[lld] 00925aa - [ELF][PPC32] Fix canonical PLTs when the order does not match the PLT order
Fangrui Song via llvm-commits
llvm-commits at lists.llvm.org
Fri Feb 28 22:25:00 PST 2020
Author: Fangrui Song
Date: 2020-02-28T22:23:14-08:00
New Revision: 00925aadb3f26ed41d4f1d35c1328adad1a3eeb1
URL: https://github.com/llvm/llvm-project/commit/00925aadb3f26ed41d4f1d35c1328adad1a3eeb1
DIFF: https://github.com/llvm/llvm-project/commit/00925aadb3f26ed41d4f1d35c1328adad1a3eeb1.diff
LOG: [ELF][PPC32] Fix canonical PLTs when the order does not match the PLT order
Reviewed By: Bdragon28
Differential Revision: https://reviews.llvm.org/D75394
Added:
Modified:
lld/ELF/Arch/PPC.cpp
lld/ELF/Relocations.cpp
lld/ELF/SyntheticSections.cpp
lld/ELF/SyntheticSections.h
lld/ELF/Writer.cpp
lld/test/ELF/Inputs/canonical-plt-pcrel.s
lld/test/ELF/ppc32-canonical-plt.s
Removed:
################################################################################
diff --git a/lld/ELF/Arch/PPC.cpp b/lld/ELF/Arch/PPC.cpp
index 032674e98739..a1e81d0c34c0 100644
--- a/lld/ELF/Arch/PPC.cpp
+++ b/lld/ELF/Arch/PPC.cpp
@@ -76,12 +76,11 @@ void writePPC32GlinkSection(uint8_t *buf, size_t numEntries) {
// non-GOT-non-PLT relocations referencing external functions for -fpie/-fPIE.
uint32_t glink = in.plt->getVA(); // VA of .glink
if (!config->isPic) {
- for (const Symbol *sym : in.plt->entries)
- if (sym->needsPltAddr) {
- writePPC32PltCallStub(buf, sym->getGotPltVA(), nullptr, 0);
- buf += 16;
- glink += 16;
- }
+ for (const Symbol *sym : cast<PPC32GlinkSection>(in.plt)->canonical_plts) {
+ writePPC32PltCallStub(buf, sym->getGotPltVA(), nullptr, 0);
+ buf += 16;
+ glink += 16;
+ }
}
// On PPC Secure PLT ABI, bl foo at plt jumps to a call stub, which loads an
diff --git a/lld/ELF/Relocations.cpp b/lld/ELF/Relocations.cpp
index 8fa183297743..60972e839ca3 100644
--- a/lld/ELF/Relocations.cpp
+++ b/lld/ELF/Relocations.cpp
@@ -1226,6 +1226,7 @@ static void processRelocAux(InputSectionBase &sec, RelExpr expr, RelType type,
// PPC32 canonical PLT entries are at the beginning of .glink
cast<Defined>(sym).value = in.plt->headerSize;
in.plt->headerSize += 16;
+ cast<PPC32GlinkSection>(in.plt)->canonical_plts.push_back(&sym);
}
}
sym.needsPltAddr = true;
diff --git a/lld/ELF/SyntheticSections.cpp b/lld/ELF/SyntheticSections.cpp
index 5de3df867c9f..d15226949e96 100644
--- a/lld/ELF/SyntheticSections.cpp
+++ b/lld/ELF/SyntheticSections.cpp
@@ -2447,12 +2447,9 @@ PltSection::PltSection()
: SyntheticSection(SHF_ALLOC | SHF_EXECINSTR, SHT_PROGBITS, 16, ".plt"),
headerSize(target->pltHeaderSize) {
// On PowerPC, this section contains lazy symbol resolvers.
- if (config->emachine == EM_PPC || config->emachine == EM_PPC64) {
+ if (config->emachine == EM_PPC64) {
name = ".glink";
alignment = 4;
- // PLTresolve is at the end.
