If you have something like
__declspec(align(8192)) int foo = 1;
in your code, the compiler makes the data to be aligned to 8192-byte
boundary, and the linker align the section containing the data to 8192.
LLD always aligned the section to 4192. So, as long as alignment
requirement is smaller than 4192, it was correct, but for larger
requirements, it's wrong.
This patch fixes the issue.
llvm-svn: 222043
AddressOfEntryPoint is overridden after we layout all atoms (until then,
we don't know the entry point address for obvious reason.)
I believe this code is leftover from very early version of the
PE/COFF port that we only had an entry function in a test object file.
llvm-svn: 222026
SECREL relocation's value is the offset to the beginning of the section.
Because of the off-by-one error, if a SECREL relocation target is at the
beginning of a section, it got wrong value.
Added a test that would have caught this.
llvm-svn: 221420
Many programs, for reasons unknown, really like to look at the
AddressOfRelocationTable to determine whether or not they are looking at
a bona fide PE file. Without this, programs like the UNIX `file'
utility will insist that they are looking at a MS DOS executable.
llvm-svn: 221335
Normally, PE files have section names of eight characters or less.
However, this is problematic for DWARF because DWARF section names are
things like .debug_aranges.
Instead of truncating the section name, redirect the section name into
the string table.
Differential Revision: http://reviews.llvm.org/D6104
llvm-svn: 221212
This is a partial patch to emit the delay-import table. With this,
LLD is now able to emit the table that llvm-readobj can read and
dump.
The table lacks a few fields, such as the address of HMODULE, the
import address table, etc. They'll be added in subsequent patches.
llvm-svn: 219384
In order to support more than x86/x86_64, we need to change the behaviour to use
the actual machine type rather than checking the bitness and assuming that we
are on X86. This replaces the use of is64bit in applyAllRelocations with a
check on the machine type. This will enable adding support for handling ARM
relocations.
Rename the existing applyRelocation methods to be similarly named and to make it
clear the types of relocations they will process.
llvm-svn: 219088
Cache the machine type value of the linking context. We need this in order to
calculate the virtual address of the atom when resolving function symbols.
Windows on ARM must check if the atom is a function and if so, set the Thumb bit
for the returned virtual address. Failure to do so will result in an abnormal
exit due to a trap caused by invalid instruction decoding. The same information
can be used to determine the relocation type that was previously being done via
is64 to select between x86 and x86_64.
llvm-svn: 218106
The contents from section .CRT$XLA to .CRT$XLZ is an array of function
pointers. They are called by the runtime when a new thread is created
or (gracefully) terminated.
You can make your own initialization function to be called by that
mechanism. All you have to do is:
- Define a pointer to a function in a .CRT$XL* section using pragma
- Make an external reference to "__tls_used" symbol
That technique is used in many projects. This patch is to support that.
What this patch does is to set the relative virtual address of
"__tls_used" to the PECOFF directory table. __tls_used is actually a
struct containing pointers to a symbol in .CRT$XLA and another symbol
in .CRT$XLZ. The runtime looks at the directory table, gets the address
of the struct, and call the function pointers between XLA and XLZ.
llvm-svn: 218007
I hope this is the last fix for x64 relocations as I've wasted
a few days on this.
This caused a mysterious issue that some C++ programs crash on
startup. It was because a null pointer is passed as argv to main.
__tmainCRTStartup calls main, but before that it calls all
initialization routines between .text$xc_a and .text$xc_z.
pre_cpp_init is one of such routines, and it is the one who
initializes a heap pointer for argv for later use. That routine
was not called for some reason.
It turned out that __tmainCRTStartup was skipping a block of
code because of the relocation bug. A condition in the function
depends on a memory load, and that memory load was referring
a wrong location. As a result a jump instruction took the
wrong branch, skipping pre_cpp_init and so on.
This patch fixes the issue. Also added more tests to fix them
once and for all.
llvm-svn: 216772
When a relocation is applied to a location, the new value needs
to be added to the existing value at the location. Existing
value is in most cases zero, but if not, the current code does
not work.
llvm-svn: 216680
Image Base field in the PE/COFF header is used as hint for the loader.
If the loader can load the executable at the specified address, that's
fine, but if not, it has to load it at a different address.
If that happens, the loader has to fix up the addresses in the
executable by adding the offset. The list of addresses that need to
be fixed is in .reloc section.
This patch is to emit x64 .reloc section contents.
llvm-svn: 216636
IMAGE_REL_AMD64_ADDR64 relocation should set 64-bit *VA* (virtual
address) instead of *RVA* (relative virtual address), so we have
to add the iamge base to the target's RVA.
llvm-svn: 216512
The implementation of AMD64 relocations was imcomplete
and wrong. On AMD64, we of course have to use AMD64
relocations instead of i386 ones. This patch fixes the
issue.
LLD is now able to link hello64.obj (created from
hello64.asm) against user32.lib and kernel32.lib to
create a Win64 binary.
llvm-svn: 216253
The PE/COFF spec says that SizeOfRawData field in the section
header must be a multiple of FileAlignment from the optional
header. LLD emits 512 as FileAlignment, so it must have been
a multiple of 512.
LLD did not follow that. It emitted the actual section size
without the last padding as the SizeOfRawData. Although it's
not correct as per the spec, the Windows loader doesn't seem
to actually bother to check that. Executables created by LLD
worked fine.
However, tools dealing with executalbe files may expect it
to be the correct value, and one instance of it is mt.exe
tool distributed as a part of Windows SDK.
If CMake is invoked with "-E vs_link_exe" option, it silently
run mt.exe to embed a resource file to the resulting file.
And mt.exe sometimes breaks an input file if it's section
header does not follow the standard. That caused a misterous
error that CMake with Ninja occasionally produces a broken
executable.
This patch fixes the section header to make mt.exe and
other tools happy.
llvm-svn: 214453
definition below all of the header #include lines, LLD edition.
IF you want to know more details about this, you can see the recent
commits to Debug.h in LLVM. This is just the LLD segment of a cleanup
I'm doing globally for this macro.
llvm-svn: 206851
This results in some simplifications to the code where an OwningPtr had to
be used with the previous api and then ownership moved to a unique_ptr for
the rest of lld.
llvm-svn: 203809
Just like x86 exception handler table, the table for x64 needs to be sorted
so that runtime can binary search on it. Unlike x86, the table entry for x64
has multiple fields, and they need to be sorted according to its BeginAddress
field. This patch also fixes a bug in relocations.
llvm-svn: 202874
It looks like the contents of the table need to be sorted according to its
value, so that the runtime can find the entry by binary search. I'm not 100%
sure if we really have to do that, but at least I can say it's safe to do
because the contents of .sxdata is just a list of exception handlers' RVAs.
llvm-svn: 202550
If all input files are compatible with Structured Exception Handling, linker
is supposed to create an exectuable with a table for SEH handlers. The table
consists of exception handlers entry point addresses.
The basic idea of SEH in x86 Microsoft ABI is to list all valid entry points
of exception handlers in an read-only memory, so that an attacker cannot
override the addresses in it. In x86 ABI, data for exception handling is mostly
on stack, so it's volnerable to stack overflow attack. In order to protect
against it, Windows runtime uses the table to check a return address, to
ensure that the address is really an valid entry point for an exception handler.
Compiler emits a list of exception handler functions to .sxdata section. It
also emits a marker symbol "@feat.00" to indicate that the object is compatible
with SEH. SEH is a relatively new feature for COFF, and mixing SEH-compatible
and SEH-incompatible objects will result in an invalid executable, so is the
marker.
If all input files are compatible with SEH, LLD emits a SEH table. SEH table
needs to be pointed by Load Configuration strucutre, so when emitting a SEH
table LLD emits it too. The address of a Load Configuration will be stored to
the file header.
llvm-svn: 202248
