Commit 32d26969 authored by Tom Stellard's avatar Tom Stellard
Browse files

Merging r345002: 

------------------------------------------------------------------------
r345002 | dim | 2018-10-22 22:53:15 -0700 (Mon, 22 Oct 2018) | 41 lines

Don't mess up RelIplt symbols during relocatable processing

Summary:
During upgrading of the FreeBSD source tree with lld 7.0.0, I noticed
that it started complaining about `crt1.o` having an "index past the
end of the symbol table".

Such a symbol table looks approximately like this, viewed with `readelf
-s` (note the `Ndx` field being messed up):

```
Symbol table '.symtab' contains 4 entries:
   Num:    Value  Size Type    Bind   Vis      Ndx Name
     0: 00000000     0 NOTYPE  LOCAL  DEFAULT  UND
     1: 00000000     0 SECTION LOCAL  DEFAULT    1
     2: 00000000     0 NOTYPE  WEAK   HIDDEN  RSV[0xffff] __rel_iplt_end
     3: 00000000     0 NOTYPE  WEAK   HIDDEN  RSV[0xffff] __rel_iplt_start
```

At first, it seemed that recent ifunc relocation work had caused this:
<https://reviews.freebsd.org/rS339351>, but it turned out that it was
due to incorrect processing of the object files by lld, when using `-r`
(a.k.a. --relocatable).

Bisecting showed that rL324421 ("Convert a use of Config->Static") was
the commit where this new behavior began.  Simply reverting it solved
the issue, and the `__rel_iplt` symbols had an index of `UND` again.

Looking at Rafael's commit message, I think he simply missed the
possibility of `--relocatable` being in effect, so I have added an
additional check for it.

I also added a simple regression test case.

Reviewers: grimar, ruiu, emaste, espindola

Reviewed By: ruiu

Subscribers: arichardson, krytarowski, llvm-commits

Differential Revision: https://reviews.llvm.org/D53515
------------------------------------------------------------------------

llvm-svn: 345739
parent 8beaae23

lld/ELF/Writer.cpp

+1 −1
Original line number Diff line number Diff line
@@ -874,7 +874,7 @@ void PhdrEntry::add(OutputSection *Sec) { 
// need these symbols, since IRELATIVE relocs are resolved through GOT

// and PLT. For details, see http://www.airs.com/blog/archives/403.

template <class ELFT> void Writer<ELFT>::addRelIpltSymbols() {

  if (needsInterpSection())

  if (Config->Relocatable || needsInterpSection())

    return;

  StringRef S = Config->IsRela ? "__rela_iplt_start" : "__rel_iplt_start";

  addOptionalRegular(S, InX::RelaIplt, 0, STV_HIDDEN, STB_WEAK);

lld/test/ELF/relocatable-rel-iplt.s

0 → 100644
+56 −0
Original line number Diff line number Diff line 
# REQUIRES: x86

# RUN: llvm-mc -filetype=obj -triple=i686-- %s -o %t1.o

# RUN: ld.lld -r %t1.o -o %t2.o

# RUN: llvm-readobj -t %t2.o | FileCheck %s



// CHECK:      Symbols [

// CHECK-NEXT:   Symbol {

// CHECK-NEXT:     Name:  (0)

// CHECK-NEXT:     Value: 0x0

// CHECK-NEXT:     Size: 0

// CHECK-NEXT:     Binding: Local (0x0)

// CHECK-NEXT:     Type: None (0x0)

// CHECK-NEXT:     Other: 0

// CHECK-NEXT:     Section: Undefined (0x0)

// CHECK-NEXT:   }

// CHECK-NEXT:   Symbol {

// CHECK-NEXT:     Name:  (0)

// CHECK-NEXT:     Value: 0x0

// CHECK-NEXT:     Size: 0

// CHECK-NEXT:     Binding: Local (0x0)

// CHECK-NEXT:     Type: Section (0x3)

// CHECK-NEXT:     Other: 0

// CHECK-NEXT:     Section: .text (0x1)

// CHECK-NEXT:   }

// CHECK-NEXT:   Symbol {

// CHECK-NEXT:     Name: __rel_iplt_end (1)

// CHECK-NEXT:     Value: 0x0

// CHECK-NEXT:     Size: 0

// CHECK-NEXT:     Binding: Weak (0x2)

// CHECK-NEXT:     Type: None (0x0)

// CHECK-NEXT:     Other [ (0x2)

// CHECK-NEXT:       STV_HIDDEN (0x2)

// CHECK-NEXT:     ]

// CHECK-NEXT:     Section: Undefined (0x0)

// CHECK-NEXT:   }

// CHECK-NEXT:   Symbol {

// CHECK-NEXT:     Name: __rel_iplt_start (16)

// CHECK-NEXT:     Value: 0x0

// CHECK-NEXT:     Size: 0

// CHECK-NEXT:     Binding: Weak (0x2)

// CHECK-NEXT:     Type: None (0x0)

// CHECK-NEXT:     Other [ (0x2)

// CHECK-NEXT:       STV_HIDDEN (0x2)

// CHECK-NEXT:     ]

// CHECK-NEXT:     Section: Undefined (0x0)

// CHECK-NEXT:   }

// CHECK-NEXT: ]



	movl	__rel_iplt_start, %eax

	movl	__rel_iplt_end, %eax

	ret



	.hidden	__rel_iplt_start

	.hidden	__rel_iplt_end

	.weak	__rel_iplt_start

	.weak	__rel_iplt_end