Commit d1797615 authored by Dave Martin's avatar Dave Martin Committed by Marc Zyngier

arm64: fpsimd: Generalise context saving for non-task contexts

In preparation for allowing non-task (i.e., KVM vcpu) FPSIMD
contexts to be handled by the fpsimd common code, this patch adapts
task_fpsimd_save() to save back the currently loaded context,
removing the explicit dependency on current.

The relevant storage to write back to in memory is now found by
examining the fpsimd_last_state percpu struct.

fpsimd_save() does nothing unless TIF_FOREIGN_FPSTATE is clear, and
fpsimd_last_state is updated under local_bh_disable() or
local_irq_disable() everywhere that TIF_FOREIGN_FPSTATE is cleared:
thus, fpsimd_save() will write back to the correct storage for the
loaded context.

No functional change.
Signed-off-by: default avatarDave Martin <Dave.Martin@arm.com>
Reviewed-by: default avatarAlex Bennée <alex.bennee@linaro.org>
Acked-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
parent ceda9fff
...@@ -270,13 +270,16 @@ static void task_fpsimd_load(void) ...@@ -270,13 +270,16 @@ static void task_fpsimd_load(void)
} }
/* /*
* Ensure current's FPSIMD/SVE storage in thread_struct is up to date * Ensure FPSIMD/SVE storage in memory for the loaded context is up to
* with respect to the CPU registers. * date with respect to the CPU registers.
* *
* Softirqs (and preemption) must be disabled. * Softirqs (and preemption) must be disabled.
*/ */
static void task_fpsimd_save(void) static void fpsimd_save(void)
{ {
struct user_fpsimd_state *st = __this_cpu_read(fpsimd_last_state.st);
/* set by fpsimd_bind_to_cpu() */
WARN_ON(!in_softirq() && !irqs_disabled()); WARN_ON(!in_softirq() && !irqs_disabled());
if (!test_thread_flag(TIF_FOREIGN_FPSTATE)) { if (!test_thread_flag(TIF_FOREIGN_FPSTATE)) {
...@@ -291,10 +294,9 @@ static void task_fpsimd_save(void) ...@@ -291,10 +294,9 @@ static void task_fpsimd_save(void)
return; return;
} }
sve_save_state(sve_pffr(current), sve_save_state(sve_pffr(current), &st->fpsr);
&current->thread.uw.fpsimd_state.fpsr);
} else } else
fpsimd_save_state(&current->thread.uw.fpsimd_state); fpsimd_save_state(st);
} }
} }
...@@ -598,7 +600,7 @@ int sve_set_vector_length(struct task_struct *task, ...@@ -598,7 +600,7 @@ int sve_set_vector_length(struct task_struct *task,
if (task == current) { if (task == current) {
local_bh_disable(); local_bh_disable();
task_fpsimd_save(); fpsimd_save();
set_thread_flag(TIF_FOREIGN_FPSTATE); set_thread_flag(TIF_FOREIGN_FPSTATE);
} }
...@@ -837,7 +839,7 @@ asmlinkage void do_sve_acc(unsigned int esr, struct pt_regs *regs) ...@@ -837,7 +839,7 @@ asmlinkage void do_sve_acc(unsigned int esr, struct pt_regs *regs)
local_bh_disable(); local_bh_disable();
task_fpsimd_save(); fpsimd_save();
fpsimd_to_sve(current); fpsimd_to_sve(current);
/* Force ret_to_user to reload the registers: */ /* Force ret_to_user to reload the registers: */
...@@ -898,7 +900,7 @@ void fpsimd_thread_switch(struct task_struct *next) ...@@ -898,7 +900,7 @@ void fpsimd_thread_switch(struct task_struct *next)
* 'current'. * 'current'.
*/ */
if (current->mm) if (current->mm)
task_fpsimd_save(); fpsimd_save();
if (next->mm) { if (next->mm) {
/* /*
...@@ -980,7 +982,7 @@ void fpsimd_preserve_current_state(void) ...@@ -980,7 +982,7 @@ void fpsimd_preserve_current_state(void)
return; return;
local_bh_disable(); local_bh_disable();
task_fpsimd_save(); fpsimd_save();
local_bh_enable(); local_bh_enable();
} }
...@@ -1121,7 +1123,7 @@ void kernel_neon_begin(void) ...@@ -1121,7 +1123,7 @@ void kernel_neon_begin(void)
/* Save unsaved task fpsimd state, if any: */ /* Save unsaved task fpsimd state, if any: */
if (current->mm) if (current->mm)
task_fpsimd_save(); fpsimd_save();
/* Invalidate any task state remaining in the fpsimd regs: */ /* Invalidate any task state remaining in the fpsimd regs: */
fpsimd_flush_cpu_state(); fpsimd_flush_cpu_state();
...@@ -1244,7 +1246,7 @@ static int fpsimd_cpu_pm_notifier(struct notifier_block *self, ...@@ -1244,7 +1246,7 @@ static int fpsimd_cpu_pm_notifier(struct notifier_block *self,
switch (cmd) { switch (cmd) {
case CPU_PM_ENTER: case CPU_PM_ENTER:
if (current->mm) if (current->mm)
task_fpsimd_save(); fpsimd_save();
fpsimd_flush_cpu_state(); fpsimd_flush_cpu_state();
break; break;
case CPU_PM_EXIT: case CPU_PM_EXIT:
......
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