diff --git a/src/runtime/defs_linux_386.go b/src/runtime/defs_linux_386.go
index d8b546cb4c..fd9b60c444 100644
--- a/src/runtime/defs_linux_386.go
+++ b/src/runtime/defs_linux_386.go
@@ -3,6 +3,8 @@
 
 package runtime
 
+import "internal/goarch"
+
 const (
 	_EINTR  = 0x4
 	_EAGAIN = 0xb
@@ -172,6 +174,11 @@ type siginfo struct {
 	si_code  int32
 	// below here is a union; si_addr is the only field we use
 	si_addr uint32
+
+	// Pad struct to the max size in the kernel. Account for the 3 32-bit
+	// fields, the alignment to this architecture's pointer size, and the final
+	// pointer-length field.
+	_ [_si_max_size - (3*4 + (1-4/goarch.PtrSize)*4 + 1*goarch.PtrSize)]byte
 }
 
 type stackt struct {
@@ -235,6 +242,10 @@ type sigevent struct {
 	notify int32
 	// below here is a union; sigev_notify_thread_id is the only field we use
 	sigev_notify_thread_id int32
+
+	// Pad struct to the max size in the kernel. Account for the pointer-length
+	// field and the 3 32-bit fields.
+	_ [_sigev_max_size - (1*goarch.PtrSize + 3*4)]byte
 }
 
 type epollevent struct {
diff --git a/src/runtime/defs_linux_amd64.go b/src/runtime/defs_linux_amd64.go
index 6afb67f77f..29dabe08dd 100644
--- a/src/runtime/defs_linux_amd64.go
+++ b/src/runtime/defs_linux_amd64.go
@@ -3,6 +3,8 @@
 
 package runtime
 
+import "internal/goarch"
+
 const (
 	_EINTR  = 0x4
 	_EAGAIN = 0xb
@@ -134,6 +136,11 @@ type siginfo struct {
 	si_code  int32
 	// below here is a union; si_addr is the only field we use
 	si_addr uint64
+
+	// Pad struct to the max size in the kernel. Account for the 3 32-bit
+	// fields, the alignment to this architecture's pointer size, and the final
+	// pointer-length field.
+	_ [_si_max_size - (3*4 + (1-4/goarch.PtrSize)*4 + 1*goarch.PtrSize)]byte
 }
 
 type itimerspec struct {
@@ -152,6 +159,10 @@ type sigevent struct {
 	notify int32
 	// below here is a union; sigev_notify_thread_id is the only field we use
 	sigev_notify_thread_id int32
+
+	// Pad struct to the max size in the kernel. Account for the pointer-length
+	// field and the 3 32-bit fields.
+	_ [_sigev_max_size - (1*goarch.PtrSize + 3*4)]byte
 }
 
 type epollevent struct {
diff --git a/src/runtime/defs_linux_arm.go b/src/runtime/defs_linux_arm.go
index ec24d76326..3ed6940647 100644
--- a/src/runtime/defs_linux_arm.go
+++ b/src/runtime/defs_linux_arm.go
@@ -4,6 +4,8 @@
 
 package runtime
 
+import "internal/goarch"
+
 // Constants
 const (
 	_EINTR  = 0x4
@@ -175,6 +177,10 @@ type sigevent struct {
 	notify int32
 	// below here is a union; sigev_notify_thread_id is the only field we use
 	sigev_notify_thread_id int32
+
+	// Pad struct to the max size in the kernel. Account for the pointer-length
+	// field and the 3 32-bit fields.
+	_ [_sigev_max_size - (1*goarch.PtrSize + 3*4)]byte
 }
 
 type siginfo struct {
@@ -183,6 +189,11 @@ type siginfo struct {
 	si_code  int32
 	// below here is a union; si_addr is the only field we use
 	si_addr uint32
+
+	// Pad struct to the max size in the kernel. Account for the 3 32-bit
+	// fields, the alignment to this architecture's pointer size, and the final
+	// pointer-length field.
+	_ [_si_max_size - (3*4 + (1-4/goarch.PtrSize)*4 + 1*goarch.PtrSize)]byte
 }
 
 type sigactiont struct {
diff --git a/src/runtime/defs_linux_arm64.go b/src/runtime/defs_linux_arm64.go
index f9f175004b..6a126c4a15 100644
--- a/src/runtime/defs_linux_arm64.go
+++ b/src/runtime/defs_linux_arm64.go
@@ -3,6 +3,8 @@
 
 package runtime
 
+import "internal/goarch"
+
 const (
 	_EINTR  = 0x4
 	_EAGAIN = 0xb
@@ -134,6 +136,11 @@ type siginfo struct {
 	si_code  int32
 	// below here is a union; si_addr is the only field we use
 	si_addr uint64
+
+	// Pad struct to the max size in the kernel. Account for the 3 32-bit
+	// fields, the alignment to this architecture's pointer size, and the final
+	// pointer-length field.
+	_ [_si_max_size - (3*4 + (1-4/goarch.PtrSize)*4 + 1*goarch.PtrSize)]byte
 }
 
