runtime: fix timespec definition on 32bits systems

The nsec field of timespec is a C long even when using
64bits time on 32bits systems.

This is because by timespec API if nsec never holds more than a
second worth of nanoseconds.
If it would theses would increment the sec field while the nsec
field would get the amount of nanoseconds modulus a second.

Fixes #77934

Change-Id: I9803998ba70123eb3b226379bd72b11cae972c38
Reviewed-on: https://go-review.googlesource.com/c/go/+/751341
Reviewed-by: Michael Pratt <mpratt@google.com>
Auto-Submit: Jorropo <jorropo.pgm@gmail.com>
Reviewed-by: David Chase <drchase@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

4 files changed, 17 insertions, 14 deletions

diff --git a/src/runtime/defs_linux_386.go b/src/runtime/defs_linux_386.go
index d1875954f3..3a8c201ff1 100644
--- a/src/runtime/defs_linux_386.go
+++ b/src/runtime/defs_linux_386.go
@@ -152,13 +152,14 @@ func (ts *timespec32) setNsec(ns int64) {
 
 type timespec struct {
 	tv_sec  int64
-	tv_nsec int64
+	tv_nsec int32
+	_       [4]byte // the C ABI aligns int64 to 8 bytes
 }
 
 //go:nosplit
 func (ts *timespec) setNsec(ns int64) {
-	ts.tv_sec = int64(ns / 1e9)
-	ts.tv_nsec = int64(ns % 1e9)
+	ts.tv_sec = ns / 1e9
+	ts.tv_nsec = int32(ns % 1e9)
 }
 
 type timeval struct {
diff --git a/src/runtime/defs_linux_arm.go b/src/runtime/defs_linux_arm.go
index 94577fc597..946f5bb230 100644
--- a/src/runtime/defs_linux_arm.go
+++ b/src/runtime/defs_linux_arm.go
@@ -111,13 +111,14 @@ func (ts *timespec32) setNsec(ns int64) {
 
 type timespec struct {
 	tv_sec  int64
-	tv_nsec int64
+	tv_nsec int32
+	_       [4]byte // the C ABI aligns int64 to 8 bytes
 }
 
 //go:nosplit
 func (ts *timespec) setNsec(ns int64) {
-	ts.tv_sec = int64(ns / 1e9)
-	ts.tv_nsec = int64(ns % 1e9)
+	ts.tv_sec = ns / 1e9
+	ts.tv_nsec = int32(ns % 1e9)
 }
 
 type stackt struct {
diff --git a/src/runtime/defs_linux_mipsx.go b/src/runtime/defs_linux_mipsx.go
index b8da4d00af..c14fa8498f 100644
--- a/src/runtime/defs_linux_mipsx.go
+++ b/src/runtime/defs_linux_mipsx.go
@@ -109,13 +109,14 @@ func (ts *timespec32) setNsec(ns int64) {
 
 type timespec struct {
 	tv_sec  int64
-	tv_nsec int64
+	tv_nsec int32
+	_       [4]byte // the C ABI aligns int64 to 8 bytes
 }
 
 //go:nosplit
 func (ts *timespec) setNsec(ns int64) {
-	ts.tv_sec = int64(ns / 1e9)
-	ts.tv_nsec = int64(ns % 1e9)
+	ts.tv_sec = ns / 1e9
+	ts.tv_nsec = int32(ns % 1e9)
 }
 
 type timeval struct {
diff --git a/src/runtime/os_linux32.go b/src/runtime/os_linux32.go
index 02cb18f32d..1ee1cdcaf9 100644
--- a/src/runtime/os_linux32.go
+++ b/src/runtime/os_linux32.go
@@ -31,7 +31,7 @@ func futex(addr unsafe.Pointer, op int32, val uint32, ts *timespec, addr2 unsafe
 	var ts32 timespec32
 	var pts32 *timespec32
 	if ts != nil {
-		ts32.setNsec(ts.tv_sec*1e9 + ts.tv_nsec)
+		ts32.setNsec(ts.tv_sec*1e9 + int64(ts.tv_nsec))
 		pts32 = &ts32
 	}
 	return futex_time32(addr, op, val, pts32, addr2, val3)
@@ -53,14 +53,14 @@ func timer_settime(timerid int32, flags int32, new, old *itimerspec) int32 {
 	var new32, old32 *itimerspec32
 
 	if new != nil {
-		newts.it_interval.setNsec(new.it_interval.tv_sec*1e9 + new.it_interval.tv_nsec)
-		newts.it_value.setNsec(new.it_value.tv_sec*1e9 + new.it_value.tv_nsec)
+		newts.it_interval.setNsec(new.it_interval.tv_sec*1e9 + int64(new.it_interval.tv_nsec))
+		newts.it_value.setNsec(new.it_value.tv_sec*1e9 + int64(new.it_value.tv_nsec))
 		new32 = &newts
 	}
 
 	if old != nil {
-		oldts.it_interval.setNsec(old.it_interval.tv_sec*1e9 + old.it_interval.tv_nsec)
-		oldts.it_value.setNsec(old.it_value.tv_sec*1e9 + old.it_value.tv_nsec)
+		oldts.it_interval.setNsec(old.it_interval.tv_sec*1e9 + int64(old.it_interval.tv_nsec))
+		oldts.it_value.setNsec(old.it_value.tv_sec*1e9 + int64(old.it_value.tv_nsec))
 		old32 = &oldts
 	}