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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alternative.c (3272B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * alternative runtime patching
      4 * inspired by the ARM64 and x86 version
      5 *
      6 * Copyright (C) 2021 Sifive.
      7 */
      8
      9#include <linux/init.h>
     10#include <linux/module.h>
     11#include <linux/cpu.h>
     12#include <linux/uaccess.h>
     13#include <asm/alternative.h>
     14#include <asm/sections.h>
     15#include <asm/vendorid_list.h>
     16#include <asm/sbi.h>
     17#include <asm/csr.h>
     18
     19struct cpu_manufacturer_info_t {
     20	unsigned long vendor_id;
     21	unsigned long arch_id;
     22	unsigned long imp_id;
     23	void (*vendor_patch_func)(struct alt_entry *begin, struct alt_entry *end,
     24				  unsigned long archid, unsigned long impid,
     25				  unsigned int stage);
     26};
     27
     28static void __init_or_module riscv_fill_cpu_mfr_info(struct cpu_manufacturer_info_t *cpu_mfr_info)
     29{
     30#ifdef CONFIG_RISCV_M_MODE
     31	cpu_mfr_info->vendor_id = csr_read(CSR_MVENDORID);
     32	cpu_mfr_info->arch_id = csr_read(CSR_MARCHID);
     33	cpu_mfr_info->imp_id = csr_read(CSR_MIMPID);
     34#else
     35	cpu_mfr_info->vendor_id = sbi_get_mvendorid();
     36	cpu_mfr_info->arch_id = sbi_get_marchid();
     37	cpu_mfr_info->imp_id = sbi_get_mimpid();
     38#endif
     39
     40	switch (cpu_mfr_info->vendor_id) {
     41#ifdef CONFIG_ERRATA_SIFIVE
     42	case SIFIVE_VENDOR_ID:
     43		cpu_mfr_info->vendor_patch_func = sifive_errata_patch_func;
     44		break;
     45#endif
     46#ifdef CONFIG_ERRATA_THEAD
     47	case THEAD_VENDOR_ID:
     48		cpu_mfr_info->vendor_patch_func = thead_errata_patch_func;
     49		break;
     50#endif
     51	default:
     52		cpu_mfr_info->vendor_patch_func = NULL;
     53	}
     54}
     55
     56/*
     57 * This is called very early in the boot process (directly after we run
     58 * a feature detect on the boot CPU). No need to worry about other CPUs
     59 * here.
     60 */
     61static void __init_or_module _apply_alternatives(struct alt_entry *begin,
     62						 struct alt_entry *end,
     63						 unsigned int stage)
     64{
     65	struct cpu_manufacturer_info_t cpu_mfr_info;
     66
     67	riscv_fill_cpu_mfr_info(&cpu_mfr_info);
     68
     69	riscv_cpufeature_patch_func(begin, end, stage);
     70
     71	if (!cpu_mfr_info.vendor_patch_func)
     72		return;
     73
     74	cpu_mfr_info.vendor_patch_func(begin, end,
     75				   cpu_mfr_info.arch_id,
     76				   cpu_mfr_info.imp_id,
     77				   stage);
     78}
     79
     80void __init apply_boot_alternatives(void)
     81{
     82	/* If called on non-boot cpu things could go wrong */
     83	WARN_ON(smp_processor_id() != 0);
     84
     85	_apply_alternatives((struct alt_entry *)__alt_start,
     86			    (struct alt_entry *)__alt_end,
     87			    RISCV_ALTERNATIVES_BOOT);
     88}
     89
     90/*
     91 * apply_early_boot_alternatives() is called from setup_vm() with MMU-off.
     92 *
     93 * Following requirements should be honoured for it to work correctly:
     94 * 1) It should use PC-relative addressing for accessing kernel symbols.
     95 *    To achieve this we always use GCC cmodel=medany.
     96 * 2) The compiler instrumentation for FTRACE will not work for setup_vm()
     97 *    so disable compiler instrumentation when FTRACE is enabled.
     98 *
     99 * Currently, the above requirements are honoured by using custom CFLAGS
    100 * for alternative.o in kernel/Makefile.
    101 */
    102void __init apply_early_boot_alternatives(void)
    103{
    104#ifdef CONFIG_RISCV_ALTERNATIVE_EARLY
    105	_apply_alternatives((struct alt_entry *)__alt_start,
    106			    (struct alt_entry *)__alt_end,
    107			    RISCV_ALTERNATIVES_EARLY_BOOT);
    108#endif
    109}
    110
    111#ifdef CONFIG_MODULES
    112void apply_module_alternatives(void *start, size_t length)
    113{
    114	_apply_alternatives((struct alt_entry *)start,
    115			    (struct alt_entry *)(start + length),
    116			    RISCV_ALTERNATIVES_MODULE);
    117}
    118#endif