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In the ELFWriter when writing aliased (.set) symbols dont blindly
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take type from the new symbol but merge them so that the type
is never "downgraded".

This is probably quite rare, except for IFUNC symbols which
we used to misassemble, losing the IFUNC type.

Fixes #18372.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198706 91177308-0d34-0410-b5e6-96231b3b80d8
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@rdivacky
rdivacky committed Jan 7, 2014
1 parent 67cc1dc commit 7e889af
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Showing 2 changed files with 233 additions and 1 deletion.
37 changes: 36 additions & 1 deletion lib/MC/ELFObjectWriter.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -532,6 +532,41 @@ void ELFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
}
}

static uint8_t mergeTypeForSet(uint8_t origType, uint8_t newType) {
uint8_t Type = newType;

// Propagation rules:
// IFUNC > FUNC > OBJECT > NOTYPE
// TLS_OBJECT > OBJECT > NOTYPE
//
// dont let the new type degrade the old type
switch (origType) {
default:
break;
case ELF::STT_GNU_IFUNC:
if (Type == ELF::STT_FUNC || Type == ELF::STT_OBJECT ||
Type == ELF::STT_NOTYPE || Type == ELF::STT_TLS)
Type = ELF::STT_GNU_IFUNC;
break;
case ELF::STT_FUNC:
if (Type == ELF::STT_OBJECT || Type == ELF::STT_NOTYPE ||
Type == ELF::STT_TLS)
Type = ELF::STT_FUNC;
break;
case ELF::STT_OBJECT:
if (Type == ELF::STT_NOTYPE)
Type = ELF::STT_OBJECT;
break;
case ELF::STT_TLS:
if (Type == ELF::STT_OBJECT || Type == ELF::STT_NOTYPE ||
Type == ELF::STT_GNU_IFUNC || Type == ELF::STT_FUNC)
Type = ELF::STT_TLS;
break;
}

return Type;
}

void ELFObjectWriter::WriteSymbol(MCDataFragment *SymtabF,
MCDataFragment *ShndxF,
ELFSymbolData &MSD,
Expand All @@ -545,7 +580,7 @@ void ELFObjectWriter::WriteSymbol(MCDataFragment *SymtabF,

// Binding and Type share the same byte as upper and lower nibbles
uint8_t Binding = MCELF::GetBinding(OrigData);
uint8_t Type = MCELF::GetType(Data);
uint8_t Type = mergeTypeForSet(MCELF::GetType(OrigData), MCELF::GetType(Data));
uint8_t Info = (Binding << ELF_STB_Shift) | (Type << ELF_STT_Shift);

// Other and Visibility share the same byte with Visibility using the lower
Expand Down
197 changes: 197 additions & 0 deletions test/MC/ELF/type.s
View file
Original file line number Diff line number Diff line change
Expand Up @@ -41,6 +41,95 @@ tls_upper_case:
.global tls_upper_case
.type tls_upper_case,STT_TLS

// Test that .set doesnt downgrade the type:
// IFUNC > FUNC > OBJECT > NOTYPE
// TLS_OBJECT > OBJECT > NOTYPE
// also TLS_OBJECT is incompatible with IFUNC and FUNC

.global sym1
.type sym1, @gnu_indirect_function
alias1:
.global alias1
.type alias1, @function
.set sym1, alias1

.global sym2
.type sym2, @gnu_indirect_function
alias2:
.global alias2
.type alias2, @object
.set sym2, alias2

.global sym3
.type sym3, @gnu_indirect_function
alias3:
.global alias3
.type alias3, @notype
.set sym3, alias3

.global sym4
.type sym4, @function
alias4:
.global alias4
.type alias4, @object
.set sym4, alias4

.global sym5
.type sym5, @function
alias5:
.global alias5
.type alias5, @notype
.set sym5, alias5

.global sym6
.type sym6, @object
alias6:
.global alias6
.type alias6, @notype
.set sym6, alias6

.global sym7
.type sym7, @gnu_indirect_function
alias7:
.global alias7
.type alias7, @tls_object
.set sym7, alias7

.global sym8
.type sym8, @function
.global alias8
alias8:
.type alias8, @tls_object
.set sym8, alias8

.global sym9
.type sym9, @tls_object
alias9:
.global alias9
.type alias9, @object
.set sym9, alias9

.global sym10
.type sym10, @tls_object
alias10:
.global alias10
.type alias10, @notype
.set sym10, alias10

.global sym11
.type sym11, @tls_object
alias11:
.global alias11
.type alias11, @gnu_indirect_function
.set sym11, alias11

.global sym12
.type sym12, @tls_object
alias12:
.global alias12
.type alias12, @function
.set sym12, alias12

