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[bpf] add bigendian support to disassembler

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. swap 4-bit register encoding, 16-bit offset and 32-bit imm to support big endian archs
. add a test

Reported-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@301653 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Alexei Starovoitov 2017-04-28 16:51:01 +00:00
parent 0bda850299
commit c01803866e
2 changed files with 37 additions and 7 deletions
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26
lib/Target/BPF/Disassembler/BPFDisassembler.cpp
View File

@ -17,6 +17,8 @@
#include "llvm/ADT/ArrayRef.h"
#include "llvm/MC/MCDisassembler/MCDisassembler.h"
#include "llvm/MC/MCFixedLenDisassembler.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCInst.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/TargetRegistry.h"
@ -88,9 +90,9 @@ static DecodeStatus decodeMemoryOpValue(MCInst &Inst, unsigned Insn,
}
#include "BPFGenDisassemblerTables.inc"
static DecodeStatus readInstruction64(ArrayRef<uint8_t> Bytes, uint64_t Address,
uint64_t &Size, uint64_t &Insn) {
uint64_t &Size, uint64_t &Insn,
bool IsLittleEndian) {
uint64_t Lo, Hi;
if (Bytes.size() < 8) {
@ -99,8 +101,14 @@ static DecodeStatus readInstruction64(ArrayRef<uint8_t> Bytes, uint64_t Address,
}
Size = 8;
Hi = (Bytes[0] << 24) | (Bytes[1] << 16) | (Bytes[2] << 0) | (Bytes[3] << 8);
Lo = (Bytes[4] << 0) | (Bytes[5] << 8) | (Bytes[6] << 16) | (Bytes[7] << 24);
if (IsLittleEndian) {
Hi = (Bytes[0] << 24) | (Bytes[1] << 16) | (Bytes[2] << 0) | (Bytes[3] << 8);
Lo = (Bytes[4] << 0) | (Bytes[5] << 8) | (Bytes[6] << 16) | (Bytes[7] << 24);
} else {
Hi = (Bytes[0] << 24) | ((Bytes[1] & 0x0F) << 20) | ((Bytes[1] & 0xF0) << 12) |
(Bytes[2] << 8) | (Bytes[3] << 0);
Lo = (Bytes[4] << 24) | (Bytes[5] << 16) | (Bytes[6] << 8) | (Bytes[7] << 0);
}
Insn = Make_64(Hi, Lo);
return MCDisassembler::Success;
@ -111,10 +119,11 @@ DecodeStatus BPFDisassembler::getInstruction(MCInst &Instr, uint64_t &Size,
uint64_t Address,
raw_ostream &VStream,
raw_ostream &CStream) const {
uint64_t Insn;
bool IsLittleEndian = getContext().getAsmInfo()->isLittleEndian();
uint64_t Insn, Hi;
DecodeStatus Result;
Result = readInstruction64(Bytes, Address, Size, Insn);
Result = readInstruction64(Bytes, Address, Size, Insn, IsLittleEndian);
if (Result == MCDisassembler::Fail) return MCDisassembler::Fail;
Result = decodeInstruction(DecoderTableBPF64, Instr, Insn,
@ -128,7 +137,10 @@ DecodeStatus BPFDisassembler::getInstruction(MCInst &Instr, uint64_t &Size,
return MCDisassembler::Fail;
}
Size = 16;
uint64_t Hi = (Bytes[12] << 0) | (Bytes[13] << 8) | (Bytes[14] << 16) | (Bytes[15] << 24);
if (IsLittleEndian)
Hi = (Bytes[12] << 0) | (Bytes[13] << 8) | (Bytes[14] << 16) | (Bytes[15] << 24);
else
Hi = (Bytes[12] << 24) | (Bytes[13] << 16) | (Bytes[14] << 8) | (Bytes[15] << 0);
auto& Op = Instr.getOperand(1);
Op.setImm(Make_64(Hi, Op.getImm()));
break;

18
test/CodeGen/BPF/mem_offset_be.ll Normal file
View File

@ -0,0 +1,18 @@
; RUN: llc -march=bpfeb -show-mc-encoding < %s | FileCheck %s
; Function Attrs: nounwind
define i32 @bpf_prog1(i8* nocapture readnone) local_unnamed_addr #0 {
; CHECK: r1 = 590618314553ll # encoding: [0x18,0x10,0x00,0x00,0x83,0x98,0x47,0x39,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x89]
; CHECK: r1 += -1879113726 # encoding: [0x07,0x10,0x00,0x00,0x8f,0xff,0x00,0x02]
; CHECK: r0 = *(u64 *)(r1 + 0) # encoding: [0x79,0x01,0x00,0x00,0x00,0x00,0x00,0x00]
%2 = alloca i64, align 8
%3 = bitcast i64* %2 to i8*
store volatile i64 590618314553, i64* %2, align 8
%4 = load volatile i64, i64* %2, align 8
%5 = add i64 %4, -1879113726
%6 = inttoptr i64 %5 to i64*
%7 = load i64, i64* %6, align 8
%8 = trunc i64 %7 to i32
ret i32 %8
}