summaryrefslogtreecommitdiffstats
path: root/arch/mips/lib/multi3.c
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2026-09-25 15:55:03 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2026-09-25 15:55:03 -0700
commit75467f60a3d14f08f86f2b353298d2826382ff23 (patch)
treeacd8a7d5b5a675042449386efa5b42ec44d8bf81 /arch/mips/lib/multi3.c
downloadlinux-stable-75467f60a3d14f08f86f2b353298d2826382ff23.tar.gz
linux-stable-75467f60a3d14f08f86f2b353298d2826382ff23.zip
Merge tag 'ipe-pr-20260925' of git://git.kernel.org/pub/scm/linux/kernel/git/wufan/ipegrafted
Pull IPE fixes from Fan Wu: "Two fixes for use-after-free issues found by recent LLM-assisted code analysis. - move successful policy load auditing under the new policy directory's inode lock, preventing a concurrent policy deletion from freeing the policy while it is still being audited - protect the dm-verity root hash with RCU, preventing policy evaluation from racing with root hash replacement during preresume" * tag 'ipe-pr-20260925' of git://git.kernel.org/pub/scm/linux/kernel/git/wufan/ipe: ipe: protect the dm-verity root hash with RCU ipe: fix use-after-free when auditing a newly loaded policy
Diffstat (limited to 'arch/mips/lib/multi3.c')
-rw-r--r--arch/mips/lib/multi3.c54
1 files changed, 54 insertions, 0 deletions
diff --git a/arch/mips/lib/multi3.c b/arch/mips/lib/multi3.c
new file mode 100644
index 000000000..92b3778bb
--- /dev/null
+++ b/arch/mips/lib/multi3.c
@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/export.h>
+
+#include "libgcc.h"
+
+/*
+ * GCC 9 & older can suboptimally generate __multi3 calls for mips64r6, so for
+ * that specific case only we implement that intrinsic here.
+ *
+ * See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82981
+ */
+#if defined(CONFIG_64BIT) && defined(CONFIG_CPU_MIPSR6) && (__GNUC__ < 10)
+
+/* multiply 64-bit values, low 64-bits returned */
+static inline long long notrace dmulu(long long a, long long b)
+{
+ long long res;
+
+ asm ("dmulu %0,%1,%2" : "=r" (res) : "r" (a), "r" (b));
+ return res;
+}
+
+/* multiply 64-bit unsigned values, high 64-bits of 128-bit result returned */
+static inline long long notrace dmuhu(long long a, long long b)
+{
+ long long res;
+
+ asm ("dmuhu %0,%1,%2" : "=r" (res) : "r" (a), "r" (b));
+ return res;
+}
+
+/* multiply 128-bit values, low 128-bits returned */
+ti_type notrace __multi3(ti_type a, ti_type b)
+{
+ TWunion res, aa, bb;
+
+ aa.ti = a;
+ bb.ti = b;
+
+ /*
+ * a * b = (a.lo * b.lo)
+ * + 2^64 * (a.hi * b.lo + a.lo * b.hi)
+ * [+ 2^128 * (a.hi * b.hi)]
+ */
+ res.s.low = dmulu(aa.s.low, bb.s.low);
+ res.s.high = dmuhu(aa.s.low, bb.s.low);
+ res.s.high += dmulu(aa.s.high, bb.s.low);
+ res.s.high += dmulu(aa.s.low, bb.s.high);
+
+ return res.ti;
+}
+EXPORT_SYMBOL(__multi3);
+
+#endif /* 64BIT && CPU_MIPSR6 && GCC9 */