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-rw-r--r--arch/arm/kernel/asm-offsets.c3
-rw-r--r--arch/arm/vfp/vfphw.S43
-rw-r--r--arch/arm/vfp/vfpmodule.c98
3 files changed, 89 insertions, 55 deletions
diff --git a/arch/arm/kernel/asm-offsets.c b/arch/arm/kernel/asm-offsets.c
index 927522cfc12e..16baba2e4369 100644
--- a/arch/arm/kernel/asm-offsets.c
+++ b/arch/arm/kernel/asm-offsets.c
@@ -59,6 +59,9 @@ int main(void)
DEFINE(TI_TP_VALUE, offsetof(struct thread_info, tp_value));
DEFINE(TI_FPSTATE, offsetof(struct thread_info, fpstate));
DEFINE(TI_VFPSTATE, offsetof(struct thread_info, vfpstate));
+#ifdef CONFIG_SMP
+ DEFINE(VFP_CPU, offsetof(union vfp_state, hard.cpu));
+#endif
#ifdef CONFIG_ARM_THUMBEE
DEFINE(TI_THUMBEE_STATE, offsetof(struct thread_info, thumbee_state));
#endif
diff --git a/arch/arm/vfp/vfphw.S b/arch/arm/vfp/vfphw.S
index 404538ae591d..2d30c7f6edd3 100644
--- a/arch/arm/vfp/vfphw.S
+++ b/arch/arm/vfp/vfphw.S
@@ -82,19 +82,22 @@ ENTRY(vfp_support_entry)
ldr r4, [r3, r11, lsl #2] @ vfp_current_hw_state pointer
bic r5, r1, #FPEXC_EX @ make sure exceptions are disabled
cmp r4, r10 @ this thread owns the hw context?
+#ifndef CONFIG_SMP
+ @ For UP, checking that this thread owns the hw context is
+ @ sufficient to determine that the hardware state is valid.
beq vfp_hw_state_valid
+ @ On UP, we lazily save the VFP context. As a different
+ @ thread wants ownership of the VFP hardware, save the old
+ @ state if there was a previous (valid) owner.
+
VFPFMXR FPEXC, r5 @ enable VFP, disable any pending
@ exceptions, so we can get at the
@ rest of it
-#ifndef CONFIG_SMP
- @ Save out the current registers to the old thread state
- @ No need for SMP since this is not done lazily
-
DBGSTR1 "save old state %p", r4
- cmp r4, #0
- beq no_old_VFP_process
+ cmp r4, #0 @ if the vfp_current_hw_state is NULL
+ beq vfp_reload_hw @ then the hw state needs reloading
VFPFSTMIA r4, r5 @ save the working registers
VFPFMRX r5, FPSCR @ current status
#ifndef CONFIG_CPU_FEROCEON
@@ -107,11 +110,33 @@ ENTRY(vfp_support_entry)
1:
#endif
stmia r4, {r1, r5, r6, r8} @ save FPEXC, FPSCR, FPINST, FPINST2
- @ and point r4 at the word at the
- @ start of the register dump
+vfp_reload_hw:
+
+#else
+ @ For SMP, if this thread does not own the hw context, then we
+ @ need to reload it. No need to save the old state as on SMP,
+ @ we always save the state when we switch away from a thread.
+ bne vfp_reload_hw
+
+ @ This thread has ownership of the current hardware context.
+ @ However, it may have been migrated to another CPU, in which
+ @ case the saved state is newer than the hardware context.
+ @ Check this by looking at the CPU number which the state was
+ @ last loaded onto.
+ ldr ip, [r10, #VFP_CPU]
+ teq ip, r11
+ beq vfp_hw_state_valid
+
+vfp_reload_hw:
+ @ We're loading this threads state into the VFP hardware. Update
+ @ the CPU number which contains the most up to date VFP context.
+ str r11, [r10, #VFP_CPU]
+
+ VFPFMXR FPEXC, r5 @ enable VFP, disable any pending
+ @ exceptions, so we can get at the
+ @ rest of it
#endif
-no_old_VFP_process:
DBGSTR1 "load state %p", r10
str r10, [r3, r11, lsl #2] @ update the vfp_current_hw_state pointer
@ Load the saved state back into the VFP
diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
index 3640351171b8..08ff93fa533c 100644
--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
@@ -35,18 +35,51 @@ void vfp_null_entry(void);
void (*vfp_vector)(void) = vfp_null_entry;
/*
+ * Dual-use variable.
+ * Used in startup: set to non-zero if VFP checks fail
+ * After startup, holds VFP architecture
+ */
+unsigned int VFP_arch;
+
+/*
* The pointer to the vfpstate structure of the thread which currently
* owns the context held in the VFP hardware, or NULL if the hardware
* context is invalid.
+ *
+ * For UP, this is sufficient to tell which thread owns the VFP context.
+ * However, for SMP, we also need to check the CPU number stored in the
+ * saved state too to catch migrations.
*/
union vfp_state *vfp_current_hw_state[NR_CPUS];
/*
- * Dual-use variable.
- * Used in startup: set to non-zero if VFP checks fail
- * After startup, holds VFP architecture
+ * Is 'thread's most up to date state stored in this CPUs hardware?
