From d945c1fd68fda7bedde3bc8dbba7831ff6c40ab3 Mon Sep 17 00:00:00 2001
From: Joey Jiao <quic_jiangenj@quicinc.com>
Date: Tue, 9 Jul 2024 10:15:44 +0800
Subject: pkg/cover: fix pc for core kernel

we use offset to symbolize pc for module,
while use absolute pc for core kernel.

Fix by removing base address from module only.
---
 pkg/cover/backend/dwarf.go   | 18 +++++++++++++++---
 pkg/cover/backend/elf.go     |  9 +++++----
 pkg/cover/backend/modules.go |  4 ----
 3 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/pkg/cover/backend/dwarf.go b/pkg/cover/backend/dwarf.go
index 23c141ea5..70ad06a63 100644
--- a/pkg/cover/backend/dwarf.go
+++ b/pkg/cover/backend/dwarf.go
@@ -390,7 +390,11 @@ func readTextRanges(debugInfo *dwarf.Data, module *vminfo.KernelModule, pcFix pc
 					continue
 				}
 			}
-			ranges = append(ranges, pcRange{r[0] + module.Addr, r[1] + module.Addr, unit})
+			if module.Name == "" {
+				ranges = append(ranges, pcRange{r[0], r[1], unit})
+			} else {
+				ranges = append(ranges, pcRange{r[0] + module.Addr, r[1] + module.Addr, unit})
+			}
 		}
 		r.SkipChildren()
 	}
@@ -427,7 +431,11 @@ func symbolizeModule(target *targets.Target, interner *symbolizer.Interner, objD
 			var res symbolizerResult
 			for pcs := range pcchan {
 				for i, pc := range pcs {
-					pcs[i] = pc - mod.Addr
+					if mod.Name == "" {
+						pcs[i] = pc
+					} else {
+						pcs[i] = pc - mod.Addr
+					}
 				}
 				frames, err := symb.SymbolizeArray(mod.Path, pcs)
 				if err != nil {
@@ -456,9 +464,13 @@ func symbolizeModule(target *targets.Target, interner *symbolizer.Interner, objD
 		}
 		for _, frame := range res.frames {
 			name, path := CleanPath(frame.File, objDir, srcDir, buildDir, splitBuildDelimiters)
+			pc := frame.PC
+			if mod.Name != "" {
+				pc = frame.PC + mod.Addr
+			}
 			frames = append(frames, Frame{
 				Module:   mod,
-				PC:       frame.PC + mod.Addr,
+				PC:       pc,
 				Name:     interner.Do(name),
 				FuncName: frame.Func,
 				Path:     interner.Do(path),
diff --git a/pkg/cover/backend/elf.go b/pkg/cover/backend/elf.go
index 05e15ad45..5073c5603 100644
--- a/pkg/cover/backend/elf.go
+++ b/pkg/cover/backend/elf.go
@@ -74,9 +74,7 @@ func elfReadSymbols(module *vminfo.KernelModule, info *symbolInfo) ([]*Symbol, e
 	if err != nil {
 		return nil, fmt.Errorf("failed to read ELF symbols: %w", err)
 	}
-	if module.Name == "" {
-		info.textAddr = text.Addr
-	}
+	info.textAddr = text.Addr
 	var symbols []*Symbol
 	for i, symb := range allSymbols {
 		if symb.Info&0xf != uint8(elf.STT_FUNC) && symb.Info&0xf != uint8(elf.STT_NOTYPE) {
@@ -85,7 +83,10 @@ func elfReadSymbols(module *vminfo.KernelModule, info *symbolInfo) ([]*Symbol, e
 		}
 		text := symb.Value >= text.Addr && symb.Value+symb.Size <= text.Addr+text.Size
 		if text && symb.Size != 0 {
-			start := symb.Value + module.Addr
+			start := symb.Value
+			if module.Name != "" {
+				start += module.Addr
+			}
 			symbols = append(symbols, &Symbol{
 				Module: module,
 				ObjectUnit: ObjectUnit{
diff --git a/pkg/cover/backend/modules.go b/pkg/cover/backend/modules.go
index 206b6986a..fbce68a49 100644
--- a/pkg/cover/backend/modules.go
+++ b/pkg/cover/backend/modules.go
@@ -170,10 +170,6 @@ func FixModules(localModules, modules []*vminfo.KernelModule, pcBase uint64) []*
 			continue
 		}
 		addr := mod.Addr - kaslrOffset
-		if mod.Name == "" {
-			// mod.Addr for core kernel from target is _stext addr
-			addr = 0
-		}
 		modules1 = append(modules1, &vminfo.KernelModule{
 			Name: mod.Name,
 			Size: size,
-- 
cgit mrf-deployment