The facility unavailable exception can be triggered from userspace by
accessing PMU registers when EBB is not enabled.  This causes the
included pr_err() to run, hence spamming the kernel log buffer.

This avoids this by rate limiting these messages.
Signed-off-by: NMichael Neuling <mikey@neuling.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Currently, if a process starts a transaction and then takes an
exception because the FPU, VMX or VSX unit is unavailable to it,
we end up corrupting any FP/VMX/VSX state that was valid before
the interrupt.  For example, if the process starts a transaction
with the FPU available to it but VMX unavailable, and then does
a VMX instruction inside the transaction, the FP state gets
corrupted.

Loading up the desired state generally involves doing a reclaim
and a recheckpoint.  To avoid corrupting already-valid state, we have
to be careful not to reload that state from the thread_struct
between the reclaim and the recheckpoint (since the thread_struct
values are stale by now), and we have to reload that state from
the transact_fp/vr arrays after the recheckpoint to get back the
current transactional values saved there by the reclaim.
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Currently, when we have a process using the transactional memory
facilities on POWER8 (that is, the processor is in transactional
or suspended state), and the process enters the kernel and the
kernel then uses the floating-point or vector (VMX/Altivec) facility,
we end up corrupting the user-visible FP/VMX/VSX state.  This
happens, for example, if a page fault causes a copy-on-write
operation, because the copy_page function will use VMX to do the
copy on POWER8.  The test program below demonstrates the bug.

The bug happens because when FP/VMX state for a transactional process
is stored in the thread_struct, we store the checkpointed state in
.fp_state/.vr_state and the transactional (current) state in
.transact_fp/.transact_vr.  However, when the kernel wants to use
FP/VMX, it calls enable_kernel_fp() or enable_kernel_altivec(),
which saves the current state in .fp_state/.vr_state.  Furthermore,
when we return to the user process we return with FP/VMX/VSX
disabled.  The next time the process uses FP/VMX/VSX, we don't know
which set of state (the current register values, .fp_state/.vr_state,
or .transact_fp/.transact_vr) we should be using, since we have no
way to tell if we are still in the same transaction, and if not,
whether the previous transaction succeeded or failed.

Thus it is necessary to strictly adhere to the rule that if FP has
been enabled at any point in a transaction, we must keep FP enabled
for the user process with the current transactional state in the
FP registers, until we detect that it is no longer in a transaction.
Similarly for VMX; once enabled it must stay enabled until the
process is no longer transactional.

In order to keep this rule, we add a new thread_info flag which we
test when returning from the kernel to userspace, called TIF_RESTORE_TM.
This flag indicates that there is FP/VMX/VSX state to be restored
before entering userspace, and when it is set the .tm_orig_msr field
in the thread_struct indicates what state needs to be restored.
The restoration is done by restore_tm_state().  The TIF_RESTORE_TM
bit is set by new giveup_fpu/altivec_maybe_transactional helpers,
which are called from enable_kernel_fp/altivec, giveup_vsx, and
flush_fp/altivec_to_thread instead of giveup_fpu/altivec.

The other thing to be done is to get the transactional FP/VMX/VSX
state from .fp_state/.vr_state when doing reclaim, if that state
has been saved there by giveup_fpu/altivec_maybe_transactional.
Having done this, we set the FP/VMX bit in the thread's MSR after
reclaim to indicate that that part of the state is now valid
(having been reclaimed from the processor's checkpointed state).

Finally, in the signal handling code, we move the clearing of the
transactional state bits in the thread's MSR a bit earlier, before
calling flush_fp_to_thread(), so that we don't unnecessarily set
the TIF_RESTORE_TM bit.

