stp x28, x29, [sp, #16 * 14]
.if \el == 0
- .if \regsize == 32
- /*
- * If we're returning from a 32-bit task on a system affected by
- * 1418040 then re-enable userspace access to the virtual counter.
- */
-#ifdef CONFIG_ARM64_ERRATUM_1418040
-alternative_if ARM64_WORKAROUND_1418040
- mrs x0, cntkctl_el1
- orr x0, x0, #2 // ARCH_TIMER_USR_VCT_ACCESS_EN
- msr cntkctl_el1, x0
-alternative_else_nop_endif
-#endif
- .endif
clear_gp_regs
mrs x21, sp_el0
ldr_this_cpu tsk, __entry_task, x20
tst x22, #PSR_MODE32_BIT // native task?
b.eq 3f
-#ifdef CONFIG_ARM64_ERRATUM_1418040
-alternative_if ARM64_WORKAROUND_1418040
- mrs x0, cntkctl_el1
- bic x0, x0, #2 // ARCH_TIMER_USR_VCT_ACCESS_EN
- msr cntkctl_el1, x0
-alternative_else_nop_endif
-#endif
-
#ifdef CONFIG_ARM64_ERRATUM_845719
alternative_if ARM64_WORKAROUND_845719
#ifdef CONFIG_PID_IN_CONTEXTIDR
}
/*
+ * 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
+ */
+static void erratum_1418040_thread_switch(struct task_struct *prev,
+ struct task_struct *next)
+{
+ bool prev32, next32;
+ u64 val;
+
+ if (!(IS_ENABLED(CONFIG_ARM64_ERRATUM_1418040) &&
+ cpus_have_const_cap(ARM64_WORKAROUND_1418040)))
+ return;
+
+ prev32 = is_compat_thread(task_thread_info(prev));
+ next32 = is_compat_thread(task_thread_info(next));
+
+ if (prev32 == next32)
+ return;
+
+ val = read_sysreg(cntkctl_el1);
+
+ if (!next32)
+ val |= ARCH_TIMER_USR_VCT_ACCESS_EN;
+ else
+ val &= ~ARCH_TIMER_USR_VCT_ACCESS_EN;
+
+ write_sysreg(val, cntkctl_el1);
+}
+
+/*
* Thread switching.
*/
__notrace_funcgraph struct task_struct *__switch_to(struct task_struct *prev,
entry_task_switch(next);
uao_thread_switch(next);
ssbs_thread_switch(next);
+ erratum_1418040_thread_switch(prev, next);
/*
* Complete any pending TLB or cache maintenance on this CPU in case