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tbr-tthenrikbrixandersen
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SPARC: Add support for single-vector trapping (SVT)
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 <[email protected]>
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‎arch/sparc/Kconfig

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@@ -26,6 +26,12 @@ config NUM_IRQS
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int
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default 32
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config SPARC_SVT
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bool "Single-vector trapping"
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help
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Use Single-vector trapping (SVT). Defined by SPARC-V8 Embedded (V8E)
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Architecture Specification and available in some LEON processors.
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config SPARC_CASA
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bool "CASA instructions"
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help

‎arch/sparc/core/CMakeLists.txt

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@@ -13,8 +13,9 @@ zephyr_library_sources(
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thread.c
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window_trap.S
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sw_trap_set_pil.S
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trap_table_mvt.S
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)
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zephyr_library_sources_ifdef(CONFIG_SPARC_SVT trap_table_svt.S)
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zephyr_library_sources_ifndef(CONFIG_SPARC_SVT trap_table_mvt.S)
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zephyr_library_sources_ifdef(CONFIG_IRQ_OFFLOAD irq_offload.c)
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zephyr_library_sources_ifdef(CONFIG_THREAD_LOCAL_STORAGE tls.c)

‎arch/sparc/core/reset_trap.S

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@@ -12,6 +12,18 @@
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GTEXT(__sparc_trap_reset)
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SECTION_FUNC(TEXT, __sparc_trap_reset)
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#ifdef CONFIG_SPARC_SVT
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#ifdef CONFIG_SOC_SPARC_LEON
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/* On LEON, enable single vector trapping by setting ASR17.SV. */
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rd %asr17, %g1
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set (1<<13), %g2
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or %g1, %g2, %g1
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wr %g1, %asr17
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#else
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#error "Don't know how to enable SVT on this SOC"
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#endif
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#endif
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set __sparc_trap_table, %g1
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wr %g1, %tbr
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wr 2, %wim

‎arch/sparc/core/trap_table_svt.S

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/*
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* Copyright (c) 2023 Frontgrade Gaisler AB
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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/*
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* This file contains the trap entry for SPARC operating with
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* single-vector trap model, defined in SPARC V8E. The processor
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* redirects execution to a single entry on any trap event. From
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* there, two levels of look-up tables are used to find the trap
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* handler.
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*
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* - Execution time is constant.
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* - Condition flags are not modified.
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* - Provides handler with PSR in l0, TBR in l6
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* - This SVT implementation is less than 400 bytes long. (An MVT
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* table is always 4096 bytes long.)
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*
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* See trap_table_mvt.S for information about SPARC trap types.
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*/
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#include <zephyr/toolchain.h>
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#include <zephyr/linker/sections.h>
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#include <zephyr/arch/sparc/sparc.h>
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#ifdef CONFIG_IRQ_OFFLOAD
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#define IRQ_OFFLOAD_HANDLER __sparc_trap_irq_offload
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#else
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#define IRQ_OFFLOAD_HANDLER __sparc_trap_fault
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#endif
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GTEXT(__sparc_trap_table)
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GTEXT(__start)
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SECTION_SUBSEC_FUNC(TEXT, traptable, __sparc_trap_table)
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__start:
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rd %psr, %l0
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mov %tbr, %l6
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and %l6, 0xf00, %l7
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srl %l7, 6, %l7
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set __sparc_trap_table_svt_level0, %l4
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ld [%l4 + %l7], %l4
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and %l6, 0x0f0, %l7
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srl %l7, 2, %l7
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ld [%l4 + %l7], %l4
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srl %l6, 4, %l3
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jmp %l4
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and %l3, 0xf, %l3 /* Interrupt level */
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__sparc_trap_svt_in_trap:
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ta 0x00
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nop
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SECTION_VAR(RODATA, __sparc_trap_table_svt_tables)
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.align 4
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__sparc_trap_table_svt_level0:
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.word __sparc_trap_table_svt_00
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.word __sparc_trap_table_svt_10
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.word __sparc_trap_table_svt_allbad
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.word __sparc_trap_table_svt_allbad
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.word __sparc_trap_table_svt_allbad
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.word __sparc_trap_table_svt_allbad
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.word __sparc_trap_table_svt_allbad
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.word __sparc_trap_table_svt_allbad
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.word __sparc_trap_table_svt_80
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.word __sparc_trap_table_svt_allbad
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.word __sparc_trap_table_svt_allbad
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.word __sparc_trap_table_svt_allbad
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.word __sparc_trap_table_svt_allbad
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.word __sparc_trap_table_svt_allbad
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.word __sparc_trap_table_svt_allbad
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.word __sparc_trap_table_svt_allbad
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__sparc_trap_table_svt_00:
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.word __sparc_trap_reset
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.word __sparc_trap_fault
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.word __sparc_trap_fault
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.word __sparc_trap_fault
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.word __sparc_trap_fault
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.word __sparc_trap_window_overflow
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.word __sparc_trap_window_underflow
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__sparc_trap_table_svt_allbad:
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.word __sparc_trap_fault
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.word __sparc_trap_fault
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.word __sparc_trap_fault
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.word __sparc_trap_fault
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.word __sparc_trap_fault
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.word __sparc_trap_fault
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.word __sparc_trap_fault
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.word __sparc_trap_fault
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.word __sparc_trap_fault
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.word __sparc_trap_fault
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.word __sparc_trap_fault
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.word __sparc_trap_fault
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.word __sparc_trap_fault
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.word __sparc_trap_fault
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.word __sparc_trap_fault
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.word __sparc_trap_fault
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__sparc_trap_table_svt_10:
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.word __sparc_trap_fault
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.word __sparc_trap_interrupt
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.word __sparc_trap_interrupt
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.word __sparc_trap_interrupt
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.word __sparc_trap_interrupt
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.word __sparc_trap_interrupt
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.word __sparc_trap_interrupt
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.word __sparc_trap_interrupt
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.word __sparc_trap_interrupt
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.word __sparc_trap_interrupt
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.word __sparc_trap_interrupt
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.word __sparc_trap_interrupt
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.word __sparc_trap_interrupt
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.word __sparc_trap_interrupt
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.word __sparc_trap_interrupt
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.word __sparc_trap_interrupt
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__sparc_trap_table_svt_80:
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.word __sparc_trap_svt_in_trap
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.word __sparc_trap_fault
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.word __sparc_trap_fault
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.word __sparc_trap_flush_windows
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.word __sparc_trap_fault
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.word __sparc_trap_fault
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.word __sparc_trap_fault
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.word __sparc_trap_fault
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.word __sparc_trap_fault
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.word __sparc_trap_sw_set_pil
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.word __sparc_trap_fault
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.word __sparc_trap_fault
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.word __sparc_trap_fault
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.word IRQ_OFFLOAD_HANDLER
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.word __sparc_trap_fault
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.word __sparc_trap_except_reason

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