arm64: simplify ptrauth initialization

Currently __cpu_setup conditionally initializes the address
authentication keys and enables them in SCTLR_EL1, doing so differently
for the primary CPU and secondary CPUs, and skipping this work for CPUs
returning from an idle state. For the latter case, cpu_do_resume
restores the keys and SCTLR_EL1 value after the MMU has been enabled.

This flow is rather difficult to follow, so instead let's move the
primary and secondary CPU initialization into their respective boot
paths. By following the example of cpu_do_resume and doing so once the
MMU is enabled, we can always initialize the keys from the values in
thread_struct, and avoid the machinery necessary to pass the keys in
secondary_data or open-coding initialization for the boot CPU.

This means we perform an additional RMW of SCTLR_EL1, but we already do
this in the cpu_do_resume path, and for other features in cpufeature.c,
so this isn't a major concern in a bringup path. Note that even while
the enable bits are clear, the key registers are accessible.

As this now renders the argument to __cpu_setup redundant, let's also
remove that entirely. Future extensions can follow a similar approach to
initialize values that differ for primary/secondary CPUs.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Reviewed-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Cc: Amit Daniel Kachhap <amit.kachhap@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20200423101606.37601-3-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

2 files changed, 22 insertions, 11 deletions

diff --git a/arch/arm64/include/asm/asm_pointer_auth.h b/arch/arm64/include/asm/asm_pointer_auth.h
index c85540a911d3..52dead2a8640 100644
--- a/arch/arm64/include/asm/asm_pointer_auth.h
+++ b/arch/arm64/include/asm/asm_pointer_auth.h
@@ -60,6 +60,28 @@ alternative_if ARM64_HAS_ADDRESS_AUTH
 alternative_else_nop_endif
 	.endm
 
+	.macro __ptrauth_keys_init_cpu tsk, tmp1, tmp2, tmp3
+	mrs	\tmp1, id_aa64isar1_el1
+	ubfx	\tmp1, \tmp1, #ID_AA64ISAR1_APA_SHIFT, #8
+	cbz	\tmp1, .Lno_addr_auth\@
+	mov_q	\tmp1, (SCTLR_ELx_ENIA | SCTLR_ELx_ENIB | \
+			SCTLR_ELx_ENDA | SCTLR_ELx_ENDB)
+	mrs	\tmp2, sctlr_el1
+	orr	\tmp2, \tmp2, \tmp1
+	msr	sctlr_el1, \tmp2
+	__ptrauth_keys_install_kernel_nosync \tsk, \tmp1, \tmp2, \tmp3
+	isb
+.Lno_addr_auth\@:
+	.endm
+
+	.macro ptrauth_keys_init_cpu tsk, tmp1, tmp2, tmp3
+alternative_if_not ARM64_HAS_ADDRESS_AUTH
+	b	.Lno_addr_auth\@
+alternative_else_nop_endif
+	__ptrauth_keys_init_cpu \tsk, \tmp1, \tmp2, \tmp3
+.Lno_addr_auth\@:
+	.endm
+
 #else /* CONFIG_ARM64_PTR_AUTH */
 
 	.macro ptrauth_keys_install_user tsk, tmp1, tmp2, tmp3
diff --git a/arch/arm64/include/asm/smp.h b/arch/arm64/include/asm/smp.h
index 40d5ba029615..ea268d88b6f7 100644
--- a/arch/arm64/include/asm/smp.h
+++ b/arch/arm64/include/asm/smp.h
@@ -23,14 +23,6 @@
 #define CPU_STUCK_REASON_52_BIT_VA	(UL(1) << CPU_STUCK_REASON_SHIFT)
 #define CPU_STUCK_REASON_NO_GRAN	(UL(2) << CPU_STUCK_REASON_SHIFT)
 
-/* Possible options for __cpu_setup */
-/* Option to setup primary cpu */
-#define ARM64_CPU_BOOT_PRIMARY		(1)
-/* Option to setup secondary cpus */
-#define ARM64_CPU_BOOT_SECONDARY	(2)
-/* Option to setup cpus for different cpu run time services */
-#define ARM64_CPU_RUNTIME		(3)
-
 #ifndef __ASSEMBLY__
 
 #include <asm/percpu.h>
@@ -96,9 +88,6 @@ asmlinkage void secondary_start_kernel(void);
 struct secondary_data {
 	void *stack;
 	struct task_struct *task;
-#ifdef CONFIG_ARM64_PTR_AUTH
-	struct ptrauth_keys_kernel ptrauth_key;
-#endif
 	long status;
 };