1 files changed, 97 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/pointer_auth.h b/arch/arm64/include/asm/pointer_auth.h
new file mode 100644
index 000000000000..15d49515efdd
--- /dev/null
+++ b/arch/arm64/include/asm/pointer_auth.h
@@ -0,0 +1,97 @@
+// SPDX-License-Identifier: GPL-2.0
+#ifndef __ASM_POINTER_AUTH_H
+#define __ASM_POINTER_AUTH_H
+
+#include <linux/bitops.h>
+#include <linux/random.h>
+
+#include <asm/cpufeature.h>
+#include <asm/memory.h>
+#include <asm/sysreg.h>
+
+#ifdef CONFIG_ARM64_PTR_AUTH
+/*
+ * Each key is a 128-bit quantity which is split across a pair of 64-bit
+ * registers (Lo and Hi).
+ */
+struct ptrauth_key {
+	unsigned long lo, hi;
+};
+
+/*
+ * We give each process its own keys, which are shared by all threads. The keys
+ * are inherited upon fork(), and reinitialised upon exec*().
+ */
+struct ptrauth_keys {
+	struct ptrauth_key apia;
+	struct ptrauth_key apib;
+	struct ptrauth_key apda;
+	struct ptrauth_key apdb;
+	struct ptrauth_key apga;
+};
+
+static inline void ptrauth_keys_init(struct ptrauth_keys *keys)
+{
+	if (system_supports_address_auth()) {
+		get_random_bytes(&keys->apia, sizeof(keys->apia));
+		get_random_bytes(&keys->apib, sizeof(keys->apib));
+		get_random_bytes(&keys->apda, sizeof(keys->apda));
+		get_random_bytes(&keys->apdb, sizeof(keys->apdb));
+	}
+
+	if (system_supports_generic_auth())
+		get_random_bytes(&keys->apga, sizeof(keys->apga));
+}
+
+#define __ptrauth_key_install(k, v)				\
+do {								\
+	struct ptrauth_key __pki_v = (v);			\
+	write_sysreg_s(__pki_v.lo, SYS_ ## k ## KEYLO_EL1);	\
+	write_sysreg_s(__pki_v.hi, SYS_ ## k ## KEYHI_EL1);	\
+} while (0)
+
+static inline void ptrauth_keys_switch(struct ptrauth_keys *keys)
+{
+	if (system_supports_address_auth()) {
+		__ptrauth_key_install(APIA, keys->apia);
+		__ptrauth_key_install(APIB, keys->apib);
+		__ptrauth_key_install(APDA, keys->apda);
+		__ptrauth_key_install(APDB, keys->apdb);
+	}
+
+	if (system_supports_generic_auth())
+		__ptrauth_key_install(APGA, keys->apga);
+}
+
+extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg);
+
+/*
+ * The EL0 pointer bits used by a pointer authentication code.
+ * This is dependent on TBI0 being enabled, or bits 63:56 would also apply.
+ */
+#define ptrauth_user_pac_mask()	GENMASK(54, vabits_user)
+
+/* Only valid for EL0 TTBR0 instruction pointers */
+static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr)
+{
+	return ptr & ~ptrauth_user_pac_mask();
+}
+
+#define ptrauth_thread_init_user(tsk)					\
+do {									\
+	struct task_struct *__ptiu_tsk = (tsk);				\
+	ptrauth_keys_init(&__ptiu_tsk->thread.keys_user);		\
+	ptrauth_keys_switch(&__ptiu_tsk->thread.keys_user);		\
+} while (0)
+
+#define ptrauth_thread_switch(tsk)	\
+	ptrauth_keys_switch(&(tsk)->thread.keys_user)
+
+#else /* CONFIG_ARM64_PTR_AUTH */
+#define ptrauth_prctl_reset_keys(tsk, arg)	(-EINVAL)
+#define ptrauth_strip_insn_pac(lr)	(lr)
+#define ptrauth_thread_init_user(tsk)
+#define ptrauth_thread_switch(tsk)
+#endif /* CONFIG_ARM64_PTR_AUTH */
+
+#endif /* __ASM_POINTER_AUTH_H */