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When using the Java Extension Module hardware, a Java stack underflow or
overflow trap may cause the system to enter an infinite exception loop.
Although there's no kernel support for the Java hardware yet, we need to
be able to recover from this situation and keep the system running.
This patch adds code to detect and fixup this situation in the critical
exception handler and terminate the faulting process. We may have to
rethink how to handle this more gracefully when the necessary kernel
support for hardware-accelerated Java is added.
Reported-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
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Expand the per-process PGDs so that they cover the kernel virtual
memory area as well. This simplifies the TLB miss handler fastpath
since it doesn't have to check for kernel addresses anymore.
If a TLB miss happens on a kernel address and a second-level page
table can't be found, we check swapper_pg_dir and copy the PGD entry
into the user PGD if it can be found there.
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
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Instead of storing physical addresses along with page flags in the
PGD, store virtual addresses and use NULL to indicate a not present
second-level page table. A non-page-aligned page table indicates a bad
PMD.
This simplifies the TLB miss handler since it no longer has to check
the Present bit and no longer has to convert the PGD entry from
physical to virtual address. Instead, it has to check for a NULL
entry, which is slightly cheaper than either.
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
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Kill the special exception handler sections .tlbx.ex.text,
.tlbr.ex.text, tlbw.ex.text and .scall.text. Use .org instead to place
the handlers at the required offsets from EVBA.
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
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Create a new file, pm-at32ap700x.S, in mach-at32ap and move the CPU
idle sleep code there. Make it possible to disable the sleep code.
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
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It's not like it really matters at this point since the system is
dying anyway, but handle_critical pushes too few registers on the
stack so the register dump, which makes the register dump look a bit
strange. This patch fixes it.
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
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The current debug trap handling code does a number of things that are
illegal according to the AVR32 Architecture manual. Most importantly,
it may try to schedule from Debug Mode, thus clearing the D bit, which
can lead to "undefined behaviour".
It seems like this works in most cases, but several people have
observed somewhat unstable behaviour when debugging programs,
including soft lockups. So there's definitely something which is not
right with the existing code.
The new code will never schedule from Debug mode, it will always exit
Debug mode with a "retd" instruction, and if something not running in
Debug mode needs to do something debug-related (like doing a single
step), it will enter debug mode through a "breakpoint" instruction.
The monitor code will then return directly to user space, bypassing
its own saved registers if necessary (since we don't actually care
about the trapped context, only the one that came before.)
This adds three instructions to the common exception handling code,
including one branch. It does not touch super-hot paths like the TLB
miss handler.
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
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Generate a new set of OCD register definitions in asm/ocd.h and rename
__mfdr() and __mtdr() to ocd_read() and ocd_write() respectively.
The bitfield definitions are a lot more complete now, and they are
entirely based on bit numbers, not masks. This is because OCD
registers are frequently accessed from assembly code, where bit
numbers are a lot more useful (can be fed directly to sbr, bfins,
etc.)
Bitfields that consist of more than one bit have two definitions:
_START, which indicates the number of the first bit, and _SIZE, which
indicates the number of bits. These directly correspond to the
parameters taken by the bfextu, bfexts and bfins instructions.
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
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Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
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As explained on:
http://www.avrfreaks.net/index.php?nameÿphpBB2&fileÿewtopic&tS307
If the current process is preempted before it can copy RAR_SUP and
RSR_SUP both register are lost and the process will segfault as soon
as it return from the syscall since the return adress will be
corrupted.
This patch disable IRQ as soon as we enter the syscall path and
reenable them when the copy is done.
In the interrupt handlers, check if we are interrupting the srrf
instruction, if so disable interrupts and return. The interrupt
handler will be re-called immediatly when the interrupts are
reenabled.
After some stressing workload:
- find / > /dev/null in loop
- top (in ssh)
- ping -f avr32
The segfaults are not seen anymore.
Signed-off-by: Philippe Rétornaz <philippe.retornaz@epfl.ch>
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
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Reorder some instructions and change the register usage to reduce
the number of pipeline stalls. Also use the bfextu and bfins
instructions for bitfield manipulations instead of shifting and
masking.
This makes gzipping a 80MB file approximately 2% faster.
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
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Fix a problem with the NMI handler entry code related to the NMI handler
sharing some code with the exception handlers. This is not a good idea
because the RSR and RAR registers are not the same, and the NMI handler
runs with interrupts masked the whole time so there's no need to check
for pending work.
Open-code the low-level NMI handling logic instead so that the pt_regs
layout is actually correct when the higher-level handler is called.
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
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This patch puts the CPU in sleep 0 when doing nothing, idle. This will
turn of the CPU clock and thus save power. The CPU is waken again when
an interrupt occurs.
Signed-off-by: Hans-Christian Egtvedt <hcegtvedt@atmel.com>
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
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This adds support for the Atmel AVR32 architecture as well as the AT32AP7000
CPU and the AT32STK1000 development board.
AVR32 is a new high-performance 32-bit RISC microprocessor core, designed for
cost-sensitive embedded applications, with particular emphasis on low power
consumption and high code density. The AVR32 architecture is not binary
compatible with earlier 8-bit AVR architectures.
The AVR32 architecture, including the instruction set, is described by the
AVR32 Architecture Manual, available from
http://www.atmel.com/dyn/resources/prod_documents/doc32000.pdf
The Atmel AT32AP7000 is the first CPU implementing the AVR32 architecture. It
features a 7-stage pipeline, 16KB instruction and data caches and a full
Memory Management Unit. It also comes with a large set of integrated
peripherals, many of which are shared with the AT91 ARM-based controllers from
Atmel.
Full data sheet is available from
http://www.atmel.com/dyn/resources/prod_documents/doc32003.pdf
while the CPU core implementation including caches and MMU is documented by
the AVR32 AP Technical Reference, available from
http://www.atmel.com/dyn/resources/prod_documents/doc32001.pdf
Information about the AT32STK1000 development board can be found at
http://www.atmel.com/dyn/products/tools_card.asp?tool_id=3918
including a BSP CD image with an earlier version of this patch, development
tools (binaries and source/patches) and a root filesystem image suitable for
booting from SD card.
Alternatively, there's a preliminary "getting started" guide available at
http://avr32linux.org/twiki/bin/view/Main/GettingStarted which provides links
to the sources and patches you will need in order to set up a cross-compiling
environment for avr32-linux.
This patch, as well as the other patches included with the BSP and the
toolchain patches, is actively supported by Atmel Corporation.
[dmccr@us.ibm.com: Fix more pxx_page macro locations]
[bunk@stusta.de: fix `make defconfig']
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Dave McCracken <dmccr@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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