[PATCH] powerpc: Define USE_PPC64_NOTOC iff compiler and linker also supports it

[Tulio Magno Quites Machado Filho]

Adhemerval Zanella via Libc-alpha <libc-alpha@sourceware.org> writes:

> On 19/11/2021 12:52, Tulio Magno Quites Machado Filho wrote:
>> 2. LLD itself crashes while linking the tests.
>>    I need to collect more details.
>
> Do you have a log of what is happening? Could it be something related to the
> debian provided LLD? Could you check with the official package?

Using the official package and --with-cpu=power9, I'm able to build and run
the tests. I get:

FAIL: elf/ifuncmain1pic
FAIL: elf/ifuncmain1pie
FAIL: elf/ifuncmain1vis
FAIL: elf/ifuncmain1vispic
FAIL: elf/ifuncmain1vispie
FAIL: elf/ifuncmain3
FAIL: elf/ifuncmain6pie
XPASS: elf/tst-protected1a
XPASS: elf/tst-protected1b
FAIL: elf/tst-tlsopt-powerpc
UNSUPPORTED: math/test-fesetexcept-traps
UNSUPPORTED: math/test-fexcept-traps
UNSUPPORTED: misc/tst-adjtimex
UNSUPPORTED: misc/tst-clock_adjtime
UNSUPPORTED: misc/tst-ntp_adjtime
UNSUPPORTED: misc/tst-pkey
FAIL: nptl/tst-execstack
UNSUPPORTED: time/tst-clock_settime
UNSUPPORTED: time/tst-settimeofday
Summary of test results:
      9 FAIL
   4663 PASS
      8 UNSUPPORTED
     16 XFAIL
      2 XPASS

All the 9 failures are unexpected.

I had to kill elf/ifuncmain1pie by hand because it was stuck in an infinite
loop in foo_protected, constantly loading its own address and jumping to it.

The contents of the function are not what I expected.  It's almost identical to
its __plt_ counterpart except that it doesn't save r2:

0000000000010d90 <foo_protected>:
   10d90:       01 00 82 3d     addis   r12,r2,1
   10d94:       a0 80 8c e9     ld      r12,-32608(r12)
   10d98:       a6 03 89 7d     mtctr   r12
   10d9c:       20 04 80 4e     bctr

=======

Going back to the discussion around the crashes, I can only reproduce them with
the Debian build and using a high number of jobs (e.g -j150).  That generates an
unusable log that I can only distinguish that a few lld processes received
SIGABRT.
If I use a lower -j value, e.g. -j10, the crashes do not happen.

This is what I managed to parse:

terminate called after throwing an instance of 'std::system_error'
what():  Resource temporarily unavailable
PLEASE submit a bug report to https://bugs.llvm.org/ and include the crash backtrace.
/usr/lib/powerpc64le-linux-gnu/libLLVM-13.so.1(_ZN4llvm3sys15PrintStackTraceERNS_11raw_ostreamEi+0x4
c)[0x7fffb262c50c]
... <= Hard to understand what is going on here
collect2: fatal error: ld terminated with signal 6 [Aborted]
compilation terminated.
make[2]: *** [../Rules:277: /build/glibc-build.lld/math/test-signgam-ullong-static] Error 1
make[2]: *** [../Rules:277: /build/glibc-build.lld/math/atest-exp] Error 1
make[2]: *** [../Rules:277: /build/glibc-build.lld/math/atest-sincos] Error 1
make[2]: *** [../Rules:230: /build/glibc-build.lld/math/test-matherr] Error 1
make[2]: *** [../Rules:230: /build/glibc-build.lld/math/test-matherr-2] Error 1
make[2]: *** [../Rules:230: /build/glibc-build.lld/math/test-math-isinff] Error 1
make[2]: *** [../Rules:277: /build/glibc-build.lld/math/test-signgam-ullong-init-static] Error 1

-- 
Tulio Magno