From: Kees Cook <keescook@chromium.org>
To: Sami Tolvanen <samitolvanen@google.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>,
Will Deacon <will@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Paul E. McKenney" <paulmck@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
clang-built-linux@googlegroups.com,
kernel-hardening@lists.openwall.com, linux-arch@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-pci@vger.kernel.org, x86@kernel.org
Subject: Re: [PATCH v2 11/28] kbuild: lto: postpone objtool
Date: Thu, 3 Sep 2020 15:19:43 -0700 [thread overview]
Message-ID: <202009031513.B558594FB9@keescook> (raw)
In-Reply-To: <20200903203053.3411268-12-samitolvanen@google.com>
On Thu, Sep 03, 2020 at 01:30:36PM -0700, Sami Tolvanen wrote:
> With LTO, LLVM bitcode won't be compiled into native code until
> modpost_link, or modfinal for modules. This change postpones calls
> to objtool until after these steps.
>
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
For a "fail fast" style of building, it makes sense to have objtool run
as early as possible, so it makes sense to keep the current behavior in
non-LTO mode. I do wonder, though, if there is a real benefit to having
"fail fast" case. I imagine a lot of automated builds are using
--keep-going with make, and actually waiting until the end to do the
validation means more code will get build-tested before objtool rejects
the results. *shrug*
> ---
> arch/Kconfig | 2 +-
> scripts/Makefile.build | 2 ++
> scripts/Makefile.modfinal | 24 ++++++++++++++++++++++--
> scripts/link-vmlinux.sh | 23 ++++++++++++++++++++++-
> 4 files changed, 47 insertions(+), 4 deletions(-)
>
> diff --git a/arch/Kconfig b/arch/Kconfig
> index 71392e4a8900..7a418907e686 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -599,7 +599,7 @@ config LTO_CLANG
> depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm)
> depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm)
> depends on ARCH_SUPPORTS_LTO_CLANG
> - depends on !FTRACE_MCOUNT_RECORD
> + depends on HAVE_OBJTOOL_MCOUNT || !(X86_64 && DYNAMIC_FTRACE)
> depends on !KASAN
> depends on !GCOV_KERNEL
> select LTO
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index c348e6d6b436..b8f1f0d65a73 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -218,6 +218,7 @@ cmd_record_mcount = $(if $(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags)),
> endif # USE_RECORDMCOUNT
>
> ifdef CONFIG_STACK_VALIDATION
> +ifndef CONFIG_LTO_CLANG
> ifneq ($(SKIP_STACK_VALIDATION),1)
>
> __objtool_obj := $(objtree)/tools/objtool/objtool
> @@ -253,6 +254,7 @@ objtool_obj = $(if $(patsubst y%,, \
> $(__objtool_obj))
>
> endif # SKIP_STACK_VALIDATION
> +endif # CONFIG_LTO_CLANG
> endif # CONFIG_STACK_VALIDATION
>
> # Rebuild all objects when objtool changes, or is enabled/disabled.
> diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal
> index 1005b147abd0..909bd509edb4 100644
> --- a/scripts/Makefile.modfinal
> +++ b/scripts/Makefile.modfinal
> @@ -34,10 +34,30 @@ ifdef CONFIG_LTO_CLANG
> # With CONFIG_LTO_CLANG, reuse the object file we compiled for modpost to
> # avoid a second slow LTO link
> prelink-ext := .lto
> -endif
> +
> +# ELF processing was skipped earlier because we didn't have native code,
> +# so let's now process the prelinked binary before we link the module.
> +
> +ifdef CONFIG_STACK_VALIDATION
> +ifneq ($(SKIP_STACK_VALIDATION),1)
> +cmd_ld_ko_o += \
> + $(objtree)/tools/objtool/objtool \
> + $(if $(CONFIG_UNWINDER_ORC),orc generate,check) \
> + --module \
> + $(if $(CONFIG_FRAME_POINTER),,--no-fp) \
> + $(if $(CONFIG_GCOV_KERNEL),--no-unreachable,) \
> + $(if $(CONFIG_RETPOLINE),--retpoline,) \
> + $(if $(CONFIG_X86_SMAP),--uaccess,) \
> + $(if $(USE_OBJTOOL_MCOUNT),--mcount,) \
> + $(@:.ko=$(prelink-ext).o);
> +
> +endif # SKIP_STACK_VALIDATION
> +endif # CONFIG_STACK_VALIDATION
I wonder if objtool_args could be reused here instead of having two
places to keep in sync? It looks like that might mean moving things
around a bit before this patch, since I can't quite see if
Makefile.build's variables are visible to Makefile.modfinal?
