /*addui t0,t0,0xa170*/
>        0x8d08a288, /*lw t0,-23928(t0) */
>        0x1000008   /* jr t0*/ }

What instruction follows this JR?  It will always be executed in the 
delay slot of the jump.  If it causes an exception, like BREAK or an 
illegal instruction would, $pc will be left pointing at the JR so that 
it can retry the whole thing once the mess is cleaned up.

David Daney

> (gdb) c
> Program received signal SIGTRAP, Trace/breakpoint trap.
> 0x01094148 in ?? () /*this is the jump instruction*/
> (gdb) i reg t0
> t0: 0x2ae13bf0      /*this is the correct address*/
>
> Any help most appreciated!
>
> Take care,
>
>
> David Daney<ddaney@caviumnetworks.com>  writes:
>
> > On 09/22/2010 04:05 PM, David Daney wrote:
> > [...]
> > > [11] .init PROGBITS 10000458 000458 000078 00 AX 0 0 8
> > > [12] .plt PROGBITS 100004e0 0004e0 000030 00 AX 0 0 32
> > > [13] .text PROGBITS 10000510 000510 0002c0 00 AX 0 0 16
> > > [14] .MIPS.stubs PROGBITS 100007d0 0007d0 000020 00 AX 0 0 4
> > > [15] .fini PROGBITS 100007f0 0007f0 000048 00 AX 0 0 8
> > > [16] .rodata PROGBITS 10000838 000838 000020 00 A 0 0 8
> > > [17] .eh_frame PROGBITS 10000858 000858 000004 00 A 0 0 4
> > > [18] .ctors PROGBITS 1001085c 00085c 000008 00 WA 0 0 4
> > [...]
> > > Look there, the PLT is section 17.
> >
> > Well really it is section 12.  But what is a difference of 5 among friends?
> >
> > David Daney