From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/9196 Path: news.gmane.org!not-for-mail From: Hauke Mehrtens Newsgroups: gmane.linux.lib.musl.general Subject: [PATCH v2] mips: add vdso support Date: Tue, 26 Jan 2016 00:00:12 +0100 Message-ID: <1453762812-3187-1-git-send-email-hauke@hauke-m.de> Reply-To: musl@lists.openwall.com NNTP-Posting-Host: plane.gmane.org X-Trace: ger.gmane.org 1453762844 22560 80.91.229.3 (25 Jan 2016 23:00:44 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Mon, 25 Jan 2016 23:00:44 +0000 (UTC) Cc: Hauke Mehrtens To: musl@lists.openwall.com Original-X-From: musl-return-9209-gllmg-musl=m.gmane.org@lists.openwall.com Tue Jan 26 00:00:39 2016 Return-path: Envelope-to: gllmg-musl@m.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by plane.gmane.org with smtp (Exim 4.69) (envelope-from ) id 1aNq7i-00072s-Gg for gllmg-musl@m.gmane.org; Tue, 26 Jan 2016 00:00:38 +0100 Original-Received: (qmail 32025 invoked by uid 550); 25 Jan 2016 23:00:37 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Original-Received: (qmail 31979 invoked from network); 25 Jan 2016 23:00:32 -0000 X-Mailer: git-send-email 2.7.0.rc3 X-Spam-Status: No, score=0.0 required=7.0 tests=UNPARSEABLE_RELAY, URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on hauke-m.de Xref: news.gmane.org gmane.linux.lib.musl.general:9196 Archived-At: vdso support is available on mips starting with kernel 4.4, see kernel commit a7f4df4e21 "MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime()" for details. In Linux kernel 4.4.0 the mips code returns -ENOSYS in case it can not handle the vdso call and assumes the libc will call the original syscall in this case. Handle this case in musl. Currently Linux kernel 4.4.0 handles the following types: CLOCK_REALTIME_COARSE, CLOCK_MONOTONIC_COARSE, CLOCK_REALTIME and CLOCK_MONOTONIC. These are some measurements of calling clock_gettime(CLOCK_MONOTONIC, &tp); 1.000.000 times. without vdso: root@OpenWrt:/# time ./vdso-test real 0m 0.95s user 0m 0.24s sys 0m 0.70s with vdso: root@OpenWrt:/# time /usr/bin/vdso-test real 0m 0.35s user 0m 0.34s sys 0m 0.00s Signed-off-by: Hauke Mehrtens --- I just saw that the mips stuff is implemented in a bad way, it returns -ENOSYS when it can not handle the vdso call. I already complained to the mips kernel developers. ;-) This code was not tested, I am still building. arch/mips/syscall_arch.h | 4 ++++ src/time/clock_gettime.c | 12 +++++++++++- 2 files changed, 15 insertions(+), 1 deletion(-) diff --git a/arch/mips/syscall_arch.h b/arch/mips/syscall_arch.h index e74e0ad..39c0ea3 100644 --- a/arch/mips/syscall_arch.h +++ b/arch/mips/syscall_arch.h @@ -161,3 +161,7 @@ static inline long __syscall6(long n, long a, long b, long c, long d, long e, lo if (n == SYS_fstatat) __stat_fix(c); return r2; } + +#define VDSO_USEFUL +#define VDSO_CGT_SYM "__vdso_clock_gettime" +#define VDSO_CGT_VER "LINUX_2.6" diff --git a/src/time/clock_gettime.c b/src/time/clock_gettime.c index 1572de0..dba99ff 100644 --- a/src/time/clock_gettime.c +++ b/src/time/clock_gettime.c @@ -26,13 +26,23 @@ void *__vdsosym(const char *, const char *); int __clock_gettime(clockid_t clk, struct timespec *ts) { #ifdef VDSO_CGT_SYM + int ret; static int (*volatile cgt)(clockid_t, struct timespec *); if (!cgt) { void *f = __vdsosym(VDSO_CGT_VER, VDSO_CGT_SYM); if (!f) f = (void *)sc_clock_gettime; a_cas_p(&cgt, 0, f); } - return cgt(clk, ts); + ret = cgt(clk, ts); + + /* + * mips in linux kernel 4.4.0 returns -ENOSYS if it can not + * handle the syscall in vdso, the original syscall should be + * called by the libc in such a case. + */ + if (ret == -ENOSYS) + return sc_clock_gettime(clk, ts); + return ret; #else return sc_clock_gettime(clk, ts); #endif -- 2.7.0.rc3