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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id 143sm704359pfw.13.2020.10.14.15.50.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 14 Oct 2020 15:50:29 -0700 (PDT) Date: Wed, 14 Oct 2020 15:50:28 -0700 From: Kees Cook To: Masahiro Yamada Cc: Sami Tolvanen , Steven Rostedt , Will Deacon , Peter Zijlstra , Greg Kroah-Hartman , "Paul E. McKenney" , Nick Desaulniers , 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 v6 14/25] kbuild: lto: remove duplicate dependencies from .mod files Message-ID: <202010141549.412F2BF0@keescook> References: <20201013003203.4168817-1-samitolvanen@google.com> <20201013003203.4168817-15-samitolvanen@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201013003203.4168817-15-samitolvanen@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org 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 > Reviewed-by: Kees Cook 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. -Kees > --- > scripts/Makefile.build | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/scripts/Makefile.build b/scripts/Makefile.build > index ab0ddf4884fd..96d6c9e18901 100644 > --- a/scripts/Makefile.build > +++ b/scripts/Makefile.build > @@ -266,7 +266,7 @@ endef > > # List module undefined symbols (or empty line if not enabled) > ifdef CONFIG_TRIM_UNUSED_KSYMS > -cmd_undef_syms = $(NM) $< | sed -n 's/^ *U //p' | xargs echo > +cmd_undef_syms = $(NM) $< | sed -n 's/^ *U //p' | sort -u | xargs echo > else > cmd_undef_syms = echo > endif > -- > 2.28.0.1011.ga647a8990f-goog > -- Kees Cook