This bug was also reported here: https://bugs.launchpad.net/ubuntu/+source/gdb/+bug/1388999 This bug causes a major slowdown for shared objects with many symbols (loading times gone from 1 minute to 15 minutes). One possible fix for this is to allocate an array of size n (n is the plt size) and fill it with the correct values via random access, doing only one pass on the binary. I will illustrate this with pseudo code. Here is the current algorithm, as implemented in _bfd_elf_get_synthetic_symtab's second for-loop. for i = 0 to count addr = bed->plt_sym_val(i, plt, p); // this function has average linear complexity // here addr is processed I would replace the second for-loop with something like this (inspired by elf_x86_64_plt_sym_val): quick_plt_table = malloc(sizeof(bfd_vma) * count); for i = 0 to count if type_doesnt_match_backend() continue bfd_get_section_contents(abfd,..., reloc_index_raw); reloc_index = H_GET_32(abfd, reloc_index_raw); quick_plt_table[reloc_index] = plt->vma + plt_offset; plt_offset += bed->plt_entry_size; rel += int_rels_per_ext_rel; for i = 0 to count addr = quick_plt[i]; // here addr is processed as done previously Note that my version runs in linear complexity, and thus takes less time.
For which target? i386, x86-64 or both?
For me it happened on x86-64 on a linux shared object with lots of exported symbols. I see no reason to assume this problem cannot happen on i386 though.
This is an automated email from the git hooks/post-receive script. It was generated because a ref change was pushed to the repository containing the project "gdb and binutils". The branch, master has been updated via 3972882e52d7199000bb5dfc753a86aa296a567a (commit) from 82cf9cb2653b39c426f330854c64028eab4cb65d (commit) Those revisions listed above that are new to this repository have not appeared on any other notification email; so we list those revisions in full, below. - Log ----------------------------------------------------------------- https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=3972882e52d7199000bb5dfc753a86aa296a567a commit 3972882e52d7199000bb5dfc753a86aa296a567a Author: H.J. Lu <hjl.tools@gmail.com> Date: Thu Dec 4 14:19:41 2014 -0800 Add _bfd_elf_ifunc_get_synthetic_symtab In i386 and x86-64 binaries with ifunc, relocations against .got.plt section may not be in the same order as entries in PLT section. This patch adds _bfd_elf_ifunc_get_synthetic_symtab. It takes a function pointer which returns an array of PLT entry symbol values. It calls the function pointer to get the PLT entry symbol value array indexed by relocation index, instead of calling plt_sym_val on each relocation index. PR binutils/17677 * elf-bfd.h (_bfd_elf_ifunc_get_synthetic_symtab): New prototype. * elf-ifunc.c (_bfd_elf_ifunc_get_synthetic_symtab): New function. * elf32-i386.c (elf_i386_plt_sym_val): Removed. (elf_backend_plt_sym_val): Likewise. (elf_i386_get_plt_sym_val): New. (elf_i386_get_synthetic_symtab): Likewise. (bfd_elf32_get_synthetic_symtab): Likewise. * elf64-x86-64.c (elf_x86_64_plt_sym_val): Removed. (elf_x86_64_plt_sym_val_offset_plt_bnd): Likewise. (elf_backend_plt_sym_val): Likewise. (elf_x86_64_get_plt_sym_val): New. (elf_x86_64_get_synthetic_symtab): Use _bfd_elf_ifunc_get_synthetic_symtab. (bfd_elf64_get_synthetic_symtab): Don't undefine for NaCl. ----------------------------------------------------------------------- Summary of changes: bfd/ChangeLog | 19 ++++ bfd/elf-bfd.h | 3 + bfd/elf-ifunc.c | 125 ++++++++++++++++++++++++++++ bfd/elf32-i386.c | 101 ++++++++++++++++------- bfd/elf64-x86-64.c | 235 ++++++++++++++++----------------------------------- 5 files changed, 292 insertions(+), 191 deletions(-)
This is an automated email from the git hooks/post-receive script. It was generated because a ref change was pushed to the repository containing the project "gdb and binutils". The branch, binutils-2_25-branch has been updated via 875896e3e6880ec4c27b4fdfc37ae44881e11ca8 (commit) from f6989d5268fbd213d889e3d81f8972dd429b1bbf (commit) Those revisions listed above that are new to this repository have not appeared on any other notification email; so we list those revisions in full, below. - Log ----------------------------------------------------------------- https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=875896e3e6880ec4c27b4fdfc37ae44881e11ca8 commit 875896e3e6880ec4c27b4fdfc37ae44881e11ca8 Author: H.J. Lu <hjl.tools@gmail.com> Date: Thu Dec 4 14:19:41 2014 -0800 Add _bfd_elf_ifunc_get_synthetic_symtab In i386 and x86-64 binaries with ifunc, relocations against .got.plt section may not be in the same order as entries in PLT section. This patch adds _bfd_elf_ifunc_get_synthetic_symtab. It takes a function pointer which returns an array of PLT entry symbol values. It calls the function pointer to get the PLT entry symbol value array indexed by relocation index, instead of calling plt_sym_val on each relocation index. PR binutils/17677 * elf-bfd.h (_bfd_elf_ifunc_get_synthetic_symtab): New prototype. * elf-ifunc.c (_bfd_elf_ifunc_get_synthetic_symtab): New function. * elf32-i386.c (elf_i386_plt_sym_val): Removed. (elf_backend_plt_sym_val): Likewise. (elf_i386_get_plt_sym_val): New. (elf_i386_get_synthetic_symtab): Likewise. (bfd_elf32_get_synthetic_symtab): Likewise. * elf64-x86-64.c (elf_x86_64_plt_sym_val): Removed. (elf_x86_64_plt_sym_val_offset_plt_bnd): Likewise. (elf_backend_plt_sym_val): Likewise. (elf_x86_64_get_plt_sym_val): New. (elf_x86_64_get_synthetic_symtab): Use _bfd_elf_ifunc_get_synthetic_symtab. (bfd_elf64_get_synthetic_symtab): Don't undefine for NaCl. ----------------------------------------------------------------------- Summary of changes: bfd/ChangeLog | 19 ++++ bfd/elf-bfd.h | 3 + bfd/elf-ifunc.c | 125 ++++++++++++++++++++++++++++ bfd/elf32-i386.c | 101 ++++++++++++++++------- bfd/elf64-x86-64.c | 235 ++++++++++++++++----------------------------------- 5 files changed, 292 insertions(+), 191 deletions(-)
Fixed on master and binutils 2.25 branch.
