I am trying to debug native code on Android using ndk-gdb, with mixed results.
When the debugger hits a breakpoint, I am able to get a nice stack trace using 'bt'.
Hhen typing 'info source', ndk-gdb tells me that the file I have hit the breakpoint in is "Compiled with DWARF 2 debugging format".
The problem arises when I enter 'info args' to get the function argument values. ndk-gdb then states that: "No symbol table info available.".
Any input to the cause of this problem would be appreciated.
It's strange that it says that about the file being compiled with DWARF 2 format, because the flags you provide there indicates it is only specifying -g, which should get GCC 4.8 to produce DWARF 4 format. Which also is consistent with the error you are seeing. Add the flag -gdwarf-2 and the NDK debugger (which is not yet at version 7.5) should be able to deal with the symbols.
I picked this up from one of the answers to this question: Debugging with gdb on a program with no optimization but still there is no symbol in the current context for local variables
Related
The problem
I'm trying to debug native (c++) code that is called from Java code (MainActivity.OnCreate) in simple android application. I'm using lldb for debugging and build the native code using cmake.
The debug works as expected until I try to step into native language function, then one of these happens:
1. The debugger steps into the function and allows making further steps, but there is no cursor, no normal stack trace, and no variable watches. The only thing in stack trace is the name of the cpp file and memory adress (instruction pointer maybe?) that increases with every step that I take. It looks to me as no debug symbols were loaded.
2. The step suceeds as it should and for a brief moment I can catch a glimpse of correct stack trace. But then the lldb crashes, the stack changes and the cursor is at art_sigsegv_fault. When I continue, I simply get a message that debugger was disconnected. The app continues to run as it should.
Additionally, I've noticed that at the moment of crash the debugger attempts to collect data from variables and never actually suceeds. The variables that are successfully resolved are a JNI pointer and jobject, while the others are jstring.
Miliseconds before the crash:
After the crash:
What I've tried
Made sure that symbols are not stripped from .so files, by adding
packagingOptions{
doNotStrip "**/*.so"
}
Made sure that CMAKE_CXX_FLAGS have -O0 -ggdb in them (no code optimization, debug compile)
Made sure that in Project Structure there is debug build, with properties Debuggable, Jni Debuggable, and Renderscript Debuggable set to true.
I believe that I've tried all the possible options that I've found here, hence a new question that may seem repetitive at first.
Currently trying to build android-5.1.0_r5. I've checked out the sources and made no modifications. However, when compiling I get the following error.
Checking API: checkpublicapi-current
out/target/common/obj/PACKAGING/public_api.txt:20: error 5: Added public field android.Manifest.permission.BACKUP
out/target/common/obj/PACKAGING/public_api.txt:82: error 5: Added public field android.Manifest.permission.INVOKE_CARRIER_SETUP
out/target/common/obj/PACKAGING/public_api.txt:106: error 5: Added public field android.Manifest.permission.READ_PRIVILEGED_PHONE_STATE
out/target/common/obj/PACKAGING/public_api.txt:116: error 5: Added public field android.Manifest.permission.RECEIVE_EMERGENCY_BROADCAST
******************************
You have tried to change the API from what has been previously approved.
To make these errors go away, you have two choices:
1) You can add "#hide" javadoc comments to the methods, etc. listed in the
errors above.
2) You can update current.txt by executing the following command:
make update-api
To submit the revised current.txt to the main Android repository,
you will need approval.
******************************
And diffing the public api txt files does indeed show a difference.
diff frameworks/base/api/current.txt out/target/common/obj/PACKAGING/public_api.txt
19a20
> field public static final java.lang.String BACKUP = "android.permission.BACKUP";
80a82
> field public static final java.lang.String INVOKE_CARRIER_SETUP = "android.permission.INVOKE_CARRIER_SETUP";
103a106
> field public static final java.lang.String READ_PRIVILEGED_PHONE_STATE = "android.permission.READ_PRIVILEGED_PHONE_STATE";
112a116
> field public static final java.lang.String RECEIVE_EMERGENCY_BROADCAST = "android.permission.RECEIVE_EMERGENCY_BROADCAST";
However, I cant figure out where those additional Public Fields are coming from. Any ideas?
Don't do 'make update-api' if you didn't touch anything. There additional apis came form frameworks/base/res/AndroidManifest.xml badly parsed by aapt that uses buggy system/core/libcore/String8.cpp##removeAll() they use memcpy but should be memmove for overlapping strings in memory.
This is issue on latest Debian (sid) or Ubuntu (16 maybe 15) build machines.
It's a google bug in libcore/String8.cpp. Fix is here:
https://android.googlesource.com/platform/system/core/+/dd060f01f68ee0e633e9cae24c4e565cda2032bd
This man found it (Michael Scott) and maybe some other people too. Here is his investigation: https://plus.google.com/+hashcode0f/posts/URHo3hBmfHY
Living on the Edge (of Ubuntu) ... can be painful!
