250 lines
8.3 KiB
C
250 lines
8.3 KiB
C
/*
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* In-kernel vector facility support functions
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*
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* Copyright IBM Corp. 2015
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* Author(s): Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
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*/
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#include <linux/kernel.h>
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#include <linux/cpu.h>
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#include <linux/sched.h>
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#include <asm/fpu/types.h>
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#include <asm/fpu/api.h>
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/*
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* Per-CPU variable to maintain FPU register ranges that are in use
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* by the kernel.
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*/
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static DEFINE_PER_CPU(u32, kernel_fpu_state);
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#define KERNEL_FPU_STATE_MASK (KERNEL_FPU_MASK|KERNEL_FPC)
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void __kernel_fpu_begin(struct kernel_fpu *state, u32 flags)
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{
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if (!__this_cpu_read(kernel_fpu_state)) {
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/*
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* Save user space FPU state and register contents. Multiple
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* calls because of interruptions do not matter and return
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* immediately. This also sets CIF_FPU to lazy restore FP/VX
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* register contents when returning to user space.
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*/
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save_fpu_regs();
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}
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/* Update flags to use the vector facility for KERNEL_FPR */
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if (MACHINE_HAS_VX && (state->mask & KERNEL_FPR)) {
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flags |= KERNEL_VXR_LOW | KERNEL_FPC;
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flags &= ~KERNEL_FPR;
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}
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/* Save and update current kernel VX state */
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state->mask = __this_cpu_read(kernel_fpu_state);
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__this_cpu_or(kernel_fpu_state, flags & KERNEL_FPU_STATE_MASK);
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/*
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* If this is the first call to __kernel_fpu_begin(), no additional
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* work is required.
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*/
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if (!(state->mask & KERNEL_FPU_STATE_MASK))
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return;
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/*
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* If KERNEL_FPR is still set, the vector facility is not available
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* and, thus, save floating-point control and registers only.
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*/
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if (state->mask & KERNEL_FPR) {
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asm volatile("stfpc %0" : "=Q" (state->fpc));
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asm volatile("std 0,%0" : "=Q" (state->fprs[0]));
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asm volatile("std 1,%0" : "=Q" (state->fprs[1]));
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asm volatile("std 2,%0" : "=Q" (state->fprs[2]));
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asm volatile("std 3,%0" : "=Q" (state->fprs[3]));
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asm volatile("std 4,%0" : "=Q" (state->fprs[4]));
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asm volatile("std 5,%0" : "=Q" (state->fprs[5]));
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asm volatile("std 6,%0" : "=Q" (state->fprs[6]));
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asm volatile("std 7,%0" : "=Q" (state->fprs[7]));
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asm volatile("std 8,%0" : "=Q" (state->fprs[8]));
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asm volatile("std 9,%0" : "=Q" (state->fprs[9]));
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asm volatile("std 10,%0" : "=Q" (state->fprs[10]));
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asm volatile("std 11,%0" : "=Q" (state->fprs[11]));
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asm volatile("std 12,%0" : "=Q" (state->fprs[12]));
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asm volatile("std 13,%0" : "=Q" (state->fprs[13]));
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asm volatile("std 14,%0" : "=Q" (state->fprs[14]));
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asm volatile("std 15,%0" : "=Q" (state->fprs[15]));
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return;
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}
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/*
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* If this is a nested call to __kernel_fpu_begin(), check the saved
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* state mask to save and later restore the vector registers that
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* are already in use. Let's start with checking floating-point
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* controls.
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*/
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if (state->mask & KERNEL_FPC)
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asm volatile("stfpc %0" : "=m" (state->fpc));
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/* Test and save vector registers */
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asm volatile (
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/*
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* Test if any vector register must be saved and, if so,
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* test if all register can be saved.
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*/
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" tmll %[m],15\n" /* KERNEL_VXR_MASK */
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" jz 20f\n" /* no work -> done */
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" la 1,%[vxrs]\n" /* load save area */
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" jo 18f\n" /* -> save V0..V31 */
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/*
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* Test if V8..V23 can be saved at once... this speeds up
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* for KERNEL_fpu_MID only. Otherwise continue to split the
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* range of vector registers into two halves and test them
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* separately.
