MULADDC_X2_CORE ARM crashes the linker (ld) (Android build)

[0x416c69]

Summary

Linker crashes only when compiling with optimization and LTO (I haven't tested if LTO is related or not, but the debug builds, i.e. no optimization compiles which I suspect is because MULADDC_CANNOT_USE_R7 is defined when compiling in debug mode which doesn't use the inline assembly at all) (As a work around I'm undefining MBEDTLS_HAVE_ASM)

By the way the build is in THUMB-v2.

 invalid instruction, any one of the following would fix this:
        ldr.w    r0, [r6,  #-4]
        ^
<inline asm>:4:25: note: too few operands for instruction
        ldr.w    r0, [r6,  #-4]
                               ^
<inline asm>:4:15: note: invalid operand for instruction
        ldr.w    r0, [r6,  #-4]
                     ^
 invalid instruction, any one of the following would fix this:
        ldr.w    r5, [r1, #-4]
        ^
<inline asm>:5:24: note: too few operands for instruction
        ldr.w    r5, [r1, #-4]
                              ^
<inline asm>:5:15: note: invalid operand for instruction
        ldr.w    r5, [r1, #-4]
                     ^
 invalid instruction, any one of the following would fix this:
        str.w    r3, [r1, #-8]
        ^
<inline asm>:8:24: note: too few operands for instruction
        str.w    r3, [r1, #-8]
                              ^
<inline asm>:8:15: note: invalid operand for instruction
        str.w    r3, [r1, #-8]
                     ^
 invalid instruction, any one of the following would fix this:
        str.w    r5, [r1, #-4]
        ^
<inline asm>:9:24: note: too few operands for instruction
        str.w    r5, [r1, #-4]
                              ^
<inline asm>:9:15: note: invalid operand for instruction
        str.w    r5, [r1, #-4]
                     ^
 invalid instruction, any one of the following would fix this:
        ldr.w    r0, [r6,  #-4]
        ^
<inline asm>:13:25: note: too few operands for instruction
        ldr.w    r0, [r6,  #-4]
                               ^
<inline asm>:13:15: note: invalid operand for instruction
        ldr.w    r0, [r6,  #-4]
                     ^
 invalid instruction, any one of the following would fix this:
        ldr.w    r5, [r1, #-4]
        ^
<inline asm>:14:24: note: too few operands for instruction
        ldr.w    r5, [r1, #-4]
                              ^
<inline asm>:14:15: note: invalid operand for instruction
        ldr.w    r5, [r1, #-4]
                     ^
 invalid instruction, any one of the following would fix this:
        str.w    r3, [r1, #-8]
        ^
<inline asm>:17:24: note: too few operands for instruction
        str.w    r3, [r1, #-8]
                              ^
<inline asm>:17:15: note: invalid operand for instruction
        str.w    r3, [r1, #-8]
                     ^
 invalid instruction, any one of the following would fix this:
        str.w    r5, [r1, #-4]
        ^
<inline asm>:18:24: note: too few operands for instruction
        str.w    r5, [r1, #-4]
                              ^
<inline asm>:18:15: note: invalid operand for instruction
        str.w    r5, [r1, #-4]
                     ^
 invalid instruction, any one of the following would fix this:
        ldr.w    r0, [r6,  #-4]
        ^
<inline asm>:22:25: note: too few operands for instruction
        ldr.w    r0, [r6,  #-4]
                               ^
<inline asm>:22:15: note: invalid operand for instruction
        ldr.w    r0, [r6,  #-4]
                     ^
 invalid instruction, any one of the following would fix this:
        ldr.w    r5, [r1, #-4]
        ^
<inline asm>:23:24: note: too few operands for instruction
        ldr.w    r5, [r1, #-4]
                              ^
<inline asm>:23:15: note: invalid operand for instruction
        ldr.w    r5, [r1, #-4]
                     ^
