rust-lang / rust-lang/rust

`tests/run-make/mte-ffi/` is broken

Open
#141,600 0 comments 0 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

A-run-make A-testsuite C-bug T-compiler
Dominant language
Rust
Stars
119k
Forks
16.1k
PR metrics pending

Description

The tests/run-make/mte-ffi run-make test is disabled because it is (1) broken, and (2) no CI runners have suitable MTE extensions enabled to run it correctly.

Context

In https://github.com/rust-lang/rust/pull/141576 when converting PR CI runners from x86_64 to aarch64 runners, it was noticed that this test failed on aarch64-gnu-llvm-19-1 but not aarch64-gnu. It turns out that:

  • aarch64-gnu-llvm-19-1
    • Uses gcc version 14.2.0 (Ubuntu 14.2.0-4ubuntu2)
    • Based on lscpu output, the hardware that was used for this runner does not have MTE enabled.
  • aarch64-gnu
    • Uses gcc version 11.4.0 (Ubuntu 11.4.0-1ubuntu1~22.04)
    • Based on lscpu output, the hardware that was used for this runner does not have MTE enabled.

Based on this comment, it seems like the test requires hardware with MTE extensions enabled to run properly (on ARMv8.5 or higher).

Furthermore, I believe this test does indeed have mismatched pointer type issues, i.e.

bar_string.c: In function ‘main’:
bar_string.c:36:9: error: assignment to ‘char *’ from incompatible pointer type ‘unsigned int *’ [-Wincompatible-pointer-types]
   36 |     ptr = (unsigned int *)((uintptr_t)ptr | 0x1fl << 56);
      |         ^

Which is only exposed by aarch64-gnu-llvm-19-1 because aarch64-gnu-llvm-19-1 uses gcc 14.2.0 whereas aarch64-gnu uses gcc 11.14.0.

Details
aarch64-gnu-llvm-19-1 
gcc_version: Using built-in specs.
COLLECT_GCC=aarch64-linux-gnu-gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/aarch64-linux-gnu/14/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: aarch64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 14.2.0-4ubuntu2' --with-bugurl=file:///usr/share/doc/gcc-14/README.Bugs --enable-languages=c,ada,c++,go,d,fortran,objc,obj-c++,m2,rust --prefix=/usr --with-gcc-major-version-only --program-suffix=-14 --program-prefix=aarch64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir=/usr/libexec --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-libstdcxx-backtrace --enable-gnu-unique-object --disable-libquadmath --disable-libquadmath-support --enable-plugin --enable-default-pie --with-system-zlib --enable-libphobos-checking=release --with-target-system-zlib=auto --enable-objc-gc=auto --enable-multiarch --enable-fix-cortex-a53-843419 --disable-werror --enable-offload-targets=nvptx-none=/build/gcc-14-T7YiXd/gcc-14-14.2.0/debian/tmp-nvptx/usr --enable-offload-defaulted --without-cuda-driver --enable-checking=release --build=aarch64-linux-gnu --host=aarch64-linux-gnu --target=aarch64-linux-gnu --with-build-config=bootstrap-lto-lean --enable-link-serialization=2
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 14.2.0 (Ubuntu 14.2.0-4ubuntu2) 
 
