Merge remote-tracking branch 'gh-fslc/5.4-2.3.x-imx' into toradex_5.4-2.3.x-imx

1 files changed, 16 insertions, 23 deletions

diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index f61ef46ebff7..d07fbc21f14c 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -500,34 +500,26 @@ static void entry_task_switch(struct task_struct *next)
 
 /*
  * ARM erratum 1418040 handling, affecting the 32bit view of CNTVCT.
- * Assuming the virtual counter is enabled at the beginning of times:
- *
- * - disable access when switching from a 64bit task to a 32bit task
- * - enable access when switching from a 32bit task to a 64bit task
+ * Ensure access is disabled when switching to a 32bit task, ensure
+ * access is enabled when switching to a 64bit task.
  */
-static void erratum_1418040_thread_switch(struct task_struct *prev,
-					  struct task_struct *next)
+static void erratum_1418040_thread_switch(struct task_struct *next)
 {
-	bool prev32, next32;
-	u64 val;
-
-	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 || !this_cpu_has_cap(ARM64_WORKAROUND_1418040))
+	if (!IS_ENABLED(CONFIG_ARM64_ERRATUM_1418040) ||
+	    !this_cpu_has_cap(ARM64_WORKAROUND_1418040))
 		return;
 
-	val = read_sysreg(cntkctl_el1);
-
-	if (!next32)
-		val |= ARCH_TIMER_USR_VCT_ACCESS_EN;
+	if (is_compat_thread(task_thread_info(next)))
+		sysreg_clear_set(cntkctl_el1, ARCH_TIMER_USR_VCT_ACCESS_EN, 0);
 	else
-		val &= ~ARCH_TIMER_USR_VCT_ACCESS_EN;
+		sysreg_clear_set(cntkctl_el1, 0, ARCH_TIMER_USR_VCT_ACCESS_EN);
+}
 
-	write_sysreg(val, cntkctl_el1);
+static void erratum_1418040_new_exec(void)
+{
+	preempt_disable();
+	erratum_1418040_thread_switch(current);
+	preempt_enable();
 }
 
 /*
@@ -546,7 +538,7 @@ __notrace_funcgraph struct task_struct *__switch_to(struct task_struct *prev,
 	uao_thread_switch(next);
 	ptrauth_thread_switch(next);
 	ssbs_thread_switch(next);
-	erratum_1418040_thread_switch(prev, next);
+	erratum_1418040_thread_switch(next);
 
 	/*
 	 * Complete any pending TLB or cache maintenance on this CPU in case
@@ -605,6 +597,7 @@ void arch_setup_new_exec(void)
 	current->mm->context.flags = is_compat_task() ? MMCF_AARCH32 : 0;
 
 	ptrauth_thread_init_user(current);
+	erratum_1418040_new_exec();
 }
 
 #ifdef CONFIG_ARM64_TAGGED_ADDR_ABI