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Diffstat (limited to 'arch/arm64/kernel/process.c')
-rw-r--r--arch/arm64/kernel/process.c39
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