linux-kernel - x86 - clang / objtool status

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Message-ID: <alpine.DEB.2.21.1907182223560.1785@nanos.tec.linutronix.de>
Date:   Thu, 18 Jul 2019 22:40:09 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
cc:     Nick Desaulniers <ndesaulniers@...gle.com>,
        Nathan Chancellor <natechancellor@...il.com>,
        clang-built-linux <clang-built-linux@...glegroups.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>, x86@...nel.org
Subject: x86 - clang / objtool status

Folks,

after picking up Josh's objtool updates I gave clang a test ride again.

clan is built with https://github.com/ClangBuiltLinux/tc-build.git

That's using the llvm master branch. top commit is:

  0c99d19470b ("[OPENMP]Fix sharing of threadprivate variables with TLS support.")

I merged

  git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git core/urgent

into the tip of Linus tree to pick up the latest objtool changes.

Here are the results for different configs:

1) defconfig

 objtool warnings:

  drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: .altinstr_replacement+0x88: redundant UACCESS disable


2) debian distro config

 objtool warnings:

  drivers/gpu/drm/amd/amdgpu/atom.o: warning: objtool: atom_op_move() falls through to next function atom_op_and()
  drivers/infiniband/hw/hfi1/platform.o: warning: objtool: tune_serdes() falls through to next function apply_tx_lanes()
  drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: .altinstr_replacement+0x86: redundant UACCESS disable
  drivers/gpu/drm/radeon/evergreen_cs.o: warning: objtool: evergreen_cs_parse() falls through to next function evergreen_dma_cs_parse()

 Build fails with:

  clang-10: error: unknown argument: '-mpreferred-stack-boundary=4'
  make[5]: *** [linux/scripts/Makefile.build:279: drivers/gpu/drm/amd/amdgpu/../display/dc/dcn20/dcn20_resource.o] Error 1


3) allmodconfig:

 objtool warnings:

  arch/x86/kernel/signal.o: warning: objtool: x32_setup_rt_frame()+0x255: call to memset() with UACCESS enabled
  arch/x86/kernel/signal.o: warning: objtool: __setup_rt_frame()+0x254: call to memset() with UACCESS enabled
  arch/x86/ia32/ia32_signal.o: warning: objtool: ia32_setup_rt_frame()+0x247: call to memset() with UACCESS enabled

  mm/kasan/common.o: warning: objtool: kasan_report()+0x52: call to __stack_chk_fail() with UACCESS enabled
  drivers/ata/sata_dwc_460ex.o: warning: objtool: sata_dwc_bmdma_start_by_tag()+0x3a0: can't find switch jump table

  lib/ubsan.o: warning: objtool: __ubsan_handle_type_mismatch()+0x88: call to memset() with UACCESS enabled
  lib/ubsan.o: warning: objtool: ubsan_type_mismatch_common()+0x610: call to __stack_chk_fail() with UACCESS enabled
  lib/ubsan.o: warning: objtool: __ubsan_handle_type_mismatch_v1()+0x88: call to memset() with UACCESS enabled
  drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: .altinstr_replacement+0x56: redundant UACCESS disable

 Build fails with:

  ERROR: "__compiletime_assert_2801" [drivers/net/wireless/intel/iwlwifi/iwlwifi.ko] undefined!
  ERROR: "__compiletime_assert_2446" [drivers/net/wireless/intel/iwlwifi/iwlwifi.ko] undefined!
  ERROR: "__compiletime_assert_2452" [drivers/net/wireless/intel/iwlwifi/iwlwifi.ko] undefined!
  ERROR: "__compiletime_assert_2790" [drivers/net/wireless/intel/iwlwifi/iwlwifi.ko] undefined!

 This also emits a boatload of warnings like this:

  linux/fs/nfs/dir.c:451:34: warning: variable 'wq' is uninitialized when used within its own initialization
      [-Wuninitialized]
        DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
                                        ^~
  linux/include/linux/wait.h:74:63: note: expanded from macro 'DECLARE_WAIT_QUEUE_HEAD_ONSTACK'
        struct wait_queue_head name = __WAIT_QUEUE_HEAD_INIT_ONSTACK(name)
                               ~~~~                                  ^~~~
  linux/include/linux/wait.h:72:33: note: expanded from macro '__WAIT_QUEUE_HEAD_INIT_ONSTACK'
        ({ init_waitqueue_head(&name); name; })

Thanks,

	tglx