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fix(freertos): optimize HWLP context switch by disabling it when unused

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This commit is contained in:
Omar Chebib
2025-03-04 13:21:06 +08:00
parent c26879d29e
commit 0bc169e735
3 changed files with 36 additions and 28 deletions
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12
components/freertos/FreeRTOS-Kernel/portable/riscv/port.c
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@@ -6,7 +6,7 @@
* *
* SPDX-License-Identifier: MIT * SPDX-License-Identifier: MIT
* *
* SPDX-FileContributor: 2023-2024 Espressif Systems (Shanghai) CO LTD * SPDX-FileContributor: 2023-2025 Espressif Systems (Shanghai) CO LTD
* *
* Permission is hereby granted, free of charge, to any person obtaining a copy of * Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in * this software and associated documentation files (the "Software"), to deal in
@@ -297,15 +297,19 @@ static void vPortCleanUpCoprocArea(void *pvTCB)
const UBaseType_t bottomstack = (UBaseType_t) task->pxDummy8; const UBaseType_t bottomstack = (UBaseType_t) task->pxDummy8;
RvCoprocSaveArea* sa = pxRetrieveCoprocSaveAreaFromStackPointer(bottomstack); RvCoprocSaveArea* sa = pxRetrieveCoprocSaveAreaFromStackPointer(bottomstack);
/* If the Task used any coprocessor, check if it is the actual owner of any. /* If the Task ever saved the original stack pointer, restore it before returning */
* If yes, reset the owner. */ if (sa->sa_allocator != 0) {
if (sa->sa_enable != 0) {
/* Restore the original lowest address of the stack in the TCB */ /* Restore the original lowest address of the stack in the TCB */
task->pxDummy6 = sa->sa_tcbstack; task->pxDummy6 = sa->sa_tcbstack;
/* Get the core the task is pinned on */ /* Get the core the task is pinned on */
#if ( configNUM_CORES > 1 ) #if ( configNUM_CORES > 1 )
const BaseType_t coreID = task->xDummyCoreID; const BaseType_t coreID = task->xDummyCoreID;
/* If the task is not pinned on any core, it didn't use any coprocessor than need to be freed (FPU or PIE).
* If it used the HWLP coprocessor, it has nothing to clear since there is no "owner" for it. */
if (coreID == tskNO_AFFINITY) {
return;
}
#else /* configNUM_CORES > 1 */ #else /* configNUM_CORES > 1 */
const BaseType_t coreID = 0; const BaseType_t coreID = 0;
#endif /* configNUM_CORES > 1 */ #endif /* configNUM_CORES > 1 */