This is the test program:

/* Michael Neuling 4/12/2013
 *
 * See if the altivec state is leaked out of an aborted transaction due to
 * kernel vmx copy loops.
 *
 *   gcc -m64 htm_vmxcopy.c -o htm_vmxcopy
 *
 */

/* We don't use all of these, but for reference: */

int main(int argc, char *argv[])
{
	long double vecin = 1.3;
	long double vecout;
	unsigned long pgsize = getpagesize();
	int i;
	int fd;
	int size = pgsize*16;
	char tmpfile[] = "/tmp/page_faultXXXXXX";
	char buf[pgsize];
	char *a;
	uint64_t aborted = 0;

	fd = mkstemp(tmpfile);
	assert(fd >= 0);

	memset(buf, 0, pgsize);
	for (i = 0; i < size; i += pgsize)
		assert(write(fd, buf, pgsize) == pgsize);

	unlink(tmpfile);

	a = mmap(NULL, size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
	assert(a != MAP_FAILED);

	asm __volatile__(
		"lxvd2x 40,0,%[vecinptr] ; " // set 40 to initial value
		TBEGIN
		"beq	3f ;"
		TSUSPEND
		"xxlxor 40,40,40 ; " // set 40 to 0
		"std	5, 0(%[map]) ;" // cause kernel vmx copy page
		TABORT
		TRESUME
		TEND
		"li	%[res], 0 ;"
		"b	5f ;"
		"3: ;" // Abort handler
		"li	%[res], 1 ;"
		"5: ;"
		"stxvd2x 40,0,%[vecoutptr] ; "
		: [res]"=r"(aborted)
		: [vecinptr]"r"(&vecin),
		  [vecoutptr]"r"(&vecout),
		  [map]"r"(a)
		: "memory", "r0", "r3", "r4", "r5", "r6", "r7");

	if (aborted && (vecin != vecout)){
		printf("FAILED: vector state leaked on abort %f != %f\n",
		       (double)vecin, (double)vecout);
		exit(1);
	}

	munmap(a, size);

	close(fd);

	printf("PASSED!\n");
	return 0;
}
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

This patch adds the early machine check function pointer in cputable for
CPU specific early machine check handling. The early machine handle routine
will be called in real mode to handle SLB and TLB errors. We can not reuse
the existing machine_check hook because it is always invoked in kernel
virtual mode and we would already be in trouble if we get SLB or TLB errors.
This patch just sets up a mechanism to invoke CPU specific handler. The
subsequent patches will populate the function pointer.
Signed-off-by: NMahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Acked-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Move machine check entry point into Linux. So far we were dependent on
firmware to decode MCE error details and handover the high level info to OS.

This patch introduces early machine check routine that saves the MCE
information (srr1, srr0, dar and dsisr) to the emergency stack. We allocate
stack frame on emergency stack and set the r1 accordingly. This allows us to be
prepared to take another exception without loosing context. One thing to note
here that, if we get another machine check while ME bit is off then we risk a
checkstop. Hence we restrict ourselves to save only MCE information and
register saved on PACA_EXMC save are before we turn the ME bit on. We use
paca->in_mce flag to differentiate between first entry and nested machine check
entry which helps proper use of emergency stack. We increment paca->in_mce
every time we enter in early machine check handler and decrement it while
leaving. When we enter machine check early handler first time (paca->in_mce ==
0), we are sure nobody is using MC emergency stack and allocate a stack frame
at the start of the emergency stack. During subsequent entry (paca->in_mce >
0), we know that r1 points inside emergency stack and we allocate separate
stack frame accordingly. This prevents us from clobbering MCE information
during nested machine checks.

The early machine check handler changes are placed under CPU_FTR_HVMODE
section. This makes sure that the early machine check handler will get executed
only in hypervisor kernel.

