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Added support for "#pragma clang section relro=<name>" 

Differential Revision: https://reviews.llvm.org/D68806

llvm-svn: 374934
This commit is contained in:
Dmitry Mikulin 2019-10-15 18:31:10 +00:00
parent 2cb27072ce
commit f14642f2f1
15 changed files with 123 additions and 22 deletions
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4
clang/docs/LanguageExtensions.rst
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@ -3445,14 +3445,14 @@ The section names can be specified as:
.. code-block:: c++
#pragma clang section bss="myBSS" data="myData" rodata="myRodata" text="myText"
#pragma clang section bss="myBSS" data="myData" rodata="myRodata" relro="myRelro" text="myText"
The section names can be reverted back to default name by supplying an empty
string to the section kind, for example:
.. code-block:: c++
#pragma clang section bss="" data="" text="" rodata=""
#pragma clang section bss="" data="" text="" rodata="" relro=""
The ``#pragma clang section`` directive obeys the following rules:

8
clang/include/clang/Basic/Attr.td
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@ -2020,6 +2020,14 @@ def PragmaClangRodataSection : InheritableAttr {
let Documentation = [Undocumented];
}
def PragmaClangRelroSection : InheritableAttr {
// This attribute has no spellings as it is only ever created implicitly.
let Spellings = [];
let Args = [StringArgument<"Name">];
let Subjects = SubjectList<[GlobalVar], ErrorDiag>;
let Documentation = [Undocumented];
}
def PragmaClangTextSection : InheritableAttr {
// This attribute has no spellings as it is only ever created implicitly.
let Spellings = [];

4
clang/include/clang/Basic/DiagnosticParseKinds.td
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@ -976,9 +976,9 @@ def err_pragma_misplaced_in_decl : Error<"this pragma cannot appear in %0 declar
// '#pragma clang section' related errors
def err_pragma_expected_clang_section_name : Error<
"expected one of [bss|data|rodata|text] section kind in '#pragma %0'">;
"expected one of [bss|data|rodata|text|relro] section kind in '#pragma %0'">;
def err_pragma_clang_section_expected_equal : Error<
"expected '=' following '#pragma clang section %select{invalid|bss|data|rodata|text}0'">;
"expected '=' following '#pragma clang section %select{invalid|bss|data|rodata|text|relro}0'">;
def warn_pragma_expected_section_name : Warning<
"expected a string literal for the section name in '#pragma %0' - ignored">,
InGroup<IgnoredPragmas>;

4
clang/include/clang/Sema/Sema.h
View File

@ -418,7 +418,8 @@ public:
PCSK_BSS = 1,
PCSK_Data = 2,
PCSK_Rodata = 3,
PCSK_Text = 4
PCSK_Text = 4,
PCSK_Relro = 5
};
enum PragmaClangSectionAction {
@ -439,6 +440,7 @@ public:
PragmaClangSection PragmaClangBSSSection;
PragmaClangSection PragmaClangDataSection;
PragmaClangSection PragmaClangRodataSection;
PragmaClangSection PragmaClangRelroSection;
PragmaClangSection PragmaClangTextSection;
enum PragmaMsStackAction {

2
clang/lib/CodeGen/CGDecl.cpp
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@ -419,6 +419,8 @@ void CodeGenFunction::EmitStaticVarDecl(const VarDecl &D,
var->addAttribute("data-section", SA->getName());
if (auto *SA = D.getAttr<PragmaClangRodataSectionAttr>())
var->addAttribute("rodata-section", SA->getName());
if (auto *SA = D.getAttr<PragmaClangRelroSectionAttr>())
var->addAttribute("relro-section", SA->getName());
if (const SectionAttr *SA = D.getAttr<SectionAttr>())
var->setSection(SA->getName());

3
clang/lib/CodeGen/CodeGenModule.cpp
View File

@ -1717,6 +1717,8 @@ void CodeGenModule::setNonAliasAttributes(GlobalDecl GD,
GV->addAttribute("data-section", SA->getName());
if (auto *SA = D->getAttr<PragmaClangRodataSectionAttr>())
GV->addAttribute("rodata-section", SA->getName());
if (auto *SA = D->getAttr<PragmaClangRelroSectionAttr>())
GV->addAttribute("relro-section", SA->getName());
}
if (auto *F = dyn_cast<llvm::Function>(GO)) {
@ -4118,6 +4120,7 @@ static bool isVarDeclStrongDefinition(const ASTContext &Context,
// If no specialized section name is applicable, it will resort to default.
if (D->hasAttr<PragmaClangBSSSectionAttr>() ||
D->hasAttr<PragmaClangDataSectionAttr>() ||
D->hasAttr<PragmaClangRelroSectionAttr>() ||
D->hasAttr<PragmaClangRodataSectionAttr>())
return true;

