Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.programming > #8401

Re: ARM - Assembly GNU Debugger Output Help

Show all headers | View raw

On 06-03-18 17:28, Ilias Abrams wrote:
> Hi guys, I was wondering, I am running a simple Assembly example with GNU Debugger (GDB) on a RPI (ARM architecture). When I execute the command "info registers" I take the following output. 
> 
> (gdb) info registers
> r0             0x1      1
> r1             0x7efff7b4       2130704308
> r2             0x7efff7bc       2130704316
> r3             0x10408  66568
> r4             0x1042c  66604
> r5             0x0      0
> r6             0x102e0  66272
> r7             0x0      0
> r8             0x0      0
> r9             0x0      0
> r10            0x76fff000       1996484608
> r11            0x0      0
> r12            0x7efff6e0       2130704096
> sp             0x7efff660       0x7efff660
> lr             0x76e8f678       1994978936
> pc             0x10408  0x10408 <main>
> cpsr           0x60000010       1610612752
> 
> From the output I can see that some register's values are memory addresses. Am I correct? 

Probably some are, yes, but it's impossible to say.

A general-purpose register holds a number. What the meaning of that
number is, depends on the code that's running on the processor. It may
be a memory address, but it may just as well be a numeric value that the
code running on the processor is doing some calculations on.

There are a few special-purpose registers (such as the stack pointer
(sp) and program counter (pc)) which by virtue of their function must
point to a memory address if the system is going to be doing anything
useful; but beyond that, in order to interpret the value of the
registers you need to inspect the code.

Try using the "disassemble" command. By default, that will give a
disassembled view of the function which the program is "currently"
executing, which should give you some hint as to what the values mean.
Beyond that, your guess is as good as mine.

Back to comp.programming | Previous | Next — Previous in thread | Find similar | Unroll thread

Thread

ARM - Assembly GNU Debugger Output Help Ilias Abrams <iliasabrams@gmail.com> - 2018-03-06 08:28 -0800
  Re: ARM - Assembly GNU Debugger Output Help Wouter Verhelst <w@uter.be> - 2018-03-06 19:04 +0100

csiph-web