Returning to userland via a signal handler

[Martin Husemann <martin%NetBSD.org@localhost>]

Maybe the following analyzis is wrong, or there is something wrong in
sparc64 machdep code...

----- Forwarded message from Martin Husemann <martin%netbsd.org@localhost> -----

Delivered-To: source-changes%NetBSD.org@localhost
Date: Thu, 21 May 2009 13:24:38 +0000
From: Martin Husemann <martin%netbsd.org@localhost>
Subject: CVS commit: src/sys/arch/sparc64/sparc64
To: source-changes%NetBSD.org@localhost
Approved: for-source-only
Reply-To: martin%netbsd.org@localhost
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Module Name:    src
Committed By:   martin
Date:           Thu May 21 13:24:38 UTC 2009

Modified Files:
        src/sys/arch/sparc64/sparc64: vm_machdep.c

Log Message:
Deja Vu: when preparing the initial trap frame for a new forked lwp,
explicitly clear condition code. Otherwise we might catch a signal
(handlers are inherited from the parent) before we ever return to
userland. The current trapframe is converted into a ucontext and after
the signal handler returns, the lwp stays in userland and directly
uses the ucontext to return to the fork call.
Fixes PR 41302.


To generate a diff of this commit:
cvs rdiff -u -r1.87 -r1.88 src/sys/arch/sparc64/sparc64/vm_machdep.c
----- End forwarded message -----

... but if this is correct, it would mean we never run through lwp_trampoline
and thus don't call lwp_startup for the new lwp.

This can't be good.


Martin