Also need this commit: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=b7365e5df5b41bc23a2a1464d93ed6435d87a056
This is an automated email from the git hooks/post-receive script. It was generated because a ref change was pushed to the repository containing the project "gdb and binutils". The branch, hjl/gdb-7.8-branch has been created at 6a8939044781191d685e0aaeb78fe34a97ee3d55 (commit) - Log ----------------------------------------------------------------- https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=6a8939044781191d685e0aaeb78fe34a97ee3d55 commit 6a8939044781191d685e0aaeb78fe34a97ee3d55 Author: H.J. Lu <hjl.tools@gmail.com> Date: Thu Dec 4 14:19:41 2014 -0800 Add _bfd_elf_ifunc_get_synthetic_symtab In i386 and x86-64 binaries with ifunc, relocations against .got.plt section may not be in the same order as entries in PLT section. This patch adds _bfd_elf_ifunc_get_synthetic_symtab. It takes a function pointer which returns an array of PLT entry symbol values. It calls the function pointer to get the PLT entry symbol value array indexed by relocation index, instead of calling plt_sym_val on each relocation index. PR binutils/17677 * elf-bfd.h (_bfd_elf_ifunc_get_synthetic_symtab): New prototype. * elf-ifunc.c (_bfd_elf_ifunc_get_synthetic_symtab): New function. * elf32-i386.c (elf_i386_plt_sym_val): Removed. (elf_backend_plt_sym_val): Likewise. (elf_i386_get_plt_sym_val): New. (elf_i386_get_synthetic_symtab): Likewise. (bfd_elf32_get_synthetic_symtab): Likewise. * elf64-x86-64.c (elf_x86_64_plt_sym_val): Removed. (elf_x86_64_plt_sym_val_offset_plt_bnd): Likewise. (elf_backend_plt_sym_val): Likewise. (elf_x86_64_get_plt_sym_val): New. (bfd_elf32_get_synthetic_symtab): Likewise. (elf_x86_64_get_synthetic_symtab): Use _bfd_elf_ifunc_get_synthetic_symtab. (bfd_elf64_get_synthetic_symtab): Don't undefine for NaCl. -----------------------------------------------------------------------
I backported my fix to hjl/gdb-7.8-branch branch. You can cherry-pick if if needed.
This is an automated email from the git hooks/post-receive script. It was generated because a ref change was pushed to the repository containing the project "gdb and binutils". The branch, gdb-7.8-branch has been updated via cd4294b2619e6b0e1ea0e553dbdfab40db814485 (commit) from dbdc8a04a60670542cfda8749a2be78779ff7720 (commit) Those revisions listed above that are new to this repository have not appeared on any other notification email; so we list those revisions in full, below. - Log ----------------------------------------------------------------- https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=cd4294b2619e6b0e1ea0e553dbdfab40db814485 commit cd4294b2619e6b0e1ea0e553dbdfab40db814485 Author: H.J. Lu <hjl.tools@gmail.com> Date: Thu Dec 4 14:19:41 2014 -0800 Add _bfd_elf_ifunc_get_synthetic_symtab In i386 and x86-64 binaries with ifunc, relocations against .got.plt section may not be in the same order as entries in PLT section. This patch adds _bfd_elf_ifunc_get_synthetic_symtab. It takes a function pointer which returns an array of PLT entry symbol values. It calls the function pointer to get the PLT entry symbol value array indexed by relocation index, instead of calling plt_sym_val on each relocation index. PR binutils/17677 * elf-bfd.h (_bfd_elf_ifunc_get_synthetic_symtab): New prototype. * elf-ifunc.c (_bfd_elf_ifunc_get_synthetic_symtab): New function. * elf32-i386.c (elf_i386_plt_sym_val): Removed. (elf_backend_plt_sym_val): Likewise. (elf_i386_get_plt_sym_val): New. (elf_i386_get_synthetic_symtab): Likewise. (bfd_elf32_get_synthetic_symtab): Likewise. * elf64-x86-64.c (elf_x86_64_plt_sym_val): Removed. (elf_x86_64_plt_sym_val_offset_plt_bnd): Likewise. (elf_backend_plt_sym_val): Likewise. (elf_x86_64_get_plt_sym_val): New. (bfd_elf32_get_synthetic_symtab): Likewise. (elf_x86_64_get_synthetic_symtab): Use _bfd_elf_ifunc_get_synthetic_symtab. (bfd_elf64_get_synthetic_symtab): Don't undefine for NaCl. ----------------------------------------------------------------------- Summary of changes: bfd/ChangeLog | 23 +++++ bfd/elf-bfd.h | 3 + bfd/elf-ifunc.c | 125 +++++++++++++++++++++++++++ bfd/elf32-i386.c | 101 ++++++++++++++++------- bfd/elf64-x86-64.c | 237 +++++++++++++++++----------------------------------- 5 files changed, 298 insertions(+), 191 deletions(-)
*** Bug 17764 has been marked as a duplicate of this bug. ***