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ea24213d80
It is important that UACCESS regions are as small as possible; furthermore the UACCESS state is not scheduled, so doing anything that might directly call into the scheduler will cause random code to be ran with UACCESS enabled. Teach objtool too track UACCESS state and warn about any CALL made while UACCESS is enabled. This very much includes the __fentry__() and __preempt_schedule() calls. Note that exceptions _do_ save/restore the UACCESS state, and therefore they can drive preemption. This also means that all exception handlers must have an otherwise redundant UACCESS disable instruction; therefore ignore this warning for !STT_FUNC code (exception handlers are not normal functions). Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
109 lines
3.0 KiB
C
109 lines
3.0 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, *alias;
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bool uaccess_safe;
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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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