From 81ff47b3a54633819fac4d973e34f1ff0c65606e Mon Sep 17 00:00:00 2001 From: "Maciej W. Rozycki" Date: Mon, 16 Jan 2017 22:10:57 +0000 Subject: [PATCH] PR ld/20828: Fix linker script symbols wrongly forced local with section GC Fix a generic ELF linker regression introduced with a chain of changes made to unused input section garbage collection: - commit 1a766c6843ce ("Also hide symbols without PLT nor GOT references."), , - commit 1d5316ab67e1 ("PR ld/13177: garbage collector retains zombie references to external libraries"), , - commit 6673f753c019 ("Fix PR 12772, garbage collection of dynamic syms"), , causing the garbage collection of unused symbols present in a DSO involved in a link to make identically named symbols ordinarily defined (i.e. not hidden or PROVIDEd) by a linker script local, even though the latter symbols are supposed to be global as if no DSO defined them as well. This is because linker script assignments are processed very late as `lang_process' proceeds, down in the call to `ldemul_before_allocation', which is made after the call to `lang_gc_sections' to do input section garbage collecting. Consequently if unused, then any such DSO-defined symbol has already been garbage-collected and internally marked local. It would ordinarily be removed from dynamic symbol table output, however a linker script assignment correctly replaces its original definition with the new one and enters it into the dynamic symbol table produced as it is supposed to be exported. The original local marking is however retained making the symbol local in the dynamic symbol table and therefore not available externally. This also causes a sorting problem with the MIPS target, which does not expect non-section local dynamic symbols to be output and produces an invalid binary. Fix the problem then, by removing the `forced_local' marking for the offending case and add suitable test cases. First to verify that unused symbols ordinarily defined with linker script assignments remain exported in the context of input section garbage collection whether or not a DSO defining identically named symbols is present in the link. Second that a linker version script still correctly retains or removes such symbols as requested. bfd/ PR ld/20828 * elflink.c (bfd_elf_record_link_assignment): Clear any `forced_local' marking for DSO symbols that are not being provided. ld/ PR ld/20828 * testsuite/ld-elf/pr20828-1.sd: New test. * testsuite/ld-elf/pr20828-2a.sd: New test. * testsuite/ld-elf/pr20828-2b.sd: New test. * testsuite/ld-elf/pr20828.ld: New test linker script. * testsuite/ld-elf/pr20828.ver: New test version script. * testsuite/ld-elf/pr20828.s: New test source. * testsuite/ld-elf/shared.exp: Run the new test. --- bfd/ChangeLog | 7 +++++ bfd/elflink.c | 11 ++++++-- ld/ChangeLog | 11 ++++++++ ld/testsuite/ld-elf/pr20828-1.sd | 12 ++++++++ ld/testsuite/ld-elf/pr20828-2a.sd | 9 ++++++ ld/testsuite/ld-elf/pr20828-2b.sd | 7 +++++ ld/testsuite/ld-elf/pr20828.ld | 19 +++++++++++++ ld/testsuite/ld-elf/pr20828.s | 2 ++ ld/testsuite/ld-elf/pr20828.ver | 1 + ld/testsuite/ld-elf/shared.exp | 47 +++++++++++++++++++++++++++++++ 10 files changed, 123 insertions(+), 3 deletions(-) create mode 100644 ld/testsuite/ld-elf/pr20828-1.sd create mode 