This is the code flow:

		Machine Check Interrupt
			|
			V
		   0x200 vector				  ME=0, IR=0, DR=0
			|
			V
	+-----------------------------------------------+
	|machine_check_pSeries_early:			| ME=0, IR=0, DR=0
	|	Alloc frame on emergency stack		|
	|	Save srr1, srr0, dar and dsisr on stack |
	+-----------------------------------------------+
			|
		(ME=1, IR=0, DR=0, RFID)
			|
			V
		machine_check_handle_early		  ME=1, IR=0, DR=0
			|
			V
	+-----------------------------------------------+
	|	machine_check_early (r3=pt_regs)	| ME=1, IR=0, DR=0
	|	Things to do: (in next patches)		|
	|		Flush SLB for SLB errors	|
	|		Flush TLB for TLB errors	|
	|		Decode and save MCE info	|
	+-----------------------------------------------+
			|
	(Fall through existing exception handler routine.)
			|
			V
		machine_check_pSerie			  ME=1, IR=0, DR=0
			|
		(ME=1, IR=1, DR=1, RFID)
			|
			V
		machine_check_common			  ME=1, IR=1, DR=1
			.
			.
			.
Signed-off-by: NMahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Commit 9863c28a ("powerpc: Emulate sync
instruction variants") introduced a build breakage with
CONFIG_PPC_EMULATED_STATS enabled.
Signed-off-by: NScott Wood <scottwood@freescale.com>
Cc: Kumar Gala <galak@kernel.org>
Cc: James Yang <James.Yang@freescale.com>
---

This patch modifies the Oops message in case of Software Emulation Exception.
The existing message is quite confusing because it refers to FPU Emulation
while most often the issue is due to either a non supported instruction
(not necessarily FPU related) or a stale instruction due to HW issues.
The new message tries to be more generic in order to make the user understand
that the Oops is due to something wrong with an instruction, not necessarily
due to an FPU instruction.
Signed-off-by: NChristophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: NScott Wood <scottwood@freescale.com>

This way we can use same data type struct with KVM and
also help in using other debug related function.
Signed-off-by: NBharat Bhushan <bharat.bhushan@freescale.com>
Acked-by: NMichael Neuling <mikey@neuling.org>
[scottwood@freescale.com: removed obvious debug_reg comment]
Signed-off-by: NScott Wood <scottwood@freescale.com>

This way we can use same data type struct with KVM and
also help in using other debug related function.
Signed-off-by: NBharat Bhushan <bharat.bhushan@freescale.com>
Signed-off-by: NAlexander Graf <agraf@suse.de>

Reserved fields of the sync instruction have been used for other
instructions (e.g. lwsync).  On processors that do not support variants
of the sync instruction, emulate it by executing a sync to subsume the
effect of the intended instruction.
Signed-off-by: NJames Yang <James.Yang@freescale.com>
[scottwood@freescale.com: whitespace and subject line fix]
Signed-off-by: NScott Wood <scottwood@freescale.com>

This creates new 'thread_fp_state' and 'thread_vr_state' structures
to store FP/VSX state (including FPSCR) and Altivec/VSX state
(including VSCR), and uses them in the thread_struct.  In the
thread_fp_state, the FPRs and VSRs are represented as u64 rather
than double, since we rarely perform floating-point computations
on the values, and this will enable the structures to be used
in KVM code as well.  Similarly FPSCR is now a u64 rather than
a structure of two 32-bit values.

This takes the offsets out of the macros such as SAVE_32FPRS,
REST_32FPRS, etc.  This enables the same macros to be used for normal
and transactional state, enabling us to delete the transactional
versions of the macros.   This also removes the unused do_load_up_fpu
and do_load_up_altivec, which were in fact buggy since they didn't
create large enough stack frames to account for the fact that
load_up_fpu and load_up_altivec are not designed to be called from C
and assume that their caller's stack frame is an interrupt frame.
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

As suggested by paulus we can simplify the Data Stream Control Register
(DSCR) Facility Status and Control Register (FSCR) handling.

Firstly, we simplify the asm by using a rldimi.

Secondly, we now use the FSCR only to control the DSCR facility, rather
than both the FSCR and HFSCR.  Users will see no functional change from
this but will get a minor speedup as they will trap into the kernel only
once (rather than twice) when they first touch the DSCR.  Also, this
changes removes a bunch of ugly FTR_SECTION code.
Signed-off-by: NMichael Neuling <mikey@neuling.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

In the program check handler we handle some causes with interrupts off
and others with interrupts on.

