New subject: [Bug 55095] Compiling preloader with -fPIE may lead to GOTPCREL(X) conversion failure when linking into non-PIE binary

20 Jun 2023


      https://bugs.winehq.org/show_bug.cgi?id=55095
Bug ID: 55095
           Summary: Compiling preloader with -fPIE may lead to GOTPCREL(X)
                    conversion failure when linking into non-PIE binary
           Product: Wine
           Version: 8.10
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: loader
          Assignee: wine-bugs@winehq.org
          Reporter: jinoh.kang.kr@gmail.com
                CC: eric.pouech@gmail.com, julliard@winehq.org
   Regression SHA1: 78ed343842dcd8ffb95c416420953e121959d40d
      Distribution: ---
Today, the preloader is linked with -fPIE in spite of the fact that the
preloader is a non-PIE statically linked binary.  This is due to a limitation
in tools/makedep that makes it difficult to specify CFLAGS for each individual
object file's recipe.
This can seemingly cause problems with some GOTPCREL(X) relocations inside the
preloader. Since preloader does not link to the system library directly, there
is no need for Global Offset Tables (GOT).  However, a few extern (non-static)
function symbols are declared, the use of which makes GCC emit instructions
that references those symbols by indirection through GOT.  The linker then
tries to optimize such instructions to eliminate GOT references, which can fail
due to various reasons.
This stands in contradiction with Jinoh Kang's suggestion (in bug 55050) that
"-fPIE is harmless even when applied to an object linked into non-PIE
executables." The claim is theoretically true since position-independent code
can in principle be relocated to any address (fixed or dynamic); however, it
fails due to some peculiar practical issues, which is arguably a limitation in
the linker's implementation (since it can be worked around --no-relax without
issues).
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[Bug 55095] New: Compiling preloader with -fPIE may lead to GOTPCREL(X) conversion failure when linking into non-PIE binary