0e0bfacff7
Alexei added may_goto insn in [1]. The asm syntax for may_goto looks
like
may_goto <label>
The instruction represents a conditional branch but the condition is
implicit. Later in bpf kernel verifier, the 'may_goto <label>' insn will
be rewritten with an explicit condition. The encoding of 'may_goto' insn
is enforced in [2] and is also implemented in this patch.
In [3], 'may_goto' insn is encoded with raw bytes. I made the following
change
```
--- a/tools/testing/selftests/bpf/bpf_experimental.h
+++ b/tools/testing/selftests/bpf/bpf_experimental.h
@@ -328,10 +328,7 @@ l_true: \
#define cond_break \
({ __label__ l_break, l_continue; \
- asm volatile goto("1:.byte 0xe5; \
- .byte 0; \
- .long ((%l[l_break] - 1b - 8) / 8) & 0xffff; \
- .short 0" \
+ asm volatile goto("may_goto %l[l_break]" \
:::: l_break); \
goto l_continue; \
l_break: break;
```
and ran the selftest with the latest llvm with this patch. All tests are
passed.
[1]
https://lore.kernel.org/bpf/20240306031929.42666-1-alexei.starovoitov@gmail.com/
[2]
https://lore.kernel.org/bpf/20240306031929.42666-2-alexei.starovoitov@gmail.com/
[3]
https://lore.kernel.org/bpf/20240306031929.42666-4-alexei.starovoitov@gmail.com/
95 lines
3.0 KiB
C++
95 lines
3.0 KiB
C++
//===--- BPF.cpp - Implement BPF target feature support -------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements BPF TargetInfo objects.
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//
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//===----------------------------------------------------------------------===//
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#include "BPF.h"
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#include "Targets.h"
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#include "clang/Basic/MacroBuilder.h"
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#include "clang/Basic/TargetBuiltins.h"
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#include "llvm/ADT/StringRef.h"
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using namespace clang;
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using namespace clang::targets;
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static constexpr Builtin::Info BuiltinInfo[] = {
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#define BUILTIN(ID, TYPE, ATTRS) \
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{#ID, TYPE, ATTRS, nullptr, HeaderDesc::NO_HEADER, ALL_LANGUAGES},
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#include "clang/Basic/BuiltinsBPF.inc"
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};
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void BPFTargetInfo::getTargetDefines(const LangOptions &Opts,
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MacroBuilder &Builder) const {
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Builder.defineMacro("__bpf__");
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Builder.defineMacro("__BPF__");
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std::string CPU = getTargetOpts().CPU;
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if (CPU == "probe") {
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Builder.defineMacro("__BPF_CPU_VERSION__", "0");
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return;
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}
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Builder.defineMacro("__BPF_FEATURE_ADDR_SPACE_CAST");
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if (CPU.empty() || CPU == "generic" || CPU == "v1") {
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Builder.defineMacro("__BPF_CPU_VERSION__", "1");
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return;
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}
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std::string CpuVerNumStr = CPU.substr(1);
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Builder.defineMacro("__BPF_CPU_VERSION__", CpuVerNumStr);
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Builder.defineMacro("__BPF_FEATURE_MAY_GOTO");
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int CpuVerNum = std::stoi(CpuVerNumStr);
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if (CpuVerNum >= 2)
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Builder.defineMacro("__BPF_FEATURE_JMP_EXT");
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if (CpuVerNum >= 3) {
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Builder.defineMacro("__BPF_FEATURE_JMP32");
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Builder.defineMacro("__BPF_FEATURE_ALU32");
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}
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if (CpuVerNum >= 4) {
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Builder.defineMacro("__BPF_FEATURE_LDSX");
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Builder.defineMacro("__BPF_FEATURE_MOVSX");
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Builder.defineMacro("__BPF_FEATURE_BSWAP");
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Builder.defineMacro("__BPF_FEATURE_SDIV_SMOD");
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Builder.defineMacro("__BPF_FEATURE_GOTOL");
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Builder.defineMacro("__BPF_FEATURE_ST");
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}
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}
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static constexpr llvm::StringLiteral ValidCPUNames[] = {"generic", "v1", "v2",
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"v3", "v4", "probe"};
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bool BPFTargetInfo::isValidCPUName(StringRef Name) const {
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return llvm::is_contained(ValidCPUNames, Name);
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}
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void BPFTargetInfo::fillValidCPUList(SmallVectorImpl<StringRef> &Values) const {
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Values.append(std::begin(ValidCPUNames), std::end(ValidCPUNames));
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}
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ArrayRef<Builtin::Info> BPFTargetInfo::getTargetBuiltins() const {
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return llvm::ArrayRef(BuiltinInfo,
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clang::BPF::LastTSBuiltin - Builtin::FirstTSBuiltin);
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}
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bool BPFTargetInfo::handleTargetFeatures(std::vector<std::string> &Features,
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DiagnosticsEngine &Diags) {
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for (const auto &Feature : Features) {
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if (Feature == "+alu32") {
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HasAlu32 = true;
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}
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}
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return true;
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}
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