- if (config->emachine == EM_PPC)
- footerSize = 64;
}
// On x86 when IBT is enabled, this section contains the second PLT (lazy
@@ -2468,11 +2465,6 @@ PltSection::PltSection()
}
void PltSection::writeTo(uint8_t *buf) {
- if (config->emachine == EM_PPC) {
- writePPC32GlinkSection(buf, entries.size());
- return;
- }
-
// At beginning of PLT, we have code to call the dynamic
// linker to resolve dynsyms at runtime. Write such code.
target->writePltHeader(buf);
@@ -2490,7 +2482,7 @@ void PltSection::addEntry(Symbol &sym) {
}
size_t PltSection::getSize() const {
- return headerSize + entries.size() * target->pltEntrySize + footerSize;
+ return headerSize + entries.size() * target->pltEntrySize;
}
bool PltSection::isNeeded() const {
@@ -2544,6 +2536,19 @@ void IpltSection::addSymbols() {
}
}
+PPC32GlinkSection::PPC32GlinkSection() {
+ name = ".glink";
+ alignment = 4;
+}
+
+void PPC32GlinkSection::writeTo(uint8_t *buf) {
+ writePPC32GlinkSection(buf, entries.size());
+}
+
+size_t PPC32GlinkSection::getSize() const {
+ return headerSize + entries.size() * target->pltEntrySize + footerSize;
+}
+
// This is an x86-only extra PLT section and used only when a security
// enhancement feature called CET is enabled. In this comment, I'll explain what
// the feature is and why we have two PLT sections if CET is enabled.
diff --git a/lld/ELF/SyntheticSections.h b/lld/ELF/SyntheticSections.h
index 5f59178fb541..190a4fd3ac9e 100644
--- a/lld/ELF/SyntheticSections.h
+++ b/lld/ELF/SyntheticSections.h
@@ -684,7 +684,6 @@ class PltSection : public SyntheticSection {
size_t getNumEntries() const { return entries.size(); }
size_t headerSize;
- size_t footerSize = 0;
std::vector<const Symbol *> entries;
};
@@ -705,6 +704,16 @@ class IpltSection final : public SyntheticSection {
void addEntry(Symbol &sym);
};
+class PPC32GlinkSection : public PltSection {
+public:
+ PPC32GlinkSection();
+ void writeTo(uint8_t *buf) override;
+ size_t getSize() const override;
+
+ std::vector<const Symbol *> canonical_plts;
+ static constexpr size_t footerSize = 64;
+};
+
// This is x86-only.
class IBTPltSection : public SyntheticSection {
public:
diff --git a/lld/ELF/Writer.cpp b/lld/ELF/Writer.cpp
index 013f7d066703..b41aceb8634b 100644
--- a/lld/ELF/Writer.cpp
+++ b/lld/ELF/Writer.cpp
@@ -525,7 +525,8 @@ template <class ELFT> void createSyntheticSections() {
add(in.ibtPlt);
}
- in.plt = make<PltSection>();
+ in.plt = config->emachine == EM_PPC ? make<PPC32GlinkSection>()
+ : make<PltSection>();
add(in.plt);
in.iplt = make<IpltSection>();
add(in.iplt);
diff --git a/lld/test/ELF/Inputs/canonical-plt-pcrel.s b/lld/test/ELF/Inputs/canonical-plt-pcrel.s
index 966f26a1e643..1547d848b65b 100644
--- a/lld/test/ELF/Inputs/canonical-plt-pcrel.s
+++ b/lld/test/ELF/Inputs/canonical-plt-pcrel.s
@@ -1,5 +1,7 @@
-.globl func, ifunc
+.globl func, func2, ifunc
.type func, @function
+.type func2, @function
.type ifunc, @gnu_indirect_function
