Commit 28a1f533 delays setting %pil to avoid potential
hardirq stack overflow in the common rtrap_irq path.
Setting %pil also needs to be delayed in the rtrap_nmi
path for the same reason.
Signed-off-by: NRob Gardner <rob.gardner@oracle.com>
Signed-off-by: NDave Aldridge <david.j.aldridge@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Mark the places when the system are in user or are in kernel.
This is used to make full dynticks system (tickless) --
CONFIG_NO_HZ_FULL dependence.
Signed-off-by: NKirill Tkhai <tkhai@yandex.ru>
CC: David Miller <davem@davemloft.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The low level preemption code fiddles with the PREEMPT_ACTIVE bit for
no reason and calls schedule() with interrupts disabled, which is
wrong to begin with. Remove the PREEMPT_ACTIVE fiddling and call the
proper schedule_preempt_irq() function.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NDavid S. Miller <davem@davemloft.net>
Cc: sparclinux@vger.kernel.org
Link: http://lkml.kernel.org/r/20130917183628.966769884@linutronix.de

Noticed by Linus.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The invocation of softirq is now handled by irq_exit(), so there is no
need for sparc64 to invoke it on the trap-return path.  In fact, doing so
is a bug because if the trap occurred in the idle loop, this invocation
can result in lockdep-RCU failures.  The problem is that RCU ignores idle
CPUs, and the sparc64 trap-return path to the softirq handlers fails to
tell RCU that the CPU must be considered non-idle while those handlers
are executing.  This means that RCU is ignoring any RCU read-side critical
sections in those handlers, which in turn means that RCU-protected data
can be yanked out from under those read-side critical sections.

The shiny new lockdep-RCU ability to detect RCU read-side critical sections
that RCU is ignoring located this problem.

The fix is straightforward: Make sparc64 stop manually invoking the
softirq handlers.
Reported-by: NMeelis Roos <mroos@linux.ee>
Suggested-by: NDavid Miller <davem@davemloft.net>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: NMeelis Roos <mroos@linux.ee>
Cc: stable@vger.kernel.org
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Analog of what commit 494486a1 had done
to alpha (another architecture with similar bug).

One note: in rtrap_32.S part clr %l6 has been a rudiment of left after
commit 28e61036 (sparc: Fix debugger syscall
restart interactions) has killed %l6 use in there.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

We can overflow the hardirq stack if we set the %pil here
so early, just let the normal control flow do it.

This is fine as we are allowed to do the actual IRQ enable
at any point after we call trace_hardirqs_on.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

People should be using the perf events interfaces, and
the way these system call facilities used the %pcr conflicts
with the usage of the NMI watchdog and perf events.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Now that the return from alloc_percpu is compatible with the address
of per-cpu vars, it makes sense to hand around the address of per-cpu
variables.  To make this sane, we remove the per_cpu__ prefix we used
created to stop people accidentally using these vars directly.

Now we have sparse, we can use that (next patch).

tj: * Updated to convert stuff which were missed by or added after the
      original patch.

    * Kill per_cpu_var() macro.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NTejun Heo <tj@kernel.org>
Reviewed-by: NChristoph Lameter <cl@linux-foundation.org>

o Move all files from sparc64/kernel/ to sparc/kernel
  - rename as appropriate
o Update sparc/Makefile to the changes
o Update sparc/kernel/Makefile to include the sparc64 files

NOTE: This commit changes link order on sparc64!

Link order had to change for either of sparc32 and sparc64.
And assuming sparc64 see more testing than sparc32 change link
order on sparc64 where issues will be caught faster.
Signed-off-by: NSam Ravnborg <sam@ravnborg.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

We don't want the rtrap path to try and run softirqs or
anything like that when returning from a PIL==15 NMI.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The fact of the matter is, all UltraSPARC-III and later chips only
implement TSO.  They don't implement PSO and RMO memory models at all.

Only the Ultra-I and Ultra-II family chips implement RMO and they are
only helped marginally by using this setting when executing kernel
code.

