From: Sami Tolvanen <samitolvanen@google.com>
To: Masahiro Yamada <masahiroy@kernel.org>
Cc: Kees Cook <keescook@chromium.org>,
Steven Rostedt <rostedt@goodmis.org>,
Will Deacon <will@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Paul E. McKenney" <paulmck@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
clang-built-linux <clang-built-linux@googlegroups.com>,
Kernel Hardening <kernel-hardening@lists.openwall.com>,
linux-arch <linux-arch@vger.kernel.org>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
PCI <linux-pci@vger.kernel.org>, X86 ML <x86@kernel.org>
Subject: Re: [PATCH v6 14/25] kbuild: lto: remove duplicate dependencies from .mod files
Date: Thu, 3 Dec 2020 10:47:48 -0800 [thread overview]
Message-ID: <CABCJKue4Gg7gGA3cgpP-uiThxR=5Qh2Pq+KctGJN_GtStpf9Fg@mail.gmail.com> (raw)
In-Reply-To: <CAK7LNAT350QjusoYCQEHDdoxAfTZjj82xp86O1qoNF=0u0PN-g@mail.gmail.com>
On Thu, Dec 3, 2020 at 10:00 AM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> On Thu, Oct 15, 2020 at 7:50 AM Kees Cook <keescook@chromium.org> wrote:
> >
> > On Mon, Oct 12, 2020 at 05:31:52PM -0700, Sami Tolvanen wrote:
> > > With LTO, llvm-nm prints out symbols for each archive member
> > > separately, which results in a lot of duplicate dependencies in the
> > > .mod file when CONFIG_TRIM_UNUSED_SYMS is enabled. When a module
> > > consists of several compilation units, the output can exceed the
> > > default xargs command size limit and split the dependency list to
> > > multiple lines, which results in used symbols getting trimmed.
> > >
> > > This change removes duplicate dependencies, which will reduce the
> > > probability of this happening and makes .mod files smaller and
> > > easier to read.
> > >
> > > Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> > > Reviewed-by: Kees Cook <keescook@chromium.org>
> >
> > Hi Masahiro,
> >
> > This appears to be a general improvement as well. This looks like it can
> > land without depending on the rest of the series.
>
> It cannot.
> Adding "sort -u" is pointless without the rest of the series
> since the symbol duplication happens only with Clang LTO.
>
> This is not a solution.
> "reduce the probability of this happening" well describes it.
>
> I wrote a different patch.
Great, thanks for looking into this. I'll drop this patch from the next version.
Sami
next prev parent reply other threads:[~2020-12-03 18:48 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-13 0:31 [PATCH v6 00/25] Add support for Clang LTO Sami Tolvanen
2020-10-13 0:31 ` [PATCH v6 01/25] kbuild: preprocess module linker script Sami Tolvanen
2020-10-13 0:31 ` [PATCH v6 02/25] objtool: Add a pass for generating __mcount_loc Sami Tolvanen
2020-10-14 16:50 ` Ingo Molnar
2020-10-14 18:21 ` Peter Zijlstra
2020-10-15 20:10 ` Josh Poimboeuf
2020-10-13 0:31 ` [PATCH v6 03/25] objtool: Don't autodetect vmlinux.o Sami Tolvanen
2020-10-13 0:31 ` [PATCH v6 04/25] tracing: move function tracer options to Kconfig Sami Tolvanen
2020-10-13 0:31 ` [PATCH v6 05/25] tracing: add support for objtool mcount Sami Tolvanen
2020-10-13 0:31 ` [PATCH v6 06/25] x86, build: use " Sami Tolvanen
