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8234160: Enable optimized mitigation for Intel jcc erratum in C2
Reviewed-by: thartmann, vlivanov, pliden
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,149 @@ | ||
| /* | ||
| * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved. | ||
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | ||
| * | ||
| * This code is free software; you can redistribute it and/or modify it | ||
| * under the terms of the GNU General Public License version 2 only, as | ||
| * published by the Free Software Foundation. | ||
| * | ||
| * This code is distributed in the hope that it will be useful, but WITHOUT | ||
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | ||
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | ||
| * version 2 for more details (a copy is included in the LICENSE file that | ||
| * accompanied this code). | ||
| * | ||
| * You should have received a copy of the GNU General Public License version | ||
| * 2 along with this work; if not, write to the Free Software Foundation, | ||
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | ||
| * | ||
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | ||
| * or visit www.oracle.com if you need additional information or have any | ||
| * questions. | ||
| * | ||
| */ | ||
|
|
||
| #include "precompiled.hpp" | ||
| #include "asm/macroAssembler.hpp" | ||
| #include "c2_intelJccErratum_x86.hpp" | ||
| #include "opto/cfgnode.hpp" | ||
| #include "opto/compile.hpp" | ||
| #include "opto/machnode.hpp" | ||
| #include "opto/node.hpp" | ||
| #include "opto/regalloc.hpp" | ||
| #include "utilities/align.hpp" | ||
| #include "utilities/debug.hpp" | ||
|
|
||
| // Compute which 32 byte boundary an address corresponds to | ||
| uintptr_t IntelJccErratum::boundary(uintptr_t addr) { | ||
| return addr >> 5; | ||
| } | ||
|
|
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| bool IntelJccErratum::is_crossing_or_ending_at_32_byte_boundary(uintptr_t start_pc, uintptr_t end_pc) { | ||
| int jcc_size = int(end_pc - start_pc); | ||
| assert(jcc_size <= largest_jcc_size(), "invalid jcc size: %d", jcc_size); | ||
| return boundary(start_pc) != boundary(end_pc); | ||
| } | ||
|
|
||
| bool IntelJccErratum::is_jcc_erratum_branch(const Block* block, const MachNode* node, uint node_index) { | ||
| if (node->is_MachCall() && !node->is_MachCallJava()) { | ||
| return true; | ||
| } | ||
| return node_index == (block->number_of_nodes() - 1); | ||
| } | ||
|
|
||
| int IntelJccErratum::jcc_erratum_taint_node(MachNode* node, PhaseRegAlloc* regalloc) { | ||
| node->add_flag(Node::Flag_intel_jcc_erratum); | ||
| return node->size(regalloc); | ||
| } | ||
|
|
||
| int IntelJccErratum::tag_affected_machnodes(Compile* C, PhaseCFG* cfg, PhaseRegAlloc* regalloc) { | ||
| ResourceMark rm; | ||
| int nop_size = 0; | ||
| MachNode* last_m = NULL; | ||
|
|
||
| for (uint i = 0; i < cfg->number_of_blocks(); ++i) { | ||
| const Block* const block = cfg->get_block(i); | ||
| for (uint j = 0; j < block->number_of_nodes(); ++j) { | ||
| const Node* const node = block->get_node(j); | ||
| if (!node->is_Mach()) { | ||
| continue; | ||
| } | ||
| MachNode* m = node->as_Mach(); | ||
| if (is_jcc_erratum_branch(block, m, j)) { | ||
| // Found a root jcc erratum branch, flag it as problematic | ||
| nop_size += jcc_erratum_taint_node(m, regalloc); | ||
|
|
||
| if (!m->is_MachReturn() && !m->is_MachCall()) { | ||
| // We might fuse a problematic jcc erratum branch with a preceding | ||
| // ALU instruction - we must catch such problematic macro fusions | ||
| // and flag the ALU instruction as problematic too. | ||
| for (uint k = 1; k < m->req(); ++k) { | ||
| const Node* const use = m->in(k); | ||
| if (use == last_m && !m->is_MachReturn()) { | ||
| // Flag fused conditions too | ||
| nop_size += jcc_erratum_taint_node(last_m, regalloc); | ||
| } | ||
| } | ||
| } | ||
| last_m = NULL; | ||
| } else { | ||
| last_m = m; | ||
| } | ||
| } | ||
| } | ||
| return nop_size; | ||
| } | ||
|
|
||
| int IntelJccErratum::compute_padding(uintptr_t current_offset, const MachNode* mach, Block* block, uint index_in_block, PhaseRegAlloc* regalloc) { | ||
| int jcc_size = mach->size(regalloc); | ||
| if (index_in_block < block->number_of_nodes() - 1) { | ||
| Node* next = block->get_node(index_in_block + 1); | ||
| if (next->is_Mach() && (next->as_Mach()->flags() & Node::Flag_intel_jcc_erratum)) { | ||
| jcc_size += mach->size(regalloc); | ||
| } | ||
| } | ||
| if (jcc_size > largest_jcc_size()) { | ||
| // Let's not try fixing this for nodes that seem unreasonably large | ||
| return false; | ||
| } | ||
| if (is_crossing_or_ending_at_32_byte_boundary(current_offset, current_offset + jcc_size)) { | ||