 type itimerspec struct {
@@ -152,6 +159,10 @@ type sigevent struct {
 	notify int32
 	// below here is a union; sigev_notify_thread_id is the only field we use
 	sigev_notify_thread_id int32
+
+	// Pad struct to the max size in the kernel. Account for the pointer-length
+	// field and the 3 32-bit fields.
+	_ [_sigev_max_size - (1*goarch.PtrSize + 3*4)]byte
 }
 
 type epollevent struct {
diff --git a/src/runtime/defs_linux_mips64x.go b/src/runtime/defs_linux_mips64x.go
index 1743bbce41..34e803331c 100644
--- a/src/runtime/defs_linux_mips64x.go
+++ b/src/runtime/defs_linux_mips64x.go
@@ -8,6 +8,8 @@
 
 package runtime
 
+import "internal/goarch"
+
 const (
 	_EINTR  = 0x4
 	_EAGAIN = 0xb
@@ -143,6 +145,11 @@ type siginfo struct {
 	__pad0   [1]int32
 	// below here is a union; si_addr is the only field we use
 	si_addr uint64
+
+	// Pad struct to the max size in the kernel. Account for the 3 32-bit
+	// fields, the alignment to this architecture's pointer size, and the final
+	// pointer-length field.
+	_ [_si_max_size - (3*4 + (1-4/goarch.PtrSize)*4 + 1*goarch.PtrSize)]byte
 }
 
 type itimerspec struct {
@@ -161,6 +168,10 @@ type sigevent struct {
 	notify int32
 	// below here is a union; sigev_notify_thread_id is the only field we use
 	sigev_notify_thread_id int32
+
+	// Pad struct to the max size in the kernel. Account for the pointer-length
+	// field and the 3 32-bit fields.
+	_ [_sigev_max_size - (1*goarch.PtrSize + 3*4)]byte
 }
 
 type epollevent struct {
diff --git a/src/runtime/defs_linux_mipsx.go b/src/runtime/defs_linux_mipsx.go
index e84d4979e1..7a7db7f181 100644
--- a/src/runtime/defs_linux_mipsx.go
+++ b/src/runtime/defs_linux_mipsx.go
@@ -8,6 +8,8 @@
 
 package runtime
 
+import "internal/goarch"
+
 const (
 	_EINTR  = 0x4
 	_EAGAIN = 0xb
@@ -137,6 +139,11 @@ type siginfo struct {
 	si_errno int32
 	// below here is a union; si_addr is the only field we use
 	si_addr uint32
+
+	// Pad struct to the max size in the kernel. Account for the 3 32-bit
+	// fields, the alignment to this architecture's pointer size, and the final
+	// pointer-length field.
+	_ [_si_max_size - (3*4 + (1-4/goarch.PtrSize)*4 + 1*goarch.PtrSize)]byte
 }
 
 type itimerspec struct {
@@ -155,6 +162,10 @@ type sigevent struct {
 	notify int32
 	// below here is a union; sigev_notify_thread_id is the only field we use
 	sigev_notify_thread_id int32
+
+	// Pad struct to the max size in the kernel. Account for the pointer-length
+	// field and the 3 32-bit fields.
+	_ [_sigev_max_size - (1*goarch.PtrSize + 3*4)]byte
 }
 
 type epollevent struct {
diff --git a/src/runtime/defs_linux_ppc64.go b/src/runtime/defs_linux_ppc64.go
index e0775e2974..7971ca7058 100644
--- a/src/runtime/defs_linux_ppc64.go
+++ b/src/runtime/defs_linux_ppc64.go
@@ -3,6 +3,8 @@
 
 package runtime
 
+import "internal/goarch"
+
 const (
 	_EINTR  = 0x4
 	_EAGAIN = 0xb
@@ -135,6 +137,11 @@ type siginfo struct {
 	si_code  int32
 	// below here is a union; si_addr is the only field we use
 	si_addr uint64
+
+	// Pad struct to the max size in the kernel. Account for the 3 32-bit
+	// fields, the alignment to this architecture's pointer size, and the final
+	// pointer-length field.
+	_ [_si_max_size - (3*4 + (1-4/goarch.PtrSize)*4 + 1*goarch.PtrSize)]byte
 }
 
 type itimerspec struct {
@@ -153,6 +160,10 @@ type sigevent struct {
 	notify int32
 	// below here is a union; sigev_notify_thread_id is the only field we use
 	sigev_notify_thread_id int32
+
+	// Pad struct to the max size in the kernel. Account for the pointer-length
+	// field and the 3 32-bit fields.
+	_ [_sigev_max_size - (1*goarch.PtrSize + 3*4)]byte
 }
 
 type epollevent struct {
diff --git a/src/runtime/defs_linux_ppc64le.go b/src/runtime/defs_linux_ppc64le.go
index e0775e2974..7971ca7058 100644
--- a/src/runtime/defs_linux_ppc64le.go
+++ b/src/runtime/defs_linux_ppc64le.go
@@ -3,6 +3,8 @@
 
