On 01/29/2015 03:43 PM, Bruce Korb wrote:
Thank you!
On Thu, Jan 29, 2015 at 3:01 PM, David Daney <ddaney.cavm@xxxxxxxxx> wrote:
Anyway, I need to set a hardware breakpoint on a Mips CPU on a "Cavium"
platform
in a kernel module.
This would appear to be for the most part, completely independent of GDB,
I had guessed as much, but did not have a better guess, either.
Since many years ago, WatchLo and WatchHi have been under the control of the
Linux kernel. If you set these registers and a Watch Exception is
triggered, it will cause the registers to be cleared and the exception will
be ignored, unless they were configured via ptrace(2) for userspace
addresses.
Can a hacked ptrace set it up to panic instead?
All I need is a stack trace once this one single spot in memory gets written.
Look at do_watch() in traps.c, you would have to doctor that function up
to generate the stacktrace.
For debugging kernel space with watchpoint registers on OCTEON it is
probably best to use the facilities in the EJTAG unit.
Which, I'll hazard a guess, requires physical access.
I'll have to go begging and pleading for special access to the Hardware Lab.
Please don't ask me why we software types are kept out.
I've not gotten a straight answer, so I could only answer with speculation.
*sigh*. Thank you.
