Re: [Qemu-devel] [PATCH 2/2] ppc: Add dump-stack implementation

[David Gibson]

On Thu, May 02, 2019 at 01:47:32PM +1000, Alexey Kardashevskiy wrote:
> 
> 
> On 02/05/2019 10:43, David Gibson wrote:
> > On Wed, May 01, 2019 at 07:48:48PM +1000, Alexey Kardashevskiy wrote:
> >>
> >>
> >> On 01/05/2019 15:35, Suraj Jitindar Singh wrote:
> >>> The monitor function dump-stack is used to dump the stack for a cpu.
> >>> This can be useful for debugging purposes when the stack cannot be
> >>> dumped by another means.
> >>>
> >>> Add a ppc implementation ppc_cpu_dump_stack().
> >>> The stack pointer is stored in R1 with the back pointer at offset 0 and
> >>> the link register at offset 2.
> >>> Also dump the registers from the stack frame if the marker "regshere" is
> >>> found.
> >>
> >> Is this a Linux only marker? ABI does not mentioned this.
> >>
> >>> This only dumps the kernel stack, stopping if a non-kernel address is
> >>> found in the stack.
> >>
> >> Why enforce this limit?
> > 
> > It's also making a Linux specific assumption about addresses.
> 
> It does not have to if it used ppc_cpu_get_phys_page_debug(), the only
> linux specific left is that "regshere" marker, otherwise it could work
> for AIX or FreeBSD (obviously without the exception frame).

Sorry, I thought this was relying on the fact that Linux put its
linear mapping at 0xc0..., but I realized I was misreading what was
just the masking of the top two real mode address bits which is in the
hardware.

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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