> +
> +endif # CONFIG_LTO_CLANG
>
> quiet_cmd_ld_ko_o = LD [M] $@
> - cmd_ld_ko_o = \
> + cmd_ld_ko_o += \
> $(LD) -r $(KBUILD_LDFLAGS) \
> $(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE) \
> $(addprefix -T , $(KBUILD_LDS_MODULE)) \
> diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
> index 3e99a19b9195..a352a5ad9ef7 100755
> --- a/scripts/link-vmlinux.sh
> +++ b/scripts/link-vmlinux.sh
> @@ -93,8 +93,29 @@ objtool_link()
> {
> local objtoolopt;
>
> + if [ "${CONFIG_LTO_CLANG} ${CONFIG_STACK_VALIDATION}" = "y y" ]; then
> + # Don't perform vmlinux validation unless explicitly requested,
> + # but run objtool on vmlinux.o now that we have an object file.
> + if [ -n "${CONFIG_UNWINDER_ORC}" ]; then
> + objtoolopt="orc generate"
> + else
> + objtoolopt="check"
> + fi
> +
> + if [ -n ${USE_OBJTOOL_MCOUNT} ]; then
> + objtoolopt="${objtoolopt} --mcount"
> + fi
> + fi
> +
> if [ -n "${CONFIG_VMLINUX_VALIDATION}" ]; then
> - objtoolopt="check --vmlinux"
> + if [ -z "${objtoolopt}" ]; then
> + objtoolopt="check --vmlinux"
> + else
> + objtoolopt="${objtoolopt} --vmlinux"
> + fi
> + fi
> +
> + if [ -n "${objtoolopt}" ]; then
> if [ -z "${CONFIG_FRAME_POINTER}" ]; then
> objtoolopt="${objtoolopt} --no-fp"
> fi
> --
> 2.28.0.402.g5ffc5be6b7-goog
>
--
Kees Cook
next prev parent reply other threads:[~2020-09-03 22:20 UTC|newest]
Thread overview: 213+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-24 20:31 [PATCH 00/22] add support for Clang LTO Sami Tolvanen
2020-06-24 20:31 ` [PATCH 01/22] objtool: use sh_info to find the base for .rela sections Sami Tolvanen
2020-06-24 20:31 ` [PATCH 02/22] kbuild: add support for Clang LTO Sami Tolvanen
2020-06-24 20:53 ` Nick Desaulniers
2020-06-24 21:29 ` Sami Tolvanen
2020-06-25 2:26 ` Nathan Chancellor
2020-06-25 16:13 ` Sami Tolvanen
2020-06-24 20:31 ` [PATCH 03/22] kbuild: lto: fix module versioning Sami Tolvanen
2020-06-24 20:31 ` [PATCH 04/22] kbuild: lto: fix recordmcount Sami Tolvanen
2020-06-24 21:27 ` Peter Zijlstra
2020-06-24 21:45 ` Sami Tolvanen
2020-06-25 7:45 ` Peter Zijlstra
2020-06-25 16:15 ` Sami Tolvanen
2020-06-25 20:02 ` [RFC][PATCH] objtool,x86_64: Replace recordmcount with objtool Peter Zijlstra
2020-06-25 20:54 ` Nick Desaulniers
2020-06-25 22:40 ` Sami Tolvanen
2020-06-26 11:29 ` Peter Zijlstra
2020-06-26 11:42 ` Peter Zijlstra
2020-07-17 17:28 ` Sami Tolvanen
2020-07-17 17:36 ` Steven Rostedt
2020-07-17 17:47 ` Sami Tolvanen
2020-07-17 18:05 ` Steven Rostedt
2020-07-20 16:52 ` Sami Tolvanen
2020-07-22 17:58 ` Steven Rostedt
2020-07-22 18:07 ` Sami Tolvanen
2020-07-22 17:55 ` Steven Rostedt
2020-07-22 18:41 ` Peter Zijlstra
2020-07-22 19:09 ` Steven Rostedt
2020-07-22 20:03 ` Sami Tolvanen
2020-07-22 23:56 ` Peter Zijlstra
2020-07-23 0:06 ` Steven Rostedt
2020-08-06 22:09 ` Sami Tolvanen
2020-06-24 20:31 ` [PATCH 05/22] kbuild: lto: postpone objtool Sami Tolvanen
