Symptom: failure of -Bsymbolic-functions to resolve libgcc references at link-time under certain circumstances. In particular, Sabotage Linux (https://github.com/rofl0r/sabotage) ends up building a broken musl libc.so on MIPS; its dynamic linker attempts to call libgcc functions before symbolic relocations have been processed. Cause: When gcc generates calls to libgcc functions for long division, etc., it adds a .globl directive to the output asm for those functions. This is entirely unnecessary, but should be harmless. However, the mips target for gas, upon seeing a .globl directive, adds OBJECT type to the undefined symbol reference unless there is a .type directive. On other targets, the type remains UNKNOWN. This in turn prevents the linker's -Bsymbolic-functions option from resolving the symbol reference at link-time. Assuming libgcc was compiled correctly with visibility, these functions have hidden visibility and thus they get resolved at link time anyway; however, if libgcc was built with --disable-shared, they don't. Really, this bug is an interaction of 3 separate issues in 3 pieces of software: 1. gcc: outputting useless .globl 2. gas mips target: treating .globl as implying type==OBJECT 3. libgcc: failure to use visibility when --disable-shared is specified I believe at least numbers 2 and 3, and maybe all three of them, should be fixed, but only 2 pertains to binutils.
The master branch has been updated by Faraz Shahbazker <farazs@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=d87343802b81ad123a27beccb140d406f54727c6 commit d87343802b81ad123a27beccb140d406f54727c6 Author: Faraz Shahbazker <fshahbazker@wavecomp.com> Date: Mon May 6 09:09:02 2019 -0700 [MIPS] PR gas/14798: Limit IRIX5 specific default typing to IRIX targets On IRIX 5, every global symbol that is not explicitly labelled as being a function is assumed to be an object. There is no reason why IRIX behaviour should extend to all MIPS targets, so limit this to only IRIX targets. gas/ PR 14798 * config/tc-mips.c (s_mips_globl): Only treat symbols that are not explicitly labelled as BSF_OBJECTs for IRIX targets. * testsuite/gas/mips/pr14798.s: New test source. * testsuite/gas/mips/pr14798-irix.d: New test. * testsuite/gas/mips/pr14798.d: Likewise. * testsuite/gas/mips/mips.exp: Run the new tests. binutils/ PR 14798 * testsuite/binutils-all/readelf.ss-mips: Update reference output. * testsuite/binutils-all/readelf.ss-tmips: Likewise. ld/ PR 14798 * testsuite/ld-mips-elf/reloc-6a.s: Specify .text section for global code symbols. * testsuite/ld-mips-elf/reloc-6b.s: Likewise.
The master branch has been updated by Maciej W. Rozycki <macro@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=b83d958fc7050bf990d7c24596b9dcdc130433a7 commit b83d958fc7050bf990d7c24596b9dcdc130433a7 Author: Maciej W. Rozycki <macro@linux-mips.org> Date: Wed Jul 22 12:46:00 2020 +0100 MIPS/GAS/testsuite: Use a helper variable for IRIX/non-IRIX test selection Define a helper variable for IRIX/non-IRIX test selection and use it with the PR 14798 test case. gas/ * testsuite/gas/mips/mips.exp: Use a helper variable for IRIX/non-IRIX test selection.