998f8bd02c
mips returns -ENOSYS in case it can not handle the vdso call and wants the libc to call the original syscall in such a case. This fixes the patch to add such handling. I hope this fixes the random reboots I got. Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de> SVN-Revision: 48501
80 lines
2.4 KiB
Diff
80 lines
2.4 KiB
Diff
From 93332ebdcd54b0e0c0e86bced537cc96247bc1f1 Mon Sep 17 00:00:00 2001
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From: Hauke Mehrtens <hauke@hauke-m.de>
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Date: Sat, 23 Jan 2016 16:23:09 +0100
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Subject: [PATCH 2/2] mips: add vdso support
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vdso support is available on mips starting with kernel 4.4, see kernel
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commit a7f4df4e21 "MIPS: VDSO: Add implementations of gettimeofday()
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and clock_gettime()" for details.
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In Linux kernel 4.4.0 the mips code returns -ENOSYS in case it can not
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handle the vdso call and assumes the libc will call the original
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syscall in this case. Handle this case in musl. Currently Linux kernel
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4.4.0 handles the following types: CLOCK_REALTIME_COARSE,
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CLOCK_MONOTONIC_COARSE, CLOCK_REALTIME and CLOCK_MONOTONIC.
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These are some measurements of calling clock_gettime(CLOCK_MONOTONIC,
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&tp); 1.000.000 times.
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without vdso:
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root@OpenWrt:/# time ./vdso-test
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real 0m 0.95s
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user 0m 0.24s
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sys 0m 0.70s
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with vdso:
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root@OpenWrt:/# time /usr/bin/vdso-test
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real 0m 0.35s
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user 0m 0.34s
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sys 0m 0.00s
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Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
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---
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arch/mips/syscall_arch.h | 4 ++++
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src/time/clock_gettime.c | 12 +++++++++++-
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2 files changed, 15 insertions(+), 1 deletion(-)
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diff --git a/arch/mips/syscall_arch.h b/arch/mips/syscall_arch.h
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index e74e0ad..39c0ea3 100644
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--- a/arch/mips/syscall_arch.h
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+++ b/arch/mips/syscall_arch.h
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@@ -161,3 +161,7 @@ static inline long __syscall6(long n, long a, long b, long c, long d, long e, lo
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if (n == SYS_fstatat) __stat_fix(c);
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return r2;
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}
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+
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+#define VDSO_USEFUL
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+#define VDSO_CGT_SYM "__vdso_clock_gettime"
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+#define VDSO_CGT_VER "LINUX_2.6"
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diff --git a/src/time/clock_gettime.c b/src/time/clock_gettime.c
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index 1572de0..dba99ff 100644
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--- a/src/time/clock_gettime.c
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+++ b/src/time/clock_gettime.c
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@@ -26,13 +26,23 @@ void *__vdsosym(const char *, const char *);
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int __clock_gettime(clockid_t clk, struct timespec *ts)
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{
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#ifdef VDSO_CGT_SYM
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+ int ret;
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static int (*volatile cgt)(clockid_t, struct timespec *);
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if (!cgt) {
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void *f = __vdsosym(VDSO_CGT_VER, VDSO_CGT_SYM);
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if (!f) f = (void *)sc_clock_gettime;
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a_cas_p(&cgt, 0, f);
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}
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- return cgt(clk, ts);
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+ ret = cgt(clk, ts);
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+
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+ /*
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+ * mips in linux kernel 4.4.0 returns -ENOSYS if it can not
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+ * handle the syscall in vdso, the original syscall should be
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+ * called by the libc in such a case.
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+ */
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+ if (ret == -ENOSYS)
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+ return sc_clock_gettime(clk, ts);
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+ return ret;
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#else
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return sc_clock_gettime(clk, ts);
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#endif
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--
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2.7.0.rc3
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