I've been running Ubuntu 15.04 for a while now. It's been great
having a very current kernel alongside the latest improvements from
Ubuntu and Debian. (My past post on using zRAM ramdisk is one
example).
However, having the newest greatest toys also has it's downsides. I
recently spent 4 days troubleshooting a build break in Android which
started some time after March 25th. I'm guessing I updated packages
or inadvertently changed my glibc version.
The outcome was a build error during the checkapi stage of Android
build:
Install: /out/mydroid-ara/host/linux-x86/bin/apicheck Checking API:
checkpublicapi-last Checking API: checkpublicapi-current
/out/mydroid-ara/target/common/obj/PACKAGING/public_api.txt:20: error
5: Added public field android.Manifest.permission.BACKUP
/out/mydroid-ara/target/common/obj/PACKAGING/public_api.txt:82: error
5: Added public field android.Manifest.permission.INVOKE_CARRIER_SETUP
/out/mydroid-ara/target/common/obj/PACKAGING/public_api.txt:106: error
5: Added public field
android.Manifest.permission.READ_PRIVILEGED_PHONE_STATE
/out/mydroid-ara/target/common/obj/PACKAGING/public_api.txt:116: error
5: Added public field
android.Manifest.permission.RECEIVE_EMERGENCY_BROADCAST
**************************** You have tried to change the API from what has been previously approved.
To make these errors go away, you have two choices: 1) You can add
"#hide" javadoc comments to the methods, etc. listed in the
errors above.
2) You can update current.txt by executing the following command:
make update-api
To submit the revised current.txt to the main Android repository,
you will need approval.
This occurred on both of my Ubuntu 15.04 boxes and was present when
when build AOSP android-5.0.2_r1 and android-5.1.0_r1.
For those of you who are unfamiliar with this portion of the Android
build, the Android framework exports all of the public portions of the
API and makes sure that the current build matches up with what's
located under frameworks/base/api/current.txt. It does this by
parsing frameworks/base/res/AndroidManifest.xml and any of the current
device's overlay .xml files and processes items marked with various
flags in the comments above them:#SystemApi, #hide, etc. This
parsing and processing portion of the checkapi stage is done by a
binary "aapt" (Android Asset Packagng Tool). It's source is located
under frameworks/base/tools/aapt.
I started by checking for upstream fixes to the platform/build or
platform/frameworks/base projects. After striking out, I began
debugging the android build via the use of: "make checkapi
showcommands" and then manually running the commands with "strace" to
see how each binary was involved and what output it generated.
After the first few hours of debugging, it became apparent that
out/target/common/obj/APPS/frameworks-res_intermediates/src/android/Manifest.java
file had comments which were being corrupted when aapt was generating
it. I was able to make some manual changes to the AndroidManifest.xml
file and get the build to pass (removing extra portions of the
comments).
Digging deeper via strace and then looking at various static link
sources, I found that during the AndroidManifest.xml comments
processing the #SystemApi token was being filtered out via a
String8.removeAll("#SystemApi") function call. Experimentally, I
removed this part of the processing. Lo and Behold! The build
worked. Taking a closer look at the removeAll function, I was able to
pin point a memcpy function as the part of the function which was
causing corruption.
I then researched memcpy a bit and noted that you are not supposed to
use memcpy on overlapping memory addresses, instead memmove was
preferred, because it makes a copy of the source prior to any changes
being made to the destination. After changing the use of memcpy to
memmove the build was fixed and all was well with the world!
As a good player in the open source world, I immediately thought I
should upstream this incredible feat of debugging to the master branch
of system/core. BUT, alas! The fix has been in the master branch
since November 11th 2014! And hasn't been brought into any of the
current development tags! grumble
https://android.googlesource.com/platform/system/core/+/dd060f01f68ee0e633e9cae24c4e565cda2032bd
I've since contacted the Google team about this change and let them
know of my experience in hopes that we may yet see this patch in
future release tags of Android.
Conclusion: apparently glibc is undergoeing some changes and some of
those have now filtered onto my Ubuntu boxes. Where previously the
memcpy usage was incorrect but still usable, it now causes the build
break I was seeing.
If you see this kind of error in your Android builds, and you're on a
newish version of Ubuntu or Debian distrobution, you may want to try
this simple patch and see if it helps.
Hash
Big up himself!
I do see the entries in my r8 code so you are probably safe running make update-api, and when that finishes then run your make command as normal.
Ok so first off,
Im brand new to android dev. This is my first attempt at any form of kernel anything. I have a limited knowledge of java and python, but no C.