 invalid instruction, any one of the following would fix this:
        str.w    r3, [r1, #-8]
        ^
<inline asm>:26:24: note: too few operands for instruction
        str.w    r3, [r1, #-8]
                              ^
<inline asm>:26:15: note: invalid operand for instruction
        str.w    r3, [r1, #-8]
                     ^
 invalid instruction, any one of the following would fix this:
        str.w    r5, [r1, #-4]
        ^
<inline asm>:27:24: note: too few operands for instruction
        str.w    r5, [r1, #-4]
                              ^
<inline asm>:27:15: note: invalid operand for instruction
        str.w    r5, [r1, #-4]
                     ^
 invalid instruction, any one of the following would fix this:
        ldr.w    r0, [r6,  #-4]
        ^
<inline asm>:31:25: note: too few operands for instruction
        ldr.w    r0, [r6,  #-4]
                               ^
<inline asm>:31:15: note: invalid operand for instruction
        ldr.w    r0, [r6,  #-4]
                     ^
 invalid instruction, any one of the following would fix this:
        ldr.w    r5, [r1, #-4]
        ^
<inline asm>:32:24: note: too few operands for instruction
        ldr.w    r5, [r1, #-4]
                              ^
<inline asm>:32:15: note: invalid operand for instruction
        ldr.w    r5, [r1, #-4]
                     ^
 invalid instruction, any one of the following would fix this:
        str.w    r3, [r1, #-8]
        ^
<inline asm>:35:24: note: too few operands for instruction
        str.w    r3, [r1, #-8]
                              ^
<inline asm>:35:15: note: invalid operand for instruction
        str.w    r3, [r1, #-8]
                     ^
 invalid instruction, any one of the following would fix this:
        str.w    r5, [r1, #-4]
        ^
<inline asm>:36:24: note: too few operands for instruction
        str.w    r5, [r1, #-4]
                              ^
<inline asm>:36:15: note: invalid operand for instruction
        str.w    r5, [r1, #-4]
                     ^
LLVM ERROR: Error parsing inline asm
PLEASE submit a bug report to https://github.com/android-ndk/ndk/issues and include the crash backtrace.
Stack dump:
0.	Program arguments: D:\\android-ndk-r23\\toolchains\\llvm\\prebuilt\\windows-x86_64\\bin\\ld --sysroot=D:\\android-ndk-r23\\toolchains\\llvm\\prebuilt\\windows-x86_64\\sysroot -z noexecstack -EL --warn-shared-textrel -z now -z relro -z max-page-size=4096 -X --hash-style=both --enable-new-dtags --eh-frame-hdr -m armelf_linux_eabi -shared -o obj/ARM/Beta/UnitTestLib\\libUnitTestLib.so D:\\android-ndk-r23\\toolchains\\llvm\\prebuilt\\windows-x86_64\\sysroot/usr/lib/arm-linux-androideabi/16\\crtbegin_so.o -LD:\\android-ndk-r23\\toolchains\\llvm\\prebuilt\\windows-x86_64\\lib64\\clang\\12.0.9\\lib\\linux\\arm -LD:\\android-ndk-r23\\toolchains\\llvm\\prebuilt\\windows-x86_64\\sysroot/usr/lib/arm-linux-androideabi/16 -LD:\\android-ndk-r23\\toolchains\\llvm\\prebuilt\\windows-x86_64\\sysroot/usr/lib/arm-linux-androideabi -LD:\\android-ndk-r23\\toolchains\\llvm\\prebuilt\\windows-x86_64\\sysroot/usr/lib/../lib -LD:\\android-ndk-r23\\toolchains\\llvm\\prebuilt\\windows-x86_64\\sysroot/usr/lib -plugin D:\\android-ndk-r23\\toolchains\\llvm\\prebuilt\\windows-x86_64\\bin\\..\\lib64\\LLVMgold.dll -plugin-opt=mcpu=generic -soname=libUnitTestLib.so -rpath-link=D:\\android-ndk-r23\\toolchains\\llvm\\prebuilt\\windows-x86_64\\sysroot\\usr\\lib\\arm-linux-androideabi -rpath-link=D:\\android-ndk-r23\\toolchains\\llvm\\prebuilt\\windows-x86_64\\sysroot\\usr\\lib\\arm-linux-androideabi\\16 -LD:\\android-ndk-r23\\toolchains\\llvm\\prebuilt\\windows-x86_64\\sysroot\\usr\\lib\\arm-linux-androideabi -LD:\\android-ndk-r23\\toolchains\\llvm\\prebuilt\\windows-x86_64\\sysroot\\usr\\lib\\arm-linux-androideabi\\16 -LD:\\android-ndk-r23\\toolchains\\arm-linux-androideabi-4.9\\prebuilt\\windows-x86_64\\lib\\gcc\\arm-linux-androideabi\\4.9.x\\armv7-a -LD:\\android-ndk-r23\\sources\\cxx-stl\\llvm-libc++\\libs\\armeabi-v7a --no-undefined -z relro -z now -z noexecstack obj/ARM/Beta/UnitTestLib\\tests.o obj/ARM/Beta/UnitTestLib\\Exports.o D:\\[Redacted]\\ARM\\Beta\\libsdk.a D:\\[Redacted]\\ARM\\Beta\\libmbedtls.a D:\\[Redacted]\\ARM\\Beta\\libcurl.a D:\\[Redacted]\\ARM\\Beta\\libzlib.a -lc++_shared -lc++abi -llog -landroid -lm -llog D:\\android-ndk-r23\\toolchains\\llvm\\prebuilt\\windows-x86_64\\lib64\\clang\\12.0.9\\lib\\linux\\libclang_rt.builtins-arm-android.a -l:libunwind.a -ldl -lc D:\\android-ndk-r23\\toolchains\\llvm\\prebuilt\\windows-x86_64\\lib64\\clang\\12.0.9\\lib\\linux\\libclang_rt.builtins-arm-android.a -l:libunwind.a -ldl D:\\android-ndk-r23\\toolchains\\llvm\\prebuilt\\windows-x86_64\\sysroot/usr/lib/arm-linux-androideabi/16\\crtend_so.o
1.	Running pass 'Function Pass Manager' on module 'ld-temp.o'.
2.	Running pass 'ARM Assembly Printer' on function '@mbedtls_mpi_mul_int'
 #0 0x00007ff6ed584e76 (D:\android-ndk-r23\toolchains\llvm\prebuilt\windows-x86_64\bin\ld.exe+0xc4e76)
 #1 0x00007ffc10401881 (C:\WINDOWS\System32\ucrtbase.dll+0x71881)
 #2 0x00007ffc10402851 (C:\WINDOWS\System32\ucrtbase.dll+0x72851)
 #3 0x00007ff6ed582e1e (D:\android-ndk-r23\toolchains\llvm\prebuilt\windows-x86_64\bin\ld.exe+0xc2e1e)
 #4 0x00007ff6ed582c55 (D:\android-ndk-r23\toolchains\llvm\prebuilt\windows-x86_64\bin\ld.exe+0xc2c55)
 #5 0x00007ff6edef5ee7 (D:\android-ndk-r23\toolchains\llvm\prebuilt\windows-x86_64\bin\ld.exe+0xa35ee7)
 #6 0x00007ff6edef76c8 (D:\android-ndk-r23\toolchains\llvm\prebuilt\windows-x86_64\bin\ld.exe+0xa376c8)
 #7 0x00007ff6edeceb7f (D:\android-ndk-r23\toolchains\llvm\prebuilt\windows-x86_64\bin\ld.exe+0xa0eb7f)
 #8 0x00007ff6ed6c8f84 (D:\android-ndk-r23\toolchains\llvm\prebuilt\windows-x86_64\bin\ld.exe+0x208f84)
 #9 0x00007ff6edb6e0b3 (D:\android-ndk-r23\toolchains\llvm\prebuilt\windows-x86_64\bin\ld.exe+0x6ae0b3)
#10 0x00007ff6edac9388 (D:\android-ndk-r23\toolchains\llvm\prebuilt\windows-x86_64\bin\ld.exe+0x609388)
#11 0x00007ff6edacfb93 (D:\android-ndk-r23\toolchains\llvm\prebuilt\windows-x86_64\bin\ld.exe+0x60fb93)
#12 0x00007ff6edac9bb2 (D:\android-ndk-r23\toolchains\llvm\prebuilt\windows-x86_64\bin\ld.exe+0x609bb2)
#13 0x00007ff6ee006ca6 (D:\android-ndk-r23\toolchains\llvm\prebuilt\windows-x86_64\bin\ld.exe+0xb46ca6)
#14 0x00007ff6ee00600b (D:\android-ndk-r23\toolchains\llvm\prebuilt\windows-x86_64\bin\ld.exe+0xb4600b)
#15 0x00007ff6ed6fd803 (D:\android-ndk-r23\toolchains\llvm\prebuilt\windows-x86_64\bin\ld.exe+0x23d803)
#16 0x00007ff6ed6fcbf5 (D:\android-ndk-r23\toolchains\llvm\prebuilt\windows-x86_64\bin\ld.exe+0x23cbf5)
#17 0x00007ff6ed8de091 (D:\android-ndk-r23\toolchains\llvm\prebuilt\windows-x86_64\bin\ld.exe+0x41e091)
#18 0x00007ff6ed552f93 (D:\android-ndk-r23\toolchains\llvm\prebuilt\windows-x86_64\bin\ld.exe+0x92f93)
#19 0x00007ff6ed54bb1e (D:\android-ndk-r23\toolchains\llvm\prebuilt\windows-x86_64\bin\ld.exe+0x8bb1e)
#20 0x00007ff6ed539f54 (D:\android-ndk-r23\toolchains\llvm\prebuilt\windows-x86_64\bin\ld.exe+0x79f54)
#21 0x00007ff6ed5387c2 (D:\android-ndk-r23\toolchains\llvm\prebuilt\windows-x86_64\bin\ld.exe+0x787c2)
#22 0x00007ff6ed4c1f7c (D:\android-ndk-r23\toolchains\llvm\prebuilt\windows-x86_64\bin\ld.exe+0x1f7c)
#23 0x00007ff6ed4c16cb (D:\android-ndk-r23\toolchains\llvm\prebuilt\windows-x86_64\bin\ld.exe+0x16cb)
#24 0x00007ff6ed4c1395 (D:\android-ndk-r23\toolchains\llvm\prebuilt\windows-x86_64\bin\ld.exe+0x1395)
#25 0x00007ff6ed4c14c8 (D:\android-ndk-r23\toolchains\llvm\prebuilt\windows-x86_64\bin\ld.exe+0x14c8)
#26 0x00007ffc11d47034 (C:\WINDOWS\System32\KERNEL32.DLL+0x17034)
#27 0x00007ffc12ca2651 (C:\WINDOWS\SYSTEM32\ntdll.dll+0x52651)
clang: error: linker command failed due to signal (use -v to see invocation)

