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Makefile: extend 32B aligned debug option to 64B aligned

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Commit 09c60546f0 ("./Makefile: add debug option to enable
function aligned on 32 bytes") was introduced to help debugging
strange kernel performance changes caused by code alignment
change.

Recently we found 2 similar cases [1][2] caused by code-alignment
changes, which can only be identified by forcing 64 bytes aligned
for all functions.

Originally, 32 bytes was used mainly for not wasting too much
text space, but this option is only for debug anyway where text
space is not a big concern. So extend the alignment to 64 bytes
to cover more similar cases.

[1].https://lore.kernel.org/lkml/20210427090013.GG32408@xsang-OptiPlex-9020/
[2].https://lore.kernel.org/lkml/20210420030837.GB31773@xsang-OptiPlex-9020/
Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
This commit is contained in:
Feng Tang 2021-05-06 15:34:59 +08:00 committed by Masahiro Yamada
parent c4681547bc
commit cf536e1858
2 changed files with 4 additions and 4 deletions
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4
Makefile
View File

@ -953,8 +953,8 @@ KBUILD_CFLAGS += $(CC_FLAGS_CFI)
export CC_FLAGS_CFI
endif
ifdef CONFIG_DEBUG_FORCE_FUNCTION_ALIGN_32B
KBUILD_CFLAGS += -falign-functions=32
ifdef CONFIG_DEBUG_FORCE_FUNCTION_ALIGN_64B
KBUILD_CFLAGS += -falign-functions=64
endif
# arch Makefile may override CC so keep this after arch Makefile is included

4
lib/Kconfig.debug
View File

@ -400,8 +400,8 @@ config SECTION_MISMATCH_WARN_ONLY
If unsure, say Y.
config DEBUG_FORCE_FUNCTION_ALIGN_32B
bool "Force all function address 32B aligned" if EXPERT
config DEBUG_FORCE_FUNCTION_ALIGN_64B
bool "Force all function address 64B aligned" if EXPERT
help
There are cases that a commit from one domain changes the function
address alignment of other domains, and cause magic performance