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crypto: aes-generic - fix aes-generic regression on powerpc 

commit 6e36719fbe upstream.

My last bugfix added -Os on the command line, which unfortunately caused
a build regression on powerpc in some configurations.

I've done some more analysis of the original problem and found slightly
different workaround that avoids this regression and also results in
better performance on gcc-7.0: -fcode-hoisting is an optimization step
that got added in gcc-7 and that for all gcc-7 versions causes worse
performance.

This disables -fcode-hoisting on all compilers that understand the option.
For gcc-7.1 and 7.2 I found the same performance as my previous patch
(using -Os), in gcc-7.0 it was even better. On gcc-8 I could see no
change in performance from this patch. In theory, code hoisting should
not be able make things better for the AES cipher, so leaving it
disabled for gcc-8 only serves to simplify the Makefile change.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Link: https://www.mail-archive.com/linux-crypto@vger.kernel.org/msg30418.html
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83356
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83651
Fixes: 148b974dee ("crypto: aes-generic - build with -Os on gcc-7+")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Horia Geanta <horia.geanta@nxp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
pull/10/head
Arnd Bergmann 2018-01-15 17:07:22 +01:00 committed by Greg Kroah-Hartman
parent 0fad94cf10
commit 64def6f353
1 changed files with 1 additions and 1 deletions
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crypto/Makefile
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@ -98,7 +98,7 @@ obj-$(CONFIG_CRYPTO_TWOFISH_COMMON) += twofish_common.o
obj-$(CONFIG_CRYPTO_SERPENT) += serpent_generic.o
CFLAGS_serpent_generic.o := $(call cc-option,-fsched-pressure) # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79149
obj-$(CONFIG_CRYPTO_AES) += aes_generic.o
CFLAGS_aes_generic.o := $(call cc-ifversion, -ge, 0701, -Os) # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83356
CFLAGS_aes_generic.o := $(call cc-option,-fno-code-hoisting) # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83356
obj-$(CONFIG_CRYPTO_AES_TI) += aes_ti.o
obj-$(CONFIG_CRYPTO_CAMELLIA) += camellia_generic.o
obj-$(CONFIG_CRYPTO_CAST_COMMON) += cast_common.o