With implementation of data breakpoints debug exceptions raised when
PS.EXCM is set need to be handled, e.g. window overflow code can write
to watched userspace address. Currently debug exception handler uses
EXCSAVE and DEPC SRs to save temporary registers, but DEPC may not be
available when PS.EXCM is set and more space will be needed to save
additional state.
Reorganize debug context: create per-CPU structure debug_table instance
and store its address in the EXCSAVE<debug level> instead of
debug_exception function address. Expand this structure when more save
space is needed.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
There are multiple factors adding to the issue in different
configurations:
- commit 17290231df ("xtensa: add fixup for double exception raised
in window overflow") added function window_overflow_restore_a0_fixup to
double exception vector overlapping reset vector location of secondary
processor cores.
- on MMUv2 cores RESET_VECTOR1_VADDR may point to uncached kernel memory
making code overlapping depend on cache type and size, so that without
cache or with WT cache reset vector code overwrites double exception
code, making issue even harder to detect.
- on MMUv3 cores RESET_VECTOR1_VADDR may point to unmapped area, as
MMUv3 cores change virtual address map to match MMUv2 layout, but
reset vector virtual address is given for the original MMUv3 mapping.
- physical memory region of the secondary reset vector is not reserved
in the physical memory map, and thus may be allocated and overwritten
at arbitrary moment.
Fix it as follows:
- move window_overflow_restore_a0_fixup code to .text section.
- define RESET_VECTOR1_VADDR so that it points to reset vector in the
cacheable MMUv2 map for cores with MMU.
- reserve reset vector region in the physical memory map. Drop separate
literal section and build mxhead.S with text section literals.
Cc: <stable@vger.kernel.org>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
In case perf IRQ is the highest of the medium-level IRQs, and is alone
on its level, it may be treated as NMI:
- LOCKLEVEL is defined to be one level less than EXCM level,
- IRQ masking never lowers current IRQ level,
- new fake exception cause code, EXCCAUSE_MAPPED_NMI is assigned to that
IRQ; new second level exception handler, do_nmi, assigned to it
handles it as NMI,
- atomic operations in configurations without s32c1i still need to mask
all interrupts.
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Double exceptions that happen during register window overflow/underflow
are handled in the topmost stack frame, as if it was the only exception
that occured. However unaligned access exception handler is special
because it needs to analyze instruction that caused the exception, but
the userspace instruction that triggered window exception is completely
irrelevant. Unaligned data access is rather normal in the generic
userspace code, but stack pointer manipulation must always be done by
architecture-aware code and thus unaligned stack means a serious problem
anyway.
Use the default unaligned access handler that raises SIGBUS in case
of unaligned access in window overflow/underflow handler.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
There are two FIXMEs in the double exception handler 'for the extremely
unlikely case'. This case gets hit by gcc during kernel build once in
a few hours, resulting in an unrecoverable exception condition.
Provide missing fixup routine to handle this case. Double exception
literals now need 8 more bytes, add them to the linker script.
Also replace bbsi instructions with bbsi.l as we're branching depending
on 8th and 7th LSB-based bits of exception address.
This may be tested by adding the explicit DTLB invalidation to window
overflow handlers, like the following:
--- a/arch/xtensa/kernel/vectors.S
+++ b/arch/xtensa/kernel/vectors.S
@@ -592,6 +592,14 @@ ENDPROC(_WindowUnderflow4)
ENTRY_ALIGN64(_WindowOverflow8)
s32e a0, a9, -16
+ bbsi.l a9, 31, 1f
+ rsr a0, ccount
+ bbsi.l a0, 4, 1f
+ pdtlb a0, a9
+ idtlb a0
+ movi a0, 9
+ idtlb a0
+1:
l32e a0, a1, -12
s32e a2, a9, -8
s32e a1, a9, -12
Cc: stable@vger.kernel.org
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
The original implementation could clobber registers under certain conditions.
The Xtensa processor architecture uses windowed registers and the original
implementation was using a4 as a temporary register, which under certain
conditions could be register a0 of the oldest window frame, and didn't always
restore the content correctly.
By moving the _spill_registers routine inside the fast system call, it frees
up one more register (the return address is not required anymore) for the
spill routine.
Signed-off-by: Chris Zankel <chris@zankel.net>
Based on the SMP patch by Joe Taylor and subsequent fixes.
Preserve exception table pointer (normally stored in excsave1 SR) as it
cannot be easily restored in SMP environment.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
IRQ handlers are expected to run with IRQs disabled.
See e.g. http://lwn.net/Articles/380931/ for a longer story.
This was overlooked in the commit
2d1c645 xtensa: dispatch medium-priority interrupts
Revert to old behavior and simplify interrupt entry and exit code.
Interrupt handler still honours IRQ priority.
do_notify_resume/schedule must be called with interrupts enabled, enable
interrupts if we return from user exception.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
Add support for dispatching medium-priority interrupts, that is,
interrupts of priority levels 2 to EXCM_LEVEL. IRQ handling may be
preempted by higher priority IRQ.
Signed-off-by: Marc Gauthier <marc@tensilica.com>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
Remove heading and trailing spaces, trim trailing lines, and wrap lines
that are longer than 80 characters.
Signed-off-by: Chris Zankel <chris@zankel.net>
Manually load references to exc_table from the explicit literal in order
to fit DoubleExceptionVector.literals into the available 16-byte gap
before DoubleExceptionVector.text in the absence of link time
relaxation. Without this fix DoubleExceptionVector.literal section
overlaps DoubleExceptionVector.text section in the linked vmlinux image.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
- reference SRs by names where possible, not by numbers;
- get rid of __stringify around SR names where possible;
- remove unneeded SR names from asm/regs.h;
- add SREG_ prefix to remaining SR names;
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
fix the following 'make includecheck' warnings:
arch/xtensa/kernel/vectors.S: asm/processor.h is included more than once.
arch/xtensa/kernel/vectors.S: asm/ptrace.h is included more than once.
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Cc: Chris Zankel <chris@zankel.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The Xtensa port contained many header files that were never needed. This
rather lengthy patch removes all those files. Unfortunately, there were
many dependencies that needed to be updated, so this patch touches quite a
few source files.
Signed-off-by: Chris Zankel <chris@zankel.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The attached patches provides part 3 of an architecture implementation for the
Tensilica Xtensa CPU series.
Signed-off-by: Chris Zankel <chris@zankel.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Max Filippov
Chris Zankel
Marc Gauthier
Jaswinder Singh Rajput
Johannes Weiner
Chris Zankel
Sam Ravnborg