bpflbr: Remove vmlinux requirement for disasm

Signed-off-by: Leon Hwang <[email protected]>
Asphaltt · Dec 5, 2024 · f997662 · f997662
1 parent 27c3189
commit f997662
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Showing 6 changed files with 76 additions and 29 deletions.
diff --git a/internal/bpflbr/disasm.go b/internal/bpflbr/disasm.go
@@ -5,6 +5,7 @@ package bpflbr
 
 import (
 	"debug/elf"
+	"errors"
 	"fmt"
 	"os"
 	"strconv"
@@ -81,19 +82,29 @@ func dumpKfunc(kfunc string, bytes uint) {
 	data, ok := readKcore(kaddr, uint(bytes))
 	assert.True(ok, "Failed to read kcore for %s", kfunc)
 
+	var addr2line *Addr2Line
+
 	vmlinux, err := FindVmlinux()
-	assert.NoErr(err, "Failed to find vmlinux: %v")
-	VerboseLog("Found vmlinux: %s", vmlinux)
+	if err != nil {
+		if errors.Is(err, ErrNotFound) {
+			VerboseLog("Dbgsym vmlinux not found")
+		} else {
+			assert.NoErr(err, "Failed to find vmlinux: %v")
+		}
+	}
+	if err == nil {
+		VerboseLog("Found vmlinux: %s", vmlinux)
 
-	textAddr, err := ReadTextAddrFromVmlinux(vmlinux)
-	assert.NoErr(err, "Failed to read .text address from vmlinux: %v")
+		textAddr, err := ReadTextAddrFromVmlinux(vmlinux)
+		assert.NoErr(err, "Failed to read .text address from vmlinux: %v")
 
-	kaslrOffset := textAddr - kallsyms.Stext()
-	VerboseLog("KASLR offset: %#x", kaslrOffset)
+		kaslrOffset := textAddr - kallsyms.Stext()
+		VerboseLog("KASLR offset: 0x%x", kaslrOffset)
 
-	VerboseLog("Creating addr2line from vmlinux ..")
-	addr2line, err := NewAddr2Line(vmlinux, kaslrOffset, kallsyms.SysBPF())
-	assert.NoErr(err, "Failed to create addr2line: %v")
+		VerboseLog("Creating addr2line from vmlinux ..")
+		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")

diff --git a/internal/bpflbr/dump.go b/internal/bpflbr/dump.go
@@ -4,6 +4,7 @@
 package bpflbr
 
 import (
+	"errors"
 	"fmt"
 	"log"
 	"strconv"
@@ -35,19 +36,29 @@ func DumpProg(pf []ProgFlag) {
 	kallsyms, err := NewKallsyms()
 	assert.NoErr(err, "Failed to read /proc/kallsyms: %v")
 
+	var addr2line *Addr2Line
+
 	vmlinux, err := FindVmlinux()
-	assert.NoErr(err, "Failed to find vmlinux: %v")
-	VerboseLog("Found vmlinux: %s", vmlinux)
+	if err != nil {
+		if errors.Is(err, ErrNotFound) {
+			VerboseLog("Dbgsym vmlinux not found")
+		} else {
+			assert.NoErr(err, "Failed to find vmlinux: %v")
+		}
+	}
+	if err == nil {
+		VerboseLog("Found vmlinux: %s", vmlinux)
 
-	textAddr, err := ReadTextAddrFromVmlinux(vmlinux)
-	assert.NoErr(err, "Failed to read .text address from vmlinux: %v")
+		textAddr, err := ReadTextAddrFromVmlinux(vmlinux)
+		assert.NoErr(err, "Failed to read .text address from vmlinux: %v")
 
-	kaslrOffset := textAddr - kallsyms.Stext()
-	VerboseLog("KASLR offset: %#x", kaslrOffset)
+		kaslrOffset := textAddr - kallsyms.Stext()
+		VerboseLog("KASLR offset: 0x%x", kaslrOffset)
 