We need to enable interrupts to handle the emulation cases, because they
access userspace memory and might sleep.

For faults in the kernel we don't want to do any emulation, and
emulate_instruction() enforces that. do_mathemu() doesn't but probably
should.

The other disadvantage of enabling interrupts for kernel faults is that
we may take another interrupt, and recurse. As seen below:

  --- Exception: e40 at c000000000004ee0 performance_monitor_relon_pSeries_1
  [link register   ] c00000000000f858 .arch_local_irq_restore+0x38/0x90
  [c000000fb185dc10] 0000000000000000 (unreliable)
  [c000000fb185dc80] c0000000007d8558 .program_check_exception+0x298/0x2d0
  [c000000fb185dd00] c000000000002f40 emulation_assist_common+0x140/0x180
  --- Exception: e40 at c000000000004ee0 performance_monitor_relon_pSeries_1
  [link register   ] c00000000000f858 .arch_local_irq_restore+0x38/0x90
  [c000000fb185dff0] 00000000008b9190 (unreliable)
  [c000000fb185e060] c0000000007d8558 .program_check_exception+0x298/0x2d0

So avoid both problems by checking if the fault was in the kernel and
skipping the enable of interrupts and the emulation. Go straight to
delivering the SIGILL, which for kernel faults calls die() and so on,
dropping us in the debugger etc.
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Alistair noticed we got a SIGILL on userspace mfpvr instructions.

Remove the little endian check in the emulation code, it is
probably there to protect against the old pseudo little endian
implementations but doesn't make sense for real little endian.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

There are two invocations of do_mathemu() in traps.c. And the codes
in these two places are almost the same. Introduce a locale function
to eliminate the duplication. With this change we can also make sure
that in program_check_exception() the PPC_WARN_EMULATED is invoked for
the correctly emulated math instructions.
Signed-off-by: NKevin Hao <haokexin@gmail.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

By doing this we can make sure that the FPU state is only flushed to
the thread struct when it is really needed.
Signed-off-by: NKevin Hao <haokexin@gmail.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

POWER8 allows the DSCR to be accessed directly from userspace via a new SPR
number 0x3 (Rather than 0x11.  DSCR SPR number 0x11 is still used on POWER8 but
like POWER7, is only accessible in HV and OS modes).  Currently, we allow this
by setting H/FSCR DSCR bit on boot.

Unfortunately this doesn't work, as the kernel needs to see the DSCR change so
that it knows to no longer restore the system wide version of DSCR on context
switch (ie. to set thread.dscr_inherit).

This clears the H/FSCR DSCR bit initially.  If a process then accesses the DSCR
(via SPR 0x3), it'll trap into the kernel where we set thread.dscr_inherit in
facility_unavailable_exception().

We also change _switch() so that we set or clear the H/FSCR DSCR bit based on
the thread.dscr_inherit.
Signed-off-by: NMichael Neuling <mikey@neuling.org>
Cc: <stable@vger.kernel.org> [v3.10]
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

A PCIe erratum of mpc85xx may causes a core hang when a link of PCIe
goes down. when the link goes down, Non-posted transactions issued
via the ATMU requiring completion result in an instruction stall.
At the same time a machine-check exception is generated to the core
to allow further processing by the handler. We implements the handler
which skips the instruction caused the stall.

This patch depends on patch:
powerpc/85xx: Add platform_device declaration to fsl_pci.h
Signed-off-by: NZhao Chenhui <b35336@freescale.com>
Signed-off-by: NLi Yang <leoli@freescale.com>
Signed-off-by: NLiu Shuo <soniccat.liu@gmail.com>
Signed-off-by: NJia Hongtao <hongtao.jia@freescale.com>
Signed-off-by: NScott Wood <scottwood@freescale.com>

Similar to the facility unavailble exception, except the facilities are
controlled by HFSCR.