I have a galaxy tab 4 sm-t330nu running 4.4.2. its running a qualcomm snapdragon 400 msm8226 cpu. im simply trying to do a test build with a vanilla kernel at this point. (also my build environment is the newest kali 1.1 and im loosely following the tutorial at https://github.com/offensive-security/kali-nethunter/wiki/Porting-Nethunter)
so i have all of the required dependencies (i hope), and ive downloaded my source from samsung opensource. unzipped and went through the available defconfigs. after finding "msm8226-sec_milletwifiue_defconfig" i decided it was the most likely candidate for my tablet. (when doing a custom recovery i remember it being "philz touch milletwifiue something)
Ive done my exports (arch= subarch= cross_compile=) and all seems well. When i run a build following exactly as the tutorial says (using the defconfig in their example as a test) i receive an error stating "must define variant_defconfig". So i instead do "make variant_defconfig=msm8974_sec_defconfig" and it builds great.
Now the issue:
When i change "msm8974_sec_defconfig" to my actual msm8226 i receive an error on every build that i cannot seem to workaround. (cut down for size)
CC arch/arm/kernel/armksyms.o
CC arch/arm/kernel/module.o
AS arch/arm/kernel/sleep.o
CC arch/arm/kernel/suspend.o
CC arch/arm/kernel/io.o
arch/arm/kernel/io.c: In function '_memcpy_fromio':
arch/arm/kernel/io.c:14:3: error: implicit declaration of function 'nop' [-Werror=implicit-function-declaration]
cc1: some warnings being treated as errors
make[1]: *** [arch/arm/kernel/io.o] Error 1
make: *** [arch/arm/kernel] Error 2
My exact bash line reads
make VARIANT_DEFCONFIG=msm8226-sec_milletwifiue_defconfig
Any assistance on clearing this up would be great
edit
although im not familiar with c, it seems to me that '_memcpy_fromio' is where the error lies. and my google searches tell me that the error is that a function is used without being declared. however i dont know if memcpy is a function? or is the function within class memcpy (dont know if c has classes just closest equivalent that i know of) how do i debug this code and declare what needs to be declared (more importantly, if this is a stock kernel thats used by thousands of devices, how can it possibly have an undeclared function?
/edit
found the answer! needed
#import linux/modules.h
#import linux/kernel.h
The conversion of my Android application to the iPhone ObjectX environment as described in the XMLVM user manual works almost fine on my MAC, but I end up with 3 errors in the resulting XCode:
The first two errors simply relate to missing files, namely:
org_w3c_dom_Node.h
android_app_DatePickerDialog_OnDateSetListener.h
These are clearly not files from the converted Android application. Where can I get these from?
The third is an error that keeps coming up in the file
java_lang_String.h
The error message is:
typedef NSMutableString java_lang_String: redefinition as different kind of symbol
This error has been reported before in the XMLVM user group but as far as I know has never been answered sufficiently.
About the first error:
this is part of the Android API that has not yet been implemented.
This is the reason why it can't find the files.
Now, the second problem is not actually an error, but a warning and shouldn't stop you form compiling.
If it does, it means that in your project you have set the option to make errors from these types of warnings.
You can safely turn this off and completely ignore this warning.
I'm porting some C++ code to Android using NDK and GCC. The code basically runs. At one point, when debugging in Eclipse, the call
Dabbler::Android::Factory* pFactory = new Dabbler::Android::Factory;
causes this error:
Thread [1] (Suspended: Signal 'SIGILL' received. Description: Illegal instruction.)
1 <symbol is not available> 0x812feb44
What does that mean? Has the compiler generated illegal code for some reason? I have a breakpoint in the constructor (which does nothing), and it's not hit. I have already done a full rebuild.
What could I be doing wrong to cause this problem?
Make sure that all functions with non-void return type have a return statement.
While some compilers automatically provide a default return value, others will send a SIGILL or SIGTRAP at runtime when trying to leave a function without a return value.
It means the CPU attempted to execute an instruction it didn't understand. This could be caused by corruption I guess, or maybe it's been compiled for the wrong architecture (in which case I would have thought the O/S would refuse to run the executable). Not entirely sure what the root issue is.
It could be some un-initialized function pointer, in particular if you have corrupted memory (then the bogus vtable of C++ bad pointers to invalid objects might give that).
BTW gdb watchpoints & tracepoints, and also valgrind might be useful (if available) to debug such issues. Or some address sanitizer.
LeetCode's online compiler and dev environment generates SIGILL errors for mistakes that do not generate the same error in my desktop IDE.
For example, array access with an out-of-bounds index:
["foo", "bar"][2]
LeetCode's compiler shows only the error:
Runtime Error
process exited with signal SIGILL
in a local Xcode playground this same code instead results in the error:
error: Execution was interrupted, reason: EXC_BREAKPOINT (code=1, subcode=0x18f2ea5d8).
The process has been left at the point where it was interrupted, use "thread return -x" to return to the state before expression evaluation.
Only in a full Xcode project compilation and run does it report the actual error:
Thread 1: Fatal error: Index out of range