[lldb-dev] [Bug 18637] New: Incorrect ARM disassembly annotation for symbol stubs

bugzilla-daemon at llvm.org bugzilla-daemon at llvm.org
Mon Jan 27 15:32:09 PST 2014


            Bug ID: 18637
           Summary: Incorrect ARM disassembly annotation for symbol stubs
           Product: lldb
           Version: 3.4
          Hardware: Macintosh
                OS: MacOS X
            Status: NEW
          Severity: normal
          Priority: P
         Component: All Bugs
          Assignee: lldb-dev at cs.uiuc.edu
          Reporter: zach at fb.com
    Classification: Unclassified

The lldb from Xcode 5.1b4 (lldb-310.2.32) to incorrectly annotates ARM
instructions corresponding to indirect function calls when running on an
iPhone. This reproduces when generating both arm64 or armv7s code.

Here is an example using armv7s.

Steps to reproduce:
1) Place a breakpoint onn CFSocketCreate in a simple iOS app with the following
code in main.c:

int main(int argc, char * argv[])
  @autoreleasepool {
    CFSocketCreate(kCFAllocatorDefault, 0, 0, 0, 0, NULL, NULL);
    return 0;

2) Breakpoint is hit, instructions appear:

0x30539848:  push   {r4, r5, r6, r7, lr}
0x305398d8:  mov    r1, r6
0x305398da:  blx    0x305a68dc ; symbol stub for: __copy_helper_block_457
0x305398de:  mov    r1, r0

The annotation on 0x305398da is incorrect:

(lldb) p/a 0x305a68dc
(int) $3 = 0x305a68dc CoreFoundation`symbol stub for: __copy_helper_block_457

0x305a68dc is actually a symbol stub that will branch to
libsystem_kernel.dylib`socket, which you can verify below:

(lldb) disas -s0x305a68dc -c4
CoreFoundation`symbol stub for: __copy_helper_block_457:
   0x305a68dc:  ldr    r12, [pc, #4]             ; symbol stub for:
__copy_helper_block_457 + 12
   0x305a68e0:  add    r12, pc, r12
   0x305a68e4:  ldr    pc, [r12]
   0x305a68e8:  beq    0x2f0575a0
(lldb) x/4w 0x305a68dc
0x305a68dc: 0xe59fc004
0x305a68e0: 0xe08fc00c
0x305a68e4: 0xe59cf000
0x305a68e8: 0x0aaac32c
(lldb) x/a `0x305a68e8 + 0x0aaac32c`
0x3b052c14: 0x3ae6cce4 libsystem_kernel.dylib`socket

You are receiving this mail because:
You are the assignee for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/lldb-dev/attachments/20140127/949c94f5/attachment.html>

More information about the lldb-dev mailing list