Date: Fri, 4 Jan 2002 17:46:13 +0100
From: Bernd Walter <ticso@cicely8.cicely.de>
To: Daniel Eischen <eischen@pcnet1.pcnet.com>
Cc: alpha@FreeBSD.ORG
Subject: Re: {get,set,make,swap}context for alpha
Message-ID: <20020104174613.C8703@cicely8.cicely.de>
In-Reply-To: <Pine.SUN.3.91.1020104092820.20776A-100000@pcnet1.pcnet.com>
References: <20020104143622.A8703@cicely8.cicely.de> <Pine.SUN.3.91.1020104092820.20776A-100000@pcnet1.pcnet.com>
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On Fri, Jan 04, 2002 at 09:36:23AM -0500, Daniel Eischen wrote:
> On Fri, 4 Jan 2002, Bernd Walter wrote:
> > On Thu, Jan 03, 2002 at 04:05:25PM -0500, Daniel Eischen wrote:
> [...]
> > > The first problem I'm having is that getcontext is getting caught
> > > in an infinite loop. After the call to sigprocmask, the return
> > > value is checked and the next branch instruction doesn't jump to
> > > the label; it jumps to a few instructions prior and repeats all
> > > over again.
> > >
> > > ...
> > > CALL(_sigprocmask) /* see what's blocked */
> > > mov s0, a0 /* restore ptr to ucontext */
> > > --> beq v0, Lgc2 /* check for error */
> > > ldiq v0, -1 /* return -1 */
> > > br Lgcend
> > > Lgc2:
> > > ...
>
> OK, I changed the above to be:
>
> CALL(_sigprocmask) /* see what's blocked */
> mov s0, a0 /* restore ptr to ucontext */
> ldq ra, ((FRAME_RA + 3) * 8)(a0) /* restore ra */
> ldq s0, ((FRAME_S0 + 3) * 8)(a0) /* restore s0 */
> beq v0, Lgc2 /* check for error */
> ldiq v0, -1 /* return -1 */
> br Lgcend
> Lgc2:
> ...
>
> and getcontext now seems to work. I think getcontext can remain a
> LEAF function because it can save and restore anything it wants in
> the context; that's it's raison d'etre. setcontext probably needs
> to be a NESTED function because it doesn't have a place to save
> and restore anything -- unless it uses some unused slots in the
> ucontext...
Lsc_sm: lda sp, -16(sp) /* get stack space */
stq ra, 0(sp) /* save ra */
stq a0, 8(sp) /* save ptr to ucontext */
mov a0, a1 /* set: &ucp->uc_sigmask */
mov zero, a2 /* oset: NULL */
ldiq a0, 3 /* how: SIG_SETMASK */
CALL(_sigprocmask) /* set new signal mask */
ldq a0, 8(sp) /* restore ptr to ucontext */
ldq ra, 0(sp) /* restore ra */
lda sp, 16(sp) /* restore sp */
bne v0, Lscbad /* check for error */
/* restore floating point regs first */
ldq t0, ((71 + 3) * 8)(a0) /* if FP regs not saved, */
What I found so far with the core dump is that proc3 is called with a
bogus t12 value.
I still have to search why.
--
B.Walter COSMO-Project http://www.cosmo-project.de
ticso@cicely.de Usergroup info@cosmo-project.de
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