1.55.0 segfault compiling stage1 rustc_codegen_llvm on powerpc64le

[infinity0]

Failure log (warning very large): 1.55

There was no failure on 1.54; the same version of LLVM was used in both cases - 12.0.1 (Debian version 1:12.0.1-9)

The only change made to rustc_codegen_llvm between 1.54 and 1.55 was #86416 so CC @Amanieu .

There was a later MR #88350 to fix something on powerpc64, however this just mentions "lack of support" rather than a segfault, so I don't know if this is related. Shall I try backporting it onto 1.55 in the meantime?

I will continue trying to debug the segfault.

The output contains the following stack-trace-like dump, not sure if it's useful:

/<<PKGBUILDDIR>>/build/powerpc64le-unknown-linux-gnu/stage1/lib/librustc_driver-8a51db685c3a3652.so(+0x786b6c)[0x7fffa65f6b6c]
linux-vdso64.so.1(__kernel_sigtramp_rt64+0x0)[0x7fffaa190514]
/<<PKGBUILDDIR>>/build/powerpc64le-unknown-linux-gnu/stage1/lib/librustc_driver-8a51db685c3a3652.so(+0x2b16f64)[0x7fffa8986f64]
/<<PKGBUILDDIR>>/build/powerpc64le-unknown-linux-gnu/stage1-rustc/release/deps/libcstr-786feb209dfce7ae.so(+0xc433c)[0x7fff87f7433c]
/<<PKGBUILDDIR>>/build/powerpc64le-unknown-linux-gnu/stage1-rustc/release/deps/libcstr-786feb209dfce7ae.so(+0xb1e50)[0x7fff87f61e50]
/<<PKGBUILDDIR>>/build/powerpc64le-unknown-linux-gnu/stage1-rustc/release/deps/libcstr-786feb209dfce7ae.so(_ZN10proc_macro12token_stream95_$LT$impl$u20$core..iter..traits..collect..IntoIterator$u20$for$u20$proc_macro..TokenStream$GT$9
into_iter17h32ab5102ba0e87e0E+0x28)[0x7fff87f47978]
/<<PKGBUILDDIR>>/build/powerpc64le-unknown-linux-gnu/stage1-rustc/release/deps/libcstr-786feb209dfce7ae.so(_ZN91_$LT$proc_macro2..imp..TokenStream$u20$as$u20$core..iter..traits..collect..IntoIterator$GT$9into_iter17h2efdc81b2e8ae367E+
0x1e0)[0x7fff87f35280]
/<<PKGBUILDDIR>>/build/powerpc64le-unknown-linux-gnu/stage1-rustc/release/deps/libcstr-786feb209dfce7ae.so(_ZN11proc_macro212token_stream96_$LT$impl$u20$core..iter..traits..collect..IntoIterator$u20$for$u20$proc_macro2..TokenStream$GT
$9into_iter17h315ff4dea038bfc3E+0x54)[0x7fff87f3ab84]
/<<PKGBUILDDIR>>/build/powerpc64le-unknown-linux-gnu/stage1-rustc/release/deps/libcstr-786feb209dfce7ae.so(+0x6a200)[0x7fff87f1a200]
/<<PKGBUILDDIR>>/build/powerpc64le-unknown-linux-gnu/stage1-rustc/release/deps/libcstr-786feb209dfce7ae.so(+0x6bfa0)[0x7fff87f1bfa0]
/<<PKGBUILDDIR>>/build/powerpc64le-unknown-linux-gnu/stage1-rustc/release/deps/libcstr-786feb209dfce7ae.so(+0x6dbf8)[0x7fff87f1dbf8]
