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99ce7962d5
Linus reported that GCC-7.3 generated a switch-table construct that confused objtool. It turns out that, in particular due to KASAN, it is possible to have unrelated .rodata usage in between the .rodata setup for the switch-table and the following indirect jump. The simple linear reverse search from the indirect jump would hit upon the KASAN .rodata usage first and fail to find a switch_table, resulting in a spurious 'sibling call with modified stack frame' warning. Fix this by creating a 'jump-stack' which we can 'unwind' during reversal, thereby skipping over much of the in-between code. This is not fool proof by any means, but is sufficient to make the known cases work. Future work would be to construct more comprehensive flow analysis code. Reported-and-tested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20180208130232.GF25235@hirez.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
82 lines
2.2 KiB
C
82 lines
2.2 KiB
C
/*
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* Copyright (C) 2017 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 _CHECK_H
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#define _CHECK_H
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#include <stdbool.h>
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#include "elf.h"
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#include "cfi.h"
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#include "arch.h"
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#include "orc.h"
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#include <linux/hashtable.h>
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struct insn_state {
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struct cfi_reg cfa;
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struct cfi_reg regs[CFI_NUM_REGS];
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int stack_size;
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unsigned char type;
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bool bp_scratch;
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bool drap;
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int drap_reg, drap_offset;
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struct cfi_reg vals[CFI_NUM_REGS];
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};
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struct instruction {
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struct list_head list;
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struct hlist_node hash;
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struct section *sec;
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unsigned long offset;
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unsigned int len;
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unsigned char type;
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unsigned long immediate;
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bool alt_group, visited, dead_end, ignore, hint, save, restore, ignore_alts;
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struct symbol *call_dest;
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struct instruction *jump_dest;
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struct instruction *first_jump_src;
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struct list_head alts;
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struct symbol *func;
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struct stack_op stack_op;
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struct insn_state state;
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struct orc_entry orc;
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};
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struct objtool_file {
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struct elf *elf;
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struct list_head insn_list;
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DECLARE_HASHTABLE(insn_hash, 16);
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struct section *rodata, *whitelist;
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bool ignore_unreachables, c_file, hints;
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};
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int check(const char *objname, bool no_fp, bool no_unreachable, bool orc);
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struct instruction *find_insn(struct objtool_file *file,
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struct section *sec, unsigned long offset);
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#define for_each_insn(file, insn) \
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list_for_each_entry(insn, &file->insn_list, list)
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#define sec_for_each_insn(file, sec, insn) \
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for (insn = find_insn(file, sec, 0); \
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insn && &insn->list != &file->insn_list && \
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insn->sec == sec; \
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insn = list_next_entry(insn, list))
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#endif /* _CHECK_H */
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