The big plus to doing this is that we can eliminate all of the non-Sync
memory barriers in the kernel except for the ones used in the optimized
memcpy/memset code (these use block load and store operations which
have their own memory ordering rules).
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This adds TIF_NOTIFY_RESUME support for sparc64.
When set, we call tracehook_notify_resume() on the way to user mode.
Signed-off-by: NRoland McGrath <roland@redhat.com>

When we fully commit to returning back to kernel mode from
a trap, zero out the regs->magic value to prevent false
positives during stack backtraces.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch removes the CVS keywords that weren't updated for a long time
from comments.
Signed-off-by: NAdrian Bunk <bunk@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This mirrors x86 changeset 5a8da0ea
("signals: x86 TS_RESTORE_SIGMASK") on sparc64.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

So, forever, we've had this ptrace_signal_deliver implementation
which tries to handle all of the nasties that can occur when the
debugger looks at a process about to take a signal.  It's meant
to address all of these issues inside of the kernel so that the
debugger need not be mindful of such things.

Problem is, this doesn't work.

The idea was that we should do the syscall restart business first, so
that the debugger captures that state.  Otherwise, if the debugger for
example saves the child's state, makes the child execute something
else, then restores the saved state, we won't handle the syscall
restart properly because we lose the "we're in a syscall" state.

The code here worked for most cases, but if the debugger actually
passes the signal through to the child unaltered, it's possible that
we would do a syscall restart when we shouldn't have.

In particular this breaks the case of debugging a process under a gdb
which is being debugged by yet another gdb.  gdb uses sigsuspend
to wait for SIGCHLD of the inferior, but if gdb itself is being
debugged by a top-level gdb we get a ptrace_stop().  The top-level gdb
does a PTRACE_CONT with SIGCHLD to let the inferior gdb see the
signal.  But ptrace_signal_deliver() assumed the debugger would cancel
out the signal and therefore did a syscall restart, because the return
error was ERESTARTNOHAND.

Fix this by simply making ptrace_signal_deliver() a nop, and providing
a way for the debugger to control system call restarting properly:

1) Report a "in syscall" software bit in regs->{tstate,psr}.
   It is set early on in trap entry to a system call and is fully
   visible to the debugger via ptrace() and regsets.

2) Test this bit right before doing a syscall restart.  We have
   to do a final recheck right after get_signal_to_deliver() in
   case the debugger cleared the bit during ptrace_stop().

3) Clear the bit in trap return so we don't accidently try to set
   that bit in the real register.

As a result we also get a ptrace_{is,clear}_syscall() for sparc32 just
like sparc64 has.

M68K has this same exact bug, and is now the only other user of the
ptrace_signal_deliver hook.  It needs to be fixed in the same exact
way as sparc.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Now that we indicate the "restart system call" in the
trap type field of pt_regs->magic, we don't need to
set the %l6 boolean in all of the trap return paths.

And we therefore don't need to pass it to do_notify_resume().
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NJörn Engel <joern@wohnheim.fh-wedel.de>
Signed-off-by: NAdrian Bunk <bunk@stusta.de>

If we take a window fault, on SUN4V set %gl to zero before we
turn PSTATE_IE back on in %pstate.  Otherwise if we take an
interrupt we'll end up with corrupt register state.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

We need to set the global register set _AND_ disable
PSTATE_IE in %pstate.  The original patch sequence was
leaving PSTATE_IE enabled when returning to kernel mode,
oops.

This fixes the random register corruption being seen
on SUN4V.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

sun4v uses ASI_MMU instead of ASI_DMMU
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NDavid S. Miller <davem@davemloft.net>

They are totally unnecessary because:

1) Interrupts are already disabled when switch_to()
   runs.

2) We don't use hard-coded alternate globals any longer.

This found a case in rtrap, which still assumed alternate
global %g6 was current_thread_info(), and that is fixed
by this changeset as well.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Instead of setting/clearing PSTATE_AG we have to change
the %gl register value on sun4v.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When saving and restoing trap state, do the window spill/fill
handling inline so that we never trap deeper than 2 trap levels.
This is important for chips like Niagara.

