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When GCC realigns a function's stack, it sometimes uses %r13 as the DRAP
register, like:
push %r13
lea 0x10(%rsp), %r13
and $0xfffffffffffffff0, %rsp
pushq -0x8(%r13)
push %rbp
mov %rsp, %rbp
push %r13
...
mov -0x8(%rbp),%r13
leaveq
lea -0x10(%r13), %rsp
pop %r13
retq
Since %r13 was pushed onto the stack twice, its two stack locations need
to be stored separately. The first push of %r13 is its original value,
and the second push of %r13 is the caller's stack frame address.
Since %r13 is a callee-saved register, we need to track the stack
location of its original value separately from the DRAP register.
This fixes the following false positive warning:
lib/ubsan.o: warning: objtool: val_to_string.constprop.7()+0x97: leave instruction with modified stack frame
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: baa41469a7 ("objtool: Implement stack validation 2.0")
Link: http://lkml.kernel.org/r/3da23a6d4c5b3c1e21fc2ccc21a73941b97ff20a.1502401017.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
80 lines
2.1 KiB
C
80 lines
2.1 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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};
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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;
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struct symbol *call_dest;
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struct instruction *jump_dest;
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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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