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
If section size is not multiple of 512, the writer added NULL bytes at the end
of it to make it so. That is not required by the PE/COFF spec, and the MSVC's
linker does not do that too. So we don't need to do that, too.
llvm-svn: 197002
Instead of having multiple SectionChunks for each section (.text, .data,
.rdata and .bss), we could have one chunk writer that can emit any sections.
This patch does that -- removing all section-sepcific chunk writers and
replace them with one "generic" writer.
This change should simplify the code because it eliminates similar-but-
slightly-different classes.
It also fixes an issue in the previous design. Before this patch, we could
emit only limited set of sections (i.e. .text, .data, .rdata and .bss). With
this patch, we can emit any sections.
llvm-svn: 195797
If /subsystem option is not specified, the linker needs to infer it from the
entry point function. If "main" or "wmain" is defined, it's a console
application. If "WinMain" or "wWinMain" is defined, it's a GUI application.
llvm-svn: 195592
With this patch the entry symbol is treated as an undefined symbol, to force
the resolver to resolve the entry symbol.
Differential Revision: http://llvm-reviews.chandlerc.com/D1524
llvm-svn: 189307
Emit .reloc section. This is the first step to support DLL creation. The
executable doesn't need .reloc section, but the DLL does.
Reviewers: Bigcheese
CC: llvm-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D1126
llvm-svn: 186336
Summary:
COFFReference class is defined to represent relocation information for
COFFDefinedAtom, as ELFReference for ELFDefinedAtom. ReaderCOFF can now
read relocation entries and create COFFReferences accordingly.
I need to make WriterPECOFF to handle the relocation references created by
the reader, but this patch is already big, so I think it's probably better
to get it reviewed now.
Reviewers: Bigcheese
CC: llvm-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D976
llvm-svn: 183964
Rui Ueyama