4
clang/lib/Parse/ParsePragma.cpp
View File

@ -1790,7 +1790,7 @@ void PragmaMSStructHandler::HandlePragma(Preprocessor &PP,
/*IsReinject=*/false);
}
// #pragma clang section bss="abc" data="" rodata="def" text=""
// #pragma clang section bss="abc" data="" rodata="def" text="" relro=""
void PragmaClangSectionHandler::HandlePragma(Preprocessor &PP,
PragmaIntroducer Introducer,
Token &FirstToken) {
@ -1812,6 +1812,8 @@ void PragmaClangSectionHandler::HandlePragma(Preprocessor &PP,
SecKind = Sema::PragmaClangSectionKind::PCSK_Data;
else if (SecType->isStr("rodata"))
SecKind = Sema::PragmaClangSectionKind::PCSK_Rodata;
else if (SecType->isStr("relro"))
SecKind = Sema::PragmaClangSectionKind::PCSK_Relro;
else if (SecType->isStr("text"))
SecKind = Sema::PragmaClangSectionKind::PCSK_Text;
else {

3
clang/lib/Sema/SemaAttr.cpp
View File

@ -266,6 +266,9 @@ void Sema::ActOnPragmaClangSection(SourceLocation PragmaLoc, PragmaClangSectionA
case PragmaClangSectionKind::PCSK_Rodata:
CSec = &PragmaClangRodataSection;
break;
case PragmaClangSectionKind::PCSK_Relro:
CSec = &PragmaClangRelroSection;
break;
case PragmaClangSectionKind::PCSK_Text:
CSec = &PragmaClangTextSection;
break;

5
clang/lib/Sema/SemaDecl.cpp
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@ -12657,6 +12657,11 @@ void Sema::FinalizeDeclaration(Decl *ThisDecl) {
Context, PragmaClangRodataSection.SectionName,
PragmaClangRodataSection.PragmaLocation,
AttributeCommonInfo::AS_Pragma));
if (PragmaClangRelroSection.Valid)
VD->addAttr(PragmaClangRelroSectionAttr::CreateImplicit(
Context, PragmaClangRelroSection.SectionName,
PragmaClangRelroSection.PragmaLocation,
AttributeCommonInfo::AS_Pragma));
}
if (auto *DD = dyn_cast<DecompositionDecl>(ThisDecl)) {