/<<PKGBUILDDIR>>/build/powerpc64le-unknown-linux-gnu/stage1-rustc/release/deps/libcstr-786feb209dfce7ae.so(+0x6e654)[0x7fff87f1e654]
/<<PKGBUILDDIR>>/build/powerpc64le-unknown-linux-gnu/stage1-rustc/release/deps/libcstr-786feb209dfce7ae.so(+0x6d478)[0x7fff87f1d478]
/<<PKGBUILDDIR>>/build/powerpc64le-unknown-linux-gnu/stage1/lib/librustc_driver-8a51db685c3a3652.so(+0x2a474f0)[0x7fffa88b74f0]
/<<PKGBUILDDIR>>/build/powerpc64le-unknown-linux-gnu/stage1/lib/librustc_driver-8a51db685c3a3652.so(_ZN89_$LT$rustc_expand..proc_macro..BangProcMacro$u20$as$u20$rustc_expand..base..ProcMacro$GT$6expand17h4da03810eb58a713E+0x12c)[0x7ff
fa889171c]
/<<PKGBUILDDIR>>/build/powerpc64le-unknown-linux-gnu/stage1/lib/librustc_driver-8a51db685c3a3652.so(_ZN12rustc_expand6expand13MacroExpander21fully_expand_fragment17hf42bf6c7c5cee112E+0x17f0)[0x7fffa8875590]
/<<PKGBUILDDIR>>/build/powerpc64le-unknown-linux-gnu/stage1/lib/librustc_driver-8a51db685c3a3652.so(_ZN12rustc_expand6expand13MacroExpander12expand_crate17h900deade1746e5d6E+0x6e0)[0x7fffa8873540]
/<<PKGBUILDDIR>>/build/powerpc64le-unknown-linux-gnu/stage1/lib/librustc_driver-8a51db685c3a3652.so(+0x855080)[0x7fffa66c5080]
/<<PKGBUILDDIR>>/build/powerpc64le-unknown-linux-gnu/stage1/lib/librustc_driver-8a51db685c3a3652.so(+0x88ed34)[0x7fffa66fed34]
/<<PKGBUILDDIR>>/build/powerpc64le-unknown-linux-gnu/stage1/lib/librustc_driver-8a51db685c3a3652.so(_ZN15rustc_interface7queries7Queries9expansion17h4bcb4cf9c0b271cfE+0x38c)[0x7fffa672a07c]
/<<PKGBUILDDIR>>/build/powerpc64le-unknown-linux-gnu/stage1/lib/librustc_driver-8a51db685c3a3652.so(+0x6fd664)[0x7fffa656d664]
/<<PKGBUILDDIR>>/build/powerpc64le-unknown-linux-gnu/stage1/lib/librustc_driver-8a51db685c3a3652.so(+0x6e53fc)[0x7fffa65553fc]
/<<PKGBUILDDIR>>/build/powerpc64le-unknown-linux-gnu/stage1/lib/librustc_driver-8a51db685c3a3652.so(+0x6fed88)[0x7fffa656ed88]
/<<PKGBUILDDIR>>/build/powerpc64le-unknown-linux-gnu/stage1/lib/librustc_driver-8a51db685c3a3652.so(+0x6f59a8)[0x7fffa65659a8]
/<<PKGBUILDDIR>>/build/powerpc64le-unknown-linux-gnu/stage1/lib/librustc_driver-8a51db685c3a3652.so(+0x75d010)[0x7fffa65cd010]
/<<PKGBUILDDIR>>/build/powerpc64le-unknown-linux-gnu/stage1/lib/librustc_driver-8a51db685c3a3652.so(+0x6db274)[0x7fffa654b274]
/<<PKGBUILDDIR>>/build/powerpc64le-unknown-linux-gnu/stage1/lib/libstd-5259f91ddc4e5b37.so(rust_metadata_std_f9b0c9e9385aeadc6c2155a37e531624+0x8df54)[0x7fffa5ccdf54]
/lib/powerpc64le-linux-gnu/libpthread.so.0(+0x90a4)[0x7fff9f5e90a4]
/lib/powerpc64le-linux-gnu/libc.so.6(clone+0x74)[0x7fffa5b4d054]

