cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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dc_fpu.c (4479B)

      1// SPDX-License-Identifier: MIT
      2/*
      3 * Copyright 2021 Advanced Micro Devices, Inc.
      4 *
      5 * Permission is hereby granted, free of charge, to any person obtaining a
      6 * copy of this software and associated documentation files (the "Software"),
      7 * to deal in the Software without restriction, including without limitation
      8 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
      9 * and/or sell copies of the Software, and to permit persons to whom the
     10 * Software is furnished to do so, subject to the following conditions:
     11 *
     12 * The above copyright notice and this permission notice shall be included in
     13 * all copies or substantial portions of the Software.
     14 *
     15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
     18 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
     19 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
     20 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
     21 * OTHER DEALINGS IN THE SOFTWARE.
     22 *
     23 * Authors: AMD
     24 *
     25 */
     26
     27#include "dc_trace.h"
     28
     29#if defined(CONFIG_X86)
     30#include <asm/fpu/api.h>
     31#elif defined(CONFIG_PPC64)
     32#include <asm/switch_to.h>
     33#include <asm/cputable.h>
     34#endif
     35
     36/**
     37 * DOC: DC FPU manipulation overview
     38 *
     39 * DC core uses FPU operations in multiple parts of the code, which requires a
     40 * more specialized way to manage these areas' entrance. To fulfill this
     41 * requirement, we created some wrapper functions that encapsulate
     42 * kernel_fpu_begin/end to better fit our need in the display component. In
     43 * summary, in this file, you can find functions related to FPU operation
     44 * management.
     45 */
     46
     47static DEFINE_PER_CPU(int, fpu_recursion_depth);
     48
     49/**
     50 * dc_assert_fp_enabled - Check if FPU protection is enabled
     51 *
     52 * This function tells if the code is already under FPU protection or not. A
     53 * function that works as an API for a set of FPU operations can use this
     54 * function for checking if the caller invoked it after DC_FP_START(). For
     55 * example, take a look at dcn20_fpu.c file.
     56 */
     57inline void dc_assert_fp_enabled(void)
     58{
     59	int *pcpu, depth = 0;
     60
     61	pcpu = get_cpu_ptr(&fpu_recursion_depth);
     62	depth = *pcpu;
     63	put_cpu_ptr(&fpu_recursion_depth);
     64
     65	ASSERT(depth >= 1);
     66}
     67
     68/**
     69 * dc_fpu_begin - Enables FPU protection
     70 * @function_name: A string containing the function name for debug purposes
     71 *   (usually __func__)
     72 *
     73 * @line: A line number where DC_FP_START was invoked for debug purpose
     74 *   (usually __LINE__)
     75 *
     76 * This function is responsible for managing the use of kernel_fpu_begin() with
     77 * the advantage of providing an event trace for debugging.
     78 *
     79 * Note: Do not call this function directly; always use DC_FP_START().
     80 */
     81void dc_fpu_begin(const char *function_name, const int line)
     82{
     83	int *pcpu;
     84
     85	pcpu = get_cpu_ptr(&fpu_recursion_depth);
     86	*pcpu += 1;
     87
     88	if (*pcpu == 1) {
     89#if defined(CONFIG_X86)
     90		kernel_fpu_begin();
     91#elif defined(CONFIG_PPC64)
     92		if (cpu_has_feature(CPU_FTR_VSX_COMP)) {
     93			preempt_disable();
     94			enable_kernel_vsx();
     95		} else if (cpu_has_feature(CPU_FTR_ALTIVEC_COMP)) {
     96			preempt_disable();
     97			enable_kernel_altivec();
     98		} else if (!cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE)) {
     99			preempt_disable();
    100			enable_kernel_fp();
    101		}
    102#endif
    103	}
    104
    105	TRACE_DCN_FPU(true, function_name, line, *pcpu);
    106	put_cpu_ptr(&fpu_recursion_depth);
    107}
    108
    109/**
    110 * dc_fpu_end - Disable FPU protection
    111 * @function_name: A string containing the function name for debug purposes
    112 * @line: A-line number where DC_FP_END was invoked for debug purpose
    113 *
    114 * This function is responsible for managing the use of kernel_fpu_end() with
    115 * the advantage of providing an event trace for debugging.
    116 *
    117 * Note: Do not call this function directly; always use DC_FP_END().
    118 */
    119void dc_fpu_end(const char *function_name, const int line)
    120{
    121	int *pcpu;
    122
    123	pcpu = get_cpu_ptr(&fpu_recursion_depth);
    124	*pcpu -= 1;
    125	if (*pcpu <= 0) {
    126#if defined(CONFIG_X86)
    127		kernel_fpu_end();
    128#elif defined(CONFIG_PPC64)
    129		if (cpu_has_feature(CPU_FTR_VSX_COMP)) {
    130			disable_kernel_vsx();
    131			preempt_enable();
    132		} else if (cpu_has_feature(CPU_FTR_ALTIVEC_COMP)) {
    133			disable_kernel_altivec();
    134			preempt_enable();
    135		} else if (!cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE)) {
    136			disable_kernel_fp();
    137			preempt_enable();
    138		}
    139#endif
    140	}
    141
    142	TRACE_DCN_FPU(false, function_name, line, *pcpu);
    143	put_cpu_ptr(&fpu_recursion_depth);
    144}