From 0fe935763404d30cb1f0e04b6b515fcba4b64972 Mon Sep 17 00:00:00 2001
From: Leon Hwang <hffilwlqm@gmail.com>
Date: Wed, 20 Nov 2024 21:52:18 +0800
Subject: [PATCH] bpflbr: Dump line info for call/jmp insn

Signed-off-by: Leon Hwang <hffilwlqm@gmail.com>
---
 internal/bpflbr/dump.go      | 43 +++++++++++++++++++++++++++++++-----
 internal/bpflbr/lbr.go       |  1 +
 internal/bpflbr/lbr_stack.go |  1 +
 3 files changed, 40 insertions(+), 5 deletions(-)

diff --git a/internal/bpflbr/dump.go b/internal/bpflbr/dump.go
index f90cb91..4302276 100644
--- a/internal/bpflbr/dump.go
+++ b/internal/bpflbr/dump.go
@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"log"
 	"os"
+	"strconv"
 	"strings"
 
 	"github.com/cilium/ebpf"
@@ -31,6 +32,26 @@ func DumpProg(pf []ProgFlag) {
 		log.Fatalf("No prog found")
 	}
 
+	kallsyms, err := NewKallsyms()
+	assert.NoErr(err, "Failed to read /proc/kallsyms: %v")
+
+	vmlinux, err := FindVmlinux()
+	assert.NoErr(err, "Failed to find vmlinux: %v")
+
+	textAddr, err := ReadTextAddrFromVmlinux(vmlinux)
+	assert.NoErr(err, "Failed to read .text address from vmlinux: %v")
+
+	kaslrOffset := textAddr - kallsyms.Stext()
+	addr2line, err := NewAddr2Line(vmlinux, kaslrOffset, kallsyms.SysBPF())
+	assert.NoErr(err, "Failed to create addr2line: %v")
+
+	engine, err := gapstone.New(int(gapstone.CS_ARCH_X86), int(gapstone.CS_MODE_64))
+	assert.NoErr(err, "Failed to create engine: %v")
+	defer engine.Close()
+
+	bpfProgs, err := NewBPFProgs(engine, nil, false)
+	assert.NoErr(err, "Failed to get bpf progs: %v")
+
 	info, err := prog.Info()
 	assert.NoErr(err, "Failed to get prog info: %v")
 
@@ -63,10 +84,6 @@ func DumpProg(pf []ProgFlag) {
 		jited2LineInfos[kaddr] = lines[i]
 	}
 
-	engine, err := gapstone.New(int(gapstone.CS_ARCH_X86), int(gapstone.CS_MODE_64))
-	assert.NoErr(err, "Failed to create engine: %v")
-	defer engine.Close()
-
 	intelSyntax := os.Getenv("BPFLBR_DUMP_INTEL_SYNTAX") == "1"
 	if !intelSyntax {
 		err = engine.SetOption(uint(gapstone.CS_OPT_SYNTAX), uint(gapstone.CS_OPT_SYNTAX_ATT))
@@ -98,7 +115,23 @@ func DumpProg(pf []ProgFlag) {
 				opcodes = append(opcodes, fmt.Sprintf("%02x", insn))
 			}
 			opcode := strings.Join(opcodes, " ")
-			fmt.Fprintf(&sb, "%#x: %-19s\t%s\t%s\n", kaddr, opcode, inst[0].Mnemonic, inst[0].OpStr)
+			opstr := inst[0].OpStr
+			fmt.Fprintf(&sb, "%#x: %-19s\t%s\t%s", kaddr, opcode, inst[0].Mnemonic, opstr)
+
+			var endpoint *branchEndpoint
+			if strings.HasPrefix(opstr, "0x") {
+				n, err := strconv.ParseUint(opstr, 0, 64)
+				if err == nil {
+					endpoint = getLineInfo(uintptr(n), bpfProgs, addr2line, kallsyms)
+				}
+			}
+			if endpoint != nil {
+				fmt.Fprintf(&sb, "\t; %s+%#x %s:%d", endpoint.funcName, endpoint.offset, endpoint.fileName, endpoint.fileLine)
+				if endpoint.isProg {
+					fmt.Fprintf(&sb, " [bpf]")
+				}
+			}
+			fmt.Fprintln(&sb)
 
 			insnSize := uint64(inst[0].Size)
 			pc += insnSize
diff --git a/internal/bpflbr/lbr.go b/internal/bpflbr/lbr.go
index 06607b5..c5486f1 100644
--- a/internal/bpflbr/lbr.go
+++ b/internal/bpflbr/lbr.go
@@ -130,6 +130,7 @@ func getLineInfo(addr uintptr, progs *bpfProgs, a2l *Addr2Line, ksyms *Kallsyms)
 		ep.funcName = li.funcName
 		ep.fileName = li.fileName
 		ep.fileLine = li.fileLine
+		ep.isProg = true
 		ep.updateInfo()
 		return &ep
 	}
diff --git a/internal/bpflbr/lbr_stack.go b/internal/bpflbr/lbr_stack.go
index fc49638..d47c1f4 100644
--- a/internal/bpflbr/lbr_stack.go
+++ b/internal/bpflbr/lbr_stack.go
@@ -18,6 +18,7 @@ type branchEndpoint struct {
 	fileName string
 	fileLine uint32
 	lineInfo string // (${fileName}:${fileLine})
+	isProg   bool
 }
 
 func (b *branchEndpoint) updateInfo() {