The window fixup code is massively simplified, and many more
improvements are now possible.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This, as well as making the code cleaner, allows a simplification in
the TSB miss handling path.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Since we use %g5 itself as a temporary, it can get clobbered
if we take an interrupt mid-stream and thus cause end up with
the final %g5 value too early as a result of rtrap processing.

Set %g5 at the very end, atomically, to avoid this problem.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Some of the trap code was still assuming that alternate
global %g6 was hard coded with current_thread_info().
Let's just consistently flush at KERNBASE when we need
a pipeline synchronization.  That's locked into the TLB
and will always work.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

UltraSPARC has special sets of global registers which are switched to
for certain trap types.  There is one set for MMU related traps, one
set of Interrupt Vector processing, and another set (called the
Alternate globals) for all other trap types.

For what seems like forever we've hard coded the values in some of
these trap registers.  Some examples include:

1) Interrupt Vector global %g6 holds current processors interrupt
   work struct where received interrupts are managed for IRQ handler
   dispatch.

2) MMU global %g7 holds the base of the page tables of the currently
   active address space.

3) Alternate global %g6 held the current_thread_info() value.

Such hardcoding has resulted in some serious issues in many areas.
There are some code sequences where having another register available
would help clean up the implementation.  Taking traps such as
cross-calls from the OBP firmware requires some trick code sequences
wherein we have to save away and restore all of the special sets of
global registers when we enter/exit OBP.

We were also using the IMMU TSB register on SMP to hold the per-cpu
area base address, which doesn't work any longer now that we actually
use the TSB facility of the cpu.

The implementation is pretty straight forward.  One tricky bit is
getting the current processor ID as that is different on different cpu
variants.  We use a stub with a fancy calling convention which we
patch at boot time.  The calling convention is that the stub is
branched to and the (PC - 4) to return to is in register %g1.  The cpu
number is left in %g6.  This stub can be invoked by using the
__GET_CPUID macro.

We use an array of per-cpu trap state to store the current thread and
physical address of the current address space's page tables.  The
TRAP_LOAD_THREAD_REG loads %g6 with the current thread from this
table, it uses __GET_CPUID and also clobbers %g1.

TRAP_LOAD_IRQ_WORK is used by the interrupt vector processing to load
the current processor's IRQ software state into %g6.  It also uses
__GET_CPUID and clobbers %g1.

Finally, TRAP_LOAD_PGD_PHYS loads the physical address base of the
current address space's page tables into %g7, it clobbers %g1 and uses
__GET_CPUID.

Many refinements are possible, as well as some tuning, with this stuff
in place.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

We now use the TSB hardware assist features of the UltraSPARC
MMUs.

SMP is currently knowingly broken, we need to find another place
to store the per-cpu base pointers.  We hid them away in the TSB
base register, and that obviously will not work any more :-)

Another known broken case is non-8KB base page size.

Also noticed that flush_tlb_all() is not referenced anywhere, only
the internal __flush_tlb_all() (local cpu only) is used by the
sparc64 port, so we can get rid of flush_tlb_all().

The kernel gets it's own 8KB TSB (swapper_tsb) and each address space
gets it's own private 8K TSB.  Later we can add code to dynamically
increase the size of per-process TSB as the RSS grows.  An 8KB TSB is
good enough for up to about a 4MB RSS, after which the TSB starts to
incur many capacity and conflict misses.

We even accumulate OBP translations into the kernel TSB.

Another area for refinement is large page size support.  We could use
a secondary address space TSB to handle those.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This also includes by necessity _TIF_RESTORE_SIGMASK support,
which actually resulted in a lot of cleanups.

The sparc signal handling code is quite a mess and I should
clean it up some day.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

We need to use stricter memory barriers around the block
load and store instructions we use to save and restore the
FPU register file.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Instead of code patching to handle the page size fields in
the context registers, just use variables from which we get
the proper values.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

We can put the __softirq_pending mask in the cpudata,
no need for the silly NR_CPUS array in kernel/softirq.c
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!