+ * Must be called from non-preemptible context.
*/
-unsigned int VFP_arch;
+static bool vfp_state_in_hw(unsigned int cpu, struct thread_info *thread)
+{
+#ifdef CONFIG_SMP
+ if (thread->vfpstate.hard.cpu != cpu)
+ return false;
+#endif
+ return vfp_current_hw_state[cpu] == &thread->vfpstate;
+}
+
+/*
+ * Force a reload of the VFP context from the thread structure. We do
+ * this by ensuring that access to the VFP hardware is disabled, and
+ * clear last_VFP_context. Must be called from non-preemptible context.
+ */
+static void vfp_force_reload(unsigned int cpu, struct thread_info *thread)
+{
+ if (vfp_state_in_hw(cpu, thread)) {
+ fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN);
+ vfp_current_hw_state[cpu] = NULL;
+ }
+#ifdef CONFIG_SMP
+ thread->vfpstate.hard.cpu = NR_CPUS;
+#endif
+}
/*
* Per-thread VFP initialization.
@@ -60,6 +93,9 @@ static void vfp_thread_flush(struct thread_info *thread)
vfp->hard.fpexc = FPEXC_EN;
vfp->hard.fpscr = FPSCR_ROUND_NEAREST;
+#ifdef CONFIG_SMP
+ vfp->hard.cpu = NR_CPUS;
+#endif
/*
* Disable VFP to ensure we initialize it first. We must ensure
@@ -90,6 +126,9 @@ static void vfp_thread_copy(struct thread_info *thread)
vfp_sync_hwstate(parent);
thread->vfpstate = parent->vfpstate;
+#ifdef CONFIG_SMP
+ thread->vfpstate.hard.cpu = NR_CPUS;
+#endif
}
/*
@@ -135,17 +174,8 @@ static int vfp_notifier(struct notifier_block *self, unsigned long cmd, void *v)
* case the thread migrates to a different CPU. The
* restoring is done lazily.
*/
- if ((fpexc & FPEXC_EN) && vfp_current_hw_state[cpu]) {
+ if ((fpexc & FPEXC_EN) && vfp_current_hw_state[cpu])
vfp_save_state(vfp_current_hw_state[cpu], fpexc);
- vfp_current_hw_state[cpu]->hard.cpu = cpu;
- }
- /*
- * Thread migration, just force the reloading of the
- * state on the new CPU in case the VFP registers
- * contain stale data.
- */
- if (thread->vfpstate.hard.cpu != cpu)
- vfp_current_hw_state[cpu] = NULL;
#endif
/*
@@ -449,15 +479,15 @@ static void vfp_pm_init(void)
static inline void vfp_pm_init(void) { }
#endif /* CONFIG_PM */
+/*
+ * Ensure that the VFP state stored in 'thread->vfpstate' is up to date
+ * with the hardware state.
+ */
void vfp_sync_hwstate(struct thread_info *thread)
{
unsigned int cpu = get_cpu();
- /*
- * If the thread we're interested in is the current owner of the
- * hardware VFP state, then we need to save its state.
- */
- if (vfp_current_hw_state[cpu] == &thread->vfpstate) {
+ if (vfp_state_in_hw(cpu, thread)) {
u32 fpexc = fmrx(FPEXC);
/*
@@ -471,36 +501,13 @@ void vfp_sync_hwstate(struct thread_info *thread)
put_cpu();
}
+/* Ensure that the thread reloads the hardware VFP state on the next use. */
void vfp_flush_hwstate(struct thread_info *thread)
{
unsigned int cpu = get_cpu();
- /*
- * If the thread we're interested in is the current owner of the
- * hardware VFP state, then we need to save its state.
- */
- if (vfp_current_hw_state[cpu] == &thread->vfpstate) {
- u32 fpexc = fmrx(FPEXC);
+ vfp_force_reload(cpu, thread);
- fmxr(FPEXC, fpexc & ~FPEXC_EN);
-
- /*
- * Set the context to NULL to force a reload the next time
- * the thread uses the VFP.
- */
- vfp_current_hw_state[cpu] = NULL;
- }
-
-#ifdef CONFIG_SMP
- /*
- * For SMP we still have to take care of the case where the thread
- * migrates to another CPU and then back to the original CPU on which
- * the last VFP user is still the same thread. Mark the thread VFP
- * state as belonging to a non-existent CPU so that the saved one will
- * be reloaded in the above case.
- */
- thread->vfpstate.hard.cpu = NR_CPUS;
-#endif
put_cpu();
}
@@ -519,8 +526,7 @@ static int vfp_hotplug(struct notifier_block *b, unsigned long action,
void *hcpu)
{
if (action == CPU_DYING || action == CPU_DYING_FROZEN) {
- unsigned int cpu = (long)hcpu;
- vfp_current_hw_state[cpu] = NULL;
+ vfp_force_reload((long)hcpu, current_thread_info());
} else if (action == CPU_STARTING || action == CPU_STARTING_FROZEN)
vfp_enable(NULL);
return NOTIFY_OK;
generated by cgit v1.2.3 (git 2.0.4) at 2024-11-07 12:35:34 +0000