Patch by Patricio Villalobos.
I discovered that lld for darwin is generating the wrong code for lazy
bindings in the __stub_helper section (at least for osx 10.12). This is
the way i can reproduce this problem, using this program:
#include <stdio.h>
int main(int argc, char **argv) {
printf("C: printf!\n");
puts("C: puts!\n");
return 0;
}
Then I link it using i have tested it in 3.9, 4.0 and 4.1 versions:
$ clang -c hello.c
$ lld -flavor darwin hello.o -o h1 -lc
When i execute the binary h1 the system gives me the following error:
C: printf!
dyld: lazy symbol binding failed:
BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB
has segment 4 which is too large (0..3)
dyld: BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB has segment 4 which is too
large (0..3)
Trace/BPT trap: 5
Investigating the code, it seems that the problem is that the asm code
generated in the file StubPass.cpp, specifically in the line 323,when it
adds, what it seems an arbitrary number (12) to the offset into the lazy
bind opcodes section, but it should be calculated depending on the
MachONormalizedFileBinaryWrite::lazyBindingInfo result.
I confirmed this bug by patching the code manually in the binary and
writing the right offset in the asm code (__stub_helper).
This patch fixes the content of the atom that contains the assembly code
when the offset is known.
Differential Revision: https://reviews.llvm.org/D35387
llvm-svn: 311734
An upcoming commit will change how we choose to reference a dylib. Currently
dylibs are only given an LC_LOAD_DYLIB in the final image if an atom is used.
This is different from ld64 which adds the load command when the dylib is referenced
on the cmdline.
In order to change this behaviour, we need libSystem.yaml to actually contain a mach header
so that it is parsed as a dylib, instead of currently being parsed as a normalised file.
To get a mach header, we also require an arch, so now we have one libsystem per arch and
all the tests have been updated to choose the correct one.
llvm-svn: 278372
The non lazy atoms generated in the stubs pass use an image cache to
hold all of the pointers. On arm archs, this is the __got section,
but on x86 archs it should be __nl_symbol_ptr.
rdar://problem/24572729
llvm-svn: 260271
ld64 aligns most of the stub's to 2 byte alignment, expect for
the stub helper common atoms which are 4 byte aligned.
This adds a new field to StubInfo which tracks this alignment
and ensures that this is the alignment we get in the final image.
rdar://problem/24570220
llvm-svn: 260248
loadFile could load mulitple files just because yaml has a feature for
putting multiple documents in one file.
Designing a linker around what yaml can do seems like a bad idea to
me. This patch changes it to read a single file.
There are further improvements to be done to the api and they
will follow shortly.
llvm-svn: 235724
Mach-o does not use a simple SO_NEEDED to track dependent dylibs. Instead,
the linker copies four things from each dylib to each client: the runtime path
(aka "install name"), the build time, current version (dylib build number), and
compatibility version The build time is no longer used (it cause every rebuild
of a dylib to be different). The compatibility version is usually just 1.0
and never changes, or the dylib becomes incompatible.
This patch copies that information into the NormalizedMachO format and
propagates it to clients.
llvm-svn: 222300
The way lazy binding works in mach-o is that the linker generates a helper
function and has the stub (PLT) initially jump to it. The helper function
pushes an extra parameter then jumps into dyld. The extra parameter is an
offset into the lazy binding info where dyld will find the information about
which symbol to bind and way lazy binding pointer to update.
llvm-svn: 221654
On darwin, the linker tools records which dylib (DSO) each undefined was found
in, and then at runtime, the loader (dyld) only looks in that one specific
dylib for each undefined symbol. Now that llvm-objdump can display that info
I can write test cases.
llvm-svn: 217898
Fangrui Song