This adds support for the single-vector trapping (SVT) model, defined by
SPARC-V8 Embedded (V8E) Architecture Specification. SVT is available in
most LEON processors.
With single-vector trapping enabled, all traps are vectored through a
single trap vector (TBR.A) rather than one 16-byte entry for each trap
type. This improves memory utilization because the full 4 KiB trap table
is not needed.
This implementation uses a two-level of lookup table to find the handler
for the trap type (0..255).
- Execution time is constant.
- Condition flags are preserved.
- The implementation footprint is 60 bytes .text and 284 bytes .rodata.
For comparison, a non-SVT table is always 4096 .text.
Signed-off-by: Martin Åberg <martin.aberg@gaisler.com>
Assembler files were not migrated with the new <zephyr/...> prefix.
Note that the conversion has been scripted, refer to #45388 for more
details.
Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>
This commit avoids enabling interrupts during Zephyr init.
Details:
Interrupts will be enabled only when the first thread starts or if
arch_irq_unlock() is called before that.
The logic is now:
1. Enable traps, disable interrupts globally
2. Initialize bss
3. Call _PrepC
Use in-place memset() to avoid register window overflow and underflow
traps. That is perhaps not the common scenario, but could happen with
memset() implementation which contains SAVE instructions on a system
with few register windows.
The second, and more important, item this commit addresses is that it
increases the processor interrupt level (priority) to highest. That
is, it enters _PrepC with all maskable interrupts levels disabled.
This fixes some cases where interrupts could be taken after
z_clock_driver_init() while the system was still initializing. That
seem to have occurred when clearing large thread stacks.
The third thing is that we now start out with current window pointer
0 (PSR.CWP=0) instead of 1. It has no practical implication except
for preparing for possible future support for systems with only
two windows.
Signed-off-by: Martin Åberg <martin.aberg@gaisler.com>
SPARC is an open and royalty free processor architecture.
This commit provides SPARC architecture support to Zephyr. It is
compatible with the SPARC V8 specification and the SPARC ABI and is
independent of processor implementation.
Functionality specific to SPRAC processor implementations should
go in soc/sparc. One example is the LEON3 SOC which is part of this
patch set.
The architecture port is fully SPARC ABI compatible, including trap
handlers and interrupt context.
Number of implemented register windows can be configured.
Some SPARC V8 processors borrow the CASA (compare-and-swap) atomic
instructions from SPARC V9. An option has been defined in the
architecture port to forward the corresponding code-generation option
to the compiler.
Stack size related config options have been defined in sparc/Kconfig
to match the SPARC ABI.
Co-authored-by: Nikolaus Huber <nikolaus.huber.melk@gmail.com>
Signed-off-by: Martin Åberg <martin.aberg@gaisler.com>