[Mark-Simulacrum]

That stack trace looks like it's coming from procmacro expansion (cstr), though it doesn't look like that dependency changed. It doesn't seem like anything in particular changed with the proc macro code, either...

It would be good to get a better stack trace - at least symbols...

[infinity0]

Here is a stack trace of the failing command. It's a bit spammy; I have the session still open if you want to explore e.g. the local variables or something, let me know what I should run.

GNU gdb (Debian 10.1-2) 10.1.90.20210103-git
[..]
Reading symbols from /home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1/bin/rustc...
warning: Missing auto-load script at offset 0 in section .debug_gdb_scripts
of file /home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1/bin/rustc.
Use `info auto-load python-scripts [REGEXP]' to list them.
Starting program: /home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1/bin/rustc --crate-name rustc_codegen_llvm --edition=2018 compiler/rustc_codegen_llvm/src/lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts --crate-type lib --emit=dep-info,metadata,link -C opt-level=3 -Cembed-bitcode=no -C debuginfo=2 -C metadata=a0f8a5ce0ffb9405 -C extra-filename=-a0f8a5ce0ffb9405 --out-dir /home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1-rustc/powerpc64le-unknown-linux-gnu/release/deps --target powerpc64le-unknown-linux-gnu -C linker=powerpc64le-linux-gnu-gcc -L dependency=/home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1-rustc/powerpc64le-unknown-linux-gnu/release/deps -L dependency=/home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1-rustc/release/deps --extern bitflags=/home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1-rustc/powerpc64le-unknown-linux-gnu/release/deps/libbitflags-0f94127248fffc9d.rmeta --extern cstr=/home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1-rustc/release/deps/libcstr-f6bea2880dd7718c.so --extern libc=/home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1-rustc/powerpc64le-unknown-linux-gnu/release/deps/liblibc-7c269ea4a9fc2214.rmeta --extern measureme=/home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1-rustc/powerpc64le-unknown-linux-gnu/release/deps/libmeasureme-066a5f2f13edc4f4.rmeta --extern rustc_demangle=/home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1-rustc/powerpc64le-unknown-linux-gnu/release/deps/librustc_demangle-247ac0f360f67bcb.rmeta --extern rustc_ast=/home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1-rustc/powerpc64le-unknown-linux-gnu/release/deps/librustc_ast-e121d85ccd1a64d0.rmeta --extern rustc_attr=/home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1-rustc/powerpc64le-unknown-linux-gnu/release/deps/librustc_attr-303e1522532fa990.rmeta --extern rustc_codegen_ssa=/home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1-rustc/powerpc64le-unknown-linux-gnu/release/deps/librustc_codegen_ssa-90e2d769bd05fb55.rmeta --extern rustc_data_structures=/home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1-rustc/powerpc64le-unknown-linux-gnu/release/deps/librustc_data_structures-d7f0505d6db6c0a8.rmeta --extern rustc_errors=/home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1-rustc/powerpc64le-unknown-linux-gnu/release/deps/librustc_errors-724f2ceacef136f1.rmeta --extern rustc_fs_util=/home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1-rustc/powerpc64le-unknown-linux-gnu/release/deps/librustc_fs_util-8ecaae709daadfb8.rmeta --extern rustc_hir=/home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1-rustc/powerpc64le-unknown-linux-gnu/release/deps/librustc_hir-66e497c34ad0fbcc.rmeta --extern rustc_index=/home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1-rustc/powerpc64le-unknown-linux-gnu/release/deps/librustc_index-6708adbdbe8c5839.rmeta --extern rustc_llvm=/home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1-rustc/powerpc64le-unknown-linux-gnu/release/deps/librustc_llvm-3d7c24d0753fba41.rmeta --extern rustc_metadata=/home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1-rustc/powerpc64le-unknown-linux-gnu/release/deps/librustc_metadata-5cb609062c9cff03.rmeta --extern rustc_middle=/home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1-rustc/powerpc64le-unknown-linux-gnu/release/deps/librustc_middle-bf102a055987078a.rmeta --extern rustc_serialize=/home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1-rustc/powerpc64le-unknown-linux-gnu/release/deps/librustc_serialize-35b7eafe1f685f6b.rmeta --extern rustc_session=/home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1-rustc/powerpc64le-unknown-linux-gnu/release/deps/librustc_session-56a2929db906a8a1.rmeta --extern rustc_span=/home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1-rustc/powerpc64le-unknown-linux-gnu/release/deps/librustc_span-67a862338efdbe7d.rmeta --extern rustc_target=/home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1-rustc/powerpc64le-unknown-linux-gnu/release/deps/librustc_target-c9d98e7040edf8b7.rmeta --extern smallvec=/home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1-rustc/powerpc64le-unknown-linux-gnu/release/deps/libsmallvec-a1cd9730a92c2db9.rmeta --extern snap=/home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1-rustc/powerpc64le-unknown-linux-gnu/release/deps/libsnap-3deba377bb543db8.rmeta --extern tracing=/home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1-rustc/powerpc64le-unknown-linux-gnu/release/deps/libtracing-f863a5510a5c2743.rmeta --cap-lints=warn -Clink-args=-Wl,-z,relro -Zmacro-backtrace -Ztls-model=initial-exec -Zunstable-options '-Wrustc::internal' -Cprefer-dynamic -Zbinary-dep-depinfo -L native=/home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1-rustc/powerpc64le-unknown-linux-gnu/release/build/psm-928384bbbf2b32bc/out -L native=/home/infinity0/rustc/build/powerpc64le-unknown-linux-gnu/stage1-rustc/powerpc64le-unknown-linux-gnu/release/build/rustc_llvm-9112792927bd9fe0/out -L native=/usr/lib/llvm-12/lib
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/powerpc64le-linux-gnu/libthread_db.so.1".
[New Thread 0x7fffe933ec00 (LWP 5146)]

