Android 64bit binary or JNI library segfaults on entry?
lazarus / 43-Android

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Artlav · 2022-11-30 20:54

I was trying to get aarch64 JNI or native android binaries to work,
and they crash on entry.
Doing the same for arm 32bit and x86 android works just fine, be it
hello world or complex app.

The very first instruction in system unit FPC_LIB_START_ANDROID, stp
x29, x30, [sp, #-16]!, causes a segfault.

In case of JNI library, this is what it error log looks like after
System.loadLibrary("app");
Code: [Select]11-30 18:58:50.049 11835 11835 F DEBUG   : Revision: '5'
11-30 18:58:50.049 11835 11835 F DEBUG   : ABI: 'arm64'
11-30 18:58:50.049 11835 11835 F DEBUG   : Processor: '7'
11-30 18:58:50.049 11835 11835 F DEBUG   : Timestamp: 2022-11-30
18:58:49.854873590+0100
11-30 18:58:50.049 11835 11835 F DEBUG   : Process uptime: 1s
11-30 18:58:50.049 11835 11835 F DEBUG   : Cmdline: com.pascal.sdi
11-30 18:58:50.049 11835 11835 F DEBUG   : pid: 11799, tid: 11799,
name: com.pascal.sdi  >>> com.pascal.sdi <<<
11-30 18:58:50.049 11835 11835 F DEBUG   : uid: 10337
11-30 18:58:50.049 11835 11835 F DEBUG   : tagged_addr_ctrl:
0000000000000001 (PR_TAGGED_ADDR_ENABLE)
11-30 18:58:50.049 11835 11835 F DEBUG   : pac_enabled_keys:
000000000000000f (PR_PAC_APIAKEY, PR_PAC_APIBKEY, PR_PAC_APDAKEY,
PR_PAC_APDBKEY)
11-30 18:58:50.049 11835 11835 F DEBUG   : signal 11 (SIGSEGV), code 1
(SEGV_MAPERR), fault addr 0x000000000000a9d8
11-30 18:58:50.049 11835 11835 F DEBUG   :     x0  0000000000000006 
x1  0000007fe23d6e98  x2  0000007fe23d6ed0  x3  0000007fb8c923d0
11-30 18:58:50.049 11835 11835 F DEBUG   :     x4  0000007fb8c92400 
x5  0000000001414d4c  x6  0000007fb8c923f6  x7  6c2f34366d72612f
11-30 18:58:50.049 11835 11835 F DEBUG   :     x8  0000007fb9f9d5d8 
x9  0000007fb8c92600  x10 000000000000001f  x11 0000000000000016
11-30 18:58:50.049 11835 11835 F DEBUG   :     x12 0000000000000016 
x13 0000000000000050  x14 0000000000000000  x15 0000000000000000
11-30 18:58:50.049 11835 11835 F DEBUG   :     x16 0000000000000001 
x17 0000007fb9f65080  x18 0000007fb9760000  x19 0000007fb8d04ef8
11-30 18:58:50.049 11835 11835 F DEBUG   :     x20 0000007fb8c92600 
x21 0000007c701dd9f0  x22 0000000000000000  x23 0000007fb9e72270
11-30 18:58:50.049 11835 11835 F DEBUG   :     x24 0000007fb9e6d420 
x25 0000007fb9f9e000  x26 0000007fb9e72e6c  x27 0000000000000001
11-30 18:58:50.049 11835 11835 F DEBUG   :     x28 000000000000a9d8 
x29 0000007fe23d2000
11-30 18:58:50.049 11835 11835 F DEBUG   :     lr  0000007fb9ebab2c 
sp  0000007fe23d1fc0  pc  000000000000a9d8  pst 0000000080001800
11-30 18:58:50.049 11835 11835 F DEBUG   : backtrace:
11-30 18:58:50.049 11835 11835 F DEBUG   :       #00 pc
000000000000a9d8  <unknown>
11-30 18:58:50.049 11835 11835 F DEBUG   :       #01 pc
0000000000053b28  /apex/com.android.runtime/bin/linker64
(__dl__ZN6soinfo17call_constructorsEv+752) (BuildId:
3afde223eb00a3453f5a973db57a4d66)
11-30 18:58:50.049 11835 11835 F DEBUG   :       #02 pc
000000000003e0f4  /apex/com.android.runtime/bin/linker64
(__dl__Z9do_dlopenPKciPK17android_dlextinfoPKv+2000) (BuildId:
3afde223eb00a3453f5a973db57a4d66)
11-30 18:58:50.049 11835 11835 F DEBUG   :       #03 pc
00000000000390fc  /apex/com.android.runtime/bin/linker64
(__loader_android_dlopen_ext+84) (BuildId:
3afde223eb00a3453f5a973db57a4d66)
11-30 18:58:50.049 11835 11835 F DEBUG   :       #04 pc
000000000000110c  /apex/com.android.runtime/lib64/bionic/libdl.so
(android_dlopen_ext+20) (BuildId: c3485a51b95e45a16eaf027ef6a211fb)
11-30 18:58:50.049 11835 11835 F DEBUG   :       #05 pc
000000000001cedc  /apex/com.android.art/lib64/libnativeloader.so
(android::NativeLoaderNamespace::Load(char const*) const+184)
(BuildId: 9b40489a2564965276776aae44400621)
11-30 18:58:50.049 11835 11835 F DEBUG   :       #06 pc
000000000000ce20  /apex/com.android.art/lib64/libnativeloader.so
(OpenNativeLibraryInNamespace+68) (BuildId:
9b40489a2564965276776aae44400621)
11-30 18:58:50.049 11835 11835 F DEBUG   :       #07 pc
000000000000c564  /apex/com.android.art/lib64/libnativeloader.so
(OpenNativeLibrary+132) (BuildId: 9b40489a2564965276776aae44400621)
...
64 more lines of backtrace

In case of a native binary, it's just a segmentation fault.
Curiously enough, a simple hello world static aarch64 binary built
with -Tlinux does work just fine on android, but one built with
-Tandroid crashes on entry.

Is this a compiler bug, is it not supposed to work at all, or am i
doing something wrong?

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Artlav · 2022-12-01 14:42

Ok, this turned out to be a user error.
For some unclear reason "--defsym CPU64=1" was not passed to the
assembler when system unit was built, and that screwed up prt0.as and
dllprt0.as and made .init_array section malformed.
Doing a fully clean recompile of everything fixed the issue.