-	VerboseLog("Creating addr2line from vmlinux ..")
-	addr2line, err := NewAddr2Line(vmlinux, kaslrOffset, kallsyms.SysBPF())
-	assert.NoErr(err, "Failed to create addr2line: %v")
+		VerboseLog("Creating addr2line from vmlinux ..")
+		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")
@@ -134,7 +145,10 @@ func DumpProg(pf []ProgFlag) {
 				}
 			}
 			if endpoint != nil {
-				fmt.Fprintf(&sb, "\t; %s+%#x %s:%d", endpoint.funcName, endpoint.offset, endpoint.fileName, endpoint.fileLine)
+				fmt.Fprintf(&sb, "\t; %s+%#x", endpoint.funcName, endpoint.offset)
+				if endpoint.fileName != "" {
+					fmt.Fprintf(&sb, " %s:%d", endpoint.fileName, endpoint.fileLine)
+				}
 				if endpoint.isProg {
 					fmt.Fprintf(&sb, " [bpf]")
 				}

diff --git a/internal/bpflbr/error.go b/internal/bpflbr/error.go
@@ -0,0 +1,8 @@
+// Copyright 2024 Leon Hwang.
+// SPDX-License-Identifier: Apache-2.0
+
+package bpflbr
+
+import "errors"
+
+var ErrNotFound = errors.New("not found")
diff --git a/internal/bpflbr/lbr.go b/internal/bpflbr/lbr.go
@@ -144,6 +144,10 @@ func getLineInfo(addr uintptr, progs *bpfProgs, a2l *Addr2Line, ksyms *Kallsyms)
 		ep.offset = addr - uintptr(ksym.addr)
 	}
 
+	if a2l == nil {
+		return &ep
+	}
+
 	li, err := a2l.get(addr)
 	if err != nil {
 		return &ep

diff --git a/internal/bpflbr/vmlinux.go b/internal/bpflbr/vmlinux.go
@@ -58,7 +58,7 @@ func FindVmlinux() (string, error) {
 		}
 	}
 
-	return "", errors.New("vmlinux file not found")
+	return "", ErrNotFound
 }
 
 // ReadTextAddrFromVmlinux reads .text section address from vmlinux file.

diff --git a/main.go b/main.go
@@ -58,19 +58,29 @@ func main() {
 	kallsyms, err := bpflbr.NewKallsyms()
 	assert.NoErr(err, "Failed to read /proc/kallsyms: %v")
 
+	var addr2line *bpflbr.Addr2Line
+
 	vmlinux, err := bpflbr.FindVmlinux()
-	assert.NoErr(err, "Failed to find vmlinux: %v")
-	bpflbr.VerboseLog("Found vmlinux: %s", vmlinux)
+	if err != nil {
+		if errors.Is(err, bpflbr.ErrNotFound) {
+			bpflbr.VerboseLog("Dbgsym vmlinux not found")
+		} else {
+			assert.NoErr(err, "Failed to find vmlinux: %v")
+		}
+	}
+	if err == nil {
+		bpflbr.VerboseLog("Found vmlinux: %s", vmlinux)
 
-	textAddr, err := bpflbr.ReadTextAddrFromVmlinux(vmlinux)
-	assert.NoErr(err, "Failed to read .text address from vmlinux: %v")
+		textAddr, err := bpflbr.ReadTextAddrFromVmlinux(vmlinux)
+		assert.NoErr(err, "Failed to read .text address from vmlinux: %v")
 
-	kaslrOffset := textAddr - kallsyms.Stext()
-	bpflbr.VerboseLog("KASLR offset: 0x%x", kaslrOffset)
+		kaslrOffset := textAddr - kallsyms.Stext()
+		bpflbr.VerboseLog("KASLR offset: 0x%x", kaslrOffset)
 
-	bpflbr.VerboseLog("Creating addr2line from vmlinux ..")
-	addr2line, err := bpflbr.NewAddr2Line(vmlinux, kaslrOffset, kallsyms.SysBPF())
-	assert.NoErr(err, "Failed to create addr2line: %v")
+		bpflbr.VerboseLog("Creating addr2line from vmlinux ..")
+		addr2line, err = bpflbr.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 capstone engine: %v")
-Original file line number
+Diff line change
@@ Expand Up / @@ -58,7 +58,7 @@ func FindVmlinux() (string, error) { @@
     		}
     	}
-    	return "", errors.New("vmlinux file not found")
+    	return "", ErrNotFound
     }
     // ReadTextAddrFromVmlinux reads .text section address from vmlinux file.
@@ Expand Down @@