lscpu: Architecture:                         aarch64
CPU op-mode(s):                       32-bit, 64-bit
Byte Order:                           Little Endian
CPU(s):                               4
On-line CPU(s) list:                  0-3
Vendor ID:                            ARM
Model name:                           Neoverse-N2
Model:                                0
Thread(s) per core:                   1
Core(s) per socket:                   4
Socket(s):                            1
Stepping:                             r0p0
BogoMIPS:                             2000.00
Flags:                                fp asimd evtstrm aes pmull sha1 sha2 crc32 atomics fphp asimdhp cpuid asimdrdm jscvt fcma lrcpc dcpop sha3 sm3 sm4 asimddp sha512 sve asimdfhm uscat ilrcpc flagm sb paca pacg dcpodp sve2 sveaes svebitperm svesha3 svesm4 flagm2 frint svei8mm svebf16 i8mm bf16
L1d cache:                            256 KiB (4 instances)
L1i cache:                            256 KiB (4 instances)
L2 cache:                             4 MiB (4 instances)
L3 cache:                             128 MiB (1 instance)
NUMA node(s):                         1
NUMA node0 CPU(s):                    0-3
Vulnerability Gather data sampling:   Not affected
Vulnerability Itlb multihit:          Not affected
Vulnerability L1tf:                   Not affected
Vulnerability Mds:                    Not affected
Vulnerability Meltdown:               Not affected
Vulnerability Mmio stale data:        Not affected
Vulnerability Reg file data sampling: Not affected
Vulnerability Retbleed:               Not affected
Vulnerability Spec rstack overflow:   Not affected
Vulnerability Spec store bypass:      Mitigation; Speculative Store Bypass disabled via prctl
Vulnerability Spectre v1:             Mitigation; __user pointer sanitization
Vulnerability Spectre v2:             Mitigation; CSV2, BHB
Vulnerability Srbds:                  Not affected
Vulnerability Tsx async abort:        Not affected
aarch64-gnu 
gcc_version: Using built-in specs.
COLLECT_GCC=aarch64-linux-gnu-gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/aarch64-linux-gnu/11/lto-wrapper
Target: aarch64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 11.4.0-1ubuntu1~22.04' --with-bugurl=file:///usr/share/doc/gcc-11/README.Bugs --enable-languages=c,ada,c++,go,d,fortran,objc,obj-c++,m2 --prefix=/usr --with-gcc-major-version-only --program-suffix=-11 --program-prefix=aarch64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-libquadmath --disable-libquadmath-support --enable-plugin --enable-default-pie --with-system-zlib --enable-libphobos-checking=release --with-target-system-zlib=auto --enable-objc-gc=auto --enable-multiarch --enable-fix-cortex-a53-843419 --disable-werror --enable-checking=release --build=aarch64-linux-gnu --host=aarch64-linux-gnu --target=aarch64-linux-gnu --with-build-config=bootstrap-lto-lean --enable-link-serialization=2
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 11.4.0 (Ubuntu 11.4.0-1ubuntu1~22.04) 

lscpu: Architecture:                         aarch64
CPU op-mode(s):                       32-bit, 64-bit
Byte Order:                           Little Endian
CPU(s):                               4
On-line CPU(s) list:                  0-3
Vendor ID:                            ARM
Model:                                0
Thread(s) per core:                   1
Core(s) per socket:                   4
Socket(s):                            1
Stepping:                             r0p0
BogoMIPS:                             2000.00
Flags:                                fp asimd evtstrm aes pmull sha1 sha2 crc32 atomics fphp asimdhp cpuid asimdrdm jscvt fcma lrcpc dcpop sha3 sm3 sm4 asimddp sha512 sve asimdfhm uscat ilrcpc flagm sb paca pacg dcpodp sve2 sveaes svebitperm svesha3 svesm4 flagm2 frint svei8mm svebf16 i8mm bf16
L1d cache:                            256 KiB (4 instances)
L1i cache:                            256 KiB (4 instances)
L2 cache:                             4 MiB (4 instances)
L3 cache:                             128 MiB (1 instance)
NUMA node(s):                         1
NUMA node0 CPU(s):                    0-3
Vulnerability Gather data sampling:   Not affected
Vulnerability Itlb multihit:          Not affected
Vulnerability L1tf:                   Not affected
Vulnerability Mds:                    Not affected
Vulnerability Meltdown:               Not affected
Vulnerability Mmio stale data:        Not affected
Vulnerability Reg file data sampling: Not affected
Vulnerability Retbleed:               Not affected
Vulnerability Spec rstack overflow:   Not affected
Vulnerability Spec store bypass:      Mitigation; Speculative Store Bypass disabled via prctl
Vulnerability Spectre v1:             Mitigation; __user pointer sanitization
Vulnerability Spectre v2:             Mitigation; CSV2, BHB
Vulnerability Srbds:                  Not affected
Vulnerability Tsx async abort:        Not affected
References

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reading the disabled tests/run-make/mte-ffi test and bar_string.c, then reproduce its failure on an AArch64 environment with MTE enabled if available. Compare the pointer-type diagnostics from GCC 14 with the existing test behavior; done means the test has corrected type handling and a clearly supported, reliable way to run in CI.

Written by the indexing model from the issue text.

Assessment

Tech stack
c, rust
Domain
testing-qa
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
35/100

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.