[Bug ld/22842] New: Handling of R_X86_64_PC32 in a PIE against a function in a shared library could be better

[rafael.espindola at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=22842

            Bug ID: 22842
           Summary: Handling of R_X86_64_PC32 in a PIE against a function
                    in a shared library could be better
           Product: binutils
           Version: unspecified
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: ld
          Assignee: unassigned at sourceware dot org
          Reporter: rafael.espindola at gmail dot com
                CC: ccoutant at gmail dot com, hjl.tools at gmail dot com
  Target Milestone: ---

Created attachment 10815
  --> https://sourceware.org/bugzilla/attachment.cgi?id=10815&action=edit
testcase

The attached testcase has a shared library that defines a function foo with
default visibility. The function just prints its own address and argument:

void foo(void *bar) {
  printf("%p %p\n", bar, foo);
}

There is also a position independent executable that uses a R_X86_64_PC32 to
find the address of foo and call it with that value.

The expected result is to see the same value printed twice.

If we try to use gold it errors out when linking the executable:

error: test.o: requires dynamic R_X86_64_PC32 reloc against 'foo' which may
overflow at runtime; recompile with -fPIC

With ld.bfd it links but fails at runtime:

./test: Symbol `foo' causes overflow in R_X86_64_PC32 relocation         
0x55ae794c62d0 0x7f0b794c62d0

With lld it works since lld create a canonical plt entry for foo in the main
executable:

 6: 00000000000011f0     0 FUNC    GLOBAL DEFAULT  UND foo

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