lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Sun, 17 Jan 2021 18:32:25 -0800 From: Bill Wendling <morbo@...gle.com> To: Sedat Dilek <sedat.dilek@...il.com> Cc: Jonathan Corbet <corbet@....net>, Masahiro Yamada <masahiroy@...nel.org>, Linux Doc Mailing List <linux-doc@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>, Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>, Clang-Built-Linux ML <clang-built-linux@...glegroups.com>, Andrew Morton <akpm@...ux-foundation.org>, Nathan Chancellor <natechancellor@...il.com>, Nick Desaulniers <ndesaulniers@...gle.com>, Sami Tolvanen <samitolvanen@...gle.com>, Fangrui Song <maskray@...gle.com> Subject: Re: [PATCH v5] pgo: add clang's Profile Guided Optimization infrastructure On Sun, Jan 17, 2021 at 4:27 PM Sedat Dilek <sedat.dilek@...il.com> wrote: > > [ big snip ] [More snippage.] > [ CC Fangrui ] > > With the attached... > > [PATCH v3] module: Ignore _GLOBAL_OFFSET_TABLE_ when warning for > undefined symbols > > ...I was finally able to boot into a rebuild PGO-optimized Linux-kernel. > For details see ClangBuiltLinux issue #1250 "Unknown symbol > _GLOBAL_OFFSET_TABLE_ loading kernel modules". > Thanks for confirming that this works with the above patch. > @ Bill Nick Sami Nathan > > 1, Can you say something of the impact passing "LLVM_IAS=1" to make? The integrated assembler and this option are more-or-less orthogonal to each other. One can still use the GNU assembler with PGO. If you're having an issue, it may be related to ClangBuiltLinux issue #1250. > 2. Can you please try Nick's DWARF v5 support patchset v5 and > CONFIG_DEBUG_INFO_DWARF5=y (see attachments)? > I know Nick did several tests with PGO. He may have looked into it already, but we can check. > I would like to know what the impact of the Clang's Integrated > Assembler and DWARF v5 are. > > I dropped both means... > > 1. Do not pass "LLVM_IAS=1" to make. > 2. Use default DWARF v2 (with Nick's patchset: CONFIG_DEBUG_INFO_DWARF2=y). > > ...for a successfull build and boot on bare metal. > [Next message] > On each rebuild I need to pass to make ...? > > LLVM=1 -fprofile-use=vmlinux.profdata > Yes. > Did you try together with passing LLVM_IAS=1 to make? One of my tests was with the integrated assembler enabled. Are you finding issues with it? The problem with using top-of-tree clang is that it's not necessarily stable. You could try using the clang 11.x release (changing the "CLANG_VERSION >= 120000" in kernel/pgo/Kconfig/ to "CLANG_VERSION >= 110000"). -bw
Powered by blists - more mailing lists