Overview
========
The errata is worked around in the kernel without requiring toolchain
modifications. It is triggered the JMPL/RETT return from trap instruction
sequence never generated by the compiler and. There are also other
conditions that must must be true to trigger the errata, for example the
instruction that the trap returns to has to be a JMPL instruction. The
errata can only be triggered if certain data is corrected by ECC
(inflicted by radiation), thus it can not be triggered under normal
operation. For more information see:
www.gaisler.com/notes
Affected RTEMS target BSPs:
* GR712RC
* UT699
* UT700/699E
The work around is enabled by defining __FIX_LEON3_TN0018 at build time.
After applying the following GCC patch, GCC will set the define when
compiling for an affected multilib:
* GR712RC (-mcpu=leon3 -mfix-gr712rc)
* UT700/UT699E (-mpcu=leon3 -mfix-ut700)
* UT699 (-mcpu=leon -mfix-ut699)
When building for another multilib and TN0018 is still required, it
is possible to enable it on the RTEMS kernel configure line using the
TARGET_CFLAGS (-D__FIX_LEON3FT_TN0018) or other by other means.
The following GCC patch sets __FIX_LEON3FT_TN0018 for the affected RTEMS
multilibs:
---------
diff --git a/gcc/config/sparc/rtemself.h b/gcc/config/sparc/rtemself.h
index 6570590..ddec98c 100644
--- a/gcc/config/sparc/rtemself.h
+++ b/gcc/config/sparc/rtemself.h
@@ -33,6 +33,8 @@
builtin_assert ("system=rtems"); \
if (sparc_fix_b2bst) \
builtin_define ("__FIX_LEON3FT_B2BST"); \
+ if (sparc_fix_gr712rc || sparc_fix_ut700 || sparc_fix_ut699) \
+ builtin_define ("__FIX_LEON3FT_TN0018"); \
} \
while (0)
---------
Workaround Implementation
=========================
In general there are two approaches that the workaround uses:
A) avoid ECC restarting the RETT instruction
B) avoid returning from trap to a JMPL instruction
Where A) comes at a higher performance cost than B), so B) is used
where posssible. B) can be achived for certain returns from trap
handlers if trap entry is controlled by assembly, such as system calls.
A)
A special JMPL/RETT sequence where instruction cache is disabled
temporarily to avoid RETT containing ECC errors, and reading of RETT
source registers to "clean" them from incorrect ECC just before RETT
is executed.
B)
The work around prevents JMPL after system calls (TA instruction) and
modifies assembly code on return from traps jumping back to application
code. Note that for some traps the trapped instruction is always
re-executed and can therefore not trigger the errata, for example the
SAVE instruction causing window overflow or an float instruction causing
FPU disabled trap.
RTEMS SPARC traps workaround implementation:
NAME NOTE TRAP COMMENT
* window overflow 1 - 0x05 always returns to a SAVE
* window underflow 1 - 0x06 always returns to a RESTORE
* interrupt traps 2 - 0x10..1f special rett sequence workaround
* syscall 3 - 0x80 shutdown system - never returns
* ABI flush windows 2 - 0x83 special rett sequence workaround
* syscall_irqdis 4 - 0x89
* syscall_irqen 4 - 0x8A
* syscall_irqdis_fp 1 - 0x8B always jumps back to FP instruction
* syscall_lazy_fp_switch 5 - 0x04 A) jumps back to FP instruction, or to
B) _Internal_error() starting with SAVE
Notes:
1) no workaround needed because trap always returns to non-JMPL instruction
2) workaround implemented by special rett sequence
3) no workaround needed because system call never returns
4) workaround implemented by inserting NOP in system call generation. Thus
fall into 1) when workaround is enabled and no trap handler fix needed.
5) trap handler branches into both 1) and returning to _Internal_error()
which starts with a SAVE and besides since it shuts down the system that
RETT should never be in cache (only executed once) so fix not necessary
in this case.
Any custom trap handlers may also have to be updated. To simplify that,
helper work around assembly code in macros are available in a separate
include file <libcpu/grlib-tn-0018.h>.
Close#4155.
Moves drvmgr_drivers[] from amba.c to a separate file in order
to avoid the dependecy on APBUART/GPTIMER drivers. This has
an effect when user configured not to use timer or uart
in their project.
The current ZynqMP BSPs don't have _qemu in their name as do all other
RTEMS BSPs that are specifically made to run on QEMU. This fixes the
naming for those ZynqMP BSP variants for easier identification.
AArch64 on hardware is often started at EL2 instead of EL1 from either
u-boot or a first stage bootloader. This allows RTEMS to drop from EL2
execution to EL1 to operate as normal.
Remove usage of SUBALIGN() in aarch64 linkcmds which works around a
difference in behavior on AArch64 platforms. This is no longer necessary
since alignment is now enforced explicitly.
Closes#4178.
- Add support to the BSP to enable irq-generic management
- Update the powerpc shared irq code to support irq-generic. This
is an opt in option for existing powerpc bsps. This change
should be simpler now
- Fix a number of issues in ISA IRQ controller handling by porting
fixes from the i386 (PC) BSP
Closes#4238Closes#4239
This allows an application to get the registers of the LPSPI. That is
usefull for applications that want to use DMA for a very specialized and
highly optimized communication.
Update #4180
Note: The changes have been done with portability in mind. The driver
should (in theory) be able to replace the original one in the MPC BSPs
too. For full compatibility an adaption layer and especially a test
would be necessary. Because both are missing, don't integrate it into
the MPC BSP now.
Update #4180
RTEMS OFW is a FDT only implementation of the OpenFirmWare
interface. This API is created to be compatible with FreeBSD
OpenFirmWare interface. The main intention is to make
porting of FreeBSD drivers to RTEMS easier.
Most functions implemented have an direct one-one mapping
with the original OFW API and some extra auxiliary functions
were implemented to make working with device trees easier in
RTEMS.
Update #3784
This BSP supports the Arm Fixed Virtual Platform. Only the Cortex-R52
processor configuration is supported by the BSP. It should be easy to
add support for other variants if needed.
Update #4202.
Set the VBAR to the vector table in the start section before
bsp_start_hook_0() is called to earlier handle exceptions in RTEMS.
Set the VBAR to the normal vector table in start.S for the main
processor. Secondary processors set it in bsp_start_hook_0().
Update #4202.