25
clang/test/CodeGenCXX/clang-sections.cpp
View File

@ -29,17 +29,20 @@ int goo(void) { // my_text.2
static int lstat_h; // my_bss.2
return zoo(g, &lstat_h);
}
#pragma clang section rodata="my_rodata.2" data="my_data.2"
#pragma clang section rodata="my_rodata.2" data="my_data.2" relro="my_relro.2"
int l = 5; // my_data.2
extern const int m;
const int m = 6; // my_rodata.2
typedef int (*fptr_t)(void);
const fptr_t fptrs[2] = {&foo, &goo};
#pragma clang section rodata="" data="" bss="" text=""
int n; // default
int o = 6; // default
extern const int p;
const int p = 7; // default
int hoo(void) {
return b;
return b + fptrs[f]();
}
}
//CHECK: @a = global i32 0, align 4 #0
@ -62,17 +65,19 @@ int hoo(void) {
//CHECK: @n = global i32 0, align 4
//CHECK: @o = global i32 6, align 4
//CHECK: @p = constant i32 7, align 4
//CHECK: @_ZL5fptrs = internal constant [2 x i32 ()*] [i32 ()* @foo, i32 ()* @goo], align 4 #3
//CHECK: define i32 @foo() #4 {
//CHECK: define i32 @goo() #5 {
//CHECK: declare i32 @zoo(i32*, i32*) #6
//CHECK: define i32 @hoo() #7 {
//CHECK: define i32 @foo() #5 {
//CHECK: define i32 @goo() #6 {
//CHECK: declare i32 @zoo(i32*, i32*) #7
//CHECK: define i32 @hoo() #8 {
//CHECK: attributes #0 = { "bss-section"="my_bss.1" "data-section"="my_data.1" "rodata-section"="my_rodata.1" }
//CHECK: attributes #1 = { "data-section"="my_data.1" "rodata-section"="my_rodata.1" }
//CHECK: attributes #2 = { "bss-section"="my_bss.2" "rodata-section"="my_rodata.1" }
//CHECK: attributes #3 = { "bss-section"="my_bss.2" "data-section"="my_data.2" "rodata-section"="my_rodata.2" }
//CHECK: attributes #4 = { {{.*"implicit-section-name"="my_text.1".*}} }
//CHECK: attributes #5 = { {{.*"implicit-section-name"="my_text.2".*}} }
//CHECK-NOT: attributes #6 = { {{.*"implicit-section-name".*}} }
//CHECK: attributes #3 = { "bss-section"="my_bss.2" "data-section"="my_data.2" "relro-section"="my_relro.2" "rodata-section"="my_rodata.2" }
//CHECK: attributes #4 = { "relro-section"="my_relro.2" }
//CHECK: attributes #5 = { {{.*"implicit-section-name"="my_text.1".*}} }
//CHECK: attributes #6 = { {{.*"implicit-section-name"="my_text.2".*}} }
//CHECK-NOT: attributes #7 = { {{.*"implicit-section-name".*}} }
//CHECK-NOT: attributes #8 = { {{.*"implicit-section-name".*}} }

14
clang/test/Sema/pragma-clang-section.c
View File

@ -3,15 +3,17 @@
#pragma clang section bss="" data="" rodata="" text=""
#pragma clang section
#pragma clang section dss="mybss.2" // expected-error {{expected one of [bss|data|rodata|text] section kind in '#pragma clang section'}}
#pragma clang section deta="mydata.2" // expected-error {{expected one of [bss|data|rodata|text] section kind in '#pragma clang section'}}
#pragma clang section rodeta="rodata.2" // expected-error {{expected one of [bss|data|rodata|text] section kind in '#pragma clang section'}}
#pragma clang section taxt="text.2" // expected-error {{expected one of [bss|data|rodata|text] section kind in '#pragma clang section'}}
#pragma clang section dss="mybss.2" // expected-error {{expected one of [bss|data|rodata|text|relro] section kind in '#pragma clang section'}}
#pragma clang section deta="mydata.2" // expected-error {{expected one of [bss|data|rodata|text|relro] section kind in '#pragma clang section'}}
#pragma clang section rodeta="rodata.2" // expected-error {{expected one of [bss|data|rodata|text|relro] section kind in '#pragma clang section'}}
#pragma clang section taxt="text.2" // expected-error {{expected one of [bss|data|rodata|text|relro] section kind in '#pragma clang section'}}
#pragma clang section section bss="mybss.2" // expected-error {{expected one of [bss|data|rodata|text] section kind in '#pragma clang section'}}
#pragma clang section section bss="mybss.2" // expected-error {{expected one of [bss|data|rodata|text|relro] section kind in '#pragma clang section'}}
#pragma clang section bss "mybss.2" // expected-error {{expected '=' following '#pragma clang section bss'}}
#pragma clang section data "mydata.2" // expected-error {{expected '=' following '#pragma clang section data'}}
#pragma clang section rodata "myrodata.2" // expected-error {{expected '=' following '#pragma clang section rodata'}}
#pragma clang section bss="" data="" rodata="" text="" more //expected-error {{expected one of [bss|data|rodata|text] section kind in '#pragma clang section'}}
#pragma clang section text "text.2" // expected-error {{expected '=' following '#pragma clang section text'}}
#pragma clang section relro "relro.2" // expected-error {{expected '=' following '#pragma clang section relro'}}
#pragma clang section bss="" data="" rodata="" text="" more //expected-error {{expected one of [bss|data|rodata|text|relro] section kind in '#pragma clang section'}}
int a;

1
llvm/include/llvm/IR/GlobalVariable.h
View File

@ -243,6 +243,7 @@ public:
bool hasImplicitSection() const {
return getAttributes().hasAttribute("bss-section") ||
getAttributes().hasAttribute("data-section") ||
getAttributes().hasAttribute("relro-section") ||
getAttributes().hasAttribute("rodata-section");
}

