linux-toradex.git/arch/powerpc/kernel/irq.c, branch v3.9.2

powerpc: Add code to handle soft-disabled doorbells on server

2013-01-10T04:09:07+00:00

This patch adds the logic to properly handle doorbells that come in when
interrupts have been soft disabled and to replay them when interrupts
are re-enabled:

- masked_##_H##interrupt is modified to leave interrupts enabled when a
  doorbell has come in since doorbells are edge sensitive and as such
  won't be automatically re-raised.

- __check_irq_replay now tests if a doorbell happened on book3s, and
  returns either 0xe80 or 0xa00 depending on whether we are the
  hypervisor or not.

- restore_check_irq_replay now tests for the two possible server
  doorbell vector numbers to replay.

- __replay_interrupt also adds tests for the two server doorbell vector
  numbers, and is modified to use a compare instruction rather than an
  andi. on the single bit difference between 0x500 and 0x900.

The last two use a CPU feature section to avoid needlessly testing
against the hypervisor vector if it is not the hypervisor, and vice
versa.

Signed-off-by: Ian Munsie 
Signed-off-by: Benjamin Herrenschmidt

powerpc/trace: Fix interrupt tracepoints vs. RCU

2012-09-17T06:31:54+00:00

There are a few tracepoints in the interrupt code path, which is before
irq_enter(), or after irq_exit(), like
trace_irq_entry()/trace_irq_exit() in do_IRQ(),
trace_timer_interrupt_entry()/trace_timer_interrupt_exit() in
timer_interrupt().

If the interrupt is from idle(), and because tracepoint contains RCU
read-side critical section, we could see following suspicious RCU usage
reported:

[  145.127743] ===============================
[  145.127747] [ INFO: suspicious RCU usage. ]
[  145.127752] 3.6.0-rc3+ #1 Not tainted
[  145.127755] -------------------------------
[  145.127759] /root/.workdir/linux/arch/powerpc/include/asm/trace.h:33
suspicious rcu_dereference_check() usage!
[  145.127765]
[  145.127765] other info that might help us debug this:
[  145.127765]
[  145.127771]
[  145.127771] RCU used illegally from idle CPU!
[  145.127771] rcu_scheduler_active = 1, debug_locks = 0
[  145.127777] RCU used illegally from extended quiescent state!
[  145.127781] no locks held by swapper/0/0.
[  145.127785]
[  145.127785] stack backtrace:
[  145.127789] Call Trace:
[  145.127796] [c00000000108b530] [c000000000013c40] .show_stack
+0x70/0x1c0 (unreliable)
[  145.127806] [c00000000108b5e0]
[c0000000000f59d8] .lockdep_rcu_suspicious+0x118/0x150
[  145.127813] [c00000000108b680] [c00000000000fc58] .do_IRQ+0x498/0x500
[  145.127820] [c00000000108b750] [c000000000003950]
hardware_interrupt_common+0x150/0x180
[  145.127828] --- Exception: 501 at .plpar_hcall_norets+0x84/0xd4
[  145.127828]     LR = .check_and_cede_processor+0x38/0x70
[  145.127836] [c00000000108bab0] [c0000000000665dc] .shared_cede_loop
+0x5c/0x100
[  145.127844] [c00000000108bb70] [c000000000588ab0] .cpuidle_enter
+0x30/0x50
[  145.127850] [c00000000108bbe0]
[c000000000588b0c] .cpuidle_enter_state+0x3c/0xb0
[  145.127857] [c00000000108bc60] [c000000000589730] .cpuidle_idle_call
+0x150/0x6c0
[  145.127863] [c00000000108bd30] [c000000000058440] .pSeries_idle
+0x10/0x40
[  145.127870] [c00000000108bda0] [c00000000001683c] .cpu_idle
+0x18c/0x2d0
[  145.127876] [c00000000108be60] [c00000000000b434] .rest_init
+0x124/0x1b0
[  145.127884] [c00000000108bef0] [c0000000009d0d28] .start_kernel
+0x568/0x588
[  145.127890] [c00000000108bf90] [c000000000009660] .start_here_common
+0x20/0x40

This is because the RCU usage in interrupt context should be used in
area marked by rcu_irq_enter()/rcu_irq_exit(), called in
irq_enter()/irq_exit() respectively.

Move them into the irq_enter()/irq_exit() area to avoid the reporting.

Signed-off-by: Li Zhong 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Fix build of some debug irq code

2012-07-10T09:16:20+00:00

There was a typo, checking for CONFIG_TRACE_IRQFLAG instead of
CONFIG_TRACE_IRQFLAGS causing some useful debug code to not be
built

This in turns causes a build error on BookE 64-bit due to incorrect
semicolons at the end of a couple of macros, so let's fix that too

Signed-off-by: Benjamin Herrenschmidt 
CC: stable@vger.kernel.org [v3.4]

powerpc: More fixes for lazy IRQ vs. idle

2012-07-10T09:16:07+00:00

Looks like we still have issues with pSeries and Cell idle code
vs. the lazy irq state. In fact, the reset fixes that went upstream
are exposing the problem more by causing BUG_ON() to trigger (which
this patch turns into a WARN_ON instead).