2020-06-24 21:19 ` Peter Zijlstra
2020-06-24 21:49 ` Sami Tolvanen
2020-06-25 7:47 ` Peter Zijlstra
2020-06-25 16:22 ` Sami Tolvanen
2020-06-25 18:33 ` Peter Zijlstra
2020-06-25 19:32 ` Sami Tolvanen
2020-06-24 20:31 ` [PATCH 06/22] kbuild: lto: limit inlining Sami Tolvanen
2020-06-24 21:20 ` Peter Zijlstra
2020-06-24 23:37 ` Sami Tolvanen
2020-06-24 20:31 ` [PATCH 07/22] kbuild: lto: merge module sections Sami Tolvanen
2020-06-24 21:01 ` Nick Desaulniers
2020-06-24 21:31 ` Sami Tolvanen
2020-06-24 20:31 ` [PATCH 08/22] kbuild: lto: remove duplicate dependencies from .mod files Sami Tolvanen
2020-06-24 21:13 ` Nick Desaulniers
2020-06-24 20:31 ` [PATCH 09/22] init: lto: ensure initcall ordering Sami Tolvanen
2020-06-25 0:58 ` kernel test robot
2020-06-25 4:19 ` kernel test robot
2020-06-24 20:31 ` [PATCH 10/22] init: lto: fix PREL32 relocations Sami Tolvanen
2020-06-24 20:31 ` [PATCH 11/22] pci: " Sami Tolvanen
2020-06-24 22:49 ` kernel test robot
2020-06-24 23:03 ` Nick Desaulniers
2020-06-24 23:21 ` Sami Tolvanen
2020-07-17 20:26 ` Bjorn Helgaas
2020-07-22 18:15 ` Sami Tolvanen
2020-06-24 20:31 ` [PATCH 12/22] modpost: lto: strip .lto from module names Sami Tolvanen
2020-06-24 22:05 ` Nick Desaulniers
2020-06-24 20:31 ` [PATCH 13/22] scripts/mod: disable LTO for empty.c Sami Tolvanen
2020-06-24 20:57 ` Nick Desaulniers
2020-06-24 20:31 ` [PATCH 14/22] efi/libstub: disable LTO Sami Tolvanen
2020-06-24 20:31 ` [PATCH 15/22] drivers/misc/lkdtm: disable LTO for rodata.o Sami Tolvanen
2020-06-24 20:31 ` [PATCH 16/22] arm64: export CC_USING_PATCHABLE_FUNCTION_ENTRY Sami Tolvanen
2020-06-24 20:31 ` [PATCH 17/22] arm64: vdso: disable LTO Sami Tolvanen
2020-06-24 20:58 ` Nick Desaulniers
2020-06-24 21:09 ` Nick Desaulniers
2020-06-24 23:51 ` Andi Kleen
2020-06-24 21:52 ` Sami Tolvanen
2020-06-24 23:05 ` Nick Desaulniers
2020-06-24 23:39 ` Sami Tolvanen
2020-06-24 20:31 ` [PATCH 18/22] arm64: allow LTO_CLANG and THINLTO to be selected Sami Tolvanen
2020-06-24 20:31 ` [PATCH 19/22] x86, vdso: disable LTO only for vDSO Sami Tolvanen
2020-06-24 20:31 ` [PATCH 20/22] x86, ftrace: disable recordmcount for ftrace_make_nop Sami Tolvanen
2020-06-24 20:31 ` [PATCH 21/22] x86, relocs: Ignore L4_PAGE_OFFSET relocations Sami Tolvanen
2020-06-24 20:32 ` [PATCH 22/22] x86, build: allow LTO_CLANG and THINLTO to be selected Sami Tolvanen
2020-06-24 21:15 ` [PATCH 00/22] add support for Clang LTO Peter Zijlstra
2020-06-24 21:30 ` Sami Tolvanen
2020-06-25 8:27 ` Will Deacon
2020-06-24 21:31 ` Nick Desaulniers
2020-06-25 8:03 ` Peter Zijlstra
2020-06-25 8:24 ` Peter Zijlstra
2020-06-25 8:57 ` Peter Zijlstra
2020-06-30 19:19 ` Marco Elver
2020-06-30 20:12 ` Peter Zijlstra
2020-06-30 20:30 ` Paul E. McKenney
2020-07-01 9:10 ` Peter Zijlstra
2020-07-01 14:20 ` David Laight
2020-07-01 16:06 ` Paul E. McKenney
