[llvm] r302055 - [bpf] add relocation support
Alexei Starovoitov via llvm-commits
llvm-commits at lists.llvm.org
Wed May 3 10:30:57 PDT 2017
Author: ast
Date: Wed May 3 12:30:56 2017
New Revision: 302055
URL: http://llvm.org/viewvc/llvm-project?rev=302055&view=rev
Log:
[bpf] add relocation support
. there should be no runtime relocation inside the bpf function.
. relocation supported here mostly for debugging.
. a test case is added.
Signed-off-by: Yonghong Song <yhs at fb.com>
Signed-off-by: Alexei Starovoitov <ast at kernel.org>
Added:
llvm/trunk/test/CodeGen/BPF/reloc.ll
Modified:
llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.h
llvm/trunk/lib/MC/MCObjectFileInfo.cpp
Modified: llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp?rev=302055&r1=302054&r2=302055&view=diff
==============================================================================
--- llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp (original)
+++ llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp Wed May 3 12:30:56 2017
@@ -819,6 +819,34 @@ void RuntimeDyldELF::resolveSystemZReloc
}
}
+void RuntimeDyldELF::resolveBPFRelocation(const SectionEntry &Section,
+ uint64_t Offset, uint64_t Value,
+ uint32_t Type, int64_t Addend) {
+ bool isBE = Arch == Triple::bpfeb;
+
+ switch (Type) {
+ default:
+ llvm_unreachable("Relocation type not implemented yet!");
+ break;
+ case ELF::R_BPF_NONE:
+ break;
+ case ELF::R_BPF_64_64: {
+ write(isBE, Section.getAddressWithOffset(Offset), Value + Addend);
+ DEBUG(dbgs() << "Writing " << format("%p", (Value + Addend)) << " at "
+ << format("%p\n", Section.getAddressWithOffset(Offset)));
+ break;
+ }
+ case ELF::R_BPF_64_32: {
+ Value += Addend;
+ assert(Value <= UINT32_MAX);
+ write(isBE, Section.getAddressWithOffset(Offset), static_cast<uint32_t>(Value));
+ DEBUG(dbgs() << "Writing " << format("%p", Value) << " at "
+ << format("%p\n", Section.getAddressWithOffset(Offset)));
+ break;
+ }
+ }
+}
+
// The target location for the relocation is described by RE.SectionID and
// RE.Offset. RE.SectionID can be used to find the SectionEntry. Each
// SectionEntry has three members describing its location.
@@ -879,6 +907,10 @@ void RuntimeDyldELF::resolveRelocation(c
case Triple::systemz:
resolveSystemZRelocation(Section, Offset, Value, Type, Addend);
break;
+ case Triple::bpfel:
+ case Triple::bpfeb:
+ resolveBPFRelocation(Section, Offset, Value, Type, Addend);
+ break;
default:
llvm_unreachable("Unsupported CPU type!");
}
Modified: llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.h?rev=302055&r1=302054&r2=302055&view=diff
==============================================================================
--- llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.h (original)
+++ llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.h Wed May 3 12:30:56 2017
@@ -58,6 +58,9 @@ class RuntimeDyldELF : public RuntimeDyl
void resolveSystemZRelocation(const SectionEntry &Section, uint64_t Offset,
uint64_t Value, uint32_t Type, int64_t Addend);
+ void resolveBPFRelocation(const SectionEntry &Section, uint64_t Offset,
+ uint64_t Value, uint32_t Type, int64_t Addend);
+
unsigned getMaxStubSize() override {
if (Arch == Triple::aarch64 || Arch == Triple::aarch64_be)
