OK, I've got the following code in __dump_execute:
__dump_execute(struct file *dump_file, char *panic_str,
struct pt_regs *regs, int dump_level, int dump_compress_pages)
{
dump_here:
( some code skipped here)
/* For Alpha, save the Program Counter and Stack Pointer */
dump_header.dh_esp = __asm__("$30"); /* get stack pointer */
dump_header.dh_eip = &&dump_here; /* get Program Counter */
Sound OK?
I removed the cmd directory temporarily from the top level Makefile so I could
do a test build (lots of work todo there!). Had to fix a type in sd.c, but the
compile died completely when it reached arch/alpha/kernel/vmdump.c, apparently
because it couldn't see vmdump.h. Huh? File does exist as requested in
include/linux; adding an include line with the explicit path to it didn't help.
Any idea why this fails to see the include? /usr/src/linux is actually
symlinked to a mounted NFS share that holds the kernel source; doesn't seem
like that would be the problem since the rest of the kernel was building fine.
/usr/include/linux points to ../src/linux/include/linux/.
On 21-Dec-1999 Matt Robinson wrote:
> On Thu, 23 Dec 1999, Brian Hall wrote:
>|>Well, it's not clear to me how to get the PC and RA of interest off the
>|>stack
>|>when we are in the vmdump functions. We could retreive the RA from register
>|>26
>|>in the panic() function itself, and pass that to the dump_execute function.
>|>Then the dump code could at least tell where panic was called from. Is this
>|>sufficient, or at least a start?
>
> In the __dump_execute() function, just save the PC into the right
> registers, and that'll be enough. You don't have to fill the pt_regs
> structure.
>
> The big keys are the stack pointer and the PC for that process within
> the __dump_execute() function. Save the stack pointer into
> dump_header.dh_esp, and the PC into dump_header.dh_eip. That's all
> 'lcrash' should need in order to figure out the stack trace of the
> failing process (for now). Having the RA is nice, but not entirely
> necessary.
>
> I should have named dh_esp and dh_eip into something like dh_sp and
> dh_pc, for simplicity's sake. Next revision ...
>
> --Matt
>
>|>On 18-Dec-1999 Brian Hall wrote:
>|>> Okay, after some research, I think I figured out how to get at the needed
>|>> Alpha registers:
>|>>
>|>> register unsigned long fptr __asm__("$15"); /* get frame pointer? */
>|>> register unsigned long sptr __asm__("$30"); /* get stack pointer? */
>|>>
>|>> Now, my understanding of the problem is that I need to go back two frames
>|>> on
>|>> the stack to get the PC of interest, and three for the RA of interest. How
>|>> do
>|>> I
>|>> do this? I haven't had much luck yet trying to figure out how to navigate
>|>> the
>|>> kernel stack. I see the pt_regs structure, but I'm not exactly sure how to
>|>> figure the frame size, since that can vary with each frame.
>|>>
>|>> On 13-Dec-1999 Matt Robinson wrote:
>|>>> The problem is from panic(), you don't have the registers, so you
>|>>> need to grab them. That way the 'lcrash' code has a point to start
>|>>> with as far as the failing process is concerned. Hence the "if (regs)"
>|>>> stuff.
>|>
>|>--
>|>Brian Hall <brianw.hall@xxxxxxxxxx>
>|>Linux Consultant
--
Brian Hall <brianw.hall@xxxxxxxxxx>
Linux Consultant
|