From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757737AbdJKNzX (ORCPT ); Wed, 11 Oct 2017 09:55:23 -0400 Received: from mout.kundenserver.de ([217.72.192.73]:50614 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757721AbdJKNzU (ORCPT ); Wed, 11 Oct 2017 09:55:20 -0400 From: Arnd Bergmann To: David Woodhouse , Brian Norris , Boris Brezillon , Marek Vasut , Richard Weinberger , Cyrille Pitchen Cc: Arnd Bergmann , stable@vger.kernel.org, linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH] mtd: cfi: convert inline functions to macros Date: Wed, 11 Oct 2017 15:54:10 +0200 Message-Id: <20171011135419.3492681-1-arnd@arndb.de> X-Mailer: git-send-email 2.9.0 X-Provags-ID: V03:K0:AJ1vGdDg34rD7dfcOCSJWs48QkPfhK3xOSk09N7UaFc3soBavaC F1pzrp8N+Oluocmj7jo4+H818zp7fdrBcyTBrZRCCd8dwCUqvLEnUuFfxDKWaSZRrvJwPUs zr1QWSWVe/8VZXhga2/dL/Q72ttwrvRCooqTcdiHwqo71aK+2Ok7scMQcvsGxIZYXBSg18z CCJ/4xJS5tdb1PuyS84xA== X-UI-Out-Filterresults: notjunk:1;V01:K0:vTvfS+POAA4=:UrrspnB1ZVb4O9ArkThUBZ g3s+XvFlWHwM1Yqi16v+1om2AyL19iXybZwGL66XjOhK9dN0GbDXdK1VW/I3ROUHVXB+8NKRI G1zj2viNLnb+fp1u1vquJfXgeKJeKbc2AQjdWepktWKYmN2ADZvp1YaIl38IC70g5+l4dhEux VRavF8CZKSdgy0WlQiTF+G7BFPCdF5nlAge1L+UNlpECgEyK4WZcgrlO3up8s8Rt/PQo/PiWP mqX3oKALiHVI95kscOyKj9B0NLQJGwy2XezKqJtvstExTZZBDgNdpavy7K+W31lPrMKY4tCiT TTF8MsvqQunMeQAGEjRbKW41aKT7onk4cxMB0yUpebr3cFIoR4r+CBmDXgxQQAcgoQye9rTOI mTdMjVFo7uJbNVk/2xBmN+qTpLSKCAvDPkmbIVYW3z2aRiueRHJIiPTnLQHqefD9gv90u80ID ygCbU5vP4Bhn/7ec35r5yQlyY4ayEtD7YPH/sutRZ4TYSjNXM3QTtElMmxc0Rvn8j0RcIEkaZ R75aWYJLz/FJLOWdCgXZBLVczyn+hOlG/b4rRxibgCLtJVJ1bMKQpppgbAmjaWRtRcjgkCeXE FaKTCxvDwUf85Nf5+GE8x3CzKx3UYa9kDiNpCZuFWMWtA7iQT5w9FIrBP5pfCZ5sHLGTn3o90 5s6+kwmvBDjWw4ZERz9b2UGlLJtJJ34eB4bolZvw+tqQIwuKDE69A9sVGUrb7767VuGan6+Rc uY/NLnNN6RSUx55PTx3ngvZZ2pEwzMFzuACjMA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The map_word_() functions, dating back to linux-2.6.8, try to perform bitwise operations on a 'map_word' structure. This may have worked with compilers that were current then (gcc-3.4 or earlier), but end up being rather inefficient on any version I could try now (gcc-4.4 or higher). Specifically we hit a problem analyzed in gcc PR81715 where we fail to reuse the stack space for local variables. This can be seen immediately in the stack consumption for cfi_staa_erase_varsize() and other functions that (with CONFIG_KASAN) can be up to 2200 bytes. Changing the inline functions into macros brings this down to 1280 bytes. Without KASAN, the same problem exists, but the stack consumption is lower to start with, my patch shrinks it from 920 to 496 bytes on with arm-linux-gnueabi-gcc-5.4, and saves around 1KB in .text size for cfi_cmdset_0020.c, as it avoids copying map_word structures for each call to one of these helpers. With the latest gcc-8 snapshot, the problem is fixed in upstream gcc, but nobody uses that yet, so we should still work around it in mainline kernels and probably backport the workaround to stable kernels as well. We had a couple of other functions that suffered from the same gcc bug, and all of those had a simpler workaround involving dummy variables in the inline function. Unfortunately that did not work here, the macro hack was the best I could come up with. It would also be helpful to have someone to a little performance testing on the patch, to see how much it helps in terms of CPU utilitzation. Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81715 Cc: stable@vger.kernel.org Signed-off-by: Arnd Bergmann --- include/linux/mtd/map.h | 130 +++++++++++++++++++++++------------------------- 1 file changed, 61 insertions(+), 69 deletions(-) diff --git a/include/linux/mtd/map.h b/include/linux/mtd/map.h index 3aa56e3104bb..b5b43f94f311 100644 --- a/include/linux/mtd/map.h +++ b/include/linux/mtd/map.h @@ -270,75 +270,67 @@ void map_destroy(struct mtd_info *mtd); #define INVALIDATE_CACHED_RANGE(map, from, size) \ do { if (map->inval_cache) map->inval_cache(map, from, size); } while (0) - -static inline int map_word_equal(struct map_info *map, map_word val1, map_word val2) -{ - int i; - - for (i = 0; i < map_words(map); i++) { - if (val1.x[i] != val2.x[i]) - return 0; - } - - return 1; -} - -static inline map_word map_word_and(struct map_info *map, map_word val1, map_word val2) -{ - map_word r; - int i; - - for (i = 0; i < map_words(map); i++) - r.x[i] = val1.x[i] & val2.x[i]; - - return r; -} - -static inline map_word map_word_clr(struct map_info *map, map_word val1, map_word val2) -{ - map_word r; - int i; - - for (i = 0; i < map_words(map); i++) - r.x[i] = val1.x[i] & ~val2.x[i]; - - return r; -} - -static inline map_word map_word_or(struct map_info *map, map_word val1, map_word val2) -{ - map_word r; - int i; - - for (i = 0; i < map_words(map); i++) - r.x[i] = val1.x[i] | val2.x[i]; - - return r; -} - -static inline int map_word_andequal(struct map_info *map, map_word val1, map_word val2, map_word val3) -{ - int i; - - for (i = 0; i < map_words(map); i++) { - if ((val1.x[i] & val2.x[i]) != val3.x[i]) - return 0; - } - - return 1; -} - -static inline int map_word_bitsset(struct map_info *map, map_word val1, map_word val2) -{ - int i; - - for (i = 0; i < map_words(map); i++) { - if (val1.x[i] & val2.x[i]) - return 1; - } - - return 0; -} +#define map_word_equal(map, val1, val2) \ +({ \ + int i, ret = 1; \ + for (i = 0; i < map_words(map); i++) \ + if ((val1).x[i] != (val2).x[i]) { \ + ret = 0; \ + break; \ + } \ + ret; \ +}) + +#define map_word_and(map, val1, val2) \ +({ \ + map_word r; \ + int i; \ + for (i = 0; i < map_words(map); i++) \ + r.x[i] = (val1).x[i] & (val2).x[i]; \ + r; \ +}) + +#define map_word_clr(map, val1, val2) \ +({ \ + map_word r; \ + int i; \ + for (i = 0; i < map_words(map); i++) \ + r.x[i] = (val1).x[i] & ~(val2).x[i]; \ + r; \ +}) + +#define map_word_or(map, val1, val2) \ +({ \ + map_word r; \ + int i; \ + for (i = 0; i < map_words(map); i++) \ + r.x[i] = (val1).x[i] | (val2).x[i]; \ + r; \ +}) + +#define map_word_andequal(map, val1, val2, val3) \ +({ \ + int i, ret = 1; \ + for (i = 0; i < map_words(map); i++) { \ + if (((val1).x[i] & (val2).x[i]) != (val2).x[i]) { \ + ret = 0; \ + break; \ + } \ + } \ + ret; \ +}) + +#define map_word_bitsset(map, val1, val2) \ +({ \ + int i, ret = 0; \ + for (i = 0; i < map_words(map); i++) { \ + if ((val1).x[i] & (val2).x[i]) { \ + ret = 1; \ + break; \ + } \ + } \ + ret; \ +}) static inline map_word map_word_load(struct map_info *map, const void *ptr) { -- 2.9.0