return 20; // movz; movk; movk; movk; br
Modified: llvm/trunk/lib/MC/MCObjectFileInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCObjectFileInfo.cpp?rev=302055&r1=302054&r2=302055&view=diff
==============================================================================
--- llvm/trunk/lib/MC/MCObjectFileInfo.cpp (original)
+++ llvm/trunk/lib/MC/MCObjectFileInfo.cpp Wed May 3 12:30:56 2017
@@ -286,6 +286,10 @@ void MCObjectFileInfo::initELFMCObjectFi
((CMModel == CodeModel::Large) ? dwarf::DW_EH_PE_sdata8
: dwarf::DW_EH_PE_sdata4);
break;
+ case Triple::bpfel:
+ case Triple::bpfeb:
+ FDECFIEncoding = dwarf::DW_EH_PE_sdata8;
+ break;
default:
FDECFIEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
break;
Added: llvm/trunk/test/CodeGen/BPF/reloc.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/BPF/reloc.ll?rev=302055&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/BPF/reloc.ll (added)
+++ llvm/trunk/test/CodeGen/BPF/reloc.ll Wed May 3 12:30:56 2017
@@ -0,0 +1,43 @@
+; RUN: llc -march=bpfel -filetype=obj < %s | llvm-objdump -r - | FileCheck --check-prefix=CHECK-RELOC %s
+
+%struct.bpf_context = type { i64, i64, i64, i64, i64, i64, i64 }
+%struct.sk_buff = type { i64, i64, i64, i64, i64, i64, i64 }
+%struct.net_device = type { i64, i64, i64, i64, i64, i64, i64 }
+
+ at bpf_prog1.devname = private unnamed_addr constant [3 x i8] c"lo\00", align 1
+ at bpf_prog1.fmt = private unnamed_addr constant [15 x i8] c"skb %x dev %x\0A\00", align 1
+
+; Function Attrs: norecurse
+define i32 @bpf_prog1(%struct.bpf_context* nocapture %ctx) #0 section "events/net/netif_receive_skb" {
+ %devname = alloca [3 x i8], align 1
+ %fmt = alloca [15 x i8], align 1
+ %1 = getelementptr inbounds [3 x i8], [3 x i8]* %devname, i64 0, i64 0
+ call void @llvm.memcpy.p0i8.p0i8.i64(i8* %1, i8* getelementptr inbounds ([3 x i8], [3 x i8]* @bpf_prog1.devname, i64 0, i64 0), i64 3, i32 1, i1 false)
+ %2 = getelementptr inbounds %struct.bpf_context, %struct.bpf_context* %ctx, i64 0, i32 0
+ %3 = load i64, i64* %2, align 8
+ %4 = inttoptr i64 %3 to %struct.sk_buff*
+ %5 = getelementptr inbounds %struct.sk_buff, %struct.sk_buff* %4, i64 0, i32 2
+ %6 = bitcast i64* %5 to i8*
+ %7 = call i8* inttoptr (i64 4 to i8* (i8*)*)(i8* %6) #1
+ %8 = call i32 inttoptr (i64 9 to i32 (i8*, i8*, i32)*)(i8* %7, i8* %1, i32 2) #1
+ %9 = icmp eq i32 %8, 0
+ br i1 %9, label %10, label %13
+
+; <label>:10 ; preds = %0
+ %11 = getelementptr inbounds [15 x i8], [15 x i8]* %fmt, i64 0, i64 0
+ call void @llvm.memcpy.p0i8.p0i8.i64(i8* %11, i8* getelementptr inbounds ([15 x i8], [15 x i8]* @bpf_prog1.fmt, i64 0, i64 0), i64 15, i32 1, i1 false)
+ %12 = call i32 (i8*, i32, ...) inttoptr (i64 11 to i32 (i8*, i32, ...)*)(i8* %11, i32 15, %struct.sk_buff* %4, i8* %7) #1
+ br label %13
+
+; <label>:13 ; preds = %10, %0
+ ret i32 0
+
+; CHECK-RELOC: file format ELF64-BPF
+; CHECK-RELOC: RELOCATION RECORDS FOR [.rel.eh_frame]:
+; CHECK-RELOC: R_BPF_64_64 events/net/netif_receive_skb
+}
+
+; Function Attrs: nounwind
+declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture, i64, i32, i1) #1
+
+attributes #0 = { norecurse }
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