 package runtime
 
+import "internal/goarch"
+
 const (
 	_EINTR  = 0x4
 	_EAGAIN = 0xb
@@ -135,6 +137,11 @@ type siginfo struct {
 	si_code  int32
 	// below here is a union; si_addr is the only field we use
 	si_addr uint64
+
+	// Pad struct to the max size in the kernel. Account for the 3 32-bit
+	// fields, the alignment to this architecture's pointer size, and the final
+	// pointer-length field.
+	_ [_si_max_size - (3*4 + (1-4/goarch.PtrSize)*4 + 1*goarch.PtrSize)]byte
 }
 
 type itimerspec struct {
@@ -153,6 +160,10 @@ type sigevent struct {
 	notify int32
 	// below here is a union; sigev_notify_thread_id is the only field we use
 	sigev_notify_thread_id int32
+
+	// Pad struct to the max size in the kernel. Account for the pointer-length
+	// field and the 3 32-bit fields.
+	_ [_sigev_max_size - (1*goarch.PtrSize + 3*4)]byte
 }
 
 type epollevent struct {
diff --git a/src/runtime/defs_linux_riscv64.go b/src/runtime/defs_linux_riscv64.go
index 1052213a4c..92f4563dd5 100644
--- a/src/runtime/defs_linux_riscv64.go
+++ b/src/runtime/defs_linux_riscv64.go
@@ -4,6 +4,8 @@
 
 package runtime
 
+import "internal/goarch"
+
 const (
 	_EINTR  = 0x4
 	_EAGAIN = 0xb
@@ -132,6 +134,11 @@ type siginfo struct {
 	si_code  int32
 	// below here is a union; si_addr is the only field we use
 	si_addr uint64
+
+	// Pad struct to the max size in the kernel. Account for the 3 32-bit
+	// fields, the alignment to this architecture's pointer size, and the final
+	// pointer-length field.
+	_ [_si_max_size - (3*4 + (1-4/goarch.PtrSize)*4 + 1*goarch.PtrSize)]byte
 }
 
 type itimerspec struct {
@@ -150,6 +157,10 @@ type sigevent struct {
 	notify int32
 	// below here is a union; sigev_notify_thread_id is the only field we use
 	sigev_notify_thread_id int32
+
+	// Pad struct to the max size in the kernel. Account for the pointer-length
+	// field and the 3 32-bit fields.
+	_ [_sigev_max_size - (1*goarch.PtrSize + 3*4)]byte
 }
 
 type epollevent struct {
diff --git a/src/runtime/defs_linux_s390x.go b/src/runtime/defs_linux_s390x.go
index b072955d4a..8a56ef0b80 100644
--- a/src/runtime/defs_linux_s390x.go
+++ b/src/runtime/defs_linux_s390x.go
@@ -4,6 +4,8 @@
 
 package runtime
 
+import "internal/goarch"
+
 const (
 	_EINTR  = 0x4
 	_EAGAIN = 0xb
@@ -131,6 +133,11 @@ type siginfo struct {
 	si_code  int32
 	// below here is a union; si_addr is the only field we use
 	si_addr uint64
+
+	// Pad struct to the max size in the kernel. Account for the 3 32-bit
+	// fields, the alignment to this architecture's pointer size, and the final
+	// pointer-length field.
+	_ [_si_max_size - (3*4 + (1-4/goarch.PtrSize)*4 + 1*goarch.PtrSize)]byte
 }
 
 type itimerspec struct {
@@ -149,6 +156,10 @@ type sigevent struct {
 	notify int32
 	// below here is a union; sigev_notify_thread_id is the only field we use
 	sigev_notify_thread_id int32
+
+	// Pad struct to the max size in the kernel. Account for the pointer-length
+	// field and the 3 32-bit fields.
+	_ [_sigev_max_size - (1*goarch.PtrSize + 3*4)]byte
 }
 
 type epollevent struct {
diff --git a/src/runtime/os_linux.go b/src/runtime/os_linux.go
index 06773c2193..d5a5ff763b 100644
--- a/src/runtime/os_linux.go
+++ b/src/runtime/os_linux.go
@@ -440,6 +440,18 @@ func pipe() (r, w int32, errno int32)
 func pipe2(flags int32) (r, w int32, errno int32)
 func setNonblock(fd int32)
 
+const (
+	_si_max_size    = 128
+	_sigev_max_size = 64
+)
+
+// Assert that the Go definitions of structures exchanged with the kernel are
+// the same size as what the kernel defines.
+var (
+	_ [_si_max_size]struct{}    = [unsafe.Sizeof(siginfo{})]struct{}{}
+	_ [_sigev_max_size]struct{} = [unsafe.Sizeof(sigevent{})]struct{}{}
+)
+
 //go:nosplit
 //go:nowritebarrierrec
 func setsig(i uint32, fn uintptr) {