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// SPDX-License-Identifier: GPL-2.0-only
/*
* alternative runtime patching
* inspired by the ARM64 and x86 version
*
* Copyright (C) 2021 Sifive.
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/cpu.h>
#include <linux/uaccess.h>
#include <asm/alternative.h>
#include <asm/sections.h>
#include <asm/vendorid_list.h>
#include <asm/sbi.h>
#include <asm/csr.h>
struct cpu_manufacturer_info_t {
unsigned long vendor_id;
unsigned long arch_id;
unsigned long imp_id;
void (*patch_func)(struct alt_entry *begin, struct alt_entry *end,
unsigned long archid, unsigned long impid,
unsigned int stage);
};
static void __init_or_module riscv_fill_cpu_mfr_info(struct cpu_manufacturer_info_t *cpu_mfr_info)
{
#ifdef CONFIG_RISCV_M_MODE
cpu_mfr_info->vendor_id = csr_read(CSR_MVENDORID);
cpu_mfr_info->arch_id = csr_read(CSR_MARCHID);
cpu_mfr_info->imp_id = csr_read(CSR_MIMPID);
#else
cpu_mfr_info->vendor_id = sbi_get_mvendorid();
cpu_mfr_info->arch_id = sbi_get_marchid();
cpu_mfr_info->imp_id = sbi_get_mimpid();
#endif
switch (cpu_mfr_info->vendor_id) {
#ifdef CONFIG_ERRATA_SIFIVE
case SIFIVE_VENDOR_ID:
cpu_mfr_info->patch_func = sifive_errata_patch_func;
break;
#endif
#ifdef CONFIG_ERRATA_THEAD
case THEAD_VENDOR_ID:
cpu_mfr_info->patch_func = thead_errata_patch_func;
break;
#endif
default:
cpu_mfr_info->patch_func = NULL;
}
}
/*
* This is called very early in the boot process (directly after we run
* a feature detect on the boot CPU). No need to worry about other CPUs
* here.
*/
static void __init_or_module _apply_alternatives(struct alt_entry *begin,
struct alt_entry *end,
unsigned int stage)
{
struct cpu_manufacturer_info_t cpu_mfr_info;
riscv_fill_cpu_mfr_info(&cpu_mfr_info);
riscv_cpufeature_patch_func(begin, end, stage);
if (!cpu_mfr_info.patch_func)
return;
cpu_mfr_info.patch_func(begin, end,
cpu_mfr_info.arch_id,
cpu_mfr_info.imp_id,
stage);
}
void __init apply_boot_alternatives(void)
{
/* If called on non-boot cpu things could go wrong */
WARN_ON(smp_processor_id() != 0);
_apply_alternatives((struct alt_entry *)__alt_start,
(struct alt_entry *)__alt_end,
RISCV_ALTERNATIVES_BOOT);
}
/*
* apply_early_boot_alternatives() is called from setup_vm() with MMU-off.
*
* Following requirements should be honoured for it to work correctly:
* 1) It should use PC-relative addressing for accessing kernel symbols.
* To achieve this we always use GCC cmodel=medany.
* 2) The compiler instrumentation for FTRACE will not work for setup_vm()
* so disable compiler instrumentation when FTRACE is enabled.
*
* Currently, the above requirements are honoured by using custom CFLAGS
* for alternative.o in kernel/Makefile.
*/
void __init apply_early_boot_alternatives(void)
{
#ifdef CONFIG_RISCV_ALTERNATIVE_EARLY
_apply_alternatives((struct alt_entry *)__alt_start,
(struct alt_entry *)__alt_end,
RISCV_ALTERNATIVES_EARLY_BOOT);
#endif
}
#ifdef CONFIG_MODULES
void apply_module_alternatives(void *start, size_t length)
{
_apply_alternatives((struct alt_entry *)start,
(struct alt_entry *)(start + length),
RISCV_ALTERNATIVES_MODULE);
}
#endif
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