2020-07-02 9:37 ` David Laight
2020-07-02 18:00 ` Paul E. McKenney
2020-07-01 9:41 ` Marco Elver
2020-07-01 10:03 ` Will Deacon
2020-07-01 11:40 ` Peter Zijlstra
2020-07-01 14:06 ` Paul E. McKenney
2020-07-01 15:05 ` Peter Zijlstra
2020-07-01 16:03 ` Paul E. McKenney
2020-07-02 8:20 ` Peter Zijlstra
2020-07-02 17:59 ` Paul E. McKenney
2020-07-03 13:13 ` Peter Zijlstra
2020-07-03 13:25 ` Peter Zijlstra
2020-07-03 14:51 ` Paul E. McKenney
2020-07-03 14:42 ` Paul E. McKenney
2020-07-06 16:26 ` Paul E. McKenney
2020-07-06 18:29 ` Peter Zijlstra
2020-07-06 18:39 ` Paul E. McKenney
2020-07-06 19:40 ` Peter Zijlstra
2020-07-06 23:41 ` Paul E. McKenney
2020-06-28 16:56 ` Masahiro Yamada
2020-06-29 23:20 ` Sami Tolvanen
2020-07-07 15:51 ` Sami Tolvanen
2020-07-07 16:05 ` Sami Tolvanen
2020-07-07 16:56 ` Jakub Kicinski
2020-07-07 17:17 ` Nick Desaulniers
2020-07-07 17:30 ` Jakub Kicinski
2020-07-11 16:32 ` Paul Menzel
2020-07-12 8:59 ` Sedat Dilek
2020-07-12 18:40 ` Nathan Chancellor
2020-07-14 9:44 ` Sedat Dilek
2020-07-14 17:54 ` Nick Desaulniers
2020-07-12 23:34 ` Sami Tolvanen
2020-07-14 12:16 ` Paul Menzel
2020-07-14 12:35 ` Sedat Dilek
2020-07-14 13:40 ` Paul Menzel
2020-09-03 20:30 ` [PATCH v2 00/28] Add " Sami Tolvanen
2020-09-03 20:30 ` [PATCH v2 01/28] x86/boot/compressed: Disable relocation relaxation Sami Tolvanen
2020-09-03 21:44 ` Kees Cook
2020-09-03 23:42 ` Arvind Sankar
2020-09-04 7:14 ` Nathan Chancellor
2020-09-03 20:30 ` [PATCH v2 02/28] x86/asm: Replace __force_order with memory clobber Sami Tolvanen
2020-09-03 21:45 ` Kees Cook
2020-09-03 20:30 ` [PATCH v2 03/28] lib/string.c: implement stpcpy Sami Tolvanen
2020-09-03 21:47 ` Kees Cook
2020-09-03 20:30 ` [PATCH v2 04/28] RAS/CEC: Fix cec_init() prototype Sami Tolvanen
2020-09-03 21:50 ` Kees Cook
2020-09-03 20:30 ` [PATCH v2 05/28] objtool: Add a pass for generating __mcount_loc Sami Tolvanen
2020-09-03 21:51 ` Kees Cook
2020-09-03 22:03 ` Sami Tolvanen
2020-09-04 9:31 ` peterz
2020-09-10 18:29 ` Kees Cook
2020-09-03 20:30 ` [PATCH v2 06/28] objtool: Don't autodetect vmlinux.o Sami Tolvanen
2020-09-03 21:52 ` Kees Cook
2020-09-03 20:30 ` [PATCH v2 07/28] kbuild: add support for objtool mcount Sami Tolvanen
2020-09-03 21:56 ` Kees Cook
2020-09-03 20:30 ` [PATCH v2 08/28] x86, build: use " Sami Tolvanen
2020-09-03 21:58 ` Kees Cook
2020-09-03 22:11 ` Sami Tolvanen
2020-09-03 20:30 ` [PATCH v2 09/28] kbuild: add support for Clang LTO Sami Tolvanen
2020-09-03 22:08 ` Kees Cook
2020-09-08 17:02 ` Sami Tolvanen
2020-09-05 19:36 ` Masahiro Yamada
2020-09-08 17:10 ` Sami Tolvanen
2020-09-05 20:17 ` Masahiro Yamada
2020-09-08 17:14 ` Sami Tolvanen
2020-09-07 15:30 ` Masahiro Yamada
2020-09-08 17:30 ` Sami Tolvanen
2020-09-03 20:30 ` [PATCH v2 10/28] kbuild: lto: fix module versioning Sami Tolvanen
2020-09-03 22:11 ` Kees Cook
