sys-apps/kmod: Add s390 build fix

Bug: https://github.com/kmod-project/kmod/issues/402
Closes: https://bugs.gentoo.org/962314
Signed-off-by: Andreas K. Hüttel <dilfridge@gentoo.org>

sys-apps/kmod/files/kmod-34.2-s390.patch

@@ -0,0 +1,53 @@
+From 4e18b842b3dae5486adb2c6cc11bdfdd53ee8646 Mon Sep 17 00:00:00 2001
+From: Tobias Stoeckmann <tobias@stoeckmann.org>
+Date: Wed, 14 Jan 2026 20:58:50 +0100
+Subject: [PATCH] util: Add s390 31 bit mode support
+
+Even though size_t is of the same size as a uint32_t, the s390
+architecture is a bit picky about its 31 bit mode with size_t.
+
+Use custom code to fix this issue in a rather architecture
+independent but unfortunately slower way for s390 31 bit mode.
+
+Reference: https://github.com/kmod-project/kmod/issues/402
+Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org>
+---
+ shared/util.h | 16 ++++++++++++++++
+ 1 file changed, 16 insertions(+)
+
+diff --git a/shared/util.h b/shared/util.h
+index bf3f1009..b785f5b1 100644
+--- a/shared/util.h
++++ b/shared/util.h
+@@ -123,7 +123,15 @@ static inline bool uaddsz_overflow(size_t a, size_t b, size_t *res)
+ #if __SIZEOF_SIZE_T__ == 8
+ 	return uadd64_overflow(a, b, res);
+ #elif __SIZEOF_SIZE_T__ == 4
++#ifdef __s390__
++	if (b < SIZE_MAX - a) {
++		*res = a + b;
++		return true;
++	}
++	return false;
++#else
+ 	return uadd32_overflow(a, b, res);
++#endif
+ #else
+ #error "Unknown sizeof(size_t)"
+ #endif
+@@ -167,7 +175,15 @@ static inline bool umulsz_overflow(size_t a, size_t b, size_t *res)
+ #if __SIZEOF_SIZE_T__ == 8
+ 	return umul64_overflow(a, b, res);
+ #elif __SIZEOF_SIZE_T__ == 4
++#ifdef __s390__
++	if (a == 0 || b <= SIZE_MAX / a) {
++		*res = a * b;
++		return true;
++	}
++	return false;
++#else
+ 	return umul32_overflow(a, b, res);
++#endif
+ #else
+ #error "Unknown sizeof(size_t)"
+ #endif

sys-apps/kmod/kmod-34.2.ebuild

@@ -1,4 +1,4 @@
-# Copyright 1999-2025 Gentoo Authors
+# Copyright 1999-2026 Gentoo Authors
 # Distributed under the terms of the GNU General Public License v2
 
 EAPI=8
@@ -40,6 +40,10 @@ BDEPEND="
 	zlib? ( virtual/pkgconfig )
 "
 
+PATCHES=(
+	"${FILESDIR}/${P}-s390.patch"
+)
+
 pkg_setup() {
 	:
 }