arm64: suspend: restore the kernel ptrauth keys

This patch restores the kernel keys from current task during cpu resume
after the mmu is turned on and ptrauth is enabled.

A flag is added in macro ptrauth_keys_install_kernel to check if isb
instruction needs to be executed.
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/include/asm/asm_pointer_auth.h

@@ -39,14 +39,16 @@ alternative_if ARM64_HAS_GENERIC_AUTH
 alternative_else_nop_endif
 	.endm
 
-	.macro ptrauth_keys_install_kernel tsk, tmp1, tmp2, tmp3
+	.macro ptrauth_keys_install_kernel tsk, sync, tmp1, tmp2, tmp3
 alternative_if ARM64_HAS_ADDRESS_AUTH
 	mov	\tmp1, #THREAD_KEYS_KERNEL
 	add	\tmp1, \tsk, \tmp1
 	ldp	\tmp2, \tmp3, [\tmp1, #PTRAUTH_KERNEL_KEY_APIA]
 	msr_s	SYS_APIAKEYLO_EL1, \tmp2
 	msr_s	SYS_APIAKEYHI_EL1, \tmp3
+	.if     \sync == 1
 	isb
+	.endif
 alternative_else_nop_endif
 	.endm
 
@@ -55,7 +57,7 @@ alternative_else_nop_endif
 	.macro ptrauth_keys_install_user tsk, tmp1, tmp2, tmp3
 	.endm
 
-	.macro ptrauth_keys_install_kernel tsk, tmp1, tmp2, tmp3
+	.macro ptrauth_keys_install_kernel tsk, sync, tmp1, tmp2, tmp3
 	.endm
 
 #endif /* CONFIG_ARM64_PTR_AUTH */

arch/arm64/kernel/entry.S

@@ -178,7 +178,7 @@ alternative_cb_end
 
 	apply_ssbd 1, x22, x23
 
-	ptrauth_keys_install_kernel tsk, x20, x22, x23
+	ptrauth_keys_install_kernel tsk, 1, x20, x22, x23
 	.else
 	add	x21, sp, #S_FRAME_SIZE
 	get_current_task tsk
@@ -900,7 +900,7 @@ ENTRY(cpu_switch_to)
 	ldr	lr, [x8]
 	mov	sp, x9
 	msr	sp_el0, x1
-	ptrauth_keys_install_kernel x1, x8, x9, x10
+	ptrauth_keys_install_kernel x1, 1, x8, x9, x10
 	ret
 ENDPROC(cpu_switch_to)
 NOKPROBE(cpu_switch_to)

arch/arm64/mm/proc.S

@@ -11,6 +11,7 @@
 #include <linux/linkage.h>
 #include <asm/assembler.h>
 #include <asm/asm-offsets.h>
+#include <asm/asm_pointer_auth.h>
 #include <asm/hwcap.h>
 #include <asm/pgtable.h>
 #include <asm/pgtable-hwdef.h>
@@ -137,6 +138,7 @@ alternative_if ARM64_HAS_RAS_EXTN
 	msr_s	SYS_DISR_EL1, xzr
 alternative_else_nop_endif
 
+	ptrauth_keys_install_kernel x14, 0, x1, x2, x3
 	isb
 	ret
 SYM_FUNC_END(cpu_do_resume)