Thread 2 "rustc" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fffe933ec00 (LWP 5146)]
proc_macro::bridge::closure::{{impl}}::from::call<proc_macro::bridge::buffer::Buffer<u8>,proc_macro::bridge::buffer::Buffer<u8>,closure-0> (env=0x141a, arg=...) at /usr/src/rustc-1.55.0/library/proc_macro/src/bridge/closure.rs:19
19                  (*(env as *mut _ as *mut F))(arg)
(gdb) bt
#0  proc_macro::bridge::closure::{{impl}}::from::call<proc_macro::bridge::buffer::Buffer<u8>,proc_macro::bridge::buffer::Buffer<u8>,closure-0> (env=0x141a, arg=...) at /usr/src/rustc-1.55.0/library/proc_macro/src/bridge/closure.rs:19
#1  0x00007fffd5cc9c0c in proc_macro::bridge::closure::Closure<proc_macro::bridge::buffer::Buffer<u8>, proc_macro::bridge::buffer::Buffer<u8>>::call<proc_macro::bridge::buffer::Buffer<u8>, proc_macro::bridge::buffer::Buffer<u8>> (
    self=<optimized out>, arg=...) at library/proc_macro/src/bridge/closure.rs:27
#2  proc_macro::bridge::client::{impl#154}::into_iter::{closure#0} (bridge=<optimized out>) at library/proc_macro/src/bridge/client.rs:244
#3  proc_macro::bridge::client::{impl#9}::with::{closure#0}<proc_macro::bridge::client::TokenStreamIter, proc_macro::bridge::client::{impl#154}::into_iter::{closure#0}> (state=0x7fffe932fe28)
    at library/proc_macro/src/bridge/client.rs:336
#4  proc_macro::bridge::client::{impl#8}::with::{closure#0}::{closure#0}<proc_macro::bridge::client::TokenStreamIter, proc_macro::bridge::client::{impl#9}::with::{closure#0}> (state=...) at library/proc_macro/src/bridge/client.rs:293
#5  proc_macro::bridge::scoped_cell::ScopedCell<proc_macro::bridge::client::BridgeStateL>::replace<proc_macro::bridge::client::BridgeStateL, proc_macro::bridge::client::TokenStreamIter, proc_macro::bridge::client::{impl#8}::with::{closure#0}::{closure#0}> (self=<optimized out>, replacement=..., f=...) at library/proc_macro/src/bridge/scoped_cell.rs:75
#6  0x00007fffd5cc1760 in proc_macro::bridge::client::{impl#8}::with::{closure#0}<proc_macro::bridge::client::TokenStreamIter, proc_macro::bridge::client::{impl#9}::with::{closure#0}> (state=<optimized out>)
    at library/proc_macro/src/bridge/client.rs:291
#7  std::thread::local::LocalKey<proc_macro::bridge::scoped_cell::ScopedCell<proc_macro::bridge::client::BridgeStateL>>::try_with<proc_macro::bridge::scoped_cell::ScopedCell<proc_macro::bridge::client::BridgeStateL>, proc_macro::bridge::client::{impl#8}::with::{closure#0}, proc_macro::bridge::client::TokenStreamIter> (self=<optimized out>, f=...) at /usr/src/rustc-1.55.0/library/std/src/thread/local.rs:399
#8  std::thread::local::LocalKey<proc_macro::bridge::scoped_cell::ScopedCell<proc_macro::bridge::client::BridgeStateL>>::with<proc_macro::bridge::scoped_cell::ScopedCell<proc_macro::bridge::client::BridgeStateL>, proc_macro::bridge::client::{impl#8}::with::{closure#0}, proc_macro::bridge::client::TokenStreamIter> (self=<optimized out>, f=...) at /usr/src/rustc-1.55.0/library/std/src/thread/local.rs:375
#9  0x00007fffd5ca7978 in proc_macro::bridge::client::BridgeState::with<proc_macro::bridge::client::TokenStreamIter, proc_macro::bridge::client::{impl#9}::with::{closure#0}> (f=...) at library/proc_macro/src/bridge/client.rs:290
#10 proc_macro::bridge::Bridge::with<proc_macro::bridge::client::TokenStreamIter, proc_macro::bridge::client::{impl#154}::into_iter::{closure#0}> (f=...) at library/proc_macro/src/bridge/client.rs:329
#11 proc_macro::bridge::client::TokenStream::into_iter (self=...) at library/proc_macro/src/bridge/client.rs:237
#12 proc_macro::token_stream::{impl#1}::into_iter (self=...) at library/proc_macro/src/lib.rs:259
#13 0x00007fffd5c95320 in proc_macro2::imp::{impl#19}::into_iter (self=...) at /usr/src/rustc-1.55.0/vendor/proc-macro2/src/wrapper.rs:314
#14 0x00007fffd5c9ac24 in proc_macro2::token_stream::{impl#2}::into_iter (self=...) at /usr/src/rustc-1.55.0/vendor/proc-macro2/src/lib.rs:1267
#15 0x00007fffd5c7a200 in cstr::parse::parse_input (input=...) at /usr/src/rustc-1.55.0/vendor/cstr/src/parse.rs:13
#16 0x00007fffd5c7bfa0 in cstr::build_byte_str (input=...) at /usr/src/rustc-1.55.0/vendor/cstr/src/lib.rs:56
#17 cstr::cstr (input=...) at /usr/src/rustc-1.55.0/vendor/cstr/src/lib.rs:39
#18 0x00007fffd5c7d8d8 in core::ops::function::FnOnce::call_once<fn(proc_macro::TokenStream) -> proc_macro::TokenStream, (proc_macro::TokenStream)> () at /usr/src/rustc-1.55.0/library/core/src/ops/function.rs:227