2020-09-08 18:23 ` Sami Tolvanen
2020-09-03 20:30 ` [PATCH v2 11/28] kbuild: lto: postpone objtool Sami Tolvanen
2020-09-03 22:19 ` Kees Cook [this message]
2020-09-08 20:56 ` Sami Tolvanen
2020-09-03 20:30 ` [PATCH v2 12/28] kbuild: lto: limit inlining Sami Tolvanen
2020-09-03 22:20 ` Kees Cook
2020-09-03 20:30 ` [PATCH v2 13/28] kbuild: lto: merge module sections Sami Tolvanen
2020-09-03 22:23 ` Kees Cook
2020-09-07 15:25 ` Masahiro Yamada
2020-09-08 21:07 ` Sami Tolvanen
2020-09-03 20:30 ` [PATCH v2 14/28] kbuild: lto: remove duplicate dependencies from .mod files Sami Tolvanen
2020-09-03 22:29 ` Kees Cook
2020-09-03 20:30 ` [PATCH v2 15/28] init: lto: ensure initcall ordering Sami Tolvanen
2020-09-03 22:40 ` Kees Cook
2020-09-08 21:16 ` Sami Tolvanen
2020-09-10 9:25 ` David Woodhouse
2020-09-10 15:07 ` Sami Tolvanen
2020-09-03 20:30 ` [PATCH v2 16/28] init: lto: fix PREL32 relocations Sami Tolvanen
2020-09-03 22:41 ` Kees Cook
2020-09-03 20:30 ` [PATCH v2 17/28] PCI: Fix PREL32 relocations for LTO Sami Tolvanen
2020-09-03 22:42 ` Kees Cook
2020-09-03 20:30 ` [PATCH v2 18/28] modpost: lto: strip .lto from module names Sami Tolvanen
2020-09-03 22:42 ` Kees Cook
2020-09-03 20:30 ` [PATCH v2 19/28] scripts/mod: disable LTO for empty.c Sami Tolvanen
2020-09-03 22:43 ` Kees Cook
2020-09-03 20:30 ` [PATCH v2 20/28] efi/libstub: disable LTO Sami Tolvanen
2020-09-03 22:43 ` Kees Cook
2020-09-03 20:30 ` [PATCH v2 21/28] drivers/misc/lkdtm: disable LTO for rodata.o Sami Tolvanen
2020-09-03 20:30 ` [PATCH v2 22/28] arm64: export CC_USING_PATCHABLE_FUNCTION_ENTRY Sami Tolvanen
2020-09-03 22:44 ` Kees Cook
2020-09-08 21:23 ` Sami Tolvanen
2020-09-03 20:30 ` [PATCH v2 23/28] arm64: vdso: disable LTO Sami Tolvanen
2020-09-03 22:45 ` Kees Cook
2020-09-03 20:30 ` [PATCH v2 24/28] KVM: arm64: disable LTO for the nVHE directory Sami Tolvanen
2020-09-03 22:45 ` Kees Cook
2020-09-03 20:30 ` [PATCH v2 25/28] arm64: allow LTO_CLANG and THINLTO to be selected Sami Tolvanen
2020-09-03 22:45 ` Kees Cook
2020-09-03 20:30 ` [PATCH v2 26/28] x86, vdso: disable LTO only for vDSO Sami Tolvanen
2020-09-03 22:46 ` Kees Cook
2020-09-03 20:30 ` [PATCH v2 27/28] x86, relocs: Ignore L4_PAGE_OFFSET relocations Sami Tolvanen
2020-09-03 22:47 ` Kees Cook
2020-09-08 23:28 ` Sami Tolvanen
2020-09-03 20:30 ` [PATCH v2 28/28] x86, build: allow LTO_CLANG and THINLTO to be selected Sami Tolvanen
2020-09-03 22:48 ` Kees Cook
2020-09-03 23:34 ` [PATCH v2 00/28] Add support for Clang LTO Kees Cook
2020-09-04 4:45 ` Nathan Chancellor
2020-09-03 23:38 ` Kees Cook
2020-09-04 7:53 ` Sedat Dilek
2020-09-04 8:55 ` peterz
2020-09-04 9:08 ` Sedat Dilek
2020-09-06 0:24 ` Masahiro Yamada
2020-09-08 23:46 ` Sami Tolvanen
2020-09-10 1:18 ` Masahiro Yamada
2020-09-10 15:17 ` Sami Tolvanen
2020-09-10 18:18 ` Kees Cook
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