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| author | Masahiro Yamada <yamada.masahiro@socionext.com> | 2019-09-09 13:53:17 +0300 |
|---|---|---|
| committer | Masahiro Yamada <yamada.masahiro@socionext.com> | 2019-09-14 05:40:13 +0300 |
| commit | 69a94abb82eed2789d52b58665ddf4b454d9adb9 (patch) | |
| tree | 44726fe41be6d99ecadfbedeae87722f317ad77a /scripts | |
| parent | a0469f989fe1d051820cda7ead496f1a7371f3d8 (diff) | |
| download | linux-69a94abb82eed2789d52b58665ddf4b454d9adb9.tar.xz | |
export.h, genksyms: do not make genksyms calculate CRC of trimmed symbols
Arnd Bergmann reported false-positive modpost warnings detected by his
randconfig testing of linux-next.
Actually, this happens under the combination of CONFIG_MODVERSIONS
and CONFIG_TRIM_UNUSED_KSYMS since commit 15bfc2348d54 ("modpost:
check for static EXPORT_SYMBOL* functions").
For example, arch/arm/config/multi_v7_defconfig + CONFIG_MODVERSIONS
+ CONFIG_TRIM_UNUSED_KSYMS produces the following false-positives:
WARNING: "__lshrdi3" [vmlinux] is a static (unknown)
WARNING: "__ashrdi3" [vmlinux] is a static (unknown)
WARNING: "__aeabi_lasr" [vmlinux] is a static (unknown)
WARNING: "__aeabi_llsr" [vmlinux] is a static (unknown)
WARNING: "ftrace_set_clr_event" [vmlinux] is a static (unknown)
WARNING: "__muldi3" [vmlinux] is a static (unknown)
WARNING: "__aeabi_ulcmp" [vmlinux] is a static (unknown)
WARNING: "__ucmpdi2" [vmlinux] is a static (unknown)
WARNING: "__aeabi_lmul" [vmlinux] is a static (unknown)
WARNING: "__bswapsi2" [vmlinux] is a static (unknown)
WARNING: "__bswapdi2" [vmlinux] is a static (unknown)
WARNING: "__ashldi3" [vmlinux] is a static (unknown)
WARNING: "__aeabi_llsl" [vmlinux] is a static (unknown)
The root cause of the problem is not in the modpost, but in the
implementation of CONFIG_TRIM_UNUSED_KSYMS.
If there is at least one untrimmed symbol in the file, genksyms is
invoked to calculate CRC of *all* the exported symbols in that file
even if some of them have been trimmed due to no caller existing.
As a result, .tmp_*.ver files contain CRC of trimmed symbols, thus
unneeded, orphan __crc* symbols are added to objects. It had been
harmless until recently.
With commit 15bfc2348d54 ("modpost: check for static EXPORT_SYMBOL*
functions"), it is now harmful because the bogus __crc* symbols make
modpost call sym_update_crc() to add the symbols to the hash table,
but there is no one that clears the ->is_static member.
I gave Fixes to the first commit that uncovered the issue, but the
potential problem has long existed since commit f235541699bc
("export.h: allow for per-symbol configurable EXPORT_SYMBOL()").
Fixes: 15bfc2348d54 ("modpost: check for static EXPORT_SYMBOL* functions")
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Tested-by: Arnd Bergmann <arnd@arndb.de>
Diffstat (limited to 'scripts')
| -rw-r--r-- | scripts/genksyms/keywords.c | 6 |
1 files changed, 1 insertions, 5 deletions
diff --git a/scripts/genksyms/keywords.c b/scripts/genksyms/keywords.c index c586d32dd2c3..7a85c4e21175 100644 --- a/scripts/genksyms/keywords.c +++ b/scripts/genksyms/keywords.c @@ -3,11 +3,7 @@ static struct resword { const char *name; int token; } keywords[] = { - { "EXPORT_SYMBOL", EXPORT_SYMBOL_KEYW }, - { "EXPORT_SYMBOL_GPL", EXPORT_SYMBOL_KEYW }, - { "EXPORT_SYMBOL_GPL_FUTURE", EXPORT_SYMBOL_KEYW }, - { "EXPORT_UNUSED_SYMBOL", EXPORT_SYMBOL_KEYW }, - { "EXPORT_UNUSED_SYMBOL_GPL", EXPORT_SYMBOL_KEYW }, + { "__GENKSYMS_EXPORT_SYMBOL", EXPORT_SYMBOL_KEYW }, { "__asm", ASM_KEYW }, { "__asm__", ASM_KEYW }, { "__attribute", ATTRIBUTE_KEYW }, |