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.

diff --git a/binutils/ChangeLog b/binutils/ChangeLog
index 6fa4bf48e45885f0c0ccd9497a9d3ac1c2e319de..121c54d9919bea8bf1fca800071f8cb1f3a08639 100644 (file)
--- a/binutils/ChangeLog
+++ b/binutils/ChangeLog
@@ -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

diff --git a/binutils/objdump.c b/binutils/objdump.c
index 79aed757ae85d7f04f80af2d9a439d83dd044f33..d80b3f5a8890063baf567e850ed73162788dc702 100644 (file)
--- a/binutils/objdump.c
+++ b/binutils/objdump.c
@@ -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;

diff --git a/binutils/testsuite/binutils-all/aarch64/out-of-order.T b/binutils/testsuite/binutils-all/aarch64/out-of-order.T
new file mode 100644 (file)
index 0000000..489ae80
--- /dev/null
+++ b/binutils/testsuite/binutils-all/aarch64/out-of-order.T
@@ -0,0 +1,14 @@
+ENTRY(v1)
+SECTIONS
+{
+  . = 0xffe00000;
+  .global : { *(.global) }
+  . = 0x4018280;
+  .func2 : { *(.func2) }
+  . = 0x4005000;
+  .func1 : { *(.func1) }
+  . = 0x4015000;
+  .func3 : { *(.func3) }
+  .data : { *(.data) }
+  .rodata : { *(.rodata) }
+}
\ No newline at end of file

diff --git a/binutils/testsuite/binutils-all/aarch64/out-of-order.d b/binutils/testsuite/binutils-all/aarch64/out-of-order.d
new file mode 100644 (file)
index 0000000..410f37f
--- /dev/null
+++ b/binutils/testsuite/binutils-all/aarch64/out-of-order.d
@@ -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

diff --git a/binutils/testsuite/binutils-all/aarch64/out-of-order.s b/binutils/testsuite/binutils-all/aarch64/out-of-order.s
new file mode 100644 (file)
index 0000000..6c52e85
--- /dev/null
+++ b/binutils/testsuite/binutils-all/aarch64/out-of-order.s
@@ -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

diff --git a/include/ChangeLog b/include/ChangeLog
index b4a0907e80fdcf020768d0806657cbb47bc24f36..ae79b9f47fcf2b20f512823777486ff42f5b0800 100644 (file)
--- a/include/ChangeLog
+++ b/include/ChangeLog
@@ -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.

diff --git a/include/dis-asm.h b/include/dis-asm.h
index 22c593ece6e1d13214987f98f8dfee271d527dce..4e1263c90e3bed06195ad3481d0a4d1885f744e5 100644 (file)
--- a/include/dis-asm.h
+++ b/include/dis-asm.h
@@ -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

diff --git a/opcodes/ChangeLog b/opcodes/ChangeLog
index 204c008ab4cc834b234c07cc10a1cf40c3d33e4a..81fe9f00b2b62b8adb7ffbc7d8530e2d9828c434 100644 (file)
--- a/opcodes/ChangeLog
+++ b/opcodes/ChangeLog
@@ -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

diff --git a/opcodes/aarch64-dis.c b/opcodes/aarch64-dis.c
index 4c31f57451d20d8029624e601b15e41cf56f5a19..fc7e95d066807f2909d1a1c891d7a89a5f31204b 100644 (file)
--- a/opcodes/aarch64-dis.c
+++ b/opcodes/aarch64-dis.c
@@ -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,