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https://github.com/rui314/mold.git
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e0bc74ad8a
Previously, we make all PLT entries canonical if we are creating a position dependent executable, because I was thinking that promoting usual PLT entries to canonical ones is harmless; symbol equality still holds. However, it looks like Qt depends on the usual linker's behavior not to make PLT canonical if not necessary. I believe they are maintaining some hidden symbol as aliases for exported symbols and compare their addresses at runtime. Of course this doesn't work if your program is not compiled with -fPIC, but qt5/QtCore/qglobal.h has a macro to abort compilation if PIC is disabled. (They check for __PIC__ and __PIE__ macros.) So, all object files are guaranteed to be compiled with -fPIC if they are using QT functions, and they assume that the linker doesn't create a canonical PLT for Qt functions. This commit makes mold to create canonical PLTs only when needed. That is, if an address of a function is directly taken (i.e. not via GOT), then mold makes its PLT canonical. Fixes https://github.com/rui314/mold/issues/352
54 lines
904 B
Bash
Executable File
54 lines
904 B
Bash
Executable File
#!/bin/bash
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export LC_ALL=C
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set -e
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CC="${CC:-cc}"
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CXX="${CXX:-c++}"
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GCC="${GCC:-gcc}"
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GXX="${GXX:-g++}"
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OBJDUMP="${OBJDUMP:-objdump}"
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MACHINE="${MACHINE:-$(uname -m)}"
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testname=$(basename "$0" .sh)
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echo -n "Testing $testname ... "
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cd "$(dirname "$0")"/../..
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mold="$(pwd)/mold"
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t=out/test/elf/$testname
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mkdir -p $t
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cat <<EOF | $CC -o $t/a.so -fPIC -shared -xc -
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void *foo() {
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return foo;
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}
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void *bar() {
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return bar;
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}
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EOF
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cat <<EOF | $CC -o $t/b.o -c -xc - -fPIC
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void *bar();
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void *baz() {
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return bar;
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}
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EOF
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cat <<EOF | $CC -o $t/c.o -c -xc - -fPIC
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#include <stdio.h>
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void *foo();
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void *bar();
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void *baz();
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int main() {
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printf("%d %d %d\n", foo == foo(), bar == bar(), bar == baz());
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}
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EOF
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$CC -B. -no-pie -o $t/exe $t/a.so $t/b.o $t/c.o
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$QEMU $t/exe | grep -q '^1 1 1$'
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readelf --dyn-syms $t/exe | grep -q '00000000 .* foo'
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readelf --dyn-syms $t/exe | grep -q '00000000 .* bar'
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echo OK
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