| return int(align_up(current_offset, 32) - current_offset); | ||
| } else { | ||
| return 0; | ||
| } | ||
| } | ||
|
|
||
| #define __ _masm. | ||
|
|
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| uintptr_t IntelJccErratumAlignment::pc() { | ||
| return (uintptr_t)__ pc(); | ||
| } | ||
|
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| IntelJccErratumAlignment::IntelJccErratumAlignment(MacroAssembler& masm, int jcc_size) : | ||
| _masm(masm), | ||
| _start_pc(pc()) { | ||
| if (!VM_Version::has_intel_jcc_erratum()) { | ||
| return; | ||
| } | ||
|
|
||
| if (Compile::current()->in_scratch_emit_size()) { | ||
| // When we measure the size of this 32 byte alignment, we apply a conservative guess. | ||
| __ nop(jcc_size); | ||
| } else if (IntelJccErratum::is_crossing_or_ending_at_32_byte_boundary(_start_pc, _start_pc + jcc_size)) { | ||
| // The affected branch might get slowed down by micro code mitigations | ||
| // as it could be susceptible to the erratum. Place nops until the next | ||
| // 32 byte boundary to make sure the branch will be cached. | ||
| const int alignment_nops = (int)(align_up(_start_pc, 32) - _start_pc); | ||
| __ nop(alignment_nops); | ||
| _start_pc = pc(); | ||
| } | ||
| } | ||
|
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| IntelJccErratumAlignment::~IntelJccErratumAlignment() { | ||
| if (!VM_Version::has_intel_jcc_erratum() || | ||
| Compile::current()->in_scratch_emit_size()) { | ||
| return; | ||
| } | ||
|
|
||
| assert(!IntelJccErratum::is_crossing_or_ending_at_32_byte_boundary(_start_pc, pc()), "Invalid jcc_size estimate"); | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,68 @@ | ||
| /* | ||
| * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved. | ||
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | ||
| * | ||
| * This code is free software; you can redistribute it and/or modify it | ||
| * under the terms of the GNU General Public License version 2 only, as | ||
| * published by the Free Software Foundation. | ||
| * | ||
| * This code is distributed in the hope that it will be useful, but WITHOUT | ||
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | ||
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | ||
| * version 2 for more details (a copy is included in the LICENSE file that | ||
| * accompanied this code). | ||
| * | ||
| * You should have received a copy of the GNU General Public License version | ||
| * 2 along with this work; if not, write to the Free Software Foundation, | ||
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | ||
| * | ||
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | ||
| * or visit www.oracle.com if you need additional information or have any | ||
| * questions. | ||
| * | ||
| */ | ||
|
|
||
| #ifndef CPU_X86_INTELJCCERRATUM_X86_HPP | ||
| #define CPU_X86_INTELJCCERRATUM_X86_HPP | ||
|
|
||
| #include "memory/allocation.hpp" | ||
| #include "utilities/globalDefinitions.hpp" | ||
|
|
||
| class Block; | ||
| class Compile; | ||
| class MachNode; | ||
| class MacroAssembler; | ||
| class PhaseCFG; | ||
| class PhaseRegAlloc; | ||
|
|
||
| class IntelJccErratum : public AllStatic { | ||
| private: | ||
| // Compute which 32 byte boundary an address corresponds to | ||
| static uintptr_t boundary(uintptr_t addr); | ||
| static int jcc_erratum_taint_node(MachNode* node, PhaseRegAlloc* regalloc); | ||
|
|
||
| public: | ||
| static bool is_crossing_or_ending_at_32_byte_boundary(uintptr_t start_pc, uintptr_t end_pc); | ||
| static bool is_jcc_erratum_branch(const Block* block, const MachNode* node, uint node_index); | ||
| // Analyze JCC erratum branches. Affected nodes get tagged with Flag_intel_jcc_erratum. | ||
| // The function returns a conservative estimate of all required nops on all mach nodes. | ||
| static int tag_affected_machnodes(Compile* C, PhaseCFG* cfg, PhaseRegAlloc* regalloc); | ||
| // Computes the exact padding for a mach node | ||
| static int compute_padding(uintptr_t current_offset, const MachNode* mach, Block* block, uint index_in_block, PhaseRegAlloc* regalloc); | ||
| static int largest_jcc_size() { return 20; } | ||
| }; | ||
|
|
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| class IntelJccErratumAlignment { | ||
| private: | ||
| MacroAssembler& _masm; | ||
| uintptr_t _start_pc; | ||
|
|
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| uintptr_t pc(); | ||
|
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| public: | ||
| IntelJccErratumAlignment(MacroAssembler& masm, int jcc_size); | ||
| ~IntelJccErratumAlignment(); | ||
| }; | ||
|
|
||
| #endif // CPU_X86_INTELJCCERRATUM_X86_HPP | ||
|
|
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