arm64: Consolidate hotplug notifier for instruction emulation

As of now each insn_emulation has a cpu hotplug notifier that
enables/disables the CPU feature bit for the functionality. This
patch re-arranges the code, such that there is only one notifier
that runs through the list of registered emulation hooks and runs
their corresponding set_hw_mode.

We do nothing when a CPU is dying as we will set the appropriate bits
as it comes back online based on the state of the hooks.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Punit Agrawal <punit.agrawal@arm.com>
[catalin.marinas@arm.com: fix pr_warn compilation error]
[catalin.marinas@arm.com: remove unnecessary "insn" check]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/include/asm/cputype.h b/arch/arm64/include/asm/cputype.h
index ee6403d..68732e9 100644 (file)
--- a/arch/arm64/include/asm/cputype.h
+++ b/arch/arm64/include/asm/cputype.h
@@ -81,6 +81,8 @@
 #define ID_AA64MMFR0_BIGEND(mmfr0)     \
        (((mmfr0) & ID_AA64MMFR0_BIGEND_MASK) >> ID_AA64MMFR0_BIGEND_SHIFT)
 
+#define SCTLR_EL1_CP15BEN      (0x1 << 5)
+
 #ifndef __ASSEMBLY__
 
 /*

diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c
index c363671..68b955e 100644 (file)
--- a/arch/arm64/kernel/armv8_deprecated.c
+++ b/arch/arm64/kernel/armv8_deprecated.c
@@ -19,6 +19,7 @@
 #include <asm/system_misc.h>
 #include <asm/traps.h>
 #include <asm/uaccess.h>
+#include <asm/cpufeature.h>
 
 #define CREATE_TRACE_POINTS
 #include "trace-events-emulation.h"
@@ -85,6 +86,57 @@ static void remove_emulation_hooks(struct insn_emulation_ops *ops)
        pr_notice("Removed %s emulation handler\n", ops->name);
 }
 
+static void enable_insn_hw_mode(void *data)
+{
+       struct insn_emulation *insn = (struct insn_emulation *)data;
+       if (insn->ops->set_hw_mode)
+               insn->ops->set_hw_mode(true);
+}
+
+static void disable_insn_hw_mode(void *data)
+{
+       struct insn_emulation *insn = (struct insn_emulation *)data;
+       if (insn->ops->set_hw_mode)
+               insn->ops->set_hw_mode(false);
+}
+
+/* Run set_hw_mode(mode) on all active CPUs */
+static int run_all_cpu_set_hw_mode(struct insn_emulation *insn, bool enable)
+{
+       if (!insn->ops->set_hw_mode)
+               return -EINVAL;
+       if (enable)
+               on_each_cpu(enable_insn_hw_mode, (void *)insn, true);
+       else
+               on_each_cpu(disable_insn_hw_mode, (void *)insn, true);
+       return 0;
+}
+
+/*
+ * Run set_hw_mode for all insns on a starting CPU.
+ * Returns:
+ *  0          - If all the hooks ran successfully.
+ * -EINVAL     - At least one hook is not supported by the CPU.
+ */
+static int run_all_insn_set_hw_mode(unsigned long cpu)
+{
+       int rc = 0;
+       unsigned long flags;
+       struct insn_emulation *insn;
+
+       raw_spin_lock_irqsave(&insn_emulation_lock, flags);
+       list_for_each_entry(insn, &insn_emulation, node) {
+               bool enable = (insn->current_mode == INSN_HW);
+               if (insn->ops->set_hw_mode && insn->ops->set_hw_mode(enable)) {
+                       pr_warn("CPU[%ld] cannot support the emulation of %s",
+                               cpu, insn->ops->name);
+                       rc = -EINVAL;
+               }
+       }
+       raw_spin_unlock_irqrestore(&insn_emulation_lock, flags);
+       return rc;
+}
+
 static int update_insn_emulation_mode(struct insn_emulation *insn,
                                       enum insn_emulation_mode prev)
 {
@@ -97,10 +149,8 @@ static int update_insn_emulation_mode(struct insn_emulation *insn,
                remove_emulation_hooks(insn->ops);
                break;
        case INSN_HW:
-               if (insn->ops->set_hw_mode) {
-                       insn->ops->set_hw_mode(false);
+               if (!run_all_cpu_set_hw_mode(insn, false))
                        pr_notice("Disabled %s support\n", insn->ops->name);
-               }
                break;
        }
 
