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Differential D43613

Msan, cmake configuration changes
ClosedPublic

Authored by devnexen on Feb 22 2018, 1:10 AM.

Details

Reviewers
vitalybuka
krytarowski
eugenis
emaste
dim
Summary
  • Applies tls-exec generally, on FreeBSD despite enabling it in Msan, the TLS part does not execute.
  • Suppress PIE which does not go together with PIC in FreeBSD (linkage issue when trying to compile code with msan flag).

Diff Detail

Event Timeline

devnexen created this revision.Feb 22 2018, 1:10 AM
Herald added subscribers: Restricted Project, llvm-commits, krytarowski and 2 others. · View Herald TranscriptFeb 22 2018, 1:10 AM
devnexen added a comment.Feb 22 2018, 1:10 AM

As discussed here https://reviews.llvm.org/D43080 this is the specific change into Msan cmake configuration part.

devnexen added reviewers: vitalybuka, krytarowski.Feb 22 2018, 1:11 AM
vitalybuka added a reviewer: eugenis.Feb 22 2018, 10:48 AM
eugenis added a comment.Feb 22 2018, 11:46 AM

What is the problem with -fPIE? Is it not supported to link PIE and PIC objects in one binary?

devnexen added a comment.Feb 22 2018, 11:55 AM
In D43613#1016338, @eugenis wrote:

What is the problem with -fPIE? Is it not supported to link PIE and PIC objects in one binary?

I ve tried with and if I compile any code with msan sanitizer I get linkage issue.

eugenis added a comment.Feb 22 2018, 12:05 PM

What kind of linkage issue?
I mean, in my view of the world, it is completely fine to build a static library with -fPIE and then link it to an executable. I'd like to understand what is wrong with that on FreeBSD.

krytarowski added reviewers: emaste, dim.Feb 22 2018, 3:36 PM
krytarowski added a subscriber: dim.

Naively looking at https://hardenedbsd.org/content/easy-feature-comparison PIE on FreeBSD might need more work.

Adding @emaste and @dim from FreeBSD.

devnexen added a comment.EditedFeb 22 2018, 3:43 PM
In D43613#1016354, @eugenis wrote:

What kind of linkage issue?
I mean, in my view of the world, it is completely fine to build a static library with -fPIE and then link it to an executable. I'd like to understand what is wrong with that on FreeBSD.

This is the error I get with both PIE and PIC
... relocation R_X86_64_TPOFF32 against `a local symbol' can not be used when making a shared object; recompile with -fPIC

devnexen added a comment.Mar 2 2018, 8:24 AM

ping

eugenis accepted this revision.Mar 2 2018, 10:46 AM

OK, sure, as long as it's under if(FreeBSD).

Does it mean you are building MSan runtime as not position-independent code (i.e. not PIE nor PIC)? It would be suitable for non-PIE executables only.

This revision is now accepted and ready to land.Mar 2 2018, 10:46 AM
Diffusion mentioned this in rL326649: [msan] Restrict -ftls-model=initial-exec to FreeBSD.Mar 3 2018, 4:02 AM
Diffusion mentioned this in rCRT326649: [msan] Restrict -ftls-model=initial-exec to FreeBSD.
krytarowski closed this revision.Mar 3 2018, 4:02 AM

Hmm, this already landed as a part of D43080

I've added this -ftls flag as a separate commit SVN r. 326649

Revision Contents

PathSize
lib/
msan/
5 lines

Diff 135371

lib/msan/CMakeLists.txt

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set(MSAN_RTL_CFLAGS ${SANITIZER_COMMON_CFLAGS}) set(MSAN_RTL_CFLAGS ${SANITIZER_COMMON_CFLAGS})
append_list_if(COMPILER_RT_HAS_FTLS_MODEL_INITIAL_EXEC -ftls-model=initial-exec MSAN_RTL_CFLAGS)
append_rtti_flag(OFF MSAN_RTL_CFLAGS) append_rtti_flag(OFF MSAN_RTL_CFLAGS)
append_list_if(COMPILER_RT_HAS_FPIE_FLAG -fPIE MSAN_RTL_CFLAGS) if(NOT CMAKE_SYSTEM_NAME MATCHES "FreeBSD")
append_list_if(COMPILER_RT_HAS_FPIE_FLAG -fPIE MSAN_RTL_CFLAGS)
endif()
# Prevent clang from generating libc calls. # Prevent clang from generating libc calls.
append_list_if(COMPILER_RT_HAS_FFREESTANDING_FLAG -ffreestanding MSAN_RTL_CFLAGS) append_list_if(COMPILER_RT_HAS_FFREESTANDING_FLAG -ffreestanding MSAN_RTL_CFLAGS)
Context not available.