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Fix TLSDESC relocations for statically-linked executables

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We shouldn't create TLSDESC dynamic relocations for statically-
linked executables because such executables don't contain the
tranpoline function needed for TLSDESC. Instead, we should
always relax these relocations.
This commit is contained in:
Rui Ueyama 2021-08-22 21:02:57 +09:00
parent 3c79d672dc
commit 4c710df347
2 changed files with 44 additions and 2 deletions
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7
arch-x86-64.cc
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@ -410,7 +410,7 @@ void InputSection<X86_64>::apply_reloc_alloc(Context<X86_64> &ctx, u8 *base) {
write(sym.esym().st_size + A); write(sym.esym().st_size + A);
continue; continue;
case R_X86_64_TLSDESC_CALL: case R_X86_64_TLSDESC_CALL:
if (ctx.arg.relax && !ctx.arg.shared) { if (ctx.arg.is_static || (ctx.arg.relax && !ctx.arg.shared)) {
// call *(%rax) -> nop // call *(%rax) -> nop
loc[0] = 0x66; loc[0] = 0x66;
loc[1] = 0x90; loc[1] = 0x90;
@ -644,7 +644,10 @@ void InputSection<X86_64>::scan_relocations(Context<X86_64> &ctx) {
Fatal(ctx) << *this << ": GOTPC32_TLSDESC relocation is used" Fatal(ctx) << *this << ": GOTPC32_TLSDESC relocation is used"
<< " against an invalid code sequence"; << " against an invalid code sequence";
if (!ctx.arg.relax || ctx.arg.shared) // TLSDESC relocs must be relaxed for a statically-linked executable
// even if -no-relax is given. It is because a statically-linked
// executable doesn't contain a tranpoline function needed for TLSDESC.
if (!ctx.arg.is_static && (!ctx.arg.relax || ctx.arg.shared))
sym.flags |= NEEDS_TLSDESC; sym.flags |= NEEDS_TLSDESC;
break; break;
case R_X86_64_TPOFF32: case R_X86_64_TPOFF32:

39
test/tlsdesc-static.sh Executable file
View File

@ -0,0 +1,39 @@
#!/bin/bash
set -e
cd $(dirname $0)
mold=`pwd`/../mold
echo -n "Testing $(basename -s .sh $0) ... "
t=$(pwd)/tmp/$(basename -s .sh $0)
mkdir -p $t
if [ $(uname -m) = x86_64 ]; then
dialect=gnu2
elif [ $(uname -m) = aarch64 ]; then
dialect=desc
else
echo skipped
exit 0
fi
cat <<EOF | gcc -fPIC -mtls-dialect=$dialect -c -o $t/a.o -xc -
#include <stdio.h>
extern _Thread_local int foo;
int main() {
foo = 42;
printf("%d\n", foo);
}
EOF
cat <<EOF | gcc -fPIC -mtls-dialect=$dialect -c -o $t/b.o -xc -
_Thread_local int foo;
EOF
clang -fuse-ld=$mold -o $t/exe $t/a.o $t/b.o -static
$t/exe | grep -q 42
clang -fuse-ld=$mold -o $t/exe $t/a.o $t/b.o -static -Wl,-no-relax
$t/exe | grep -q 42
echo OK