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Fix incorrect tests and DTV extraction, it is always indirect for gli… #34

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dalehamel wants to merge 1 commit into from
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Fix incorrect tests and DTV extraction, it is always indirect for gli… #34

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1 change: 0 additions & 1 deletion libc/libc_aarch64.go
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Original file line number Diff line number Diff line change
Expand Up @@ -408,6 +408,5 @@ func extractDTVInfoARM(code []byte) (DTVInfo, error) {
return DTVInfo{
Offset: dtvOffset,
Multiplier: uint8(entryWidth),
Indirect: 1,
}, nil
}
20 changes: 0 additions & 20 deletions libc/libc_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -313,7 +313,6 @@ func TestExtractDTVOffset(t *testing.T) {
info: DTVInfo{
Offset: 8,
Multiplier: 16,
Indirect: 0,
},
},
"glibc 2.32 / Fedora 33 / x86_64": {
Expand Down Expand Up @@ -361,7 +360,6 @@ func TestExtractDTVOffset(t *testing.T) {
info: DTVInfo{
Offset: 8,
Multiplier: 16,
Indirect: 0,
},
},
"musl 1.2.5 / alpine 3.22.2 / x86_64": {
Expand All @@ -383,7 +381,6 @@ func TestExtractDTVOffset(t *testing.T) {
info: DTVInfo{
Offset: 8,
Multiplier: 8,
Indirect: 1,
},
},
"musl 1.1.5 / alpine 3.1 / x86_64": {
Expand Down Expand Up @@ -411,7 +408,6 @@ func TestExtractDTVOffset(t *testing.T) {
info: DTVInfo{
Offset: 8,
Multiplier: 8,
Indirect: 1,
},
},
"glibc 2.39 / ubuntu 24.04 / aarch64": {
Expand Down Expand Up @@ -447,7 +443,6 @@ func TestExtractDTVOffset(t *testing.T) {
info: DTVInfo{
Offset: 0,
Multiplier: 16,
Indirect: 1,
},
},
"glibc / Fedora 39 / aarch64": {
Expand Down Expand Up @@ -486,7 +481,6 @@ func TestExtractDTVOffset(t *testing.T) {
info: DTVInfo{
Offset: 0,
Multiplier: 16,
Indirect: 1,
},
},
"glibc / Fedora 33 / aarch64": {
Expand Down Expand Up @@ -515,7 +509,6 @@ func TestExtractDTVOffset(t *testing.T) {
info: DTVInfo{
Offset: 0,
Multiplier: 16,
Indirect: 1,
},
},

Expand All @@ -532,7 +525,6 @@ func TestExtractDTVOffset(t *testing.T) {
info: DTVInfo{
Offset: -8,
Multiplier: 8,
Indirect: 1,
},
},
}
Expand Down Expand Up @@ -575,7 +567,6 @@ func TestLibcInfoIsEqual(t *testing.T) {
DTVInfo{
Offset: -8,
Multiplier: 16,
Indirect: 0,
},
},
right: LibcInfo{
Expand All @@ -587,7 +578,6 @@ func TestLibcInfoIsEqual(t *testing.T) {
DTVInfo{
Offset: -8,
Multiplier: 16,
Indirect: 0,
},
},
expectEqual: true,
Expand All @@ -598,7 +588,6 @@ func TestLibcInfoIsEqual(t *testing.T) {
DTVInfo{
Offset: -8,
Multiplier: 16,
Indirect: 0,
},
},
right: LibcInfo{
Expand Down Expand Up @@ -652,15 +641,13 @@ func TestLibcInfoMerge(t *testing.T) {
DTVInfo{
Offset: -8,
Multiplier: 16,
Indirect: 0,
},
},
expected: LibcInfo{
TSDInfo{},
DTVInfo{
Offset: -8,
Multiplier: 16,
Indirect: 0,
},
},
},
Expand All @@ -670,7 +657,6 @@ func TestLibcInfoMerge(t *testing.T) {
DTVInfo{
Offset: -8,
Multiplier: 16,
Indirect: 0,
},
},
right: LibcInfo{
Expand All @@ -690,7 +676,6 @@ func TestLibcInfoMerge(t *testing.T) {
DTVInfo{
Offset: -8,
Multiplier: 16,
Indirect: 0,
},
},
},
Expand All @@ -708,7 +693,6 @@ func TestLibcInfoMerge(t *testing.T) {
DTVInfo{
Offset: -8,
Multiplier: 16,
Indirect: 0,
},
},
expected: LibcInfo{
Expand All @@ -720,7 +704,6 @@ func TestLibcInfoMerge(t *testing.T) {
DTVInfo{
Offset: -8,
Multiplier: 16,
Indirect: 0,
},
},
},
Expand All @@ -737,7 +720,6 @@ func TestLibcInfoMerge(t *testing.T) {
DTVInfo{
Offset: -8,
Multiplier: 16,
Indirect: 0,
},
},
right: LibcInfo{
Expand All @@ -749,7 +731,6 @@ func TestLibcInfoMerge(t *testing.T) {
DTVInfo{
Offset: 8,
Multiplier: 16,
Indirect: 1,
},
},
expected: LibcInfo{
Expand All @@ -761,7 +742,6 @@ func TestLibcInfoMerge(t *testing.T) {
DTVInfo{
Offset: -8,
Multiplier: 16,
Indirect: 0,
},
},
},
Expand Down
8 changes: 3 additions & 5 deletions libc/libc_x86.go
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Original file line number Diff line number Diff line change
Expand Up @@ -107,7 +107,9 @@ func extractDTVInfoX86(code []byte) (DTVInfo, error) {
entryWidth = e.NewImmediateCapture("entryWidth")
)