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*/
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" tmll %[m],6\n" /* KERNEL_VXR_MID */
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" jo 17f\n" /* -> save V8..V23 */
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/* Test and save the first half of 16 vector registers */
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"1: tmll %[m],3\n" /* KERNEL_VXR_LOW */
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" jz 10f\n" /* -> KERNEL_VXR_HIGH */
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" jo 2f\n" /* 11 -> save V0..V15 */
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" brc 4,3f\n" /* 01 -> save V0..V7 */
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" brc 2,4f\n" /* 10 -> save V8..V15 */
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/* Test and save the second half of 16 vector registers */
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"10: tmll %[m],12\n" /* KERNEL_VXR_HIGH */
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" jo 19f\n" /* 11 -> save V16..V31 */
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" brc 4,11f\n" /* 01 -> save V16..V23 */
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" brc 2,12f\n" /* 10 -> save V24..V31 */
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" j 20f\n" /* 00 -> done */
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/*
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* Below are the vstm combinations to save multiple vector
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* registers at once.
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*/
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"2: .word 0xe70f,0x1000,0x003e\n" /* vstm 0,15,0(1) */
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" j 10b\n" /* -> VXR_HIGH */
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"3: .word 0xe707,0x1000,0x003e\n" /* vstm 0,7,0(1) */
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" j 10b\n" /* -> VXR_HIGH */
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"4: .word 0xe78f,0x1080,0x003e\n" /* vstm 8,15,128(1) */
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" j 10b\n" /* -> VXR_HIGH */
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"\n"
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"11: .word 0xe707,0x1100,0x0c3e\n" /* vstm 16,23,256(1) */
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" j 20f\n" /* -> done */
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"12: .word 0xe78f,0x1180,0x0c3e\n" /* vstm 24,31,384(1) */
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" j 20f\n" /* -> done */
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"\n"
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"17: .word 0xe787,0x1080,0x043e\n" /* vstm 8,23,128(1) */
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" nill %[m],249\n" /* m &= ~VXR_MID */
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" j 1b\n" /* -> VXR_LOW */
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"\n"
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"18: .word 0xe70f,0x1000,0x003e\n" /* vstm 0,15,0(1) */
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"19: .word 0xe70f,0x1100,0x0c3e\n" /* vstm 16,31,256(1) */
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"20:"
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: [vxrs] "=Q" (*(struct vx_array *) &state->vxrs)
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: [m] "d" (state->mask)
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: "1", "cc");
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}
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EXPORT_SYMBOL(__kernel_fpu_begin);
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void __kernel_fpu_end(struct kernel_fpu *state)
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{
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/* Just update the per-CPU state if there is nothing to restore */
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if (!(state->mask & KERNEL_FPU_STATE_MASK))
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goto update_fpu_state;
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/*
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* If KERNEL_FPR is specified, the vector facility is not available
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* and, thus, restore floating-point control and registers only.