@@ -111,10 +161,9 @@ static int update_insn_emulation_mode(struct insn_emulation *insn,
                register_emulation_hooks(insn->ops);
                break;
        case INSN_HW:
-               if (insn->ops->set_hw_mode && insn->ops->set_hw_mode(true))
+               ret = run_all_cpu_set_hw_mode(insn, true);
+               if (!ret)
                        pr_notice("Enabled %s support\n", insn->ops->name);
-               else
-                       ret = -EINVAL;
                break;
        }
 
@@ -133,6 +182,8 @@ static void register_insn_emulation(struct insn_emulation_ops *ops)
        switch (ops->status) {
        case INSN_DEPRECATED:
                insn->current_mode = INSN_EMULATE;
+               /* Disable the HW mode if it was turned on at early boot time */
+               run_all_cpu_set_hw_mode(insn, false);
                insn->max = INSN_HW;
                break;
        case INSN_OBSOLETE:
@@ -453,8 +504,6 @@ ret:
        return 0;
 }
 
-#define SCTLR_EL1_CP15BEN (1 << 5)
-
 static inline void config_sctlr_el1(u32 clear, u32 set)
 {
        u32 val;
@@ -465,48 +514,13 @@ static inline void config_sctlr_el1(u32 clear, u32 set)
        asm volatile("msr sctlr_el1, %0" : : "r" (val));
 }
 
-static void enable_cp15_ben(void *info)
-{
-       config_sctlr_el1(0, SCTLR_EL1_CP15BEN);
-}
-
-static void disable_cp15_ben(void *info)
-{
-       config_sctlr_el1(SCTLR_EL1_CP15BEN, 0);
-}
-
-static int cpu_hotplug_notify(struct notifier_block *b,
-                             unsigned long action, void *hcpu)
-{
-       switch (action) {
-       case CPU_STARTING:
-       case CPU_STARTING_FROZEN:
-               enable_cp15_ben(NULL);
-               return NOTIFY_DONE;
-       case CPU_DYING:
-       case CPU_DYING_FROZEN:
-               disable_cp15_ben(NULL);
-               return NOTIFY_DONE;
-       }
-
-       return NOTIFY_OK;
-}
-
-static struct notifier_block cpu_hotplug_notifier = {
-       .notifier_call = cpu_hotplug_notify,
-};
-
 static int cp15_barrier_set_hw_mode(bool enable)
 {
-       if (enable) {
-               register_cpu_notifier(&cpu_hotplug_notifier);
-               on_each_cpu(enable_cp15_ben, NULL, true);
-       } else {
-               unregister_cpu_notifier(&cpu_hotplug_notifier);
-               on_each_cpu(disable_cp15_ben, NULL, true);
-       }
-
-       return true;
+       if (enable)
+               config_sctlr_el1(0, SCTLR_EL1_CP15BEN);
+       else
+               config_sctlr_el1(SCTLR_EL1_CP15BEN, 0);
+       return 0;
 }
 
 static struct undef_hook cp15_barrier_hooks[] = {
@@ -534,6 +548,20 @@ static struct insn_emulation_ops cp15_barrier_ops = {
        .set_hw_mode = cp15_barrier_set_hw_mode,
 };
 
+static int insn_cpu_hotplug_notify(struct notifier_block *b,
+                             unsigned long action, void *hcpu)
+{
+       int rc = 0;
+       if ((action & ~CPU_TASKS_FROZEN) == CPU_STARTING)
+               rc = run_all_insn_set_hw_mode((unsigned long)hcpu);
+
+       return notifier_from_errno(rc);
+}
+
+static struct notifier_block insn_cpu_hotplug_notifier = {
+       .notifier_call = insn_cpu_hotplug_notify,
+};
+
 /*
  * Invoked as late_initcall, since not needed before init spawned.
  */
@@ -545,6 +573,7 @@ static int __init armv8_deprecated_init(void)
        if (IS_ENABLED(CONFIG_CP15_BARRIER_EMULATION))
                register_insn_emulation(&cp15_barrier_ops);
 
+       register_cpu_notifier(&insn_cpu_hotplug_notifier);
        register_insn_emulation_sysctl(ctl_abi);
 
        return 0;