System information

Mbed TLS version (number or commit id): 0x03020100
Operating system and version: Windows 10, cross compiling for android
Configuration (if not default, please attach mbedtls_config.h): I believe it is the default
Compiler and options (if you used a pre-built binary, please indicate how you obtained it): Visible in the summary
Additional environment information:

Expected behavior

To not crash.

Actual behavior

It crashes.

Steps to reproduce

Compile and link for ARMv7-A THUMB-2 with optimization and -flto

Additional information

Nah

[gilles-peskine-arm]

This looks like the same issue as #6089,
which will be fixed in the next release. Can you please try either the development branch, or just the patch from #6090 ?

If not, can you please share which compiler options are used, in particular the exact target? I can see the compiler version in the log, but I don't know exactly how the Android NDK settings map to compiler options.

[0x416c69]

According to https://developer.arm.com/documentation/ddi0406/latest
Head over to A8.8.63, if you have a look at Encoding T3, you shall see that ldr.w does not support negative indexing.

I believe you're using LDR.W because of this comment:

Make sure loop is 4-byte aligned to avoid stalls upon repeated non-word aligned instructions in some microarchitectures.

But how does this make any sense on thumb2 environment? What is this argument even based on?

[0x416c69]

@gilles-peskine-arm

Can you please try either the development branch, or just the patch from #6090 ?

Yeah, before you replied I wasn't aware of the PR, in fact I've fixed it by getting rid of the .w suffix and I was writing the comment for it and I was going to make a PR but that PR looks to be right. Thanks!

I hope the next release comes soon otherwise some other poor soul is gonna take some time to look into this again 😁