#19 proc_macro::bridge::client::{impl#10}::expand1::run::{closure#0}<fn(proc_macro::TokenStream) -> proc_macro::TokenStream> (input=...) at /usr/src/rustc-1.55.0/library/proc_macro/src/bridge/client.rs:410
#20 proc_macro::bridge::client::run_client::{closure#0}::{closure#0}<proc_macro::bridge::client::TokenStream, proc_macro::bridge::client::TokenStream, proc_macro::bridge::client::{impl#10}::expand1::run::{closure#0}> ()
    at /usr/src/rustc-1.55.0/library/proc_macro/src/bridge/client.rs:377
#21 proc_macro::bridge::scoped_cell::{impl#3}::set::{closure#0}<proc_macro::bridge::client::BridgeStateL, (), proc_macro::bridge::client::run_client::{closure#0}::{closure#0}> ()
    at /usr/src/rustc-1.55.0/library/proc_macro/src/bridge/scoped_cell.rs:80
#22 proc_macro::bridge::scoped_cell::ScopedCell<proc_macro::bridge::client::BridgeStateL>::replace<proc_macro::bridge::client::BridgeStateL, (), proc_macro::bridge::scoped_cell::{impl#3}::set::{closure#0}> (self=<optimized out>, 
    f=..., replacement=<error reading variable: Cannot access memory at address 0x38>) at /usr/src/rustc-1.55.0/library/proc_macro/src/bridge/scoped_cell.rs:75
#23 proc_macro::bridge::scoped_cell::ScopedCell<proc_macro::bridge::client::BridgeStateL>::set<proc_macro::bridge::client::BridgeStateL, (), proc_macro::bridge::client::run_client::{closure#0}::{closure#0}> (self=<optimized out>, 
    value=..., f=...) at /usr/src/rustc-1.55.0/library/proc_macro/src/bridge/scoped_cell.rs:80
#24 0x00007fffd5c7e334 in proc_macro::bridge::client::{impl#9}::enter::{closure#1}<(), proc_macro::bridge::client::run_client::{closure#0}::{closure#0}> (state=<optimized out>)
    at /usr/src/rustc-1.55.0/library/proc_macro/src/bridge/client.rs:325
#25 std::thread::local::LocalKey<proc_macro::bridge::scoped_cell::ScopedCell<proc_macro::bridge::client::BridgeStateL>>::try_with<proc_macro::bridge::scoped_cell::ScopedCell<proc_macro::bridge::client::BridgeStateL>, proc_macro::bridge::client::{impl#9}::enter::{closure#1}, ()> (f=..., self=<optimized out>) at /usr/src/rustc-1.55.0/library/std/src/thread/local.rs:399
#26 std::thread::local::LocalKey<proc_macro::bridge::scoped_cell::ScopedCell<proc_macro::bridge::client::BridgeStateL>>::with<proc_macro::bridge::scoped_cell::ScopedCell<proc_macro::bridge::client::BridgeStateL>, proc_macro::bridge::client::{impl#9}::enter::{closure#1}, ()> (f=..., self=<optimized out>) at /usr/src/rustc-1.55.0/library/std/src/thread/local.rs:375
#27 proc_macro::bridge::Bridge::enter<(), proc_macro::bridge::client::run_client::{closure#0}::{closure#0}> (self=..., f=...) at /usr/src/rustc-1.55.0/library/proc_macro/src/bridge/client.rs:325
#28 0x00007fffd5c7ccc8 in proc_macro::bridge::client::run_client::{closure#0}<proc_macro::bridge::client::TokenStream, proc_macro::bridge::client::TokenStream, proc_macro::bridge::client::{impl#10}::expand1::run::{closure#0}> ()
    at /usr/src/rustc-1.55.0/library/proc_macro/src/bridge/client.rs:370
#29 std::panic::{impl#30}::call_once<(), proc_macro::bridge::client::run_client::{closure#0}> (self=..., _args=<optimized out>) at /usr/src/rustc-1.55.0/library/std/src/panic.rs:347
#30 std::panicking::try::do_call<std::panic::AssertUnwindSafe<proc_macro::bridge::client::run_client::{closure#0}>, ()> (data=<optimized out>) at /usr/src/rustc-1.55.0/library/std/src/panicking.rs:401
#31 std::panicking::try<(), std::panic::AssertUnwindSafe<proc_macro::bridge::client::run_client::{closure#0}>> (f=...) at /usr/src/rustc-1.55.0/library/std/src/panicking.rs:365
#32 std::panic::catch_unwind<std::panic::AssertUnwindSafe<proc_macro::bridge::client::run_client::{closure#0}>, ()> (f=...) at /usr/src/rustc-1.55.0/library/std/src/panic.rs:434
#33 proc_macro::bridge::client::run_client<proc_macro::bridge::client::TokenStream, proc_macro::bridge::client::TokenStream, proc_macro::bridge::client::{impl#10}::expand1::run::{closure#0}> (bridge=..., f=...)
    at /usr/src/rustc-1.55.0/library/proc_macro/src/bridge/client.rs:369
#34 proc_macro::bridge::client::{impl#10}::expand1::run<fn(proc_macro::TokenStream) -> proc_macro::TokenStream> (bridge=..., f=0x7fffd5c7bf20 <cstr::cstr>) at /usr/src/rustc-1.55.0/library/proc_macro/src/bridge/client.rs:410
#35 0x00007ffff66975f0 in proc_macro::bridge::server::{{impl}}::run_bridge_and_client<fn(proc_macro::TokenStream) -> proc_macro::TokenStream,proc_macro::bridge::server::Dispatcher<proc_macro::bridge::server::MarkedTypes<rustc_expand::proc_macro_server::Rustc>>> (self=<optimized out>, dispatcher=0x7fffe9330868, run_client=0x7fffd5c7cc40 <proc_macro::bridge::client::{impl#10}::expand1::run<fn(proc_macro::TokenStream) -> proc_macro::TokenStream>>, 
