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Paul Walmsley f28d930810 modpost: skip ELF local symbols during section mismatch check 
[ Upstream commit a4d26f1a09 ]

During development of a serial console driver with a gcc 8.2.0
toolchain for RISC-V, the following modpost warning appeared:

----
WARNING: vmlinux.o(.data+0x19b10): Section mismatch in reference from the variable .LANCHOR1 to the function .init.text:sifive_serial_console_setup()
The variable .LANCHOR1 references
the function __init sifive_serial_console_setup()
If the reference is valid then annotate the
variable with __init* or __refdata (see linux/init.h) or name the variable:
*_template, *_timer, *_sht, *_ops, *_probe, *_probe_one, *_console
----

".LANCHOR1" is an ELF local symbol, automatically created by gcc's section
anchor generation code:

https://gcc.gnu.org/onlinedocs/gccint/Anchored-Addresses.html

https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/varasm.c;h=cd9591a45617464946dcf9a126dde277d9de9804;hb=9fb89fa845c1b2e0a18d85ada0b077c84508ab78#l7473

This was verified by compiling the kernel with -fno-section-anchors
and observing that the ".LANCHOR1" ELF local symbol disappeared, and
modpost no longer warned about the section mismatch.  The serial
driver code idiom triggering the warning is standard Linux serial
driver practice that has a specific whitelist inclusion in modpost.c.

I'm neither a modpost nor an ELF expert, but naively, it doesn't seem
useful for modpost to report section mismatch warnings caused by ELF
local symbols by default.  Local symbols have compiler-generated
names, and thus bypass modpost's whitelisting algorithm, which relies
on the presence of a non-autogenerated symbol name.  This increases
the likelihood that false positive warnings will be generated (as in
the above case).

Thus, disable section mismatch reporting on ELF local symbols.  The
rationale here is similar to that of commit 2e3a10a155 ("ARM: avoid
ARM binutils leaking ELF local symbols") and of similar code already
present in modpost.c:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/scripts/mod/modpost.c?h=v4.19-rc4&id=7876320f88802b22d4e2daf7eb027dd14175a0f8#n1256

This third version of the patch implements a suggestion from Masahiro
Yamada <yamada.masahiro@socionext.com> to restructure the code as an
additional pattern matching step inside secref_whitelist(), and
further improves the patch description.

Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-12-13 08:52:20 +01:00
..
basic kbuild: move bin2c back to scripts/ from scripts/basic/ 2018-07-18 01:18:05 +09:00
coccinelle fs: stream_open - opener for stream-like files so that read and write can run simultaneously without deadlock 2019-05-08 07:21:51 +02:00
dtc scripts/dtc: consolidate include path options in Makefile 2018-08-22 23:21:36 +09:00
gcc-plugins randstruct: Check member structs in is_pure_ops_struct() 2019-10-05 13:10:02 +02:00
gdb scripts/gdb: fix debugging modules compiled with hot/cold partitioning 2019-12-05 09:19:44 +01:00
genksyms genksyms: Teach parser about 128-bit built-in types 2019-07-31 07:27:02 +02:00
kconfig kconfig: Clear "written" flag to avoid data loss 2019-08-06 19:06:53 +02:00
ksymoops Fix dead URLs to ftp.kernel.org 2017-03-28 16:16:52 +02:00
mod modpost: skip ELF local symbols during section mismatch check 2019-12-13 08:52:20 +01:00
package kbuild: deb-pkg: fix bindeb-pkg breakage when O= is used 2019-04-17 08:38:45 +02:00
selinux selinux: use kernel linux/socket.h for genheaders and mdp 2019-05-04 09:20:10 +02:00
tracing scripts: Add Python 3 support to tracing/draw_functrace.py 2018-07-29 11:08:38 +09:00
.gitignore kbuild: move bin2c back to scripts/ from scripts/basic/ 2018-07-18 01:18:05 +09:00
adjust_autoksyms.sh kbuild: remove CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX 2018-05-17 22:44:57 +09:00
asn1_compiler.c kbuild: rename *-asn1.[ch] to *.asn1.[ch] 2018-04-07 19:04:02 +09:00
bin2c.c kbuild: move bin2c back to scripts/ from scripts/basic/ 2018-07-18 01:18:05 +09:00
bloat-o-meter syscalls/core, syscalls/x86: Clean up compat syscall stub naming convention 2018-04-09 16:47:28 +02:00
bootgraph.pl scripts: Switch to more portable Perl shebang 2017-05-14 11:20:44 +09:00
bpf_helpers_doc.py bpf: change eBPF helper doc parsing script to allow for smaller indent 2018-05-17 17:34:43 +02:00
cc-can-link.sh bpfilter: check compiler capability in Kconfig 2018-06-28 13:36:39 +09:00
check_00index.sh License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
check_extable.sh License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
checkincludes.pl License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
checkkconfigsymbols.py
checkpatch.pl checkpatch: add __ro_after_init to known $Attribute 2018-09-04 16:45:02 -07:00
checkstack.pl scripts/checkstack.pl: Fix arm64 wrong or unknown architecture 2019-06-25 11:35:58 +08:00
checksyscalls.sh License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
checkversion.pl License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
clang-version.sh kbuild: Add a space after ! to prevent parsing as file pattern 2018-08-22 23:21:40 +09:00
cleanfile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
cleanpatch License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
coccicheck coccicheck: return proper error code on fail 2018-08-14 08:58:56 +09:00
config License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
conmakehash.c
const_structs.checkpatch
decode_stacktrace.sh scripts/decode_stacktrace: match basepath using shell prefix operator, not regex 2019-09-16 08:21:44 +02:00
decodecode scripts/decodecode: make it take multiline Code line 2018-01-31 17:18:34 -08:00
depmod.sh kbuild: modules_install: warn when missing System.map file 2018-09-09 09:14:07 +09:00
diffconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
documentation-file-ref-check scripts/documentation-file-ref-check: ignore sched-pelt false positive 2018-07-02 11:25:00 -06:00
export_report.pl scripts: Switch to more portable Perl shebang 2017-05-14 11:20:44 +09:00
extract-cert.c
extract-ikconfig
extract-module-sig.pl License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
extract-sys-certs.pl License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
extract-vmlinux scripts: teach extract-vmlinux about LZ4 and ZSTD 2018-07-08 09:32:32 +09:00
extract_xc3028.pl MAINTAINERS & files: Canonize the e-mails I use at files 2018-05-04 06:21:06 -04:00
faddr2line scripts/faddr2line: make the new code listing format optional 2018-06-05 09:04:37 -07:00
file-size.sh kbuild: Use ls(1) instead of stat(1) to obtain file size 2018-03-26 02:01:24 +09:00
find-unused-docs.sh scripts: Add a script to find unused documentation 2017-10-23 08:01:37 -06:00
gcc-goto.sh jump_label: move 'asm goto' support test to Kconfig 2019-06-04 08:02:34 +02:00
gcc-ld License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
gcc-plugin.sh License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
gcc-version.sh License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
gcc-x86_32-has-stack-protector.sh stack-protector: test compiler capability in Kconfig and drop AUTO mode 2018-06-08 18:56:00 +09:00
gcc-x86_64-has-stack-protector.sh stack-protector: Fix test with 32-bit userland and CONFIG_64BIT=y 2018-06-25 23:21:13 +09:00
get_dvb_firmware scripts: Switch to more portable Perl shebang 2017-05-14 11:20:44 +09:00
get_maintainer.pl get_maintainer: allow option --mpath <directory> to read all files in <directory> 2018-08-22 10:52:48 -07:00