// Pattern 1: glibc - Direct DTV access
// Pattern 1: glibc - DTV pointer loaded from FS:offset, then indexed
// FS:offset is a memory load that retrieves the DTV pointer, so this is
// indirect access (two dereferences: load DTV ptr, then index into DTV).
expected := e.Add(
e.Mem8(
e.Add(
Expand All @@ -122,7 +124,6 @@ func extractDTVInfoX86(code []byte) (DTVInfo, error) {
return DTVInfo{
Offset: int16(dtvOffset.CapturedValue() & 0xFFFF),
Multiplier: uint8(entryWidth.CapturedValue()),
Indirect: 0,
}, nil
}

Expand All @@ -145,7 +146,6 @@ func extractDTVInfoX86(code []byte) (DTVInfo, error) {
return DTVInfo{
Offset: int16(dtvOffset.CapturedValue() & 0xFFFF),
Multiplier: uint8(entryWidth.CapturedValue()),
Indirect: 1,
}, nil
}

Expand All @@ -164,7 +164,6 @@ func extractDTVInfoX86(code []byte) (DTVInfo, error) {
return DTVInfo{
Offset: int16(dtvOffset.CapturedValue() & 0xFFFF),
Multiplier: uint8(entryWidth.CapturedValue()),
Indirect: 1,
}, nil
}

Expand All @@ -184,7 +183,6 @@ func extractDTVInfoX86(code []byte) (DTVInfo, error) {
return DTVInfo{
Offset: int16(dtvOffset.CapturedValue() & 0xFFFF),
Multiplier: uint8(entryWidth.CapturedValue()),
Indirect: 1,
}, nil
}

Expand Down
1 change: 0 additions & 1 deletion processmanager/processinfo_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -63,7 +63,6 @@ func TestAssignLibcInfoMergesLibcInfo(t *testing.T) {
libc.DTVInfo{
Offset: -8,
Multiplier: 16,
Indirect: 1,
},
}

Expand Down
13 changes: 7 additions & 6 deletions support/ebpf/types.h
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Original file line number Diff line number Diff line change
Expand Up @@ -389,15 +389,16 @@ typedef struct TSDInfo {
} TSDInfo;

// DTVInfo contains data needed to read Thread Local Storage (TLS) values, which
// are located using the Dynamic Thread Vector (DTV)
// are located using the Dynamic Thread Vector (DTV).
// DTV access is always indirect: TP+offset yields a pointer to the DTV array,
// which must be dereferenced before indexing by module ID. This is true for
// both glibc and musl (the DTV is a separately-allocated array, not inline
// in the thread control block).
typedef struct DTVInfo {
// Offset is the offset of DTV from FS base (or from thread pointer)
// Offset is the offset of the DTV pointer from the thread pointer base.
s16 offset;
// Multiplier is the size of each DTV entry in bytes
// Typically 8 bytes on 64bit musl and 16 bytes on 64bit glibc
// Multiplier is the size of each DTV entry in bytes.
u8 multiplier;
// Indirect is 0 if DTV is at FS+offset, 1 if at [FS+0]+offset
u8 indirect;
} DTVInfo;

// DotnetProcInfo is a container for the data needed to build stack trace for a dotnet process.
Expand Down
2 changes: 1 addition & 1 deletion support/types.go
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