100644 ld/testsuite/ld-elf/pr20828-2a.sd create mode 100644 ld/testsuite/ld-elf/pr20828-2b.sd create mode 100644 ld/testsuite/ld-elf/pr20828.ld create mode 100644 ld/testsuite/ld-elf/pr20828.s create mode 100644 ld/testsuite/ld-elf/pr20828.ver diff --git a/bfd/ChangeLog b/bfd/ChangeLog index 3fae9ddfc1..624af088fb 100644 --- a/bfd/ChangeLog +++ b/bfd/ChangeLog @@ -1,3 +1,10 @@ +2017-01-18 Maciej W. Rozycki + + PR ld/20828 + * elflink.c (bfd_elf_record_link_assignment): Clear any + `forced_local' marking for DSO symbols that are not being + provided. + 2017-01-17 Kuan-Lin Chen * elfnn-riscv.c (riscv_elf_object_p): New function. diff --git a/bfd/elflink.c b/bfd/elflink.c index 1e5fa61218..d7ed8ce6b4 100644 --- a/bfd/elflink.c +++ b/bfd/elflink.c @@ -671,12 +671,17 @@ bfd_elf_record_link_assignment (bfd *output_bfd, /* If this symbol is not being provided by the linker script, and it is currently defined by a dynamic object, but not by a regular object, - then clear out any version information because the symbol will not be - associated with the dynamic object any more. */ + then undo any forced local marking that may have been set by input + section garbage collection and clear out any version information + because the symbol will not be associated with the dynamic object + any more. */ if (!provide && h->def_dynamic && !h->def_regular) - h->verinfo.verdef = NULL; + { + h->forced_local = 0; + h->verinfo.verdef = NULL; + } h->def_regular = 1; diff --git a/ld/ChangeLog b/ld/ChangeLog index e505c84f35..0cc3393b36 100644 --- a/ld/ChangeLog +++ b/ld/ChangeLog @@ -1,3 +1,14 @@ +2017-01-18 Maciej W. Rozycki + + PR ld/20828 + * testsuite/ld-elf/pr20828-1.sd: New test. + * testsuite/ld-elf/pr20828-2a.sd: New test. + * testsuite/ld-elf/pr20828-2b.sd: New test. + * testsuite/ld-elf/pr20828.ld: New test linker script. + * testsuite/ld-elf/pr20828.ver: New test version script. + * testsuite/ld-elf/pr20828.s: New test source. + * testsuite/ld-elf/shared.exp: Run the new test. + 2017-01-18 Maciej W. Rozycki PR gas/20649 diff --git a/ld/testsuite/ld-elf/pr20828-1.sd b/ld/testsuite/ld-elf/pr20828-1.sd new file mode 100644 index 0000000000..c47eb1d60c --- /dev/null +++ b/ld/testsuite/ld-elf/pr20828-1.sd @@ -0,0 +1,12 @@ +# Make sure symbols are global rather than local in the dynamic symbol table, +# e.g.: +# Num: Value Size Type Bind Vis Ndx Name +# 1: 00000000 0 NOTYPE GLOBAL DEFAULT 1 _fdata +# 2: 00000000 0 NOTYPE GLOBAL DEFAULT 1 _edata +# vs: +# 1: 00000000 0 NOTYPE LOCAL DEFAULT 1 _fdata +# 2: 00000000 0 NOTYPE LOCAL DEFAULT 1 _edata +#... + *[0-9]+: +[0-9a-f]+ +0 +NOTYPE +GLOBAL +DEFAULT +[0-9]+ +_fdata + *[0-9]+: +[0-9a-f]+ +0 +NOTYPE +GLOBAL +DEFAULT +[0-9]+ +_edata +#pass diff --git a/ld/testsuite/ld-elf/pr20828-2a.sd b/ld/testsuite/ld-elf/pr20828-2a.sd new file mode 100644 index 0000000000..c4b239b3fa --- /dev/null +++ b/ld/testsuite/ld-elf/pr20828-2a.sd @@ -0,0 +1,9 @@ +# Make sure `_edata' is global rather than local in the dynamic symbol table, +# e.g.: +# Num: Value Size Type Bind Vis Ndx Name +# 1: 00000000 0 NOTYPE GLOBAL DEFAULT 1 _edata +# vs: +# 1: 00000000 0 NOTYPE LOCAL DEFAULT 1 _edata +#... + *[0-9]+: +[0-9a-f]+ +0 +NOTYPE +GLOBAL +DEFAULT +[0-9]+ +_edata +#pass diff --git a/ld/testsuite/ld-elf/pr20828-2b.sd b/ld/testsuite/ld-elf/pr20828-2b.sd new file mode 100644 index 0000000000..8089c486b9 --- /dev/null +++ b/ld/testsuite/ld-elf/pr20828-2b.sd @@ -0,0 +1,7 @@ +# Make sure no `_fdata' is present in the dynamic symbol table, e.g.: +# Num: Value Size Type Bind Vis Ndx Name +# 1: 00000000 0 NOTYPE LOCAL DEFAULT 1 _fdata +#failif +#... +.