[lld] 1417558 - [ELF] Improve the condition to create .interp

Fri Dec 27 14:38:13 PST 2019

The command is just the Sanitizer-x86_64-Test-Nolibc binary with no args.
You can see it failed here:
https://ci.chromium.org/p/chromium/builders/try/linux_upload_clang/740
 The binary would crash on startup in the loader.

Eric says he was able to reproduce it as well. I can send you the binary
offline if it's useful to inspect it.

On Fri, Dec 27, 2019 at 1:34 PM Fangrui Song <maskray at google.com> wrote:

> Do you have a reproduce command line?
>
> I am at commit c3dbd782f1e0578c7ebc342f2e92f54d9644cff7 (your revert).
> With it rolled forward locally, check-sanitizer works here.
> (-DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_ASSERTIONS=on)
>
> Running
> projects/compiler-rt/lib/sanitizer_common/tests/Sanitizer-x86_64-Test-Nolibc
> directly is also fine.
>
> On 2019-12-27, Reid Kleckner wrote:
> >I ended up reverting this because it causes some check-sanitizer nolibc
> test to
> >fail, hopefully it reproduces for you locally, let me know if it doesn't.
> The
> >"nolibc" version crashes on startup.
> >
> >On Thu, Dec 26, 2019 at 1:28 PM Fangrui Song via llvm-commits <
> >llvm-commits at lists.llvm.org> wrote:
> >
> >    Author: Fangrui Song
> >    Date: 2019-12-26T13:26:43-08:00
> >    New Revision: 1417558e4a61794347c6bfbafaff7cd96985b2c3
> >
> >    URL: https://github.com/llvm/llvm-project/commit/
> >    1417558e4a61794347c6bfbafaff7cd96985b2c3
> >    DIFF: https://github.com/llvm/llvm-project/commit/
> >    1417558e4a61794347c6bfbafaff7cd96985b2c3.diff
> >
> >    LOG: [ELF] Improve the condition to create .interp
> >
> >    Similar to rL362355, but with the `!config->shared` guard.
> >
> >    (1) {gcc,clang} -fuse-ld=bfd -pie -fPIE -nostdlib a.c => .interp
> created
> >    (2) {gcc,clang} -fuse-ld=lld -pie -fPIE -nostdlib a.c => .interp not
> >    created
> >    (3) {gcc,clang} -fuse-ld=lld -pie -fPIE -nostdlib a.c a.so => .interp
> >    created
> >
> >    The inconsistency of (2) is due to the condition `!Config->
> >    SharedFiles.empty()`.
> >    To make lld behave more like ld.bfd, we could change the condition to:
> >
> >        config->hasDynSymTab && !config->dynamicLinker.empty() && script->
> >    needsInterpSection();
> >
> >    However, that would bring another inconsistency as can be observed
> with:
> >
> >    (4) {gcc,clang} -fuse-ld=bfd -no-pie -nostdlib a.c => .interp not
> created
> >
> >    Added:
> >
> >    Modified:
> >        lld/ELF/Writer.cpp
> >        lld/test/ELF/dynamic-linker.s
> >        lld/test/ELF/ppc64-func-entry-points.s
> >
> >    Removed:
> >
> >
> ###########################################################################
> >    #####
> >    diff  --git a/lld/ELF/Writer.cpp b/lld/ELF/Writer.cpp
> >    index c0ad33473747..c20b74821d9c 100644
> >    --- a/lld/ELF/Writer.cpp
> >    +++ b/lld/ELF/Writer.cpp
> >    @@ -135,7 +135,7 @@ StringRef getOutputSectionName(const
> InputSectionBase
> >    *s) {
> >     }
> >
> >     static bool needsInterpSection() {
> >    -  return !sharedFiles.empty() && !config->dynamicLinker.empty() &&
> >    +  return !config->shared && !config->dynamicLinker.empty() &&
> >              script->needsInterpSection();
> >     }
> >
> >    diff  --git a/lld/test/ELF/dynamic-linker.s
> b/lld/test/ELF/dynamic-linker.s
> >    index d0da77fab295..b5e9f5f55e98 100644
> >    --- a/lld/test/ELF/dynamic-linker.s
> >    +++ b/lld/test/ELF/dynamic-linker.s
> >    @@ -1,6 +1,4 @@
> >     # REQUIRES: x86
> >    -# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux
> %p/Inputs/shared.s -o
> >    %t1.o
> >    -# RUN: ld.lld -shared %t1.o -o %t.so
> >     # RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
> >
> >     # RUN: ld.lld --dynamic-linker foo %t.o %t.so -o %t
> >    @@ -11,11 +9,11 @@
> >
> >     # CHECK: [Requesting program interpreter: foo]
> >
> >    -# RUN: ld.lld %t.o %t.so -o %t
> >    +# RUN: ld.lld %t.o -o %t
> >     # RUN: llvm-readelf -program-headers %t | FileCheck
> --check-prefix=NO %s
> >
> >    -# RUN: ld.lld --dynamic-linker foo --no-dynamic-linker %t.o %t.so -o
> %t
> >    -# RUN: llvm-readelf -program-headers %t | FileCheck
> --check-prefix=NO %s
> >    +# RUN: ld.lld --dynamic-linker foo --no-dynamic-linker %t.o -o %t
> >    +# RUN: llvm-readelf --program-headers %t | FileCheck
> --check-prefix=NO %s
> >
> >     # NO-NOT: PT_INTERP
> >
> >    diff  --git a/lld/test/ELF/ppc64-func-entry-points.s b/lld/test/ELF/
> >    ppc64-func-entry-points.s
> >    index 1411cbe1c058..c322f6563426 100644
> >    --- a/lld/test/ELF/ppc64-func-entry-points.s
> >    +++ b/lld/test/ELF/ppc64-func-entry-points.s
> >    @@ -3,13 +3,13 @@
> >     // RUN: llvm-mc -filetype=obj -triple=powerpc64le-unknown-linux %s
> -o %t.o
> >     // RUN: llvm-mc -filetype=obj -triple=powerpc64le-unknown-linux
> %p/Inputs/
> >    ppc64-func-global-entry.s -o %t2.o
> >     // RUN: llvm-mc -filetype=obj -triple=powerpc64le-unknown-linux
> %p/Inputs/
> >    ppc64-func-local-entry.s -o %t3.o
> >    -// RUN: ld.lld -dynamic-linker /lib64/ld64.so.2 %t.o %t2.o %t3.o -o
> %t
> >    +// RUN: ld.lld %t.o %t2.o %t3.o -o %t
> >     // RUN: llvm-objdump -d --no-show-raw-insn %t | FileCheck %s
> >
> >     // RUN: llvm-mc -filetype=obj -triple=powerpc64-unknown-linux %s -o
> %t.o
> >     // RUN: llvm-mc -filetype=obj -triple=powerpc64-unknown-linux
> %p/Inputs/
> >    ppc64-func-global-entry.s -o %t2.o
> >     // RUN: llvm-mc -filetype=obj -triple=powerpc64-unknown-linux
> %p/Inputs/
> >    ppc64-func-local-entry.s -o %t3.o
> >    -// RUN: ld.lld -dynamic-linker /lib64/ld64.so.2 %t.o %t2.o %t3.o -o
> %t
> >    +// RUN: ld.lld %t.o %t2.o %t3.o -o %t
> >     // RUN: llvm-objdump -d --no-show-raw-insn %t | FileCheck %s
> >
> >            .text
> >
> >    _______________________________________________
> >    llvm-commits mailing list
> >    llvm-commits at lists.llvm.org
> >    https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
> >
>
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