    client_data=0x7fffd5c7bf20 <cstr::cstr>, force_show_panics=false, input=...) at /usr/src/rustc-1.55.0/library/proc_macro/src/bridge/server.rs:155
#36 proc_macro::bridge::server::run_server<rustc_expand::proc_macro_server::Rustc,proc_macro::bridge::Marked<rustc_ast::tokenstream::TokenStream, proc_macro::bridge::client::TokenStream>,proc_macro::bridge::Marked<rustc_ast::tokenstream::TokenStream, proc_macro::bridge::client::TokenStream>,fn(proc_macro::TokenStream) -> proc_macro::TokenStream,proc_macro::bridge::server::SameThread> (strategy=<optimized out>, handle_counters=<optimized out>, server=..., 
    input=..., run_client=0x7fffd5c7cc40 <proc_macro::bridge::client::{impl#10}::expand1::run<fn(proc_macro::TokenStream) -> proc_macro::TokenStream>>, client_data=0x7fffd5c7bf20 <cstr::cstr>, force_show_panics=<optimized out>)
    at /usr/src/rustc-1.55.0/library/proc_macro/src/bridge/server.rs:291
#37 0x00007ffff667181c in proc_macro::bridge::client::Client<fn(proc_macro::TokenStream) -> proc_macro::TokenStream>::run<rustc_expand::proc_macro_server::Rustc,proc_macro::bridge::server::SameThread> (self=<optimized out>, 
    strategy=<optimized out>, server=..., input=..., force_show_panics=<optimized out>) at /usr/src/rustc-1.55.0/library/proc_macro/src/bridge/server.rs:311
#38 rustc_expand::proc_macro::{{impl}}::expand (self=<optimized out>, ecx=0x7fffe9332208, span=..., input=...) at compiler/rustc_expand/src/proc_macro.rs:28
#39 0x00007ffff6655690 in rustc_expand::expand::MacroExpander::expand_invoc (self=0x7fffe93323e0, invoc=..., ext=<optimized out>) at compiler/rustc_expand/src/expand.rs:671
#40 rustc_expand::expand::MacroExpander::fully_expand_fragment (self=0x7fffe93323e0, input_fragment=...) at compiler/rustc_expand/src/expand.rs:497
#41 0x00007ffff6653640 in rustc_expand::expand::MacroExpander::expand_crate (self=0x7fffe9332330, krate=...) at compiler/rustc_expand/src/expand.rs:396
#42 0x00007ffff44a5080 in rustc_interface::passes::configure_and_expand::{{closure}}::{{closure}} () at compiler/rustc_interface/src/passes.rs:334
#43 rustc_data_structures::profiling::VerboseTimingGuard::run<rustc_ast::ast::Crate,closure-2> (self=..., f=...) at /usr/src/rustc-1.55.0/compiler/rustc_data_structures/src/profiling.rs:611
#44 rustc_session::session::Session::time<rustc_ast::ast::Crate,closure-2> (self=<optimized out>, what=..., f=...) at /usr/src/rustc-1.55.0/compiler/rustc_session/src/utils.rs:16
#45 rustc_interface::passes::configure_and_expand::{{closure}} () at compiler/rustc_interface/src/passes.rs:334
#46 rustc_data_structures::profiling::VerboseTimingGuard::run<core::result::Result<rustc_ast::ast::Crate, rustc_errors::ErrorReported>,closure-1> (self=..., f=...)
    at /usr/src/rustc-1.55.0/compiler/rustc_data_structures/src/profiling.rs:611
#47 rustc_session::session::Session::time<core::result::Result<rustc_ast::ast::Crate, rustc_errors::ErrorReported>,closure-1> (self=<optimized out>, what=..., f=...) at /usr/src/rustc-1.55.0/compiler/rustc_session/src/utils.rs:16
#48 0x00007ffff44ded34 in rustc_interface::passes::configure_and_expand (sess=<optimized out>, lint_store=<optimized out>, krate=..., crate_name=..., resolver=<optimized out>) at compiler/rustc_interface/src/passes.rs:280
#49 0x00007ffff450a07c in rustc_interface::queries::{{impl}}::expansion::{{closure}}::{{closure}} (resolver=<optimized out>) at compiler/rustc_interface/src/queries.rs:184
#50 rustc_interface::passes::boxed_resolver::BoxedResolver::access<closure-0,core::result::Result<rustc_ast::ast::Crate, rustc_errors::ErrorReported>> (self=0x7fffe93329a8, f=...) at compiler/rustc_interface/src/passes.rs:142
#51 rustc_interface::queries::{{impl}}::expansion::{{closure}} () at compiler/rustc_interface/src/queries.rs:183
#52 rustc_interface::queries::Query<(alloc::rc::Rc<rustc_ast::ast::Crate>, alloc::rc::Rc<core::cell::RefCell<rustc_interface::passes::boxed_resolver::BoxedResolver>>, alloc::rc::Rc<rustc_lint::context::LintStore>)>::compute<(alloc::rc::Rc<rustc_ast::ast::Crate>, alloc::rc::Rc<core::cell::RefCell<rustc_interface::passes::boxed_resolver::BoxedResolver>>, alloc::rc::Rc<rustc_lint::context::LintStore>),closure-0> (self=<optimized out>, f=...)
    at compiler/rustc_interface/src/queries.rs:38
