Release build for armv7 fails with SIGILL

[glebpom]

Hi!

I'm working on a project with armv7 target. There are different binaries produced from the same codebase. I'm observing a strange behavior with one of the binaries only in release build - an "Illegal instruction" error. Debug build and other binaries (debug and release) work well.

gdb output:

(gdb) run
Starting program: /home/pi/lanlord
thread panicked while processing panic. aborting.

Program received signal SIGILL, Illegal instruction.
0x004569d4 in new_v1 () at /checkout/src/libcore/fmt/mod.rs:346
346	/checkout/src/libcore/fmt/mod.rs: No such file or directory.
(gdb) bt
#0  0x004569d4 in new_v1 () at /checkout/src/libcore/fmt/mod.rs:346
#1  std::panicking::rust_panic_with_hook::ha5eff468dabed44e () at libstd/panicking.rs:445
#2  0x00458d40 in std::panicking::begin_panic_fmt::h127c95263e9d91e1 () at libstd/panicking.rs:350
#3  0x00458d08 in rust_begin_unwind () at libstd/panicking.rs:328
#4  0x00478068 in core::panicking::panic_fmt::h61b193aee9efb823 () at libcore/panicking.rs:71
#5  0x00461d44 in core::result::unwrap_failed::h7903c94ac7c61055 () at /checkout/src/libcore/macros.rs:26
#6  0x004687a8 in _$LT$std..thread..local..LocalKey$LT$T$GT$$GT$::try_with::h4b43a500d36f0788 () at libcore/result.rs:809
#7  0x00456c2c in with<std::thread::Thread,closure> () at libstd/sys_common/thread_info.rs:26
#8  current_thread () at libstd/sys_common/thread_info.rs:39
#9  default_hook () at libstd/panicking.rs:197
#10 std::panicking::rust_panic_with_hook::ha5eff468dabed44e () at libstd/panicking.rs:463
#11 0x00458d40 in std::panicking::begin_panic_fmt::h127c95263e9d91e1 () at libstd/panicking.rs:350
#12 0x00458d08 in rust_begin_unwind () at libstd/panicking.rs:328
#13 0x00478068 in core::panicking::panic_fmt::h61b193aee9efb823 () at libcore/panicking.rs:71
#14 0x00461d44 in core::result::unwrap_failed::h7903c94ac7c61055 () at /checkout/src/libcore/macros.rs:26
#15 0x004687a8 in _$LT$std..thread..local..LocalKey$LT$T$GT$$GT$::try_with::h4b43a500d36f0788 () at libcore/result.rs:809
#16 0x00456c2c in with<std::thread::Thread,closure> () at libstd/sys_common/thread_info.rs:26
#17 current_thread () at libstd/sys_common/thread_info.rs:39
#18 default_hook () at libstd/panicking.rs:197
#19 std::panicking::rust_panic_with_hook::ha5eff468dabed44e () at libstd/panicking.rs:463
#20 0x00456948 in std::panicking::begin_panic::h4910a9b8cb3bd811 () at libstd/panicking.rs:397
#21 0x0046826c in _$LT$std..thread..local..LocalKey$LT$T$GT$$GT$::with::h71395f6ddd67275a () at libstd/sys_common/thread_info.rs:47
#22 0x000a5784 in main ()
(gdb) quit

https://github.com/rust-lang/rust/blob/1.27.0/src/libstd/sys_common/thread_info.rs#L47

[kennytm]

Hi, could you post the entire target triple (armv7-???-???), and the Rust version (output of rustc -vV)?

Would using Rust nightly (which contains a fix for #48967) solve the problem?

[glebpom]

Hi, the target is armv7-unknown-linux-musleabihf, rust version is 1.27.0 from rustup.

I tried the latest nightly, and it fails with another error:

(gdb) run
Starting program: /home/pi/lanlord

Program received signal SIGSEGV, Segmentation fault.
clone<std::thread::Inner> () at /checkout/src/liballoc/sync.rs:718
718	/checkout/src/liballoc/sync.rs: No such file or directory.
(gdb) bt
#0  clone<std::thread::Inner> () at /checkout/src/liballoc/sync.rs:718
#1  clone () at libstd/thread/mod.rs:1001
#2  {{closure}} () at libstd/sys_common/thread_info.rs:39
#3  {{closure}}<std::thread::Thread,closure> () at libstd/sys_common/thread_info.rs:33
#4  _$LT$std..thread..local..LocalKey$LT$T$GT$$GT$::try_with::h12e294fc1498f32b ()
    at libstd/thread/local.rs:294
#5  0x003d796c in std::panicking::rust_panic_with_hook::h2e0e3adddefcec58 ()
    at libstd/sys_common/thread_info.rs:26
#6  0x003d7674 in std::panicking::begin_panic::h024edfc32ac8659c ()
    at libstd/panicking.rs:409
#7  0x003e5da8 in {{closure}} () at libstd/sys_common/thread_info.rs:47
#8  try_with<core::cell::RefCell<core::option::Option<std::sys_common::thread_info::ThreadInfo>>,closure,()> () at libstd/thread/local.rs:294
#9  _$LT$std..thread..local..LocalKey$LT$T$GT$$GT$::with::hd042109b71d60bfc ()
    at libstd/thread/local.rs:248
#10 0x004d67f0 in main ()

[glebpom]

I disabled LTO and it helped. Will also try to upgrade musl to the latest version, and try with lto enabled

[sanxiyn]

Can you try again? As far as I can tell, there is no way for anyone other than the reporter to reproduce the issue, so it is hard to make any progress.

[glebpom]

I think it's no longer reproducible.