+ +_fdata +#pass diff --git a/ld/testsuite/ld-elf/pr20828.ld b/ld/testsuite/ld-elf/pr20828.ld new file mode 100644 index 0000000000..9ca19436bb --- /dev/null +++ b/ld/testsuite/ld-elf/pr20828.ld @@ -0,0 +1,19 @@ +SECTIONS +{ + .data : + { + _fdata = .; + *(.data) + _edata = .; + } + .dynamic : { *(.dynamic) } + .hash : { *(.hash) } + .dynsym : { *(.dynsym) } + .dynstr : { *(.dynstr) } + .shstrtab : { *(.shstrtab) } + .symtab : { *(.symtab) } + .strtab : { *(.strtab) } + .got.plt : { *(.got.plt) } + .got : { *(.got) } + /DISCARD/ : { *(*) } +} diff --git a/ld/testsuite/ld-elf/pr20828.s b/ld/testsuite/ld-elf/pr20828.s new file mode 100644 index 0000000000..ece49d5496 --- /dev/null +++ b/ld/testsuite/ld-elf/pr20828.s @@ -0,0 +1,2 @@ + .data + .byte 0 diff --git a/ld/testsuite/ld-elf/pr20828.ver b/ld/testsuite/ld-elf/pr20828.ver new file mode 100644 index 0000000000..7d0fa22814 --- /dev/null +++ b/ld/testsuite/ld-elf/pr20828.ver @@ -0,0 +1 @@ +{ global: _edata; local: *; }; diff --git a/ld/testsuite/ld-elf/shared.exp b/ld/testsuite/ld-elf/shared.exp index f38cd7b013..8f1f1668c2 100644 --- a/ld/testsuite/ld-elf/shared.exp +++ b/ld/testsuite/ld-elf/shared.exp @@ -31,6 +31,53 @@ if ![check_shared_lib_support] { return } +# This target requires extra GAS options when building code for shared +# libraries. +set AFLAGS_PIC "" +if [istarget "tic6x-*-*"] { + append AFLAGS_PIC " -mpic -mpid=near" +} +# This target requires a non-default emulation for successful shared +# library/executable builds. +set LFLAGS "" +if [istarget "tic6x-*-*"] { + append LFLAGS " -melf32_tic6x_le" +} + +# PR ld/20828 check for correct dynamic symbol table entries where: +# - symbols have been defined with a linker script, +# - the same symbols have been seen in shared library used in the link, +# - the shared library symbols have been swept in section garbage collection. +# Verify that the symbols are global rather than local and that a version +# script adjusts them accordingly. +if { [check_gc_sections_available] } { + run_ld_link_tests [list \ + [list \ + "PR ld/20828 dynamic symbols with section GC\ + (auxiliary shared library)" \ + "$LFLAGS -shared --gc-sections -T pr20828.ld" "" "$AFLAGS_PIC" \ + {pr20828.s} \ + {{readelf --dyn-syms pr20828-1.sd}} \ + "libpr20828.so"] \ + [list \ + "PR ld/20828 dynamic symbols with section GC (plain)" \ + "$LFLAGS -shared --gc-sections -T pr20828.ld" \ + "tmpdir/libpr20828.so" "$AFLAGS_PIC" \ + {pr20828.s} \ + {{readelf --dyn-syms pr20828-1.sd}} \ + "pr20828-1.so"] \ + [list \ + "PR ld/20828 dynamic symbols with section GC (version script)" \ + "$LFLAGS -shared --gc-sections -T pr20828.ld\ + --version-script=pr20828.ver" \ + "tmpdir/libpr20828.so" \ + "$AFLAGS_PIC" \ + {pr20828.s} \ + {{readelf --dyn-syms pr20828-2a.sd} \ + {readelf --dyn-syms pr20828-2b.sd}} \ + "pr20828-2.so"]] +} + # Check to see if the C compiler works if { [which $CC] == 0 } { return -- 2.34.1