[SR-4443] Android: Cannot run swift executable on Android 7.0 emulator (armv7) as it is not a PIE

[swift-ci]

Previous ID	SR-4443
Radar	None
Original Reporter	qasim (JIRA User)
Type	Bug
Status	Resolved
Resolution	Done

Additional Detail from JIRA

Votes	3
Component/s	Compiler
Labels	Bug, Android
Assignee	jblatecky (JIRA)
Priority	Medium

md5: c637650368058adb0695bd0eb668326a

relates to:

• SR-5405 Security: Swift on Linux not compiled as position independent executable

Issue Description:

I'm having trouble running a compiled swift file on an Android 7.0 emulator. I've set up swift based on https://github.com/apple/swift/blob/master/docs/Android.md, and the error I get on device is:

"/data/local/tmp/hello": error: only position independent executables (PIE) are supported. Aborted

Naively, I thought maybe I can pass -Xlinker -pie to the swiftc command to build hello.swift, but that results in the following when I execute the produced file:

CANNOT LINK EXECUTABLE "./hello": cannot locate symbol "__atomic_load" referenced by "/data/local/tmp/libswiftCore.so"... Aborted

I'm using android-ndk-r14b, and built the swift compiler for API level 21. All other steps seem to have run fine except for running the executable at the end.

[belkadan]

We should probably just make everything PIE on Android. I don't think we have any non-PIE features.

[swift-ci]

Comment by Qasim Iqbal (JIRA)

@belkadan Agreed. Is this something I could do with flags on my current built swiftc, or does it have to do with how Swift itself is built? I should learn more about this 😃

[swift-ci]

Comment by Amr Aboelela (JIRA)

@milseman Can you help in this? How can we generate all .so libraries with -pie ?

[swift-ci]

Comment by Amr Aboelela (JIRA)

Adding @modocache

[milseman]

My guess is that you'll want to append to SWIFT_RUNTIME_CORE_CXX_FLAGS and maybe CMAKE_CXX_FLAGS on Android. If you look at e.g. swift/CMakeLists.txt and swift/stdlib/public/CMakeLists.txt, there are conditional additions based on platform. Unfortunately I'm not too well versed beyond that.

@belkadan I think this could be a good starter task and Amr seems motivated. Could you help give direction?

[swift-ci]

Comment by Amr Aboelela (JIRA)

Adding @gottesmm

[swift-ci]

Comment by Julien Blatecky (JIRA)

Hi! I'm encountering the same problem on Android and I found a PR that seems to be similar to what it's intended to be done here. It was about disabling PIC on Windows : https://github.com/apple/swift/pull/6407/files.

I'm testing a modification on this point to be able to run a Swift library on Android 7, if it works, I could make a PR on Github.

[milseman]

If that works, please do!

[swift-ci]

Comment by Amr Aboelela (JIRA)

I tried with -fno-pic and I got error:
/usr/bin/ld.gold: error: lib/libswiftDemangling.a(Remangler.cpp.o): requires dynamic R_X86_64_PC32 reloc against '_Znwm' which may overflow at runtime; recompile with -fPIC
/usr/bin/ld.gold: error: lib/libswiftDemangling.a(Remangler.cpp.o): requires dynamic R_X86_64_PC32 reloc against '_Znwm' which may overflow at runtime; recompile with -fPIC
/usr/bin/ld.gold: error: lib/libswiftDemangling.a(Remangler.cpp.o): requires dynamic R_X86_64_PC32 reloc against 'ZNSt7_cxx1112basic_stringIcSt11char_traitsIcESaIcEE9_M_mutateEmmPKcm' which may overflow at runtime; recompile with -fPIC
clang: error: linker command failed with exit code 1 (use -v to see invocation)
ninja: build stopped: subcommand failed.

[swift-ci]

Comment by Julien Blatecky (JIRA)

I tried with -fpie and -fpic for Android and the "non-PIE" problem seems to have gone. But the missing "__atomic_load" seems to persist so I searched the NDK doc and I found that we need "-latomic" to build for Android NDK. In the AddSwift.cmake file the flag is set for Linux target, not for Android. I'm currently testing it with this flag and if it works I'll open a Pull Request.

[swift-ci]

Comment by Amr Aboelela (JIRA)

I tried with:
list(APPEND SWIFT_RUNTIME_CORE_CXX_FLAGS "-fpie")
in public/CMakeLists.txt

And I got this error:
swift/stdlib/public/stubs/LibcShims.cpp:32:1: error: static_assert failed "__swift_ssize_t must be defined as equivalent to ssize_t"
static_assert(std::is_same<ssize_t, swift::__swift_ssize_t>::value,

[swift-ci]

Comment by Amr Aboelela (JIRA)

I am still getting this error even after commenting out -fpie line:

swift/stdlib/public/stubs/LibcShims.cpp:32:1: error: static_assert failed "__swift_ssize_t must be defined as equivalent to ssize_t"
static_assert(std::is_same<ssize_t, swift::__swift_ssize_t>::value,
^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Should I create a separate bug for this?

[milseman]

Yes please

[swift-ci]

Comment by Amr Aboelela (JIRA)

Done https://bugs.swift.org/browse/SR-5059

[swift-ci]

Comment by Amr Aboelela (JIRA)

This PR #9869

Fixed the libatomic issue, but now I am getting:

CANNOT LINK EXECUTABLE: could not load library "libswiftCore.so" needed by "/data/local/tmp/hello"; caused by could not load library "libicudata.so" needed by "libswiftCore.so"; caused by library "libicudata.so" not found

Because in that PR, he also added "-licudata" "-licui18n" "-licuuc" so not sure if we really need those libraries.