arch/riscv/errata/alternative.c

   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/cpu.h>
  11 #include <linux/uaccess.h>
  12 #include <asm/alternative.h>
  13 #include <asm/sections.h>
  14 #include <asm/vendorid_list.h>
  15 #include <asm/sbi.h>
  16 #include <asm/csr.h>
  17
  18 static struct cpu_manufacturer_info_t {
  19         unsigned long vendor_id;
  20         unsigned long arch_id;
  21         unsigned long imp_id;
  22 } cpu_mfr_info;
  23
  24 static void (*vendor_patch_func)(struct alt_entry *begin, struct alt_entry *end,
  25                                  unsigned long archid,
  26                                  unsigned long impid) __initdata;
  27
  28 static inline void __init riscv_fill_cpu_mfr_info(void)
  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
  41 static void __init init_alternative(void)
  42 {
  43         riscv_fill_cpu_mfr_info();
  44
  45         switch (cpu_mfr_info.vendor_id) {
  46 #ifdef CONFIG_ERRATA_SIFIVE
  47         case SIFIVE_VENDOR_ID:
  48                 vendor_patch_func = sifive_errata_patch_func;
  49                 break;
  50 #endif
  51         default:
  52                 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  */
  61 void __init apply_boot_alternatives(void)
  62 {
  63         /* If called on non-boot cpu things could go wrong */
  64         WARN_ON(smp_processor_id() != 0);
  65
  66         init_alternative();
  67
  68         if (!vendor_patch_func)
  69                 return;
  70
  71         vendor_patch_func((struct alt_entry *)__alt_start,
  72                           (struct alt_entry *)__alt_end,
  73                           cpu_mfr_info.arch_id, cpu_mfr_info.imp_id);
  74 }
  75