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AArch64: Fix disassembler bug with out-of-order sections 

The AArch64 disassembler has an optimization that it uses to reduce the amount
it has to search for mapping symbols during disassembly.  This optimization
assumes that sections are listed in the section header in monotonic increasing
VMAs.  However this is not a requirement for the ELF specification.

Because of this when such "out of order" sections occur the disassembler would
pick the wrong mapping symbol to disassemble the section with.

This fixes it by explicitly passing along the stop offset for the current
disassembly glob and when this changes compared to the previous one we've seen
the optimization won't be performed.  In effect this restarts the search from
a well defined starting point.  Usually the symbol's address.

The existing stop_vma can't be used for this as it is allowed to be unset and
setting this unconditionally would change the semantics of this field.

binutils/ChangeLog:

	* objdump.c (disassemble_bytes): Pass stop_offset.
	* testsuite/binutils-all/aarch64/out-of-order.T: New test.
	* testsuite/binutils-all/aarch64/out-of-order.d: New test.
	* testsuite/binutils-all/aarch64/out-of-order.s: New test.

include/ChangeLog:

	* dis-asm.h (struct disassemble_info): Add stop_offset.

opcodes/ChangeLog:

	* aarch64-dis.c (last_stop_offset): New.
	(print_insn_aarch64): Use stop_offset.
This commit is contained in:
Tamar Christina 2019-03-25 12:08:53 +00:00
parent 9a93502fa8
commit 53b2f36bf6
9 changed files with 98 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
binutils/ChangeLog
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@ -1,3 +1,10 @@
2019-03-25 Tamar Christina <tamar.christina@arm.com>
* objdump.c (disassemble_bytes): Pass stop_offset.
* testsuite/binutils-all/aarch64/out-of-order.T: New test.
* testsuite/binutils-all/aarch64/out-of-order.d: New test.
* testsuite/binutils-all/aarch64/out-of-order.s: New test.
2019-03-19 Nick Clifton <nickc@redhat.com>
PR 24360

1
binutils/objdump.c
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@ -1991,6 +1991,7 @@ disassemble_bytes (struct disassemble_info * inf,
disassembling code of course, and when -D is in effect. */
inf->stop_vma = section->vma + stop_offset;
inf->stop_offset = stop_offset;
octets = (*disassemble_fn) (section->vma + addr_offset, inf);
inf->stop_vma = 0;

14
binutils/testsuite/binutils-all/aarch64/out-of-order.T Normal file
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@ -0,0 +1,14 @@
ENTRY(v1)
SECTIONS
{
. = 0xffe00000;
.global : { *(.global) }
. = 0x4018280;
.func2 : { *(.func2) }
. = 0x4005000;
.func1 : { *(.func1) }
. = 0x4015000;
.func3 : { *(.func3) }
.data : { *(.data) }
.rodata : { *(.rodata) }
}

27
binutils/testsuite/binutils-all/aarch64/out-of-order.d Normal file
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@ -0,0 +1,27 @@
#PROG: objcopy
#ld: -T out-of-order.T
#objdump: -d
#name: Check if disassembler can handle sections in different order than header
.*: +file format .*aarch64.*
Disassembly of section \.func2:
0000000004018280 <\.func2>:
4018280: 8b010000 add x0, x0, x1
Disassembly of section \.func1:
0000000004005000 <v1>:
4005000: 8b010000 add x0, x0, x1
4005004: 00000000 \.word 0x00000000
Disassembly of section \.func3:
0000000004015000 <\.func3>:
4015000: 8b010000 add x0, x0, x1
4015004: 8b010000 add x0, x0, x1
4015008: 8b010000 add x0, x0, x1
401500c: 8b010000 add x0, x0, x1
4015010: 8b010000 add x0, x0, x1
4015014: 00000000 \.word 0x00000000

28
binutils/testsuite/binutils-all/aarch64/out-of-order.s Normal file
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@ -0,0 +1,28 @@
.text
.global v1
.section .func1,"ax",@progbits
.type v1 %function
.size v1, 4
v1:
add x0, x0, x1
.word 0
.section .func2,"ax",@progbits
add x0, x0, x1
.section .func3,"ax",@progbits
add x0, x0, x1
add x0, x0, x1
add x0, x0, x1
add x0, x0, x1
add x0, x0, x1
.word 0
.data
.section .global,"aw",@progbits
.xword 1
.xword 1
.xword 1
.section .rodata
.word 4

4
include/ChangeLog
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@ -1,3 +1,7 @@
2019-03-25 Tamar Christina <tamar.christina@arm.com>
* dis-asm.h (struct disassemble_info): Add stop_offset.
2019-03-13 Sudakshina Das <sudi.das@arm.com>
* elf/aarch64.h (DT_AARCH64_PAC_PLT): New.

6
include/dis-asm.h
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@ -221,6 +221,12 @@ typedef struct disassemble_info
file being disassembled. */
bfd_vma stop_vma;
/* The end range of the current range being disassembled. This is required
in order to notify the disassembler when it's currently handling a
different range than it was before. This prevent unsafe optimizations when
disassembling such as the way mapping symbols are found on AArch64. */
bfd_vma stop_offset;
} disassemble_info;
/* This struct is used to pass information about valid disassembler

5
opcodes/ChangeLog
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@ -1,3 +1,8 @@
2019-03-25 Tamar Christina <tamar.christina@arm.com>
* aarch64-dis.c (last_stop_offset): New.
(print_insn_aarch64): Use stop_offset.
2019-03-19 H.J. Lu <hongjiu.lu@intel.com>
PR gas/24359

7
opcodes/aarch64-dis.c
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@ -37,6 +37,7 @@ enum map_type
static enum map_type last_type;
static int last_mapping_sym = -1;
static bfd_vma last_stop_offset = 0;
static bfd_vma last_mapping_addr = 0;
/* Other options */
@ -3333,7 +3334,10 @@ print_insn_aarch64 (bfd_vma pc,
/* Start scanning at the start of the function, or wherever
we finished last time. */
n = info->symtab_pos + 1;
if (n < last_mapping_sym)
/* If the last stop offset is different from the current one it means we
are disassembling a different glob of bytes. As such the optimization
would not be safe and we should start over. */
if (n < last_mapping_sym && info->stop_offset == last_stop_offset)
n = last_mapping_sym;
/* Scan up to the location being disassembled. */
@ -3370,6 +3374,7 @@ print_insn_aarch64 (bfd_vma pc,
last_mapping_sym = last_sym;
last_type = type;
last_stop_offset = info->stop_offset;
/* Look a little bit ahead to see if we should print out
less than four bytes of data. If there's a symbol,