Invalid update to pc in instruction

Invalid update to pc in instruction

[Girish Shilamkar]

Hi,
	While running kgdb kernel I got following error:

(gdb) p/x $pc
$4 = 0xc00ef530
(gdb) n
0xc00ef530 in memcpy () at uaccess.h:363
363     in uaccess.h
Invalid update to pc in instruction
(gdb) disas $pc
Dump of assembler code for function memcpy:
0xc00ef520 <memcpy+0>:  stmdb   sp!, {r0, r4, lr}
0xc00ef524 <memcpy+4>:  subs    r2, r2, #4      ; 0x4
0xc00ef528 <memcpy+8>:  blt     0xc00ef5dc <memcpy+188>
0xc00ef52c <memcpy+12>: ands    r12, r0, #3     ; 0x3
0xc00ef530 <memcpy+16>: pld     [r1]
0xc00ef534 <memcpy+20>: bne     0xc00ef5fc <memcpy+220>
0xc00ef538 <memcpy+24>: ands    r12, r1, #3     ; 0x3
0xc00ef53c <memcpy+28>: bne     0xc00ef62c <memcpy+268>


I am using cross gdb-6.4 for Intel PXA270 (armv5l) processor.
Kindly let me know in what scenario does the error msg "Invalid update
to pc in instruction" is displayed ?

Thanks & Regards,
-Girish.

Re: Invalid update to pc in instruction

[Daniel Jacobowitz]

On Tue, Mar 28, 2006 at 02:55:53PM +0530, Girish Shilamkar wrote:
> 363     in uaccess.h
> Invalid update to pc in instruction

> 0xc00ef530 <memcpy+16>: pld     [r1]

> I am using cross gdb-6.4 for Intel PXA270 (armv5l) processor.
> Kindly let me know in what scenario does the error msg "Invalid update
> to pc in instruction" is displayed ?

A quick look in the source would find this message is issued in only
two places:

            if (bits (this_instr, 22, 25) == 0
                && bits (this_instr, 4, 7) == 9)        /* multiply */
              error (_("Invalid update to pc in instruction"));

and
                  if (bit (this_instr, 22))
                    error (_("Invalid update to pc in instruction"));

The prologue analyzer thinks that pld [r1] is an instruction which sets
PC, incorrectly.  It should be updated.

-- 
Daniel Jacobowitz
CodeSourcery