29
components/freertos/FreeRTOS-Kernel/portable/riscv/portasm.S
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@@ -205,27 +205,28 @@ hwlp_restore_if_used:
li a2, HWLP_COPROC_IDX li a2, HWLP_COPROC_IDX
call pxPortGetCoprocArea call pxPortGetCoprocArea
/* Get the enable flags from the coprocessor save area */ /* Get the enable flags from the coprocessor save area */
lw a1, RV_COPROC_ENABLE(a0) lw a2, RV_COPROC_ENABLE(a0)
/* To avoid having branches below, set the coprocessor enable flag now */ andi a1, a2, 1 << HWLP_COPROC_IDX
andi a2, a1, 1 << HWLP_COPROC_IDX beqz a1, _hwlp_restore_end
beqz a2, _hwlp_restore_end
/* Enable bit was set, restore the coprocessor context */ /* Enable bit was set, restore the coprocessor context */
lw a0, RV_COPROC_SA+HWLP_COPROC_IDX*4(a0) /* a0 = RvCoprocSaveArea->sa_coprocs[HWLP_COPROC_IDX] */ lw a3, RV_COPROC_SA+HWLP_COPROC_IDX*4(a0) /* a0 = RvCoprocSaveArea->sa_coprocs[HWLP_COPROC_IDX] */
/* This will set the dirty flag for sure */ /* This will set the dirty flag for sure, a2 is preserved */
hwlp_restore_regs a0 hwlp_restore_regs a3
#if SOC_CPU_HAS_HWLOOP_STATE_BUG && ESP32P4_REV_MIN_FULL <= 1 #if SOC_CPU_HAS_HWLOOP_STATE_BUG && ESP32P4_REV_MIN_FULL <= 1
/* The hardware doesn't update the HWLP state properly after executing the last instruction, /* The hardware doesn't update the HWLP state properly after executing the last instruction,
* as such, we must manually put the state of the HWLP to dirty now if any counter is not 0 */ * as such, we must manually put the state of the HWLP to dirty now if any counter is not 0 */
csrr a0, CSR_LOOP0_COUNT csrr a3, CSR_LOOP0_COUNT
bnez a0, _hwlp_restore_end bnez a3, _hwlp_restore_end
csrr a0, CSR_LOOP1_COUNT csrr a3, CSR_LOOP1_COUNT
bnez a0, _hwlp_restore_end bnez a3, _hwlp_restore_end
/* The counters are 0, cleaning the state */ /* The counters are 0, mark the HWLP coprocessor as disabled in the enable flag and clean the state */
xori a2, a2, 1 << HWLP_COPROC_IDX
sw a2, RV_COPROC_ENABLE(a0)
#endif /* SOC_CPU_HAS_HWLOOP_STATE_BUG && ESP32P4_REV_MIN_FULL <= 1 */ #endif /* SOC_CPU_HAS_HWLOOP_STATE_BUG && ESP32P4_REV_MIN_FULL <= 1 */
csrwi CSR_HWLP_STATE_REG, HWLP_CLEAN_STATE csrwi CSR_HWLP_STATE_REG, HWLP_CLEAN_STATE
_hwlp_restore_end: _hwlp_restore_end:
lw ra, (sp) lw ra, (sp)
addi sp, sp, 16 addi sp, sp, 16
ret ret
#endif /* SOC_CPU_HAS_HWLOOP */ #endif /* SOC_CPU_HAS_HWLOOP */

23
components/riscv/vectors.S
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@@ -236,23 +236,26 @@ _panic_handler:
la ra, _return_from_exception la ra, _return_from_exception
/* EXT_ILL CSR should contain the reason for the Illegal Instruction */ /* EXT_ILL CSR should contain the reason for the Illegal Instruction */
csrrw a0, EXT_ILL_CSR, zero csrrw a0, EXT_ILL_CSR, zero
#if SOC_CPU_HAS_HWLOOP
/* Check if the HWLP bit is set. */
andi a1, a0, EXT_ILL_RSN_HWLP
beqz a1, hwlp_not_used
/* HWLP used in an ISR, abort */
mv a0, sp
j vPortCoprocUsedInISR
hwlp_not_used:
#endif /* SOC_CPU_HAS_HWLOOP */
/* Hardware loop cannot be treated lazily, so we should never end here if a HWLP instruction is used */
#if SOC_CPU_HAS_PIE #if SOC_CPU_HAS_PIE
/* Check if the PIE bit is set. */ /* Check if the PIE bit is set. */
andi a1, a0, EXT_ILL_RSN_PIE andi a1, a0, EXT_ILL_RSN_PIE
bnez a1, rtos_save_pie_coproc bnez a1, rtos_save_pie_coproc
#endif /* SOC_CPU_HAS_PIE */ #endif /* SOC_CPU_HAS_PIE */
/* We cannot check the HWLP bit in a0 since a hardware bug may set this bit even though no HWLP
* instruction was executed in the program at all, so check mtval (`t0`) */
#if SOC_CPU_HAS_HWLOOP
/* HWLP instructions all have an opcode of 0b0101011 */
andi a1, t0, 0b1111111
addi a1, a1, -0b0101011
bnez a1, hwlp_not_used
/* HWLP used in an ISR, abort */
mv a0, sp
j vPortCoprocUsedInISR
hwlp_not_used:
#endif /* SOC_CPU_HAS_HWLOOP */
#if SOC_CPU_HAS_FPU #if SOC_CPU_HAS_FPU
/* Check if the FPU bit is set. When targets have the FPU reason bug (SOC_CPU_HAS_FPU_EXT_ILL_BUG), /* Check if the FPU bit is set. When targets have the FPU reason bug (SOC_CPU_HAS_FPU_EXT_ILL_BUG),
* it is possible that another bit is set even if the reason is an FPU instruction. * it is possible that another bit is set even if the reason is an FPU instruction.