4a60aa05a0
Add support for processing switch jump tables in objects with multiple .rodata sections, such as those created by '-ffunction-sections' and '-fdata-sections'. Currently, objtool always looks in .rodata for jump table information, which results in many "sibling call from callable instruction with modified stack frame" warnings with objects compiled using those flags. The fix is comprised of three parts: 1. Flagging all .rodata sections when importing ELF information for easier checking later. 2. Keeping a reference to the section each relocation is from in order to get the list_head for the other relocations in that section. 3. Finding jump tables by following relocations to .rodata sections, rather than always referencing a single global .rodata section. The patch has been tested without data sections enabled and no differences in the resulting orc unwind information were seen. Note that as objtool adds terminators to end of each .text section the unwind information generated between a function+data sections build and a normal build aren't directly comparable. Manual inspection suggests that objtool is now generating the correct information, or at least making more of an effort to do so than it did previously. Signed-off-by: Allan Xavier <allan.x.xavier@oracle.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/099bdc375195c490dda04db777ee0b95d566ded1.1536325914.git.jpoimboe@redhat.com
108 lines
3 KiB
C
108 lines
3 KiB
C
/*
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* Copyright (C) 2015 Josh Poimboeuf <jpoimboe@redhat.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef _OBJTOOL_ELF_H
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#define _OBJTOOL_ELF_H
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#include <stdio.h>
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#include <gelf.h>
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#include <linux/list.h>
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#include <linux/hashtable.h>
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#ifdef LIBELF_USE_DEPRECATED
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# define elf_getshdrnum elf_getshnum
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# define elf_getshdrstrndx elf_getshstrndx
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#endif
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/*
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* Fallback for systems without this "read, mmaping if possible" cmd.
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*/
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#ifndef ELF_C_READ_MMAP
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#define ELF_C_READ_MMAP ELF_C_READ
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#endif
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struct section {
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struct list_head list;
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GElf_Shdr sh;
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struct list_head symbol_list;
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DECLARE_HASHTABLE(symbol_hash, 8);
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struct list_head rela_list;
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DECLARE_HASHTABLE(rela_hash, 16);
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struct section *base, *rela;
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struct symbol *sym;
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Elf_Data *data;
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char *name;
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int idx;
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unsigned int len;
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bool changed, text, rodata;
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};
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struct symbol {
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struct list_head list;
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struct hlist_node hash;
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GElf_Sym sym;
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struct section *sec;
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char *name;
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unsigned int idx;
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unsigned char bind, type;
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unsigned long offset;
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unsigned int len;
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struct symbol *pfunc, *cfunc;
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};
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struct rela {
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struct list_head list;
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struct hlist_node hash;
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GElf_Rela rela;
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struct section *rela_sec;
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struct symbol *sym;
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unsigned int type;
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unsigned long offset;
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int addend;
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};
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struct elf {
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Elf *elf;
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GElf_Ehdr ehdr;
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int fd;
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char *name;
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struct list_head sections;
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DECLARE_HASHTABLE(rela_hash, 16);
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};
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struct elf *elf_open(const char *name, int flags);
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struct section *find_section_by_name(struct elf *elf, const char *name);
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struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset);
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struct symbol *find_symbol_by_name(struct elf *elf, const char *name);
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struct symbol *find_symbol_containing(struct section *sec, unsigned long offset);
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struct rela *find_rela_by_dest(struct section *sec, unsigned long offset);
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struct rela *find_rela_by_dest_range(struct section *sec, unsigned long offset,
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unsigned int len);
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struct symbol *find_containing_func(struct section *sec, unsigned long offset);
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struct section *elf_create_section(struct elf *elf, const char *name, size_t
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entsize, int nr);
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struct section *elf_create_rela_section(struct elf *elf, struct section *base);
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int elf_rebuild_rela_section(struct section *sec);
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int elf_write(struct elf *elf);
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void elf_close(struct elf *elf);
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#define for_each_sec(file, sec) \
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list_for_each_entry(sec, &file->elf->sections, list)
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#endif /* _OBJTOOL_ELF_H */
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