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>
We need it saved because it contains a3 where we track which register
windows we still need to spill, and fixup handler may call C exception
handlers. Also fix comments.
Cc: stable@vger.kernel.org
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Most in-kernel users want registers spilled on the kernel stack and
don't require PS.EXCM to be set. That means that they don't need fixup
routine and could reuse regular window overflow mechanism for that,
which makes spill routine very simple.
Cc: stable@vger.kernel.org
Suggested-by: Chris Zankel <chris@zankel.net>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
fast_syscall_spill_registers_fixup was not correctly updated by the
'keep a3 and excsave1 on entry to exception handlers' patch: it doesn't
preserve a3 that it gets on entry, breaking _spill_registers in case of
page fault on stack during register spilling, leading to unhandled
exception in kernel mode.
Preserve a3 by saving it in the original _spill_registers stack frame's
a3 during exception handling and restoring it afterwards.
Also fix comments and function bounds annotations.
Reported-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Tested-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Chris Zankel <chris@zankel.net>
Instead of emulating movsp instruction in the kernel use window
underflow handler to load missing register window and retry failed
movsp.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
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>
Check pending signals and rescheduling thread flags with interrupts
disabled, and don't enable them if no flags are set. Call
trace_hardirqs_on after thread flags handling, so that rescheduling is
done and hardirqs tracking flag is updated in the correct task context.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
- check that user TLB mappings correspond to the current page table;
- check that TLB mapping VPN is in the kernel/user address range
in accordance with its ASID.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
Before _PAGE_WRITABLE_BIT test fast_store_prohibited must make sure that
PTE is present. Otherwise 'writable' bit is undefined and may be reused
in the 'file offset' or 'swap type' PTE fields.
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>
The Xtensa architecture provides a global register called THREADPTR
for the purpose of Thread Local Storage (TLS) support. This allows us
to use a fairly simple implementation, keeping the thread pointer in
the regset and simply saving and restoring it upon entering/exiting
the from user space.
Signed-off-by: Chris Zankel <chris@zankel.net>
Support call graph profiling.
Keep upper two bits of PC unchanged through backtrace rather than take
them from sp (a1). The stack pointer is usually in the same GB (same
upper 2 bits) as PC, but technically doesn't always have to be (and
might not in the future, when taking full advantage of MMU v3).
Signed-off-by: Dan Nicolaescu <dann@xtensa-linux.org>
Signed-off-by: Pete Delaney <piet@tensilica.com>
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>
Although scompare1 may be saved/restored by xchal_ncp_{load,store}
macros, explicit save/restore of registers manipulated by the kernel
itself is considered more correct.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
Fix two compiler warnings complaining about truncating a value on
a 64-bit host, and about declaring an unused variable that is only
used for a specific configuration.
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>
The linker script was including assembly macros from the coprocessor
header file that is not otherwise used by the script.
Signed-off-by: Chris Zankel <chris@zankel.net>
In particular, several occurances of funny versions of 'success',
'unknown', 'therefore', 'acknowledge', 'argument', 'achieve', 'address',
'beginning', 'desirable', 'separate' and 'necessary' are fixed.
Signed-off-by: Daniel Mack <daniel@caiaq.de>
Cc: Joe Perches <joe@perches.com>
Cc: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Move all header files for xtensa to arch/xtensa/include and platform and
variant header files to the appropriate arch/xtensa/platforms/ and
arch/xtensa/variants/ directories.
Moving the files gets also rid of all uses of symlinks in the Makefile.
This has been completed already for the majority of the architectures
and xtensa is one out of six missing.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Chris Zankel <chris@zankel.net>
For processor configurations that have optional registers
(compiler-used but non-coprocessor), user space registers
might get corrupted when there are only 4 registers in
the current window-frame, ie. register a4 belongs to the
oldest frame in the register file.
Signed-off-by: Chris Zankel <chris@zankel.net>
The Xtensa architecture allows to define custom instructions and
registers. Registers that are bound to a coprocessor are only
accessible if the corresponding enable bit is set, which allows
to implement a 'lazy' context switch mechanism. Other registers
needs to be saved and restore at the time of the context switch
or during interrupt handling.
This patch adds support for these additional states:
- save and restore registers that are used by the compiler upon
interrupt entry and exit.
- context switch additional registers unbound to any coprocessor
- 'lazy' context switch of registers bound to a coprocessor
- ptrace interface to provide access to additional registers
- update configuration files in include/asm-xtensa/variant-fsf
Signed-off-by: Chris Zankel <chris@zankel.net>
We will never (need to) support signal handling coming from a
double exception. There are too many things that could go wrong
and delivering signals is not the fastest method for IPC, anyway.
Signed-off-by: Chris Zankel <chris@zankel.net>
Register a2 is saved in depc but wasn't getting restored before
returning from _spill_registers when there weren't any registers
to spill. The mask to cut the top bit from the rotated WINDOWMASK
register was also one bit short.
Signed-off-by: CHris Zankel <chris@zankel.net>
Add support for processors that have cache-aliasing issues, such as
the Stretch S5000 processor. Cache-aliasing means that the size of
the cache (for one way) is larger than the page size, thus, a page
can end up in several places in cache depending on the virtual to
physical translation. The method used here is to map a user page
temporarily through the auto-refill way 0 and of of the DTLB.
We probably will want to revisit this issue and use a better
approach with kmap/kunmap.
Signed-off-by: Chris Zankel <chris@zankel.net>
Newer processor versions starting with Xtensa6/LX2 support an 'executable'
bit for memory pages. This bit replaces the 'valid' bit, so it must be
always set to one for older processor versions. To mark a page invalid, we now
set the cache-attributes to b11, which is backward compatible.
Signed-off-by: Chris Zankel <chris@zankel.net>
The non-rt signal handling was never really used, so we don't break
anything. This patch also cleans up the signal stack-frame to make
it independent from the processor configuration. It also improves
the method used for controlling single-stepping. We now save and
restore the 'icountlevel' register that controls single stepping
and set or clear the saved state to enable or disable it.
Signed-off-by: Chris Zankel <chris@zankel.net>
This is a long outstanding patch to finally fix the syscall interface. The
constants used for the system calls are those we have provided in our libc
patches. This patch also fixes the shmbuf and stat structure, and fcntl
definitions.
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 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>
verify_area() is still alive on xtensa in 2.6.17-rc3-git13 It would be nice
to finally be rid of that function across the board.
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>