We need to be careful when using a variant of low power state that
has the side effect of turning interrupts back on, to properly set
all the SW & lazy state to look as if everything is enabled before
we enter the low power state with MSR:EE off as we will return with
MSR:EE on. If not, we have a discrepancy of state which can cause
things to go very wrong later on.

This patch moves the logic into a helper and uses it from the
pseries and cell idle code. The power4/970 idle code already got
things right (in assembly even !) so I'm not touching it. The power7
"bare metal" idle code is subtly different and correct. Remains PA6T
and some hypervisor based Cell platforms which have questionable
code in there, but they are mostly dead platforms so I'll fix them
when I manage to get final answers from the respective maintainers
about how the low power state actually works on them.

Signed-off-by: Benjamin Herrenschmidt 
CC: stable@vger.kernel.org [v3.4]

powerpc/ftrace: Do not trace restore_interrupts()

2012-06-29T04:35:36+00:00

As I was adding code that affects all archs, I started testing function
tracer against PPC64 and found that it currently locks up with 3.4
kernel. I figured it was due to tracing a function that shouldn't be, so
I went through the following process to bisect to find the culprit:

 cat /debug/tracing/available_filter_functions > t
 num=`wc -l t`
 sed -ne "1,${num}p" t > t1
 let num=num+1
 sed -ne "${num},$p" t > t2
 cat t1 > /debug/tracing/set_ftrace_filter
 echo function /debug/tracing/current_tracer
 

It finally came down to this function: restore_interrupts()

I'm not sure why this locks up the system. It just seems to prevent
scheduling from occurring. Interrupts seem to still work, as I can ping
the box. But all user processes freeze.

When restore_interrupts() is not traced, function tracing works fine.

Cc: stable@kernel.org
Signed-off-by: Steven Rostedt 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Fix irq distribution

2012-05-22T04:38:26+00:00

setting CONFIG_IRQ_ALL_CPUS distributes IRQs to CPUs only when
the number of online CPUs equals NR_CPUS.  See commit
280ff97494e0fef4124bee5c52e39b23a18dd283 "sparc64: fix and
optimize irq distribution" for more details.

Using the online mask fixes IRQ-to-CPU distribution on systems
that boot with less than NR_CPUS.

Signed-off-by: Kim Phillips 
Signed-off-by: Benjamin Herrenschmidt

powerpc/irq: Fix another case of lazy IRQ state getting out of sync

2012-05-11T23:40:41+00:00

So we have another case of paca->irq_happened getting out of
sync with the HW irq state. This can happen when a perfmon
interrupt occurs while soft disabled, as it will return to a
soft disabled but hard enabled context while leaving a stale
PACA_IRQ_HARD_DIS flag set.

This patch fixes it, and also adds a test for the condition
of those flags being out of sync in arch_local_irq_restore()
when CONFIG_TRACE_IRQFLAGS is enabled.

This helps catching those gremlins faster (and so far I
can't seem see any anymore, so that's good news).

Signed-off-by: Benjamin Herrenschmidt

powerpc/irq: Fix bug with new lazy IRQ handling code

2012-05-08T23:42:21+00:00

We had a case where we could turn on hard interrupts while
leaving the PACA_IRQ_HARD_DIS bit set in the PACA. This can
in turn cause a BUG_ON() to hit in __check_irq_replay() due
to interrupt state getting out of sync.

The assembly code was also way too convoluted. Instead, we
now leave it to the C code to do the right thing which ends
up being smaller and more readable.

Signed-off-by: Benjamin Herrenschmidt

powerpc/irqdomain: Fix broken NR_IRQ references

2012-04-30T00:45:26+00:00

The switch from using irq_map to irq_alloc_desc*() for managing irq
number allocations introduced new bugs in some of the powerpc
interrupt code.  Several functions rely on the value of NR_IRQS to
determine the maximum irq number that could get allocated.  However,
with sparse_irq and using irq_alloc_desc*() the maximum possible irq
number is now specified with 'nr_irqs' which may be a number larger
than NR_IRQS.  This has caused breakage on powermac when
CONFIG_NR_IRQS is set to 32.

This patch removes most of the direct references to NR_IRQS in the
powerpc code and replaces them with either a nr_irqs reference or by
using the common for_each_irq_desc() macro.  The powerpc-specific
for_each_irq() macro is removed at the same time.

Also, the Cell axon_msi driver is refactored to remove the global
build assumption on the size of NR_IRQS and instead add a limit to the
maximum irq number when calling irq_domain_add_nomap().

Signed-off-by: Grant Likely 
Signed-off-by: Benjamin Herrenschmidt

irq: Kill pointless irqd_to_hw export

2012-04-11T04:39:17+00:00

It makes no sense to export this trivial function.  Make it a static inline
instead.

This patch also drops virq_to_hw from arch/c6x since it is unused by that
architecture.

v2: Move irq_hw_number_t into types.h to fix ARM build failure

Signed-off-by: Grant Likely 
Acked-by: Thomas Gleixner 
Cc: Benjamin Herrenschmidt