1 files changed, 15 insertions, 29 deletions

diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 4784011cecac..6616486a58fe 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -72,13 +72,13 @@ EXPORT_SYMBOL_GPL(pm_power_off);
 
 void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd);
 
-static void __cpu_do_idle(void)
+static void noinstr __cpu_do_idle(void)
 {
 	dsb(sy);
 	wfi();
 }
 
-static void __cpu_do_idle_irqprio(void)
+static void noinstr __cpu_do_idle_irqprio(void)
 {
 	unsigned long pmr;
 	unsigned long daif_bits;
@@ -108,7 +108,7 @@ static void __cpu_do_idle_irqprio(void)
  *	ensure that interrupts are not masked at the PMR (because the core will
  *	not wake up if we block the wake up signal in the interrupt controller).
  */
-void cpu_do_idle(void)
+void noinstr cpu_do_idle(void)
 {
 	if (system_uses_irq_prio_masking())
 		__cpu_do_idle_irqprio();
@@ -119,14 +119,14 @@ void cpu_do_idle(void)
 /*
  * This is our default idle handler.
  */
-void arch_cpu_idle(void)
+void noinstr arch_cpu_idle(void)
 {
 	/*
 	 * This should do all the clock switching and wait for interrupt
 	 * tricks
 	 */
 	cpu_do_idle();
-	local_irq_enable();
+	raw_local_irq_enable();
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
@@ -422,16 +422,15 @@ int copy_thread(unsigned long clone_flags, unsigned long stack_start,
 		if (clone_flags & CLONE_SETTLS)
 			p->thread.uw.tp_value = tls;
 	} else {
+		/*
+		 * A kthread has no context to ERET to, so ensure any buggy
+		 * ERET is treated as an illegal exception return.
+		 *
+		 * When a user task is created from a kthread, childregs will
+		 * be initialized by start_thread() or start_compat_thread().
+		 */
 		memset(childregs, 0, sizeof(struct pt_regs));
-		childregs->pstate = PSR_MODE_EL1h;
-		if (IS_ENABLED(CONFIG_ARM64_UAO) &&
-		    cpus_have_const_cap(ARM64_HAS_UAO))
-			childregs->pstate |= PSR_UAO_BIT;
-
-		spectre_v4_enable_task_mitigation(p);
-
-		if (system_uses_irq_prio_masking())
-			childregs->pmr_save = GIC_PRIO_IRQON;
+		childregs->pstate = PSR_MODE_EL1h | PSR_IL_BIT;
 
 		p->thread.cpu_context.x19 = stack_start;
 		p->thread.cpu_context.x20 = stk_sz;
@@ -461,17 +460,6 @@ static void tls_thread_switch(struct task_struct *next)
 	write_sysreg(*task_user_tls(next), tpidr_el0);
 }
 
-/* Restore the UAO state depending on next's addr_limit */
-void uao_thread_switch(struct task_struct *next)
-{
-	if (IS_ENABLED(CONFIG_ARM64_UAO)) {
-		if (task_thread_info(next)->addr_limit == KERNEL_DS)
-			asm(ALTERNATIVE("nop", SET_PSTATE_UAO(1), ARM64_HAS_UAO));
-		else
-			asm(ALTERNATIVE("nop", SET_PSTATE_UAO(0), ARM64_HAS_UAO));
-	}
-}
-
 /*
  * Force SSBS state on context-switch, since it may be lost after migrating
  * from a CPU which treats the bit as RES0 in a heterogeneous system.
@@ -522,14 +510,13 @@ static void erratum_1418040_thread_switch(struct task_struct *prev,
 	bool prev32, next32;
 	u64 val;
 
-	if (!(IS_ENABLED(CONFIG_ARM64_ERRATUM_1418040) &&
-	      cpus_have_const_cap(ARM64_WORKAROUND_1418040)))
+	if (!IS_ENABLED(CONFIG_ARM64_ERRATUM_1418040))
 		return;
 
 	prev32 = is_compat_thread(task_thread_info(prev));
 	next32 = is_compat_thread(task_thread_info(next));
 
-	if (prev32 == next32)
+	if (prev32 == next32 || !this_cpu_has_cap(ARM64_WORKAROUND_1418040))
 		return;
 
 	val = read_sysreg(cntkctl_el1);
@@ -555,7 +542,6 @@ __notrace_funcgraph struct task_struct *__switch_to(struct task_struct *prev,
 	hw_breakpoint_thread_switch(next);
 	contextidr_thread_switch(next);
 	entry_task_switch(next);
-	uao_thread_switch(next);
 	ssbs_thread_switch(next);
 	erratum_1418040_thread_switch(prev, next);