gfp-translate
headerdep.pl License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
headers.sh License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
headers_check.pl License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
headers_install.sh kbuild: Improve portability of some sed invocations 2018-03-26 02:01:18 +09:00
insert-sys-cert.c
kallsyms.c kallsyms: exclude kasan local symbols on s390 2019-07-31 07:27:05 +02:00
Kbuild.include x86/build: Remove jump label quirk for GCC older than 4.5.2 2018-08-30 11:37:08 +02:00
Kconfig.include kbuild: Check for unknown options with cc-option usage in Kconfig and clang 2019-08-25 10:47:56 +02:00
kernel-doc scripts/kernel-doc: Escape all literal braces in regexes 2018-08-06 13:36:20 -06:00
ld-version.sh License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
leaking_addresses.pl leaking_addresses: check if file name contains address 2018-04-07 08:50:34 +10:00
Lindent License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
link-vmlinux.sh kbuild: rename LDFLAGS to KBUILD_LDFLAGS 2018-08-24 08:22:08 +09:00
Makefile kbuild: Rename HOST_LOADLIBES to KBUILD_HOSTLDLIBS 2018-07-18 01:18:05 +09:00
Makefile.asm-generic Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Makefile.build x86/retpoline: Make CONFIG_RETPOLINE depend on compiler support 2018-12-05 19:32:01 +01:00
Makefile.clean kbuild: remove deprecated host-progs variable 2018-08-09 21:51:17 +09:00
Makefile.dtbinst DeviceTree for 4.15: 2017-11-14 18:25:40 -08:00
Makefile.extrawarn Kbuild: suppress packed-not-aligned warning for default setting only 2018-01-18 09:37:53 +09:00
Makefile.gcc-plugins gcc-plugins: Regularize Makefile.gcc-plugins 2018-07-24 16:11:07 -07:00
Makefile.headersinst Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Makefile.host kbuild: Rename HOST_LOADLIBES to KBUILD_HOSTLDLIBS 2018-07-18 01:18:05 +09:00
Makefile.kasan kasan: rework Kconfig settings 2018-02-06 18:32:47 -08:00
Makefile.kcov kcov: test compiler capability in Kconfig and correct dependency 2018-06-11 09:14:08 +09:00
Makefile.lib kbuild: disable dtc simple_bus_reg warnings by default 2019-12-13 08:52:18 +01:00
Makefile.modbuiltin Kbuild: Makefile.modbuiltin: include auto.conf and tristate.conf mandatory 2018-08-03 00:47:00 +09:00
Makefile.modinst kbuild: remove duplicated comments about PHONY 2018-07-06 22:04:03 +09:00
Makefile.modpost kbuild: modpost: handle KBUILD_EXTRA_SYMBOLS only for external modules 2019-08-25 10:47:55 +02:00
Makefile.modsign kbuild: remove duplicated comments about PHONY 2018-07-06 22:04:03 +09:00
Makefile.ubsan lib/ubsan: remove null-pointer checks 2018-08-10 20:19:58 -07:00
makelst License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
markup_oops.pl scripts: Switch to more portable Perl shebang 2017-05-14 11:20:44 +09:00
mkcompile_h Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
mkmakefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
mksysmap
mkuboot.sh License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
module-common.lds module: set .init_array alignment to 8 2017-03-13 09:40:28 -07:00
namespace.pl namespace: fix namespace.pl script to support relative paths 2019-10-29 09:19:36 +01:00
objdiff scripts: objdiff: Ignore debug info when comparing 2017-03-11 11:13:38 +09:00
parse-maintainers.pl parse-maintainers: add ability to specify filenames 2017-11-17 16:10:01 -08:00
patch-kernel License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
pnmtologo.c
profile2linkerlist.pl License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
prune-kernel License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
recordmcount.c scripts: Fixed printf format mismatch 2018-05-29 22:04:12 +09:00
recordmcount.h recordmcount: Fix spurious mcount entries on powerpc 2019-07-31 07:27:03 +02:00
recordmcount.pl nds32/ftrace: Add RECORD_MCOUNT support 2018-09-04 14:45:18 +08:00
setlocalversion scripts/setlocalversion: Improve -dirty check with git-status --no-optional-locks 2019-11-06 13:05:27 +01:00
show_delta
sign-file.c
sortextable.c
sortextable.h
spdxcheck.py scripts/spdxcheck.py: always open files in binary mode 2018-12-19 19:19:50 +01:00
spelling.txt treewide: correct "differenciate" and "instanciate" typos 2018-08-23 18:48:43 -07:00
sphinx-pre-install scripts/sphinx-pre-install: fix script for RHEL/CentOS 2019-08-16 10:12:44 +02:00
split-man.pl MAINTAINERS & files: Canonize the e-mails I use at files 2018-05-04 06:21:06 -04:00
stackdelta License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
stackusage License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
subarch.include selftests: add headers_install to lib.mk 2018-09-05 08:12:09 -06:00
tags.sh Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-07-18 19:32:54 -07:00
unifdef.c unifdef: use memcpy instead of strncpy 2018-12-08 12:59:06 +01:00
ver_linux ver_linux: Do not check for ver_linux pattern in version function 2018-07-07 17:44:52 +02:00
xen-hypercalls.sh License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
xz_wrap.sh