From ceab86af75e9870ecf2da772a0d867ca12521a24 Mon Sep 17 00:00:00 2001 From: "Maciej W. Rozycki" Date: Fri, 27 May 2016 20:41:40 +0100 Subject: [PATCH] MIPS/BFD: Fix section symbol name fetching in relocation Symbol table entries for section symbols are different between IRIX and traditional MIPS ELF targets in that IRIX entries have their `st_name' member pointing at the section's name in the string table section, while traditional entries have 0 there and the section header string table has to be referred via the relevant section header's `shn_name' member instead. This is chosen with the `elf_backend_name_local_section_symbols' backend and can be observed with `readelf -s' output for an IRIX object: Symbol table '.symtab' contains 12 entries: Num: Value Size Type Bind Vis Ndx Name 0: 00000000 0 NOTYPE LOCAL DEFAULT UND 1: 00000000 0 SECTION LOCAL DEFAULT 1 .text 2: 00000000 0 SECTION LOCAL DEFAULT 3 .data 3: 00000000 0 SECTION LOCAL DEFAULT 4 .bss 4: 00000000 0 SECTION LOCAL DEFAULT 5 .reginfo 5: 00000000 0 SECTION LOCAL DEFAULT 6 .MIPS.abiflags 6: 00000000 0 SECTION LOCAL DEFAULT 7 .pdr 7: 00000000 0 SECTION LOCAL DEFAULT 9 .gnu.attributes 8: 00002000 16 FUNC GLOBAL DEFAULT 1 foo 9: 00004008 0 FUNC LOCAL DEFAULT 1 abar 10: 00002008 0 FUNC LOCAL DEFAULT 1 afoo 11: 00004000 16 FUNC GLOBAL DEFAULT 1 bar and a corresponding traditional object: Symbol table '.symtab' contains 12 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 SECTION LOCAL DEFAULT 3 3: 00000000 0 SECTION LOCAL DEFAULT 4 4: 00004008 0 FUNC LOCAL DEFAULT 1 abar 5: 00002008 0 FUNC LOCAL DEFAULT 1 afoo 6: 00000000 0 SECTION LOCAL DEFAULT 5 7: 00000000 0 SECTION LOCAL DEFAULT 6 8: 00000000 0 SECTION LOCAL DEFAULT 7 9: 00000000 0 SECTION LOCAL DEFAULT 9 10: 00002000 16 FUNC GLOBAL DEFAULT 1 foo 11: 00004000 16 FUNC GLOBAL DEFAULT 1 bar respectively. Consequently the right way to retrieve a section symbol's name has to be chosen in `mips_elf_calculate_relocation' for the purpose of error reporting. Originally we produced symbol tables in the traditional object format only and we handled it correctly until it was lost in a rewrite with: commit 7403cb6305f5660fccc8869d3333a731102ae978 Author: Mark Mitchell Date: Wed Jun 30 20:13:43 1999 +0000 probably because of the extra pointer indirection added which made the same expression have a different meaning. With the addition of IRIX symbol table format with: commit 174fd7f9556183397625dbfa99ef68ecd325c74b Author: Richard Sandiford Date: Mon Feb 9 08:04:00 2004 +0000 the bug has been partially covered and now when a relocation error is triggered with an IRIX object the offending section symbol is correctly reported: tmpdir/dump0.o: In function `foo': (.text+0x2000): relocation truncated to fit: R_MIPS_26 against `.text' tmpdir/dump0.o: In function `bar': (.text+0x4000): relocation truncated to fit: R_MIPS_26 against `.text' because `bfd_elf_string_from_elf_section' retrieves the name from the string table section. With a traditional object however the function returns an empty string and consequently `no symbol' is printed instead: tmpdir/dump0.o: In function `foo': (.text+0x2000): relocation truncated to fit: R_MIPS_26 against `no symbol' tmpdir/dump0.o: In function `bar': (.text+0x4000): relocation truncated to fit: R_MIPS_26 against `no symbol' Restore the original semantics so that the section name is always correctly retrieved. bfd/ * elfxx-mips.c (mips_elf_calculate_relocation): Also use the section name if `bfd_elf_string_from_elf_section' returns an empty string. ld/ * testsuite/ld-mips-elf/reloc-local-overflow.d: New test. * testsuite/ld-mips-elf/reloc-local-overflow.s: Source for the new test. * testsuite/ld-mips-elf/mips-elf.exp: Run the new test. --- bfd/ChangeLog | 6 ++++++ bfd/elfxx-mips.c | 2 +- ld/ChangeLog | 7 +++++++ ld/testsuite/ld-mips-elf/mips-elf.exp | 2 ++ ld/testsuite/ld-mips-elf/reloc-local-overflow.d | 7 +++++++ ld/testsuite/ld-mips-elf/reloc-local-overflow.s | 8 ++++++++ 6 files changed, 31 insertions(+), 1 deletion(-) create mode 100644 ld/testsuite/ld-mips-elf/reloc-local-overflow.d create mode 100644 ld/testsuite/ld-mips-elf/reloc-local-overflow.s diff --git a/bfd/ChangeLog b/bfd/ChangeLog index bb9cb3c5e07..5bace1e96e9 100644 --- a/bfd/ChangeLog +++ b/bfd/ChangeLog @@ -1,3 +1,9 @@ +2016-05-27 Maciej W. Rozycki + + * elfxx-mips.c (mips_elf_calculate_relocation): Also use the + section name if `bfd_elf_string_from_elf_section' returns an + empty string. + 2016-05-26 Maciej W. Rozycki * elfxx-mips.c (_bfd_mips_elf_relocate_section) diff --git a/bfd/elfxx-mips.c b/bfd/elfxx-mips.c index 3e7b48845be..2fff306036b 100644 --- a/bfd/elfxx-mips.c +++ b/bfd/elfxx-mips.c @@ -5322,7 +5322,7 @@ mips_elf_calculate_relocation (bfd *abfd, bfd *input_bfd, *namep = bfd_elf_string_from_elf_section (input_bfd, symtab_hdr->sh_link, sym->st_name); - if (*namep == '\0') + if (*namep == NULL || **namep == '\0') *namep = bfd_section_name (input_bfd, sec); target_is_16_bit_code_p = ELF_ST_IS_MIPS16 (sym->st_other); diff --git a/ld/ChangeLog b/ld/ChangeLog index 4462450b9b6..1d683ac86e6 100644 --- a/ld/ChangeLog +++ b/ld/ChangeLog @@ -1,3 +1,10 @@ +2016-05-27 Maciej W. Rozycki + + * testsuite/ld-mips-elf/reloc-local-overflow.d: New test. + * testsuite/ld-mips-elf/reloc-local-overflow.s: Source for the + new test. + * testsuite/ld-mips-elf/mips-elf.exp: Run the new test. + 2016-05-26 Maciej W. Rozycki * testsuite/ld-mips-elf/unaligned-jalx-0.d: Fold diff --git a/ld/testsuite/ld-mips-elf/mips-elf.exp b/ld/testsuite/ld-mips-elf/mips-elf.exp index f9bbcec5dcc..0c2a93b15c7 100644 --- a/ld/testsuite/ld-mips-elf/mips-elf.exp +++ b/ld/testsuite/ld-mips-elf/mips-elf.exp @@ -440,6 +440,8 @@ if { $has_newabi } { "reloc-6b"]] } +run_dump_test "reloc-local-overflow" [list [list ld $abi_ldflags(o32)]] + if {$has_newabi && $linux_gnu} { run_dump_test "eh-frame1-n32" run_dump_test "eh-frame1-n64" diff --git a/ld/testsuite/ld-mips-elf/reloc-local-overflow.d b/ld/testsuite/ld-mips-elf/reloc-local-overflow.d new file mode 100644 index 00000000000..b5512eef15a --- /dev/null +++ b/ld/testsuite/ld-mips-elf/reloc-local-overflow.d @@ -0,0 +1,7 @@ +#name: MIPS reloc against local symbol overflow +#source: reloc-local-overflow.s +#as: -EB -32 +#ld: -EB -Tdata 0x10000 -e 0 +#error: \A[^\n]*:\(\.data\+0x1000\): relocation truncated to fit: R_MIPS_16 against `\.data'\Z + +# Verify that the section name (`.data') is printed rather than `no symbol'. diff --git a/ld/testsuite/ld-mips-elf/reloc-local-overflow.s b/ld/testsuite/ld-mips-elf/reloc-local-overflow.s new file mode 100644 index 00000000000..a07255c3f78 --- /dev/null +++ b/ld/testsuite/ld-mips-elf/reloc-local-overflow.s @@ -0,0 +1,8 @@ + .data + .space 0x1000 + + .align 2 + .type bar, @object +bar: + .half bar + .size bar, . - bar -- 2.30.2