108 lines
3.5 KiB
Diff
108 lines
3.5 KiB
Diff
From 8f1a91aeff400d572857895b7f5e863ec5a4d93e Mon Sep 17 00:00:00 2001
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From: Ian Lance Taylor <iant@golang.org>
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Date: Mon, 26 Sep 2022 15:03:53 -0400
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Subject: [PATCH] runtime: portable access to sigev_notify_thread_id
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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Previously, libgo relied on the _sigev_un implementation-specific
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field in struct sigevent, which is only available on glibc.
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This patch uses the sigev_notify_thread_id macro instead which is
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mandated by timer_create(2). In theory, this should work with any libc
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implementation for Linux. Unfortunately, there is an open glibc bug
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as glibc does not define this macro. For this reason, a glibc-specific
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workaround is required. Other libcs (such as musl) define the macro
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and don't require the workaround.
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See https://sourceware.org/bugzilla/show_bug.cgi?id=27417
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This makes libgo compatible with musl libc.
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Based on patch by Sören Tempel.
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Change-Id: I0924a53d5212730ebc395ecf9199f85967be8cc6
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Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/434755
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Reviewed-by: Cherry Mui <cherryyz@google.com>
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Reviewed-by: Than McIntosh <thanm@google.com>
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---
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libgo/go/runtime/os_linux.go | 12 +++++++++++-
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libgo/runtime/go-signal.c | 18 ++++++++++++++++++
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2 files changed, 29 insertions(+), 1 deletion(-)
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diff --git a/libgo/go/runtime/os_linux.go b/libgo/go/runtime/os_linux.go
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index 96fb1788..2b2d827c 100644
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--- a/libgo/go/runtime/os_linux.go
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+++ b/libgo/go/runtime/os_linux.go
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@@ -22,6 +22,12 @@ type mOS struct {
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profileTimerValid uint32
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}
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+// setSigeventTID is written in C to set the sigev_notify_thread_id
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+// field of a sigevent struct.
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+//
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+//go:noescape
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+func setSigeventTID(*_sigevent, int32)
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+
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func getProcID() uint64 {
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return uint64(gettid())
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}
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@@ -52,9 +58,12 @@ const (
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)
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// Atomically,
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+//
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// if(*addr == val) sleep
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+//
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// Might be woken up spuriously; that's allowed.
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// Don't sleep longer than ns; ns < 0 means forever.
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+//
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//go:nosplit
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func futexsleep(addr *uint32, val uint32, ns int64) {
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// Some Linux kernels have a bug where futex of
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@@ -73,6 +82,7 @@ func futexsleep(addr *uint32, val uint32, ns int64) {
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}
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// If any procs are sleeping on addr, wake up at most cnt.
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+//
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//go:nosplit
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func futexwakeup(addr *uint32, cnt uint32) {
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ret := futex(unsafe.Pointer(addr), _FUTEX_WAKE_PRIVATE, cnt, nil, nil, 0)
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@@ -365,7 +375,7 @@ func setThreadCPUProfiler(hz int32) {
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var sevp _sigevent
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sevp.sigev_notify = _SIGEV_THREAD_ID
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sevp.sigev_signo = _SIGPROF
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- *((*int32)(unsafe.Pointer(&sevp._sigev_un))) = int32(mp.procid)
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+ setSigeventTID(&sevp, int32(mp.procid))
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ret := timer_create(_CLOCK_THREAD_CPUTIME_ID, &sevp, &timerid)
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if ret != 0 {
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// If we cannot create a timer for this M, leave profileTimerValid false
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diff --git a/libgo/runtime/go-signal.c b/libgo/runtime/go-signal.c
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index 528d9b6d..aa1b6305 100644
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--- a/libgo/runtime/go-signal.c
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+++ b/libgo/runtime/go-signal.c
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@@ -183,6 +183,24 @@ setSigactionHandler(struct sigaction* sa, uintptr handler)
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sa->sa_sigaction = (void*)(handler);
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}
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+#ifdef __linux__
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+
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+// Workaround for https://sourceware.org/bugzilla/show_bug.cgi?id=27417
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+#ifndef sigev_notify_thread_id
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+ #define sigev_notify_thread_id _sigev_un._tid
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+#endif
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+
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+void setSigeventTID(struct sigevent*, int32_t)
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+ __asm__ (GOSYM_PREFIX "runtime.setSigeventTID");
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+
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+void
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+setSigeventTID(struct sigevent *sev, int32_t v)
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+{
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+ sev->sigev_notify_thread_id = v;
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+}
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+
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+#endif // defined(__linux__)
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+
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// C code to fetch values from the siginfo_t and ucontext_t pointers
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// passed to a signal handler.
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