linux-kernel - objtool warnings for kernel/trace/trace_selftest

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Date:   Sun, 16 Dec 2018 19:33:11 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "the arch/x86 maintainers" <x86@...nel.org>
Subject: objtool warnings for kernel/trace/trace_selftest_dynamic.o

Hi Josh,

In randconfig tests with gcc-8.1, I get this warning every
few hundred builds, tried it on both next/master and 4.19.y-stable:

kernel/trace/trace_selftest_dynamic.o: warning: objtool:
trace_selftest_dynamic_test_func()+0x5: call without frame pointer
save/setup
kernel/trace/trace_selftest_dynamic.o: warning: objtool:
trace_selftest_dynamic_test_func2()+0x5: call without frame pointer
save/setup

$ objdump -dr build/x86/0x90C84554_defconfig/kernel/trace/trace_selftest_dynamic.o

build/x86/0x90C84554_defconfig/kernel/trace/trace_selftest_dynamic.o:
   file format elf64-x86-64

Disassembly of section .text:

0000000000000000 <trace_selftest_dynamic_test_func>:
   0:    e8 00 00 00 00           callq  5
<trace_selftest_dynamic_test_func+0x5>
            1: R_X86_64_PC32    __fentry__-0x4
   5:    e8 00 00 00 00           callq  a
<trace_selftest_dynamic_test_func+0xa>
            6: R_X86_64_PC32    __sanitizer_cov_trace_pc-0x4
   a:    31 c0                    xor    %eax,%eax
   c:    c3                       retq
   d:    0f 1f 00                 nopl   (%rax)

0000000000000010 <trace_selftest_dynamic_test_func2>:
  10:    e8 00 00 00 00           callq  15
<trace_selftest_dynamic_test_func2+0x5>
            11: R_X86_64_PC32    __fentry__-0x4
  15:    e8 00 00 00 00           callq  1a
<trace_selftest_dynamic_test_func2+0xa>
            16: R_X86_64_PC32    __sanitizer_cov_trace_pc-0x4
  1a:    31 c0                    xor    %eax,%eax
  1c:    c3                       retq

I found this reported in
http://kisskb.ellerman.id.au/kisskb/buildresult/13499139/, but could
not find an existing fix or analysis.

        Arnd

Download attachment ".config.gz" of type "application/gzip" (25916 bytes)