Commit 4255b07f2c ("ARCv2: STAR 9000793984: Handle return
from intr to Delay Slot") involved a complex 2 staged trampoline.
Apparently this can be greatly simplified by returning from pure
kernel mode (iso interrupt) so drop to pure kernel mdoe and execute
the normal exception return path.
Testing this was a bit of challenge as return from interrupt is rarely
executed now after commit 4de0e52867 ("ARCv2: STAR 9000814690:
Really Re-enable interrupts to avoid deadlocks"). That fix is necessary
evil and pct interrupts etc do exercise intr return path.
Anyhow after a revert of above in my local test setup I was able to hit
this case and verify the patch works.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
- the motivation was to be remove blatent copy-paste due to hasty support
of CONFIG_ARC_IRQ_NO_AUTOSAVE support
- but with refactoring we could use LDD/STD to greatly optimize the code
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Based on 2 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation #
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 4122 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
There's a hardware bug which affects the HSDK platform, triggered by
micro-ops for auto-saving regfile on taken interrupt. The workaround is
to inhibit autosave.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Currently Kconfig knob ARC_NUMBER_OF_INTERRUPTS is used as indicator of
hard irq count. But it is flawed that it doesn't affect
- NR_IRQS : for number of virtual interrupts
- NR_CPU_IRQS : for number of hardware interrupts
Moreover the actual hardware irq count might still not be same as
ARC_NUMBER_OF_INTERRUPTS. So use the information availble in the
Build Configuration Registers and get rid of the Kconfig option.
We still need "some" build time info about irq count to set up
sufficient number of vector table entries. This is done with a
sufficiently large NR_CPU_IRQS which will eventually be used soley for
that purpose (subsequent patches will remove its usage elsewhere)
So to summarize what this patch does:
* NR_CPU_IRQS defines a maximum number of hardware interrupts.
* Remove ARC_NUMBER_OF_INTERRUPTS option and create interrupts
table for all possible hardware interrupts.
* Increase a maximum number of virtual IRQs to 512. ARCv2 can
support 240 interrupts in the core interrupts controllers
and 128 interrupts in IDU. Thus 512 virtual IRQs must be
enough for most configurations of boards.
This patch leads to NR_CPU_IRQS in 2 places, to reduce the overall
churn. The next patch will remove the 2nd definition anyways.
Signed-off-by: Yuriy Kolerov <yuriy.kolerov@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
[vgupta: reworked the changelog a bit]
And while at it - use the proper assembler macro which includes the
optional irq tracing already - de-uglify'ing the code a bit
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
- The asm helpers for calling into irq tracer were missing
- Add calls to above helpers in low level assembly entry code for ARCv2
- irq_save() uses CLRI to disable interrupts and returns the prev interrupt
state (in STATUS32) in a specific encoding (and not the raw value of
STATUS32). This is usable with SETI in irq_restore(). However
save_flags() reads the raw value of STATUS32 which doesn't pair with
irq_save/restore() and thus needs fixing.
Signed-off-by: Evgeny Voevodin <evgeny.voevodin@intel.com>
[vgupta: updated changelog and also added some comments]
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
ARConnect/MCIP Inter-Core-Interrupt module can't send interrupt to
local core. So use core intc capability to trigger software
interrupt to self, using an unsued IRQ #21.
This showed up as csd deadlock with LTP trace_sched on a dual core
system. This test acts as scheduler fuzzer, triggering all sorts of
schedulting activity. Trouble starts with IPI to self, which doesn't get
delivered (effectively lost due to H/w capability), but the msg intended
to be sent remain enqueued in per-cpu @ipi_data.
All subsequent IPIs to this core from other cores get elided due to the
IPI coalescing optimization in ipi_send_msg_one() where a pending msg
implies an IPI already sent and assumes other core is yet to ack it.
After the elided IPI, other core simply goes into csd_lock_wait()
but never comes out as this core never sees the interrupt.
Fixes STAR 9001008624
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: <stable@vger.kernel.org> [4.2]
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Returning to delay slot, riding an interrupti, had one loose end.
AUX_USER_SP used for restoring user mode SP upon RTIE was not being
setup from orig task's saved value, causing task to use wrong SP,
leading to ProtV errors.
The reason being:
- INTERRUPT_EPILOGUE returns to a kernel trampoline, thus not expected to restore it
- EXCEPTION_EPILOGUE is not used at all
Fix that by restoring AUX_USER_SP explicitly in the trampoline.
This was broken in the original workaround, but the error scenarios got
reduced considerably since v3.14 due to following:
1. The Linuxthreads.old based userspace at the time caused many more
exceptions in delay slot than the current NPTL based one.
Infact with current userspace the error doesn't happen at all.
2. Return from interrupt (delay slot or otherwise) doesn't get exercised much
after commit 4de0e52867 ("Really Re-enable interrupts to avoid deadlocks")
since IRQ_ACTIVE.active being clear means most returns are as if from pure
kernel (even for active interrupts)
Infact the issue only happened in an experimental branch where I was tinkering with
reverted 4de0e52867
Cc: stable@kernel.org # v4.2+
Fixes: 4255b07f2c ("ARCv2: STAR 9000793984: Handle return from intr to Delay Slot")
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Bus errors from userspace on ARCompact based cores are handled by core
as a high priority L2 interrupt but current code treated it as interrupt
Handling an interrupt like exception is certainly not going to go unnoticed.
(and it worked so far as we never saw a Bus error from userspace until
IPPK guys tested a DDR controller with ECC error detection etc hence
needed to explicitly trigger/handle such errors)
- So move mem_service exception handler from common code into ARCv2 code.
- In ARCompact code, define mem_service as L2 interrupt handler which
just drops down to pure kernel mode and goes of to enqueue SIGBUS
Reported-by: Nelson Pereira <npereira@synopsys.com>
Tested-by: Ana Martins <amartins@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
For Run-on-reset, non masters need to spin wait. For Halt-on-reset they
can jump to entry point directly.
Also while at it, made reset vector handler as "the" entry point for
kernel including host debugger based boot (which uses the ELF header
entry point)
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
