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Re: [Qemu-devel] [PATCH] ppc: Stop dumping state on all exceptions in li
From: |
Benjamin Herrenschmidt |
Subject: |
Re: [Qemu-devel] [PATCH] ppc: Stop dumping state on all exceptions in linux-user |
Date: |
Wed, 03 Aug 2016 21:39:49 +1000 |
On Wed, 2016-08-03 at 12:32 +0100, Peter Maydell wrote:
> Yeah, there's an LTP test that fails because of this (we
> send a SIGSEGV when we should be sending a SIGBUS). It's
> a bit painful to fix though, since as you say we've
> effectively thrown away some information. I'm inclined to
> put this in the big pile of "bugs we could fix if we
> ever implemented linux-user-with-softmmu" and otherwise
> ignore it, unless you have a real-world program that
> needs this and makes some kind of bodge fix worthwhile.
Nope, not really...
If we care, a simpler fix would be to add a "translate_user_fault" hook
to the CPU class that takes more info about the original signal than
handle_mmu_fault does, and call it when available (with a fallback)
from user-exec.c
That does mean going through all the cpu_signal_handler() variants in
there though to make them extract more useful info.
Not sure it's worthwhile...
As far user-with-softmmu, I'm not too sure... softmmu significantly
increases the overhead of load and stores. Maybe after we add 128-bit
integers to TGC to alleviate that a bit ? :-)
Cheers,
Ben
.