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/*
* Copyright © 2016 Intel Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*
*/
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/cpufeature.h>
#include <linux/bug.h>
#include <linux/build_bug.h>
#include <asm/fpu/api.h>
#include "i915_memcpy.h"
#if IS_ENABLED(CONFIG_DRM_I915_DEBUG)
#define CI_BUG_ON(expr) BUG_ON(expr)
#else
#define CI_BUG_ON(expr) BUILD_BUG_ON_INVALID(expr)
#endif
static DEFINE_STATIC_KEY_FALSE(has_movntdqa);
static void __memcpy_ntdqa(void *dst, const void *src, unsigned long len)
{
kernel_fpu_begin();
while (len >= 4) {
asm("movntdqa (%0), %%xmm0\n"
"movntdqa 16(%0), %%xmm1\n"
"movntdqa 32(%0), %%xmm2\n"
"movntdqa 48(%0), %%xmm3\n"
"movaps %%xmm0, (%1)\n"
"movaps %%xmm1, 16(%1)\n"
"movaps %%xmm2, 32(%1)\n"
"movaps %%xmm3, 48(%1)\n"
:: "r" (src), "r" (dst) : "memory");
src += 64;
dst += 64;
len -= 4;
}
while (len--) {
asm("movntdqa (%0), %%xmm0\n"
"movaps %%xmm0, (%1)\n"
:: "r" (src), "r" (dst) : "memory");
src += 16;
dst += 16;
}
kernel_fpu_end();
}
static void __memcpy_ntdqu(void *dst, const void *src, unsigned long len)
{
kernel_fpu_begin();
while (len >= 4) {
asm("movntdqa (%0), %%xmm0\n"
"movntdqa 16(%0), %%xmm1\n"
"movntdqa 32(%0), %%xmm2\n"
"movntdqa 48(%0), %%xmm3\n"
"movups %%xmm0, (%1)\n"
"movups %%xmm1, 16(%1)\n"
"movups %%xmm2, 32(%1)\n"
"movups %%xmm3, 48(%1)\n"
:: "r" (src), "r" (dst) : "memory");
src += 64;
dst += 64;
len -= 4;
}
while (len--) {
asm("movntdqa (%0), %%xmm0\n"
"movups %%xmm0, (%1)\n"
:: "r" (src), "r" (dst) : "memory");
src += 16;
dst += 16;
}
kernel_fpu_end();
}
/**
* i915_memcpy_from_wc: perform an accelerated *aligned* read from WC
* @dst: destination pointer
* @src: source pointer
* @len: how many bytes to copy
*
* i915_memcpy_from_wc copies @len bytes from @src to @dst using
* non-temporal instructions where available. Note that all arguments
* (@src, @dst) must be aligned to 16 bytes and @len must be a multiple
* of 16.
*
* To test whether accelerated reads from WC are supported, use
* i915_memcpy_from_wc(NULL, NULL, 0);
*
* Returns true if the copy was successful, false if the preconditions
* are not met.
*/
bool i915_memcpy_from_wc(void *dst, const void *src, unsigned long len)
{
if (unlikely(((unsigned long)dst | (unsigned long)src | len) & 15))
return false;
if (static_branch_likely(&has_movntdqa)) {
if (likely(len))
__memcpy_ntdqa(dst, src, len >> 4);
return true;
}
return false;
}
/**
* i915_unaligned_memcpy_from_wc: perform a mostly accelerated read from WC
* @dst: destination pointer
* @src: source pointer
* @len: how many bytes to copy
*
* Like i915_memcpy_from_wc(), the unaligned variant copies @len bytes from
* @src to @dst using * non-temporal instructions where available, but
* accepts that its arguments may not be aligned, but are valid for the
* potential 16-byte read past the end.
*/
void i915_unaligned_memcpy_from_wc(void *dst, const void *src, unsigned long len)
{
unsigned long addr;
CI_BUG_ON(!i915_has_memcpy_from_wc());
addr = (unsigned long)src;
if (!IS_ALIGNED(addr, 16)) {
unsigned long x = min(ALIGN(addr, 16) - addr, len);
memcpy(dst, src, x);
len -= x;
dst += x;
src += x;
}
if (likely(len))
__memcpy_ntdqu(dst, src, DIV_ROUND_UP(len, 16));
}
void i915_memcpy_init_early(struct drm_i915_private *dev_priv)
{
/*
* Some hypervisors (e.g. KVM) don't support VEX-prefix instructions
* emulation. So don't enable movntdqa in hypervisor guest.
*/
if (static_cpu_has(X86_FEATURE_XMM4_1) &&
!boot_cpu_has(X86_FEATURE_HYPERVISOR))
static_branch_enable(&has_movntdqa);
}
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