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Don't produce a relocation to read only memory. 

This is hopefully last case where we would produce a relocation to a
read only section.

llvm-svn: 268688
This commit is contained in:
Rafael Espindola 2016-05-05 21:19:38 +00:00
parent 28a932742c
commit d39dadeb64
2 changed files with 20 additions and 2 deletions
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10
lld/ELF/Writer.cpp
View File

@ -439,6 +439,12 @@ static bool needsPlt(RelExpr Expr) {
return Expr == R_PLT_PC || Expr == R_PPC_PLT_OPD || Expr == R_PLT;
}
// True if this expression is of the form Sym - X, where X is a position in the
// file (PC, or GOT for example).
static bool isRelExpr(RelExpr Expr) {
return Expr == R_PC || Expr == R_GOTREL || Expr == R_PAGE_PC;
}
template <class ELFT>
static bool isStaticLinkTimeConstant(RelExpr E, uint32_t Type,
const SymbolBody &Body) {
@ -460,7 +466,7 @@ static bool isStaticLinkTimeConstant(RelExpr E, uint32_t Type,
return true;
bool AbsVal = isAbsolute<ELFT>(Body) || Body.isTls();
bool RelE = E == R_PC || E == R_GOTREL || E == R_PAGE_PC;
bool RelE = isRelExpr(E);
if (AbsVal && !RelE)
return true;
if (!AbsVal && RelE)
@ -520,7 +526,7 @@ RelExpr Writer<ELFT>::adjustExpr(SymbolBody &Body, bool IsWrite, RelExpr Expr,
// This relocation would require the dynamic linker to write a value to read
// only memory. We can hack around it if we are producing an executable and
// the refered symbol can be preemepted to refer to the executable.
if (Config->Shared) {
if (Config->Shared || (Config->Pic && !isRelExpr(Expr))) {
StringRef S = getELFRelocationTypeName(Config->EMachine, Type);
error("relocation " + S + " cannot be used when making a shared "
"object; recompile with -fPIC.");

12
lld/test/ELF/copy-rel-pie-error.s Normal file
View File

@ -0,0 +1,12 @@
// RUN: llvm-mc %s -o %t.o -filetype=obj -triple=x86_64-pc-linux
// RUN: llvm-mc %p/Inputs/copy-rel-pie.s -o %t2.o -filetype=obj -triple=x86_64-pc-linux
// RUN: ld.lld %t2.o -o %t2.so -shared
// RUN: not ld.lld %t.o %t2.so -o %t.exe -pie 2>&1 | FileCheck %s
// CHECK: relocation R_X86_64_64 cannot be used when making a shared object; recompile with -fPIC.
// CHECK: relocation R_X86_64_64 cannot be used when making a shared object; recompile with -fPIC.
.global _start
_start:
.quad bar
.quad foo