From: Sami Tolvanen <samitolvanen@google.com>
To: Kees Cook <keescook@chromium.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Will Deacon <will@kernel.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
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 <linux-kbuild@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
PCI <linux-pci@vger.kernel.org>
Subject: Re: [PATCH v9 06/16] kbuild: lto: add a default list of used symbols
Date: Fri, 11 Dec 2020 11:40:23 -0800 [thread overview]
Message-ID: <CABCJKueCJhwRL1T1k6EYpUy_-Rj85K98iz5FO6K+dZLY25z8_Q@mail.gmail.com> (raw)
In-Reply-To: <202012111131.E41AFFCDB@keescook>
On Fri, Dec 11, 2020 at 11:32 AM Kees Cook <keescook@chromium.org> wrote:
>
> On Fri, Dec 11, 2020 at 10:46:23AM -0800, Sami Tolvanen wrote:
> > With CONFIG_LTO_CLANG, LLVM bitcode has not yet been compiled into a
> > binary when the .mod files are generated, which means they don't yet
> > contain references to certain symbols that will be present in the final
> > binaries. This includes intrinsic functions, such as memcpy, memmove,
> > and memset [1], and stack protector symbols [2]. This change adds a
> > default symbol list to use with CONFIG_TRIM_UNUSED_KSYMS when Clang's
> > LTO is used.
> >
> > [1] https://llvm.org/docs/LangRef.html#standard-c-c-library-intrinsics
> > [2] https://llvm.org/docs/LangRef.html#llvm-stackprotector-intrinsic
> >
> > Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
>
> Reviewed-by: Kees Cook <keescook@chromium.org>
>
> > ---
> > init/Kconfig | 1 +
> > scripts/lto-used-symbollist | 5 +++++
> > 2 files changed, 6 insertions(+)
> > create mode 100644 scripts/lto-used-symbollist
> >
> > diff --git a/init/Kconfig b/init/Kconfig
> > index 0872a5a2e759..e88c919c1bf1 100644
> > --- a/init/Kconfig
> > +++ b/init/Kconfig
> > @@ -2297,6 +2297,7 @@ config TRIM_UNUSED_KSYMS
> > config UNUSED_KSYMS_WHITELIST
> > string "Whitelist of symbols to keep in ksymtab"
> > depends on TRIM_UNUSED_KSYMS
> > + default "scripts/lto-used-symbollist" if LTO_CLANG
> > help
> > By default, all unused exported symbols will be un-exported from the
> > build when TRIM_UNUSED_KSYMS is selected.
> > diff --git a/scripts/lto-used-symbollist b/scripts/lto-used-symbollist
> > new file mode 100644
> > index 000000000000..38e7bb9ebaae
> > --- /dev/null
> > +++ b/scripts/lto-used-symbollist
> > @@ -0,0 +1,5 @@
> > +memcpy
> > +memmove
> > +memset
> > +__stack_chk_fail
> > +__stack_chk_guard
> > --
> > 2.29.2.576.ga3fc446d84-goog
> >
>
> bikeshed: Should this filename use some kind of extension, like
> lto-user-symbols.txt or .list, to make it more human-friendly?
Sure, I can rename this in the next version. Does anyone have strong
opinions about the name and/or extension?
Sami
next prev parent reply other threads:[~2020-12-11 21:12 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-11 18:46 [PATCH v9 00/16] Add support for Clang LTO Sami Tolvanen
2020-12-11 18:46 ` [PATCH v9 01/16] tracing: move function tracer options to Kconfig Sami Tolvanen
2021-02-24 20:17 ` [PATCH v9 01/16] tracing: move function tracer options to Kconfig (causing parisc build failures) Guenter Roeck
2021-02-24 20:38 ` Kees Cook
2021-02-24 20:54 ` Sami Tolvanen
2021-02-24 22:29 ` Guenter Roeck
2021-02-24 22:28 ` Guenter Roeck
2021-02-24 22:42 ` Kees Cook
2020-12-11 18:46 ` [PATCH v9 02/16] kbuild: add support for Clang LTO Sami Tolvanen
2020-12-11 18:46 ` [PATCH v9 03/16] kbuild: lto: fix module versioning Sami Tolvanen
2020-12-11 18:46 ` [PATCH v9 04/16] kbuild: lto: limit inlining Sami Tolvanen
2020-12-11 18:46 ` [PATCH v9 05/16] kbuild: lto: merge module sections Sami Tolvanen
2020-12-11 18:46 ` [PATCH v9 06/16] kbuild: lto: add a default list of used symbols Sami Tolvanen
2020-12-11 19:32 ` Kees Cook
2020-12-11 19:40 ` Sami Tolvanen [this message]
2020-12-11 19:45 ` Nick Desaulniers
2020-12-11 18:46 ` [PATCH v9 07/16] init: lto: ensure initcall ordering Sami Tolvanen
2020-12-11 18:46 ` [PATCH v9 08/16] init: lto: fix PREL32 relocations Sami Tolvanen
2020-12-11 18:46 ` [PATCH v9 09/16] PCI: Fix PREL32 relocations for LTO Sami Tolvanen
2020-12-11 18:46 ` [PATCH v9 10/16] modpost: lto: strip .lto from module names Sami Tolvanen
2020-12-11 18:46 ` [PATCH v9 11/16] scripts/mod: disable LTO for empty.c Sami Tolvanen
2020-12-11 18:46 ` [PATCH v9 12/16] efi/libstub: disable LTO Sami Tolvanen
2020-12-11 18:46 ` [PATCH v9 13/16] drivers/misc/lkdtm: disable LTO for rodata.o Sami Tolvanen
2020-12-11 18:46 ` [PATCH v9 14/16] arm64: vdso: disable LTO Sami Tolvanen
2020-12-11 18:46 ` [PATCH v9 15/16] arm64: disable recordmcount with DYNAMIC_FTRACE_WITH_REGS Sami Tolvanen
2020-12-11 18:46 ` [PATCH v9 16/16] arm64: allow LTO to be selected Sami Tolvanen
2020-12-11 19:38 ` [PATCH v9 00/16] Add support for Clang LTO Kees Cook
2021-01-09 0:27 ` Kees Cook
2021-01-09 14:54 ` Sedat Dilek
2021-01-09 15:36 ` Josh Poimboeuf
2021-01-09 15:46 ` Sedat Dilek
2021-01-09 16:07 ` Josh Poimboeuf
2021-01-09 16:21 ` Sedat Dilek
2021-01-09 16:32 ` Josh Poimboeuf
2021-01-09 16:45 ` Sedat Dilek
2021-01-09 17:03 ` Josh Poimboeuf
2021-01-09 17:05 ` Josh Poimboeuf
2021-01-09 17:33 ` Sedat Dilek
2021-01-09 23:44 ` Sedat Dilek
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