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oatdump utility. Similar to objdump, it displays information from oat files
in human-readable form. It is fast but produces a lot of output. We can get
almost all information we could need like this:
```console
$ adb shell oatdump --oat-file=/data/app/~~ICLdeF7FOXIe1b9MxToZGQ==/\
app.organicmaps-2xFay0QEb95pHRC_k_T1gA==/oat/arm64/base.odex \
> app.organicmaps.odex.oatdump
$ cat app.organicmaps.odex.oatdump
[...]
3: double app.organicmaps.util.LocationUtils.correctAngle(double, double)
(dex_method_idx=27942)
DEX CODE:
0x0000: 1400 0400 0000 | const v0, #+4
0x0003: 1401 0100 0000 | const v1, #+1
0x0006: 9000 0001 | add-int v0, v0, v1
0x0008: 9400 0001 | rem-int v0, v0, v1
0x000a: 3c00 0500 | if-gtz v0, +5
0x000c: 2a00 1200 0000 | goto/32 +18
0x000f: cb53 | add-double/2addr v3, v5
0x0010: 1805 182d 4454 fb21 1940 | const-wide v5, \
#+4618760256179416344
0x0015: cf53 | rem-double/2addr v3, v5
0x0016: 1600 0000 | const-wide/16 v0, #+0
0x0018: 3002 0300 | cmpg-double v2, v3, v0
0x001a: 3b02 0300 | if-gez v2, +3
0x001c: cb53 | add-double/2addr v3, v5
0x001d: 1003 | return-wide v3
0x001e: 2a00 f1ff ffff | goto/32 -15
[...]
CODE: (code_offset=0x00816520 size=92)...
0x00816520: d1400bf0 sub x16, sp, #0x2000 (8192)
0x00816524: b940021f ldr wzr, [x16]
StackMap[0] (native_pc=0x812528, dex_pc=0x0, register_mask=0x0, \
stack_mask=0b)
0x00816528: f81e0fe0 str x0, [sp, #-32]!
0x0081652c: f9000ffe str lr, [sp, #24]
0x00816530: fd000be8 str d8, [sp, #16]
0x00816534: f94002b5 ldr x21, [x21]
StackMap[1] (native_pc=0x812538, dex_pc=0x0, register_mask=0x0, \
stack_mask=0b)
0x00816538: 5c0001e8 ldr d8, pc+60 (addr 0x00816574) (6.28319)
0x0081653c: 1e612800 fadd d0, d0, d1
0x00816540: 1e604101 fmov d1, d8
0x00816544: f942027e ldr lr, [tr, #1024] ; pFmod
0x00816548: d63f03c0 blr lr
0x0081654c: 1e602008 fcmp d0, #0.0
0x00816550: 1a9f37e0 cset w0, hs
0x00816554: 1e682801 fadd d1, d0, d8
0x00816558: 7100001f cmp w0, #0x0 (0)
0x0081655c: 1e611c00 fcsel d0, d0, d1, ne
0x00816560: fd400be8 ldr d8, [sp, #16]
0x00816564: f9400ffe ldr lr, [sp, #24]
0x00816568: 910083ff add sp, sp, #0x20 (32)
0x0081656c: d65f03c0 ret
0x00816570: 5800007f ldr xzr, pc+12 (addr 0x0081657c) \
(0xd1400bf0006c564f / -3368679395845974449)
0x00816574: 54442d18 unallocated (Unallocated)
0x00816578: 401921fb unallocated (Unallocated)
```
We say it contains almost all information because the output refers to the
code_offset relative to the oatdata section in the OAT file. To get this
offset, we can use readelf:
```console
$ adb shell readelf -s /data/app/~~ICLdeF7FOXIe1b9MxToZGQ==/\
app.organicmaps-2xFay0QEb95pHRC_k_T1gA==/oat/arm64/base.odex \
| grep 'oatdata$'
1: 0000000000000658 2865576 OBJECT GLOBAL DEFAULT 5 oatdata
```
Now we know we need to add 0x658 to the addresses in the oatdump output. If
we want to compare it directly to Ghidra's output, we also need to add
0x100000 unless Ghidra used a different base address.
---[ 3.4 - Wait, Where Did the Arithmetic Go?
Eagle-eyed readers might have noticed some dummy arithmetic operations in
the Dalvik code, with a goto instruction at the end, that seemingly
vanished during compilation. We're sorry we were not completely honest. We
did not use the regular build of Organic Maps, but instead a version that
was repackaged with ObfuscAPK [15], using the "ArtithmeticBranch"
obfuscation. This adds a branch at the beginning of each method with an
arithmetic expression that always resolves to the same code being executed.
The ART helpfully removed this obfuscation as part of its optimizations.
This means we get some free normalization of code along the way, as a
treat! Not enough to deal with advanced techniques, but enough to make a
difference.
To compare the same method without obfuscations, here's another oatdump of
the original Organic Maps app:
```console
$ cat app.organicmaps_unobfuscated.odex.oatdump
[...]
3: double app.organicmaps.util.LocationUtils.correctAngle(double, double)
(dex_method_idx=27942)
DEX CODE: