From: Laurent Vivier <laurent@vivier.eu>
To: gerg@uclinux.org, qemu-devel@nongnu.org
Cc: peter.maydell@linaro.org
Subject: Re: [Qemu-devel] [PATCH v2 3/3] m68k: fix usp processing on interrupt entry and exception exit
Date: Fri, 19 Jun 2015 21:35:21 +0200 [thread overview]
Message-ID: <55846EF9.20302@vivier.eu> (raw)
In-Reply-To: <1434721406-25288-4-git-send-email-gerg@uclinux.org>
Le 19/06/2015 15:43, gerg@uclinux.org a écrit :
> From: Greg Ungerer <gerg@uclinux.org>
>
> The action to potentially switch sp register is not occurring at the correct
> point in the interrupt entry or exception exit sequences.
>
> For the interrupt entry case the sp on entry is used to create the stack
> exception frame - but this may well be the user stack pointer, since we
> haven't done the switch yet. Re-order the flow to switch the sp regs then
> use the current sp to create the exception frame.
>
> For the return from exception case the code is unwinding the sp after
> switching sp registers. But it should always unwind the supervisor sp
> first, then carry out any required sp switch.
>
> Note that these problems don't effect operation unless the user sp bit is
> set in the CACR register. Only a single sp is used in the default power up
> state. Previously Linux only used this single sp mode. But modern versions
> of Linux use the user sp mode now, so we need correct behavior for Linux
> to work.
>
> Signed-off-by: Greg Ungerer <gerg@uclinux.org>
> Reviewed-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
> ---
> target-m68k/op_helper.c | 7 +++----
> 1 file changed, 3 insertions(+), 4 deletions(-)
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
next prev parent reply other threads:[~2015-06-19 19:35 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-19 13:43 [Qemu-devel] [PATCH v2 0/3] m68k: fix ColdFire support gerg
2015-06-19 13:43 ` [Qemu-devel] [PATCH v2 1/3] m68k: implement more ColdFire 5208 interrupt controller functionality gerg
2015-06-19 13:43 ` [Qemu-devel] [PATCH v2 2/3] m68k: implement move to/from usp register instruction gerg
2015-06-19 19:28 ` Laurent Vivier
2015-06-19 13:43 ` [Qemu-devel] [PATCH v2 3/3] m68k: fix usp processing on interrupt entry and exception exit gerg
2015-06-19 19:35 ` Laurent Vivier [this message]
2015-06-21 23:11 ` Greg Ungerer
2015-06-19 19:39 ` [Qemu-devel] [PATCH v2 0/3] m68k: fix ColdFire support Laurent Vivier
2015-06-20 4:55 ` Greg Ungerer
2015-06-20 17:03 ` Laurent Vivier
2015-06-22 16:49 ` Andreas Färber
2015-06-23 0:37 ` Greg Ungerer
2015-06-20 17:24 ` Laurent Vivier
2015-06-22 15:34 ` Peter Maydell
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