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arm64: add support for kernel mode NEON in interrupt context

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This patch modifies kernel_neon_begin() and kernel_neon_end(), so
they may be called from any context. To address the case where only
a couple of registers are needed, kernel_neon_begin_partial(u32) is
introduced which takes as a parameter the number of bottom 'n' NEON
q-registers required. To mark the end of such a partial section, the
regular kernel_neon_end() should be used.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
This commit is contained in:
Ard Biesheuvel
2014-02-24 15:26:29 +01:00
parent 005f78cd88
commit 190f1ca85d
5 changed files with 109 additions and 15 deletions
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24
arch/arm64/kernel/entry-fpsimd.S
View File

@@ -41,3 +41,27 @@ ENTRY(fpsimd_load_state)
fpsimd_restore x0, 8
ret
ENDPROC(fpsimd_load_state)
#ifdef CONFIG_KERNEL_MODE_NEON
/*
* Save the bottom n FP registers.
*
* x0 - pointer to struct fpsimd_partial_state
*/
ENTRY(fpsimd_save_partial_state)
fpsimd_save_partial x0, 1, 8, 9
ret
ENDPROC(fpsimd_load_partial_state)
/*
* Load the bottom n FP registers.
*
* x0 - pointer to struct fpsimd_partial_state
*/
ENTRY(fpsimd_load_partial_state)
fpsimd_restore_partial x0, 8, 9
ret
ENDPROC(fpsimd_load_partial_state)
#endif

44
arch/arm64/kernel/fpsimd.c
View File

@@ -218,29 +218,45 @@ void fpsimd_flush_task_state(struct task_struct *t)
#ifdef CONFIG_KERNEL_MODE_NEON
static DEFINE_PER_CPU(struct fpsimd_partial_state, hardirq_fpsimdstate);
static DEFINE_PER_CPU(struct fpsimd_partial_state, softirq_fpsimdstate);
/*
* Kernel-side NEON support functions
*/
void kernel_neon_begin(void)
void kernel_neon_begin_partial(u32 num_regs)
{
/* Avoid using the NEON in interrupt context */
BUG_ON(in_interrupt());
preempt_disable();
if (in_interrupt()) {
struct fpsimd_partial_state *s = this_cpu_ptr(
in_irq() ? &hardirq_fpsimdstate : &softirq_fpsimdstate);
/*
* Save the userland FPSIMD state if we have one and if we haven't done
* so already. Clear fpsimd_last_state to indicate that there is no
* longer userland FPSIMD state in the registers.
*/
if (current->mm && !test_and_set_thread_flag(TIF_FOREIGN_FPSTATE))
fpsimd_save_state(&current->thread.fpsimd_state);
this_cpu_write(fpsimd_last_state, NULL);
BUG_ON(num_regs > 32);
fpsimd_save_partial_state(s, roundup(num_regs, 2));
} else {
/*
* Save the userland FPSIMD state if we have one and if we
* haven't done so already. Clear fpsimd_last_state to indicate
* that there is no longer userland FPSIMD state in the
* registers.
*/
preempt_disable();
if (current->mm &&
!test_and_set_thread_flag(TIF_FOREIGN_FPSTATE))
fpsimd_save_state(&current->thread.fpsimd_state);
this_cpu_write(fpsimd_last_state, NULL);
}
}
EXPORT_SYMBOL(kernel_neon_begin);
EXPORT_SYMBOL(kernel_neon_begin_partial);
void kernel_neon_end(void)
{
preempt_enable();
if (in_interrupt()) {
struct fpsimd_partial_state *s = this_cpu_ptr(
in_irq() ? &hardirq_fpsimdstate : &softirq_fpsimdstate);
fpsimd_load_partial_state(s);
} else {
preempt_enable();
}
}
EXPORT_SYMBOL(kernel_neon_end);