func:
+func2:
ifunc:
diff --git a/lld/test/ELF/ppc32-canonical-plt.s b/lld/test/ELF/ppc32-canonical-plt.s
index 371aa7325b2d..148e65283a94 100644
--- a/lld/test/ELF/ppc32-canonical-plt.s
+++ b/lld/test/ELF/ppc32-canonical-plt.s
@@ -14,49 +14,59 @@
# REL: Relocations [
# REL-NEXT: .rela.plt {
-# REL-NEXT: R_PPC_JMP_SLOT func 0x0
-# REL-NEXT: R_PPC_JMP_SLOT ifunc 0x0
+# REL-NEXT: 0x10030318 R_PPC_JMP_SLOT func 0x0
+# REL-NEXT: 0x1003031C R_PPC_JMP_SLOT func2 0x0
+# REL-NEXT: 0x10030320 R_PPC_JMP_SLOT ifunc 0x0
# REL-NEXT: }
# REL-NEXT: ]
-# SYM: .glink PROGBITS 100101dc
+# SYM: .glink PROGBITS 1001022c
## st_value points to the canonical PLT entry in .glink
# SYM: Symbol table '.dynsym'
-# SYM: 100101dc 0 FUNC GLOBAL DEFAULT UND func
-# SYM: 100101ec 0 FUNC GLOBAL DEFAULT UND ifunc
+# SYM: 1001023c 0 FUNC GLOBAL DEFAULT UND func
+# SYM: 1001022c 0 FUNC GLOBAL DEFAULT UND func2
+# SYM: 1001024c 0 FUNC GLOBAL DEFAULT UND ifunc
# SYM: Symbol table '.symtab'
-# SYM: 100101dc 0 FUNC GLOBAL DEFAULT UND func
-# SYM: 100101ec 0 FUNC GLOBAL DEFAULT UND ifunc
+# SYM: 1001023c 0 FUNC GLOBAL DEFAULT UND func
+# SYM: 1001022c 0 FUNC GLOBAL DEFAULT UND func2
+# SYM: 1001024c 0 FUNC GLOBAL DEFAULT UND ifunc
-# HEX: 0x100302b4 100101fc 10010200
+# HEX: 0x10030318 1001025c 10010260 10010264
-## Canonical PLT entry of func.
-## 0x100101dc + 4*2 + 64 = 0x10010224
-## 0x1001021c = 65536*4099+692
-# CHECK: 100101dc .glink:
+## Canonical PLT entry of func2.
+## 0x1003031C = 65536*4099+796
+# CHECK: 1001022c .glink:
# CHECK-NEXT: lis 11, 4099
-# CHECK-NEXT: lwz 11, 692(11)
+# CHECK-NEXT: lwz 11, 796(11)
+# CHECK-NEXT: mtctr 11
+# CHECK-NEXT: bctr
+
+## Canonical PLT entry of func.
+## 0x10030318 = 65536*4099+792
+# CHECK-NEXT: 1001023c: lis 11, 4099
+# CHECK-NEXT: lwz 11, 792(11)
# CHECK-NEXT: mtctr 11
# CHECK-NEXT: bctr
## Canonical PLT entry of ifunc.
-## 0x10010220 = 65536*4099+696
-# CHECK-NEXT: 100101ec: lis 11, 4099
-# CHECK-NEXT: lwz 11, 696(11)
+## 0x10030320 = 65536*4099+800
+# CHECK-NEXT: 1001024c: lis 11, 4099
+# CHECK-NEXT: lwz 11, 800(11)
# CHECK-NEXT: mtctr 11
# CHECK-NEXT: bctr
-## The 2 b instructions are referenced by .plt entries.
-# CHECK-NEXT: 100101fc: b .+8
+## The 3 b instructions are referenced by .plt entries.
+# CHECK-NEXT: 1001025c: b .+12
+# CHECK-NEXT: b .+8
# CHECK-NEXT: b .+4
## PLTresolve of 64 bytes is at the end.
-## Operands of addis & addi: -0x100101fc = 65536*-4097-508
+## Operands of addis & addi: -0x1001025c = 65536*-4097-604
# CHECK-NEXT: lis 12, 0
# CHECK-NEXT: addis 11, 11, -4097
# CHECK-NEXT: lwz 0, 4(12)
-# CHECK-NEXT: addi 11, 11, -508
+# CHECK-NEXT: addi 11, 11, -604
# CHECK-NEXT: mtctr 0
# CHECK-NEXT: add 0, 11, 11
# CHECK-NEXT: lwz 12, 8(12)
@@ -66,6 +76,9 @@
.globl _start
_start:
+ b func
+ lis 3, func2 at ha
+ la 3, func2 at l(3)
lis 3, func at ha
la 3, func at l(3)
lis 4, ifunc at ha
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