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*/
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if (state->mask & KERNEL_FPR) {
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asm volatile("lfpc %0" : : "Q" (state->fpc));
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asm volatile("ld 0,%0" : : "Q" (state->fprs[0]));
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asm volatile("ld 1,%0" : : "Q" (state->fprs[1]));
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asm volatile("ld 2,%0" : : "Q" (state->fprs[2]));
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asm volatile("ld 3,%0" : : "Q" (state->fprs[3]));
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asm volatile("ld 4,%0" : : "Q" (state->fprs[4]));
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asm volatile("ld 5,%0" : : "Q" (state->fprs[5]));
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asm volatile("ld 6,%0" : : "Q" (state->fprs[6]));
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asm volatile("ld 7,%0" : : "Q" (state->fprs[7]));
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asm volatile("ld 8,%0" : : "Q" (state->fprs[8]));
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asm volatile("ld 9,%0" : : "Q" (state->fprs[9]));
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asm volatile("ld 10,%0" : : "Q" (state->fprs[10]));
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asm volatile("ld 11,%0" : : "Q" (state->fprs[11]));
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asm volatile("ld 12,%0" : : "Q" (state->fprs[12]));
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asm volatile("ld 13,%0" : : "Q" (state->fprs[13]));
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asm volatile("ld 14,%0" : : "Q" (state->fprs[14]));
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asm volatile("ld 15,%0" : : "Q" (state->fprs[15]));
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goto update_fpu_state;
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}
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/* Test and restore floating-point controls */
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if (state->mask & KERNEL_FPC)
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asm volatile("lfpc %0" : : "Q" (state->fpc));
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/* Test and restore (load) vector registers */
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asm volatile (
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/*
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* Test if any vector registers must be loaded and, if so,
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* test if all registers can be loaded at once.
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*/
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" tmll %[m],15\n" /* KERNEL_VXR_MASK */
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" jz 20f\n" /* no work -> done */
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" la 1,%[vxrs]\n" /* load load area */
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" jo 18f\n" /* -> load V0..V31 */
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/*
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* Test if V8..V23 can be restored at once... this speeds up
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* for KERNEL_VXR_MID only. Otherwise continue to split the
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* range of vector registers into two halves and test them
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* separately.
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*/
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" tmll %[m],6\n" /* KERNEL_VXR_MID */
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" jo 17f\n" /* -> load V8..V23 */
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/* Test and load the first half of 16 vector registers */
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"1: tmll %[m],3\n" /* KERNEL_VXR_LOW */
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" jz 10f\n" /* -> KERNEL_VXR_HIGH */
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" jo 2f\n" /* 11 -> load V0..V15 */
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" brc 4,3f\n" /* 01 -> load V0..V7 */
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" brc 2,4f\n" /* 10 -> load V8..V15 */
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/* Test and load the second half of 16 vector registers */
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"10: tmll %[m],12\n" /* KERNEL_VXR_HIGH */
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" jo 19f\n" /* 11 -> load V16..V31 */
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" brc 4,11f\n" /* 01 -> load V16..V23 */
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" brc 2,12f\n" /* 10 -> load V24..V31 */
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" j 20f\n" /* 00 -> done */
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/*
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* Below are the vstm combinations to load multiple vector
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* registers at once.
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*/
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"2: .word 0xe70f,0x1000,0x0036\n" /* vlm 0,15,0(1) */
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" j 10b\n" /* -> VXR_HIGH */
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"3: .word 0xe707,0x1000,0x0036\n" /* vlm 0,7,0(1) */
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" j 10b\n" /* -> VXR_HIGH */
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"4: .word 0xe78f,0x1080,0x0036\n" /* vlm 8,15,128(1) */
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" j 10b\n" /* -> VXR_HIGH */
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"\n"
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"11: .word 0xe707,0x1100,0x0c36\n" /* vlm 16,23,256(1) */
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" j 20f\n" /* -> done */
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"12: .word 0xe78f,0x1180,0x0c36\n" /* vlm 24,31,384(1) */
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" j 20f\n" /* -> done */
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"\n"
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"17: .word 0xe787,0x1080,0x0436\n" /* vlm 8,23,128(1) */
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" nill %[m],249\n" /* m &= ~VXR_MID */
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" j 1b\n" /* -> VXR_LOW */
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"\n"
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"18: .word 0xe70f,0x1000,0x0036\n" /* vlm 0,15,0(1) */
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"19: .word 0xe70f,0x1100,0x0c36\n" /* vlm 16,31,256(1) */
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"20:"
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:
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: [vxrs] "Q" (*(struct vx_array *) &state->vxrs),
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[m] "d" (state->mask)
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: "1", "cc");
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update_fpu_state:
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/* Update current kernel VX state */
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__this_cpu_write(kernel_fpu_state, state->mask);
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}
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EXPORT_SYMBOL(__kernel_fpu_end);
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