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cpu: optimize core barrier
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parent
7820e5b759
commit
507ab46709
2 changed files with 78 additions and 14 deletions
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@ -17,9 +17,14 @@
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namespace ams::kern::arm64::cpu {
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/* Declare prototype to be implemented in asm. */
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void SynchronizeAllCoresImpl(s32 *sync_var, s32 num_cores);
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namespace {
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std::atomic<s32> g_all_core_sync_count;
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/* Expose this as a global, for asm to use. */
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s32 g_all_core_sync_count;
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void FlushEntireDataCacheImpl(int level) {
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/* Used in multiple locations. */
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@ -48,6 +53,14 @@ namespace ams::kern::arm64::cpu {
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}
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}
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ALWAYS_INLINE void SetEventLocally() {
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__asm__ __volatile__("sevl" ::: "memory");
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}
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ALWAYS_INLINE void WaitForEvent() {
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__asm__ __volatile__("wfe" ::: "memory");
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}
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}
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void FlushEntireDataCacheShared() {
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@ -70,19 +83,7 @@ namespace ams::kern::arm64::cpu {
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}
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NOINLINE void SynchronizeAllCores() {
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/* Wait until the count can be read. */
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while (!(g_all_core_sync_count < static_cast<s32>(cpu::NumCores))) { /* ... */ }
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const s32 per_core_idx = g_all_core_sync_count.fetch_add(1);
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/* Loop until it's our turn. This will act on each core in order. */
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while (g_all_core_sync_count != per_core_idx + static_cast<s32>(cpu::NumCores)) { /* ... */ }
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if (g_all_core_sync_count != 2 * static_cast<s32>(cpu::NumCores) - 1) {
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g_all_core_sync_count++;
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} else {
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g_all_core_sync_count = 0;
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}
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SynchronizeAllCoresImpl(&g_all_core_sync_count, static_cast<s32>(cpu::NumCores));
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}
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}
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63
libraries/libmesosphere/source/arch/arm64/kern_cpu_asm.s
Normal file
63
libraries/libmesosphere/source/arch/arm64/kern_cpu_asm.s
Normal file
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@ -0,0 +1,63 @@
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/*
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* Copyright (c) 2018-2020 Atmosphère-NX
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/* ams::kern::arm64::cpu::SynchronizeAllCoresImpl(int *sync_var, int num_cores) */
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.section .text._ZN3ams4kern5arm643cpu23SynchronizeAllCoresImplEPii, "ax", %progbits
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.global _ZN3ams4kern5arm643cpu23SynchronizeAllCoresImplEPii
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.type _ZN3ams4kern5arm643cpu23SynchronizeAllCoresImplEPii, %function
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_ZN3ams4kern5arm643cpu23SynchronizeAllCoresImplEPii:
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/* Loop until the sync var is less than num cores. */
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sevl
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1:
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wfe
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ldaxr w2, [x0]
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cmp w2, w1
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b.gt 1b
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/* Increment the sync var. */
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2:
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ldaxr w2, [x0]
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add w3, w2, #1
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stlxr w4, w3, [x0]
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cbnz w4, 2b
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/* Loop until the sync var matches our ticket. */
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add w3, w2, w1
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sevl
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3:
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wfe
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ldaxr w2, [x0]
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cmp w2, w3
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b.ne 3b
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/* Check if the ticket is the last. */
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sub w2, w1, #1
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add w2, w2, w1
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cmp w3, w2
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b.eq 5f
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/* Our ticket is not the last one. Increment. */
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4:
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ldaxr w2, [x0]
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add w3, w2, #1
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stlxr w4, w3, [x0]
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cbnz w4, 4b
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ret
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/* Our ticket is the last one. */
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5:
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stlr wzr, [x0]
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ret
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