// CHECK: Symbol {
// CHECK: Name: bar
// CHECK-NEXT: Value: 0x0
Expand Down Expand Up @@ -86,6 +175,114 @@ tls_upper_case:
// CHECK-NEXT: Other: 0
// CHECK-NEXT: Section: .text (0x1)
// CHECK-NEXT: }
// CHECK-NEXT: Symbol {
// CHECK-NEXT: Name: sym1 (54)
// CHECK-NEXT: Value: 0x0
// CHECK-NEXT: Size: 0
// CHECK-NEXT: Binding: Global (0x1)
// CHECK-NEXT: Type: GNU_IFunc (0xA)
// CHECK-NEXT: Other: 0
// CHECK-NEXT: Section: .text (0x1)
// CHECK-NEXT: }
// CHECK-NEXT: Symbol {
// CHECK-NEXT: Name: sym10 (162)
// CHECK-NEXT: Value: 0x0
// CHECK-NEXT: Size: 0
// CHECK-NEXT: Binding: Global (0x1)
// CHECK-NEXT: Type: TLS (0x6)
// CHECK-NEXT: Other: 0
// CHECK-NEXT: Section: .text (0x1)
// CHECK-NEXT: }
// CHECK-NEXT: Symbol {
// CHECK-NEXT: Name: sym11 (176)
// CHECK-NEXT: Value: 0x0
// CHECK-NEXT: Size: 0
// CHECK-NEXT: Binding: Global (0x1)
// CHECK-NEXT: Type: TLS (0x6)
// CHECK-NEXT: Other: 0
// CHECK-NEXT: Section: .text (0x1)
// CHECK-NEXT: }
// CHECK-NEXT: Symbol {
// CHECK-NEXT: Name: sym12 (190)
// CHECK-NEXT: Value: 0x0
// CHECK-NEXT: Size: 0
// CHECK-NEXT: Binding: Global (0x1)
// CHECK-NEXT: Type: TLS (0x6)
// CHECK-NEXT: Other: 0
// CHECK-NEXT: Section: .text (0x1)
// CHECK-NEXT: }
// CHECK-NEXT: Symbol {
// CHECK-NEXT: Name: sym2 (66)
// CHECK-NEXT: Value: 0x0
// CHECK-NEXT: Size: 0
// CHECK-NEXT: Binding: Global (0x1)
// CHECK-NEXT: Type: GNU_IFunc (0xA)
// CHECK-NEXT: Other: 0
// CHECK-NEXT: Section: .text (0x1)
// CHECK-NEXT: }
// CHECK-NEXT: Symbol {
// CHECK-NEXT: Name: sym3 (78)
// CHECK-NEXT: Value: 0x0
// CHECK-NEXT: Size: 0
// CHECK-NEXT: Binding: Global (0x1)
// CHECK-NEXT: Type: GNU_IFunc (0xA)
// CHECK-NEXT: Other: 0
// CHECK-NEXT: Section: .text (0x1)
// CHECK-NEXT: }
// CHECK-NEXT: Symbol {
// CHECK-NEXT: Name: sym4 (90)
// CHECK-NEXT: Value: 0x0
// CHECK-NEXT: Size: 0
// CHECK-NEXT: Binding: Global (0x1)
// CHECK-NEXT: Type: Function (0x2)
// CHECK-NEXT: Other: 0
// CHECK-NEXT: Section: .text (0x1)
// CHECK-NEXT: }
// CHECK-NEXT: Symbol {
// CHECK-NEXT: Name: sym5 (102)
// CHECK-NEXT: Value: 0x0
// CHECK-NEXT: Size: 0
// CHECK-NEXT: Binding: Global (0x1)
// CHECK-NEXT: Type: Function (0x2)
// CHECK-NEXT: Other: 0
// CHECK-NEXT: Section: .text (0x1)
// CHECK-NEXT: }
// CHECK-NEXT: Symbol {
// CHECK-NEXT: Name: sym6 (114)
// CHECK-NEXT: Value: 0x0
// CHECK-NEXT: Size: 0
// CHECK-NEXT: Binding: Global (0x1)
// CHECK-NEXT: Type: Object (0x1)
// CHECK-NEXT: Other: 0
// CHECK-NEXT: Section: .text (0x1)
// CHECK-NEXT: }
// CHECK-NEXT: Symbol {
// CHECK-NEXT: Name: sym7 (126)
// CHECK-NEXT: Value: 0x0
// CHECK-NEXT: Size: 0
// CHECK-NEXT: Binding: Global (0x1)
// CHECK-NEXT: Type: GNU_IFunc (0xA)
// CHECK-NEXT: Other: 0
// CHECK-NEXT: Section: .text (0x1)
// CHECK-NEXT: }
// CHECK-NEXT: Symbol {
// CHECK-NEXT: Name: sym8 (138)
// CHECK-NEXT: Value: 0x0
// CHECK-NEXT: Size: 0
// CHECK-NEXT: Binding: Global (0x1)
// CHECK-NEXT: Type: Function (0x2)
// CHECK-NEXT: Other: 0
// CHECK-NEXT: Section: .text (0x1)
// CHECK-NEXT: }
// CHECK-NEXT: Symbol {
// CHECK-NEXT: Name: sym9 (150)
// CHECK-NEXT: Value: 0x0
// CHECK-NEXT: Size: 0
// CHECK-NEXT: Binding: Global (0x1)
// CHECK-NEXT: Type: TLS (0x6)
// CHECK-NEXT: Other: 0
// CHECK-NEXT: Section: .text (0x1)
// CHECK-NEXT: }
// CHECK-NEXT: Symbol {
// CHECK-NEXT: Name: tls
// CHECK-NEXT: Value: 0x0
Expand Down

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