Adapt the facility_unavailable_exception() so it can be called for
either the regular or Hypervisor facility unavailable exceptions.
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
CC: <stable@vger.kernel.org> [v3.10]
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

The exception at 0xf60 is not the TM (Transactional Memory) unavailable
exception, it is the "Facility Unavailable Exception", rename it as
such.

Flesh out the handler to acknowledge the fact that it can be called for
many reasons, one of which is TM being unavailable.

Use STD_EXCEPTION_COMMON() for the exception body, for some reason we
had it open-coded, I've checked the generated code is identical.
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
CC: <stable@vger.kernel.org> [v3.10]
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

String instruction emulation would erroneously result in a segfault if
the upper bits of the EA are set and is so high that it fails access
check.  Truncate the EA to 32 bits if the process is 32-bit.
Signed-off-by: NJames Yang <James.Yang@freescale.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

This is duplicated code from math-emu and implements such a small
subset of the FPU (load/stores/fmr) that it's essentially pointless
nowdays.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

(Including 64-bit ones)

This allow SW emulation by the kernel of optional instructions
such as fsqrt which aren't implemented on some processors, and
thus fixes some Fedora 19 issues such as Anaconda since the
compiler is set to generate those by default on 64-bit.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

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.

CC: <stable@vger.kernel.org>
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

If we are emulating an instruction inside an active user transaction that
touches memory, the kernel can't emulate it as it operates in transactional
suspend context.  We need to abort these transactions and send them back to
userspace for the hardware to rollback.

We can service these if the user transaction is in suspend mode, since the
kernel will operate in the same suspend context.

This adds a check to all alignment faults and to specific instruction
emulations (only string instructions for now).  If the user process is in an
active (non-suspended) transaction, we abort the transaction go back to
userspace allowing the HW to roll back the transaction and tell the user of the
failure.  This also adds new tm abort cause codes to report the reason of the
persistent error to the user.

Crappy test case here http://neuling.org/devel/junkcode/aligntm.cSigned-off-by: NMichael Neuling <mikey@neuling.org>
Cc: <stable@vger.kernel.org> # v3.9
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

This is the exception hooks for context tracking subsystem, including
data access, program check, single step, instruction breakpoint, machine check,
alignment, fp unavailable, altivec assist, unknown exception, whose handlers
might use RCU.

This patch corresponds to
[PATCH] x86: Exception hooks for userspace RCU extended QS
  commit 6ba3c97a

But after the exception handling moved to generic code, and some changes in
following two commits:
56dd9470
  context_tracking: Move exception handling to generic code
6c1e0256
  context_tracking: Restore correct previous context state on exception exit

it is able for exception hooks to use the generic code above instead of a
redundant arch implementation.
Signed-off-by: NLi Zhong <zhong@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

POWER8 allows read and write of the DSCR in userspace. We added
kernel emulation so applications could always use the instructions
regardless of the CPU type.

Unfortunately there are two SPRs for the DSCR and we only added
emulation for the privileged one. Add code to match the non
privileged one.

A simple test was created to verify the fix:

http://ozlabs.org/~anton/junkcode/user_dscr_test.c

Without the patch we get a SIGILL and it passes with the patch.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Cc: <stable@kernel.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

This hooks the new transactional memory code into context switching, FP/VMX/VMX
unavailable and exception return.
Signed-off-by: NMatt Evans <matt@ozlabs.org>
Signed-off-by: NMichael Neuling <mikey@neuling.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

We do lazy FP but not lazy TM (ie. userspace starts with MSR TM=1 FP=0).  Hence
if userspace does an FP instruction during a transaction, we'll take an
fp unavailable exception.

This adds functions needed to handle this case.  We have to inject the current
FP state into the checkpoint so that the hardware can decide what to do with
the transaction.  We can't inject only the FP so we have to do a full treclaim
and recheckpoint to inject just the FP state.  This will cause the transaction
to be marked as aborted by the hardware.

