[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@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@302055 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
index f780137d0874f77663b50ba6717d3d9492732690..50f63fb8dd395bd9c1cbb166f0c925837a274cb2 100644 (file)
--- a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
+++ b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
@@ -819,6 +819,34 @@ void RuntimeDyldELF::resolveSystemZRelocation(const SectionEntry &Section,
   }
 }
 
+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(const SectionEntry &Section,
   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!");
   }

diff --git a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.h b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.h
index 498979705b775c71e89dd232e585581b4d9356a4..84dd810101f3c70d2f93302dcc003f26010e3d7d 100644 (file)
--- a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.h
+++ b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.h
@@ -58,6 +58,9 @@ class RuntimeDyldELF : public RuntimeDyldImpl {
   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

diff --git a/lib/MC/MCObjectFileInfo.cpp b/lib/MC/MCObjectFileInfo.cpp
index 9f94264684f947bcf4e8696be69762ff16eca3fa..b685790910d08c303769c6999d773097b762bfc7 100644 (file)
--- a/lib/MC/MCObjectFileInfo.cpp
+++ b/lib/MC/MCObjectFileInfo.cpp
@@ -286,6 +286,10 @@ void MCObjectFileInfo::initELFMCObjectFileInfo(const Triple &T) {
                      ((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;

diff --git a/test/CodeGen/BPF/reloc.ll b/test/CodeGen/BPF/reloc.ll
new file mode 100644 (file)
index 0000000..75dbebf
--- /dev/null
+++ b/test/CodeGen/BPF/reloc.ll
@@ -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 }
+
+@bpf_prog1.devname = private unnamed_addr constant [3 x i8] c"lo\00", align 1
+@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 }