Module object files can contain an undefined reference to __this_module,
which isn't resolved until we link the final .ko. The kernel doesn't
export this symbol, so ignore it in gen_autoksyms.sh.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Tested-by: Steve Muckle <smuckle@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Ramji Jiyani <ramjiyani@google.com>
(cherry picked from commit ff139766764675b9df12bcbc8928a02149b7ba95)
Bug: 235776933
Change-Id: I1152458cbc6ea5488a48516f92eef54f2c314860
Signed-off-by: Steve Muckle <smuckle@google.com>
(cherry picked from commit 5b6fcb222235c26fa1fe13ebb7f1545267a1d027)
The *.mod files have two lines; the first line lists the member objects
of the module, and the second line, if CONFIG_TRIM_UNUSED_KSYMS=y, lists
the undefined symbols.
Currently, we generate *.mod after constructing composite modules,
otherwise, we cannot compute the second line. No prerequisite is
required to print the first line.
They are orthogonal. Splitting them into separate commands will ease
further cleanups.
This commit splits the list of undefined symbols out to *.usyms files.
Previously, the list of undefined symbols ended up with a very long
line, but now it has one symbol per line.
Use sed like we did before commit 7d32358be8 ("kbuild: avoid split
lines in .mod files").
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Bug: 175420575
(cherry picked from commit 2f6b64906adf99b4c5ea9356df793766d290cfb4
https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git kbuild)
Change-Id: Ic801d2bf085aff6e50d15d196c43da4df3aa88c8
Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
With CONFIG_LTO_CLANG, we currently link modules into native
code just before modpost, which means with TRIM_UNUSED_KSYMS
enabled, we still look at the LLVM bitcode in the .o files when
generating the list of used symbols. As the bitcode doesn't
yet have calls to compiler intrinsics and llvm-nm doesn't see
function references that only exist in function-level inline
assembly, we currently need a whitelist for TRIM_UNUSED_KSYMS to
work with LTO.
This change moves module LTO linking to happen earlier, and
thus avoids the issue with LLVM bitcode and TRIM_UNUSED_KSYMS
entirely, allowing us to also drop the whitelist from
gen_autoksyms.sh.
Link: https://github.com/ClangBuiltLinux/linux/issues/1369
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Alexander Lobakin <alobakin@pm.me>
Tested-by: Alexander Lobakin <alobakin@pm.me>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Commit fbe078d397 ("kbuild: lto: add a default list of used symbols")
does not work as expected if the .config file has already specified
CONFIG_UNUSED_KSYMS_WHITELIST="my/own/white/list" before enabling
CONFIG_LTO_CLANG.
So, the user-supplied whitelist and LTO-specific white list must be
independent of each other.
I refactored the shell script so CONFIG_MODVERSIONS and CONFIG_CLANG_LTO
handle whitelists in the same way.
Fixes: fbe078d397 ("kbuild: lto: add a default list of used symbols")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Stephen Rothwell reported a build error on ppc64 when
CONFIG_TRIM_UNUSED_KSYMS is enabled.
Jessica Yu pointed out the cause of the error with the reference to the
ppc64 ELF ABI:
"Symbol names with a dot (.) prefix are reserved for holding entry
point addresses. The value of a symbol named ".FN", if it exists,
is the entry point of the function "FN".
As it turned out, CONFIG_TRIM_UNUSED_KSYMS has never worked for ppc64,
but this issue has been unnoticed until recently because this option
depends on !UNUSED_SYMBOLS hence is disabled by all{mod,yes}config.
(Then, it was uncovered by another patch removing UNUSED_SYMBOLS.)
Removing the dot prefix in scripts/gen_autoksyms.sh fixes the issue.
Please note it must be done before 'sort -u' because modules have
both ._mcount and _mcount undefined when CONFIG_FUNCTION_TRACER=y.
Link: https://lore.kernel.org/lkml/20210209210843.3af66662@canb.auug.org.au/
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Jessica Yu <jeyu@kernel.org>
When doing a cold build, autoksyms.h starts empty, and is updated late
in the build process to have visibility over the symbols used by in-tree
drivers. But since the symbol whitelist is known upfront, it can be used
to pre-populate autoksyms.h and maximize the amount of code that can be
compiled to its final state in a single pass, hence reducing build time.
Do this by using gen_autoksyms.sh to initialize autoksyms.h instead of
creating an empty file.
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Tested-by: Matthias Maennich <maennich@google.com>
Reviewed-by: Matthias Maennich <maennich@google.com>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
In order to prepare the ground for a build-time optimization, split
adjust_autoksyms.sh into two scripts: one that generates autoksyms.h
based on all currently available information (whitelist, and .mod
files), and the other to inspect the diff between two versions of
autoksyms.h and trigger appropriate rebuilds.
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Tested-by: Matthias Maennich <maennich@google.com>
Reviewed-by: Matthias Maennich <maennich@google.com>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