#53 rustc_interface::queries::Queries::expansion (self=0x7fffe9332c08) at compiler/rustc_interface/src/queries.rs:172
#54 0x00007ffff434d664 in rustc_driver::run_compiler::{{closure}}::{{closure}} (queries=0x7fffe9332c08) at compiler/rustc_driver/src/lib.rs:364
#55 rustc_interface::interface::Compiler::enter<closure-2,core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_errors::ErrorReported>> (self=0x7fffe933a420, f=...)
    at /usr/src/rustc-1.55.0/compiler/rustc_interface/src/queries.rs:390
#56 0x00007ffff43353fc in rustc_driver::run_compiler::{{closure}} (compiler=<optimized out>) at compiler/rustc_driver/src/lib.rs:312
#57 rustc_interface::interface::create_compiler_and_run::{{closure}}<core::result::Result<(), rustc_errors::ErrorReported>,closure-1> () at /usr/src/rustc-1.55.0/compiler/rustc_interface/src/interface.rs:209
#58 rustc_span::with_source_map<core::result::Result<(), rustc_errors::ErrorReported>,closure-0> (source_map=..., f=...) at /usr/src/rustc-1.55.0/compiler/rustc_span/src/lib.rs:911
#59 0x00007ffff434ed88 in rustc_interface::interface::create_compiler_and_run<core::result::Result<(), rustc_errors::ErrorReported>,closure-1> (config=..., f=...) at /usr/src/rustc-1.55.0/compiler/rustc_interface/src/interface.rs:203
#60 0x00007ffff43459a8 in rustc_interface::interface::run_compiler::{{closure}}<core::result::Result<(), rustc_errors::ErrorReported>,closure-1> () at /usr/src/rustc-1.55.0/compiler/rustc_interface/src/interface.rs:225
#61 rustc_interface::util::setup_callbacks_and_run_in_thread_pool_with_globals::{{closure}}::{{closure}}<closure-0,core::result::Result<(), rustc_errors::ErrorReported>> ()
    at /usr/src/rustc-1.55.0/compiler/rustc_interface/src/util.rs:157
#62 scoped_tls::ScopedKey<rustc_span::SessionGlobals>::set<rustc_span::SessionGlobals,closure-0,core::result::Result<(), rustc_errors::ErrorReported>> (self=<optimized out>, t=<optimized out>, f=...)
    at /usr/src/rustc-1.55.0/vendor/scoped-tls/src/lib.rs:137
#63 0x00007ffff43ad010 in rustc_span::create_session_globals_then<core::result::Result<(), rustc_errors::ErrorReported>,closure-0> (edition=<optimized out>, f=...) at /usr/src/rustc-1.55.0/compiler/rustc_span/src/lib.rs:105
#64 rustc_interface::util::setup_callbacks_and_run_in_thread_pool_with_globals::{{closure}}<closure-0,core::result::Result<(), rustc_errors::ErrorReported>> () at /usr/src/rustc-1.55.0/compiler/rustc_interface/src/util.rs:155
#65 rustc_interface::util::scoped_thread::{{closure}}<closure-0,core::result::Result<(), rustc_errors::ErrorReported>> () at /usr/src/rustc-1.55.0/compiler/rustc_interface/src/util.rs:130
#66 std::sys_common::backtrace::__rust_begin_short_backtrace<closure-0,()> (f=...) at /usr/src/rustc-1.55.0/library/std/src/sys_common/backtrace.rs:125
#67 0x00007ffff432b274 in std::thread::{{impl}}::spawn_unchecked::{{closure}}::{{closure}}<closure-0,()> () at /usr/src/rustc-1.55.0/library/std/src/thread/mod.rs:476
#68 std::panic::{{impl}}::call_once<(),closure-0> (self=..., _args=<optimized out>) at /usr/src/rustc-1.55.0/library/std/src/panic.rs:347
#69 std::panicking::try::do_call<std::panic::AssertUnwindSafe<closure-0>,()> (data=<optimized out>) at /usr/src/rustc-1.55.0/library/std/src/panicking.rs:401
#70 std::panicking::try<(),std::panic::AssertUnwindSafe<closure-0>> (f=...) at /usr/src/rustc-1.55.0/library/std/src/panicking.rs:365
#71 std::panic::catch_unwind<std::panic::AssertUnwindSafe<closure-0>,()> (f=...) at /usr/src/rustc-1.55.0/library/std/src/panic.rs:434
#72 std::thread::{{impl}}::spawn_unchecked::{{closure}}<closure-0,()> () at /usr/src/rustc-1.55.0/library/std/src/thread/mod.rs:475
#73 core::ops::function::FnOnce::call_once<closure-0,()> () at /usr/src/rustc-1.55.0/library/core/src/ops/function.rs:227
#74 0x00007ffff3aadf54 in alloc::boxed::{{impl}}::call_once<(),FnOnce<()>,alloc::alloc::Global> (self=..., args=<optimized out>) at /usr/src/rustc-1.55.0/library/alloc/src/boxed.rs:1572
#75 alloc::boxed::{{impl}}::call_once<(),alloc::boxed::Box<FnOnce<()>, alloc::alloc::Global>,alloc::alloc::Global> (self=0x1000de4e0, args=<optimized out>) at /usr/src/rustc-1.55.0/library/alloc/src/boxed.rs:1572
#76 std::sys::unix::thread::{{impl}}::new::thread_start (main=0x1000de4e0) at library/std/src/sys/unix/thread.rs:74
#77 0x00007fffed3c90a4 in start_thread () from /lib/powerpc64le-linux-gnu/libpthread.so.0
#78 0x00007ffff392d054 in clone () from /lib/powerpc64le-linux-gnu/libc.so.6