2
llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
View File

@ -568,6 +568,8 @@ MCSection *TargetLoweringObjectFileELF::getExplicitSectionGlobal(
SectionName = Attrs.getAttribute("bss-section").getValueAsString();
} else if (Attrs.hasAttribute("rodata-section") && Kind.isReadOnly()) {
SectionName = Attrs.getAttribute("rodata-section").getValueAsString();
} else if (Attrs.hasAttribute("relro-section") && Kind.isReadOnlyWithRel()) {
SectionName = Attrs.getAttribute("relro-section").getValueAsString();
} else if (Attrs.hasAttribute("data-section") && Kind.isData()) {
SectionName = Attrs.getAttribute("data-section").getValueAsString();
}

1
llvm/lib/Target/TargetLoweringObjectFile.cpp
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@ -253,6 +253,7 @@ MCSection *TargetLoweringObjectFile::SectionForGlobal(
auto Attrs = GVar->getAttributes();
if ((Attrs.hasAttribute("bss-section") && Kind.isBSS()) ||
(Attrs.hasAttribute("data-section") && Kind.isData()) ||
(Attrs.hasAttribute("relro-section") && Kind.isReadOnlyWithRel()) ||
(Attrs.hasAttribute("rodata-section") && Kind.isReadOnly())) {
return getExplicitSectionGlobal(GO, Kind, TM);
}

65
llvm/test/MC/ELF/section-relro.ll Normal file
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@ -0,0 +1,65 @@
; Tests that data and relro are correctly placed in sections
; specified by "#pragma clang section"
; RUN: llc -filetype=obj -mtriple x86_64-unknown-linux %s -o - | llvm-readobj -S -t | FileCheck %s
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux"
@funcs_relro = hidden constant [2 x i32 ()*] [i32 ()* bitcast (i32 (...)* @func1 to i32 ()*), i32 ()* bitcast (i32 (...)* @func2 to i32 ()*)], align 16 #0
@var_data = hidden global i32 33, align 4 #0
declare i32 @func1(...)
declare i32 @func2(...)
; Function Attrs: noinline nounwind optnone sspstrong uwtable
define hidden i32 @foo(i32 %i) {
entry:
%i.addr = alloca i32, align 4
store i32 %i, i32* %i.addr, align 4
%0 = load i32, i32* %i.addr, align 4
%idxprom = sext i32 %0 to i64
%arrayidx = getelementptr inbounds [2 x i32 ()*], [2 x i32 ()*]* @funcs_relro, i64 0, i64 %idxprom
%1 = load i32 ()*, i32 ()** %arrayidx, align 8
%call = call i32 %1()
%2 = load i32, i32* @var_data, align 4
%add = add nsw i32 %call, %2
ret i32 %add
}
attributes #0 = { "data-section"=".my_data" "relro-section"=".my_relro" "rodata-section"=".my_rodata" }
; CHECK: Section {
; CHECK: Index:
; CHECK: Name: .my_rodata
; CHECK: Type: SHT_PROGBITS (0x1)
; CHECK: Flags [ (0x2)
; CHECK: SHF_ALLOC (0x2)
; CHECK: ]
; CHECK: Size: 16
; CHECK: }
; CHECK: Section {
; CHECK: Index:
; CHECK: Name: .my_data
; CHECK: Type: SHT_PROGBITS (0x1)
; CHECK: Flags [ (0x3)
; CHECK: SHF_ALLOC (0x2)
; CHECK: SHF_WRITE (0x1)
; CHECK: ]
; CHECK: Size: 4
; CHECK: }
; CHECK: Symbol {
; CHECK: Name: funcs_relro
; CHECK: Value: 0x0
; CHECK: Size: 16
; CHECK: Binding: Global (0x1)
; CHECK: Type: Object (0x1)
; CHECK: Section: .my_rodata
; CHECK: }
; CHECK: Symbol {
; CHECK: Name: var_data
; CHECK: Value: 0x0
; CHECK: Size: 4
; CHECK: Binding: Global (0x1)
; CHECK: Type: Object (0x1)
; CHECK: Section: .my_data
; CHECK: }