This is a note to let you know that I've just added the patch titled
powerpc: Fix emulation of illegal instructions on PowerNV platform
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
powerpc-fix-emulation-of-illegal-instructions-on-powernv-platform.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From e4f37de094d8c0a55af0fe63d7f715457b2de3e6 Mon Sep 17 00:00:00 2001
From: Paul Mackerras <paulus@xxxxxxxxx>
Date: Fri, 14 Jun 2013 20:07:41 +1000
Subject: powerpc: Fix emulation of illegal instructions on PowerNV platform
From: Paul Mackerras <paulus@xxxxxxxxx>
commit bf593907f7236e95698a76b7c7a2bbf8b1165327 upstream.
Normally, the kernel emulates a few instructions that are unimplemented
on some processors (e.g. the old dcba instruction), or privileged (e.g.
mfpvr). The emulation of unimplemented instructions is currently not
working on the PowerNV platform. The reason is that on these machines,
unimplemented and illegal instructions cause a hypervisor emulation
assist interrupt, rather than a program interrupt as on older CPUs.
Our vector for the emulation assist interrupt just calls
program_check_exception() directly, without setting the bit in SRR1
that indicates an illegal instruction interrupt. This fixes it by
making the emulation assist interrupt set that bit before calling
program_check_interrupt(). With this, old programs that use no-longer
implemented instructions such as dcba now work again.
Signed-off-by: Paul Mackerras <paulus@xxxxxxxxx>
Signed-off-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Cc: Yijing Wang <wangyijing@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/kernel/exceptions-64s.S | 2 +-
arch/powerpc/kernel/traps.c | 10 ++++++++++
2 files changed, 11 insertions(+), 1 deletion(-)
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -491,7 +491,7 @@ machine_check_common:
STD_EXCEPTION_COMMON(0xb00, trap_0b, .unknown_exception)
STD_EXCEPTION_COMMON(0xd00, single_step, .single_step_exception)
STD_EXCEPTION_COMMON(0xe00, trap_0e, .unknown_exception)
- STD_EXCEPTION_COMMON(0xe40, emulation_assist, .program_check_exception)
+ STD_EXCEPTION_COMMON(0xe40, emulation_assist, .emulation_assist_interrupt)
STD_EXCEPTION_COMMON(0xe60, hmi_exception, .unknown_exception)
STD_EXCEPTION_COMMON_ASYNC(0xf00, performance_monitor, .performance_monitor_exception)
STD_EXCEPTION_COMMON(0x1300, instruction_breakpoint, .instruction_breakpoint_exception)
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -1074,6 +1074,16 @@ void __kprobes program_check_exception(s
_exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
}
+/*
+ * This occurs when running in hypervisor mode on POWER6 or later
+ * and an illegal instruction is encountered.
+ */
+void __kprobes emulation_assist_interrupt(struct pt_regs *regs)
+{
+ regs->msr |= REASON_ILLEGAL;
+ program_check_exception(regs);
+}
+
void alignment_exception(struct pt_regs *regs)
{
int sig, code, fixed = 0;
Patches currently in stable-queue which might be from paulus@xxxxxxxxx are
queue-3.4/powerpc-fix-emulation-of-illegal-instructions-on-powernv-platform.patch
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