1 files changed, 94 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 000000000..c6b4f0603
--- /dev/null
+++ b/arch/arm64/include/asm/pointer_auth.h
@@ -0,0 +1,94 @@
+/* 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_user {
+	struct ptrauth_key apia;
+	struct ptrauth_key apib;
+	struct ptrauth_key apda;
+	struct ptrauth_key apdb;
+	struct ptrauth_key apga;
+};
+
+struct ptrauth_keys_kernel {
+	struct ptrauth_key apia;
+};
+
+static inline void ptrauth_keys_init_user(struct ptrauth_keys_user *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_nosync(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 __always_inline void ptrauth_keys_init_kernel(struct ptrauth_keys_kernel *keys)
+{
+	if (system_supports_address_auth())
+		get_random_bytes(&keys->apia, sizeof(keys->apia));
+}
+
+static __always_inline void ptrauth_keys_switch_kernel(struct ptrauth_keys_kernel *keys)
+{
+	if (!system_supports_address_auth())
+		return;
+
+	__ptrauth_key_install_nosync(APIA, keys->apia);
+	isb();
+}
+
+extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg);
+
+static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr)
+{
+	return ptrauth_clear_pac(ptr);
+}
+
+#define ptrauth_thread_init_user(tsk)					\
+	ptrauth_keys_init_user(&(tsk)->thread.keys_user)
+#define ptrauth_thread_init_kernel(tsk)					\
+	ptrauth_keys_init_kernel(&(tsk)->thread.keys_kernel)
+#define ptrauth_thread_switch_kernel(tsk)				\
+	ptrauth_keys_switch_kernel(&(tsk)->thread.keys_kernel)
+
+#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_init_kernel(tsk)
+#define ptrauth_thread_switch_kernel(tsk)
+#endif /* CONFIG_ARM64_PTR_AUTH */
+
+#endif /* __ASM_POINTER_AUTH_H */