2020-10-13 0:31 ` [PATCH v6 07/25] treewide: remove DISABLE_LTO Sami Tolvanen
2020-10-14 22:43 ` Kees Cook
2020-10-17 1:46 ` Masahiro Yamada
2020-10-13 0:31 ` [PATCH v6 08/25] kbuild: add support for Clang LTO Sami Tolvanen
2020-10-13 0:31 ` [PATCH v6 09/25] kbuild: lto: fix module versioning Sami Tolvanen
2020-10-13 0:31 ` [PATCH v6 10/25] objtool: Split noinstr validation from --vmlinux Sami Tolvanen
2020-10-13 0:31 ` [PATCH v6 11/25] kbuild: lto: postpone objtool Sami Tolvanen
2020-10-13 0:31 ` [PATCH v6 12/25] kbuild: lto: limit inlining Sami Tolvanen
2020-10-13 0:31 ` [PATCH v6 13/25] kbuild: lto: merge module sections Sami Tolvanen
2020-10-14 22:49 ` Kees Cook
2020-10-20 16:42 ` Sami Tolvanen
2020-10-13 0:31 ` [PATCH v6 14/25] kbuild: lto: remove duplicate dependencies from .mod files Sami Tolvanen
2020-10-14 22:50 ` Kees Cook
2020-12-03 17:59 ` Masahiro Yamada
2020-12-03 18:47 ` Sami Tolvanen [this message]
2020-10-13 0:31 ` [PATCH v6 15/25] init: lto: ensure initcall ordering Sami Tolvanen
2020-10-13 0:31 ` [PATCH v6 16/25] init: lto: fix PREL32 relocations Sami Tolvanen
2020-10-14 22:53 ` Kees Cook
2020-10-15 0:12 ` Jann Horn
2020-10-13 0:31 ` [PATCH v6 17/25] PCI: Fix PREL32 relocations for LTO Sami Tolvanen
2020-10-14 22:58 ` Kees Cook
2020-10-13 0:31 ` [PATCH v6 18/25] modpost: lto: strip .lto from module names Sami Tolvanen
2020-10-13 0:31 ` [PATCH v6 19/25] scripts/mod: disable LTO for empty.c Sami Tolvanen
2020-10-13 0:31 ` [PATCH v6 20/25] efi/libstub: disable LTO Sami Tolvanen
2020-10-13 0:31 ` [PATCH v6 21/25] drivers/misc/lkdtm: disable LTO for rodata.o Sami Tolvanen
2020-10-13 0:32 ` [PATCH v6 22/25] x86/asm: annotate indirect jumps Sami Tolvanen
2020-10-14 22:46 ` Kees Cook
2020-10-14 23:23 ` Jann Horn
2020-10-15 10:22 ` Peter Zijlstra
2020-10-15 20:39 ` Josh Poimboeuf
2020-10-20 16:45 ` Sami Tolvanen
2020-10-20 18:52 ` Josh Poimboeuf
2020-10-20 19:24 ` Sami Tolvanen
2020-10-21 8:56 ` Peter Zijlstra
2020-10-21 9:08 ` Peter Zijlstra
2020-10-21 9:32 ` Peter Zijlstra
2020-10-21 21:27 ` Josh Poimboeuf
2020-10-22 7:25 ` Peter Zijlstra
2020-10-23 17:48 ` Sami Tolvanen
2020-10-23 18:04 ` Nick Desaulniers
2020-10-21 15:01 ` Sami Tolvanen
2020-10-22 0:22 ` Sami Tolvanen
2020-10-23 17:36 ` Sami Tolvanen
2020-11-09 23:11 ` Sami Tolvanen
2020-11-10 2:29 ` Josh Poimboeuf
2020-11-10 3:18 ` Nick Desaulniers
2020-11-10 4:48 ` Sami Tolvanen
2020-11-10 16:11 ` Josh Poimboeuf
2020-11-10 17:46 ` Josh Poimboeuf
2020-11-10 18:59 ` Sami Tolvanen
2020-11-13 19:54 ` Josh Poimboeuf
2020-11-13 20:24 ` Sami Tolvanen
2020-11-13 20:52 ` Josh Poimboeuf
2020-11-13 22:34 ` Josh Poimboeuf
2020-11-13 22:54 ` Sami Tolvanen
2020-11-13 22:56 ` Josh Poimboeuf
2020-11-13 23:31 ` Sami Tolvanen
2020-11-14 0:49 ` Josh Poimboeuf
2020-10-21 9:51 ` Peter Zijlstra
2020-10-21 18:30 ` Josh Poimboeuf
2020-10-13 0:32 ` [PATCH v6 23/25] x86, vdso: disable LTO only for vDSO Sami Tolvanen
2020-10-13 0:32 ` [PATCH v6 24/25] x86, cpu: disable LTO for cpu.c Sami Tolvanen
2020-10-13 0:32 ` [PATCH v6 25/25] x86, build: allow LTO_CLANG and THINLTO to be selected Sami Tolvanen
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