[PATCH v4 20/21] arm64: Defer enabling pointer authentication on boot core

Marc Zyngier
2021-01-18T10:01:54Z

From: Srinivas Ramana <sramana@codeaurora.org>

Defer enabling pointer authentication on boot core until
after its required to be enabled by cpufeature framework.
This will help in controlling the feature dynamically
with a boot parameter.

Signed-off-by: Ajay Patil <pajay@qti.qualcomm.com>
Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>
Signed-off-by: Srinivas Ramana <sramana@codeaurora.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/1610152163-16554-2-git-send-email-sramana@codeaurora.org
---
arch/arm64/include/asm/pointer_auth.h | 10 ++++++++++
arch/arm64/include/asm/stackprotector.h | 1 +
arch/arm64/kernel/head.S | 4 ----
3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/include/asm/pointer_auth.h b/arch/arm64/include/asm/pointer_auth.h
index c6b4f0603024..b112a11e9302 100644
--- a/arch/arm64/include/asm/pointer_auth.h
+++ b/arch/arm64/include/asm/pointer_auth.h
@@ -76,6 +76,15 @@ static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr)
return ptrauth_clear_pac(ptr);
}

+static __always_inline void ptrauth_enable(void)
+{
+ if (!system_supports_address_auth())
+ return;
+ sysreg_clear_set(sctlr_el1, 0, (SCTLR_ELx_ENIA | SCTLR_ELx_ENIB |
+ SCTLR_ELx_ENDA | SCTLR_ELx_ENDB));
+ isb();
+}
+
#define ptrauth_thread_init_user(tsk) \
ptrauth_keys_init_user(&(tsk)->thread.keys_user)
#define ptrauth_thread_init_kernel(tsk) \
@@ -84,6 +93,7 @@ static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr)
ptrauth_keys_switch_kernel(&(tsk)->thread.keys_kernel)

#else /* CONFIG_ARM64_PTR_AUTH */
+#define ptrauth_enable()
#define ptrauth_prctl_reset_keys(tsk, arg) (-EINVAL)
#define ptrauth_strip_insn_pac(lr) (lr)
#define ptrauth_thread_init_user(tsk)
diff --git a/arch/arm64/include/asm/stackprotector.h b/arch/arm64/include/asm/stackprotector.h
index 7263e0bac680..33f1bb453150 100644
--- a/arch/arm64/include/asm/stackprotector.h
+++ b/arch/arm64/include/asm/stackprotector.h
@@ -41,6 +41,7 @@ static __always_inline void boot_init_stack_canary(void)
#endif
ptrauth_thread_init_kernel(current);
ptrauth_thread_switch_kernel(current);
+ ptrauth_enable();
}

#endif /* _ASM_STACKPROTECTOR_H */
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index b3c4dd04f74b..2a152d96d767 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -404,10 +404,6 @@ SYM_FUNC_START_LOCAL(__primary_switched)
adr_l x5, init_task
msr sp_el0, x5 // Save thread_info

-#ifdef CONFIG_ARM64_PTR_AUTH
- __ptrauth_keys_init_cpu x5, x6, x7, x8
-#endif
-
adr_l x8, vectors // load VBAR_EL1 with virtual
msr vbar_el1, x8 // vector table address
isb
--
2.29.2