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musl: fix mips vdso handling

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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
This commit is contained in:
Hauke Mehrtens 2016-01-25 23:26:19 +00:00
parent 0b55a7904b
commit 998f8bd02c
1 changed files with 54 additions and 3 deletions
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57
toolchain/musl/patches/030-mips-add-vdso-support.patch
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@ -1,4 +1,4 @@
From c29a29c3334344e0f3cfdec6130a6261514507a0 Mon Sep 17 00:00:00 2001
From 93332ebdcd54b0e0c0e86bced537cc96247bc1f1 Mon Sep 17 00:00:00 2001
From: Hauke Mehrtens <hauke@hauke-m.de>
Date: Sat, 23 Jan 2016 16:23:09 +0100
Subject: [PATCH 2/2] mips: add vdso support
@ -7,10 +7,32 @@ 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 <hauke@hauke-m.de>
---
arch/mips/syscall_arch.h | 4 ++++
1 file changed, 4 insertions(+)
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
@ -24,6 +46,35 @@ index e74e0ad..39c0ea3 100644
+#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