[Mark-Simulacrum]

Hm, yeah, that definitely seems like something is going wrong with the procedural macro interface, but I'm not sure what would be responsible.

It looks like

rust/library/proc_macro/src/lib.rs

Line 259 in 68dfa07

IntoIter(self.0.into_iter())

is segfaulting (well, not directly there, but that's the "root" of the normal code that then calls into the proc macro C ABI shuffling code...

It seems like the segfault suggests that env is not a valid pointer here (it does look a bit too small / wrong, but not sure if that's typical on powerpc)...

proc_macro::bridge::closure::{{impl}}::from::call<proc_macro::bridge::buffer::Buffer<u8>,proc_macro::bridge::buffer::Buffer<u8>,closure-0> (env=0x141a, arg=...) at /usr/src/rustc-1.55.0/library/proc_macro/src/bridge/closure.rs:19
19                  (*(env as *mut _ as *mut F))(arg)

[Mark-Simulacrum]

It seems unlikely (AFAICT, the closure code here doesn't use any unstable details) but perhaps #81360 is somehow at fault? (cc @Aaron1011)

Maybe you can check a temporary revert of that...

[infinity0]

I've minimised the segfaulting code to:

pub use rustc_target;

fn test() {
  cstr::cstr!("cmse_nonsecure_call");
}

Deleting either the function or the use statement makes the compilation go successfully; the import can also be replaced by one of the other rustc_* modules e.g. _codegen_ssa or _middle, but switching it to e.g. std makes the segfault also go away...

[infinity0]

Further found out that rustc_data_structures as the import also works to preserve the segfault, but using any of its dependencies makes it go away. If this raises any bells let me know - I don't know what to do after that, so I'll wipe this build directory and retry with #81360 reverted.

[infinity0]

@Mark-Simulacrum unfortunately the build still fails with the same error, after reverting that PR specifically on top of 1.55.0.

Wondering if @cuviper has any ideas; apparently 1.55 built fine on Fedora https://kojipkgs.fedoraproject.org//packages/rust/1.55.0/1.el7/data/logs/ppc64le/build.log (though there are more test failures than we usually have on ppc64el in Debian).

[infinity0]

I am trying to figure out if there are any significant differences between rust and Debian's LLVM; is it just the [rust] commits in https://github.com/rust-lang/llvm-project/commits/bdb386270f55cb8e95793daa296f27a95a6d4834 ?

[infinity0]

I can work around the problem by patching away the calls to cstr! in rustc_codegen_llvm to instead directly say what the proc-macro would have generated (or actually, doing it with a regular macro also works). The rest of the rustc build then works. Do you think this is acceptable?

Separately, is there a proc-macro heavy crate or system of crates I can test this against, to ensure it doesn't break them?

[cuviper]

I noticed that you have a very old cargo ppc64el 0.47.0-3+b1, where cargo -V reports 1.46.0. It is generally expected that Rust and Cargo versions should be in sync, and while it might work with some drift, it is not going to be well-supported.

To that end, I can reproduce the crash in a debian:sid container using the system rustc, cargo, and llvm-12. However, if I configure it to use the upstream binary for cargo 1.54.0, still with system rustc and llvm-12, then it builds fine. I don't know what specifically changed in cargo that would affect this, nor why that would only affect powerpc64le.

[infinity0]

Thanks for that, then it seems I could probably use the work-around mentioned above, then un-apply it after we do find the time to update cargo in Debian.

FWIW I did check over the release notes of cargo and didn't notice anything that stood out. As I understand, the interface between rustc and cargo is a high-level interface involving basic interprocess UNIX things like envvars and command-line flags. (As opposed to, low-level ABI things like linking and CPU/hardware-specific details.) Even if cargo is out-of-sync with rustc, it would just be supplying unexpected command-line options or envvars or something along these lines, which a user could have done manually. Indeed when reproducing this segfault manually for debugging and minimisation, I am only calling rustc and not dealing with cargo at all. Even the dependencies that it's using, were ultimately directly produced by rustc, and only indirectly via cargo. So along these lines, I would imagine that rustc is not supposed to be segfaulting even if cargo goes wildly out-of-date with it, and there is still a bug somewhere?

[cuviper]

It also fails with upstream 0.47.0 / 1.46.0, but it works with cargo 0.48.0 / 1.47.0, and this does have a relevant change:

• By default, build scripts and proc-macros are now built with opt-level=0 and the default codegen units, even in release mode. #8500

So if there's a powerpc64le optimization bug arising in proc-macros, as your investigation has pinpointed in cstr, then newer cargo will avoid it by not optimizing. That's not very satisfying...

So along these lines, I would imagine that rustc is not supposed to be segfaulting even if cargo goes wildly out-of-date with it, and there is still a bug somewhere?

Yes, I agree, failures due to version mismatch should be much more obvious / less harmful than a segfault.