This just add the routines needed to do this for FP, VMX and VSX.  It doesn't
hook them into the rest of the code yet.
Signed-off-by: NMatt Evans <matt@ozlabs.org>
Signed-off-by: NMichael Neuling <mikey@neuling.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

These should never happen since we always turn on MSR TM when in userspace. We
don't do lazy TM.

Hence if we hit this, we barf and kill the task as something's gone horribly
wrong.
Signed-off-by: NMatt Evans <matt@ozlabs.org>
Signed-off-by: NMichael Neuling <mikey@neuling.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

This adds new macros for saving and restoring checkpointed architected state
from and to the thread_struct.

It also adds some debugging macros for when your brain explodes trying to debug
your transactional memory enabled kernel.
Signed-off-by: NMatt Evans <matt@ozlabs.org>
Signed-off-by: NMichael Neuling <mikey@neuling.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Fix up all callers as they were before, with make one change: an
unsigned module taints the kernel, but doesn't turn off lockdep.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

This is a rewrite so that we don't assume we are using the DABR throughout the
code.  We now use the arch_hw_breakpoint to store the breakpoint in a generic
manner in the thread_struct, rather than storing the raw DABR value.

The ptrace GET/SET_DEBUGREG interface currently passes the raw DABR in from
userspace.  We keep this functionality, so that future changes (like the POWER8
DAWR), will still fake the DABR to userspace.
Signed-off-by: NMichael Neuling <mikey@neuling.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

The watchdog and FIT code has been #if 0'd for ever, if the CPU takes
an exception to either of those vectors it will jump into the middle
of the PIT or Data TLB code and surely crash.

At least some (all?) 405 cores have both the WDT and FIT
vectors defined, so lets have proper entry points for them.

Tested that the WDT vector works on a 405F6 core.
Signed-off-by: NJason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

When we update the DSCR either via emulation of mtspr(DSCR) or via
a change to dscr_default in sysfs we don't update thread.dscr.
We will eventually update it at context switch time but there is
a period where thread.dscr is incorrect.

If we fork at this point we will copy the old value of thread.dscr
into the child. To avoid this, always keep thread.dscr in sync with
reality.

This issue was found with the following testcase:

http://ozlabs.org/~anton/junkcode/dscr_inherit_test.cSigned-off-by: NAnton Blanchard <anton@samba.org>
Cc: <stable@kernel.org> # 3.0+
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Add thread_struct.trap_nr and use it to store the last exception
the thread experienced. In this patch, we populate the field at
various places where we force_sig_info() to the process.

This is also used in uprobes to determine if the probed instruction
caused an exception.
Signed-off-by: NAnanth N Mavinakayanahalli <ananth@in.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Alignment was the last user of the ENABLE_INTS macro, which we can
now remove. All non-syscall exceptions now disable interrupts on
entry, they get re-enabled conditionally from C code. Don't
unconditionally re-enable in program check either, check the
original context.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Disintegrate asm/system.h for PowerPC.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Acked-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
cc: linuxppc-dev@lists.ozlabs.org

If we get a floating point, altivec or vsx unavaible interrupt in
kernel, we trigger a kernel error. There is no point preserving
the interrupt state, in fact, that can even make debugging harder
as the processor state might change (we may even preempt) between
taking the exception and landing in a debugger.

So just make those 3 disable interrupts unconditionally.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
---

v2: On BookE only disable when hitting the kernel unavailable
    path, otherwise it will fail to restore softe as
    fast_exception_return doesn't do it.

When registered for firmware assisted dump on powerpc, firmware preserves
the registers for the active CPUs during a system crash. This patch reads
the cpu register data stored in Firmware-assisted dump format (except for
crashing cpu) and converts it into elf notes and updates the PT_NOTE program
header accordingly. The exact register state for crashing cpu is saved to
fadump crash info structure in scratch area during crash_fadump() and read
during second kernel boot.
Signed-off-by: NMahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>