UBsan support on ARM64

[butterl]

Description

I ‘ve tried modified the android build script in AOSP to build the ubsan related libs

libclang_rt.ubsan_standalone-arm-android.so 
libclang_rt.ubsan_standalone-aarch64-android.so 
libubsan.a

with flags added in Android.mk

LOCAL_CLANG := true
LOCAL_UNDEFINED_SANITIZER := true
LOCAL_SANITIZE:= undefined
LOCAL_CFLAGS += -g -Wall -Werror -std=gnu++11 -Wno-missing-field-initializers -O0 -fsanitize=undefined

And the so have been linked to the test app

butter@desktop:~/code/prebuilts$ ./gcc/linux-x86/aarch64/aarch64-linux-android-4.9/aarch64-linux-android/bin/objdump -x ../out/target/product/generic_arm64/obj/NATIVE_TESTS/gatekeeper-unit-tests_intermediates/gatekeeper-unit-tests | grep NEEDED
NEEDED libclang_rt.ubsan_standalone-aarch64-android.so

So I added a NULL pointer UB demo to a gtest module like below to see if ubsan works:

static uint8_t gtest_UBsan_demo(void)
{
uint8_t test = 32;
uint8_t *undefined = NULL;
if (test)
{
*undefined = test;
}
return 0;
}

Then build and push the test gtest app and libclang_rt.ubsan_standalone-aarch64-android.so to my board but the simulation backtrace got no Ubsan information

backtrace:
00 pc 0000000000069bac /system/lib64/libc.so (tgkill+8)
01 pc 000000000001da48 /system/lib64/libc.so (abort+80)
02 pc 000000000003a878 /data/gatekeeper-unit-tests (_ZL16gtest_UBsan_demov+104)
03 pc 000000000002bf4c /data/gatekeeper-unit-tests (_ZL11make_bufferj+16)
04 pc 000000000002a044 /data/gatekeeper-unit-tests (_ZN54RoundTripTest_EnrollRequestNullEnrolledNullHandle_Test8TestBodyEv+52)
05 pc 00000000000845d0 /data/gatekeeper-unit-tests (_ZN7testing4Test3RunEv+392)
06 pc 000000000008504c /data/gatekeeper-unit-tests (_ZN7testing8TestInfo3RunEv+404)
07 pc 00000000000854f4 /data/gatekeeper-unit-tests (_ZN7testing8TestCase3RunEv+240)
08 pc 000000000008bc80 /data/gatekeeper-unit-tests (_ZN7testing8internal12UnitTestImpl11RunAllTestsEv+1112)
09 pc 000000000008b7f4 /data/gatekeeper-unit-tests (_ZN7testing8UnitTest3RunEv+184)
10 pc 000000000007ee84 /data/gatekeeper-unit-tests (main+64)
11 pc 000000000001b744 /system/lib64/libc.so (__libc_init+88)
12 pc 000000000002935c /data/gatekeeper-unit-tests (do_arm64_start+80)

Am I missing something that UBsan needed to run on the ARM64 board?

[DanAlbert]

Follow https://source.android.com/source/report-bugs to file a bug for AOSP. This is just for the NDK.