errata.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2021 Heiko Stuebner <[email protected]>
 */

#include <linux/bug.h>
#include <linux/kernel.h>
#include <linux/memory.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/uaccess.h>
#include <asm/alternative.h>
#include <asm/bugs.h>
#include <asm/cacheflush.h>
#include <asm/cpufeature.h>
#include <asm/dma-noncoherent.h>
#include <asm/errata_list.h>
#include <asm/hwprobe.h>
#include <asm/io.h>
#include <asm/text-patching.h>
#include <asm/vendorid_list.h>
#include <asm/vendor_extensions.h>

#define CSR_TH_SXSTATUS		0x5c0
#define SXSTATUS_MAEE		_AC(0x200000, UL)

static bool errata_probe_mae(unsigned int stage,
			     unsigned long arch_id, unsigned long impid)
{
	if (!IS_ENABLED(CONFIG_ERRATA_THEAD_MAE))
		return false;

	if (arch_id != 0 || impid != 0)
		return false;

	if (stage != RISCV_ALTERNATIVES_EARLY_BOOT &&
	    stage != RISCV_ALTERNATIVES_MODULE)
		return false;

	if (!(csr_read(CSR_TH_SXSTATUS) & SXSTATUS_MAEE))
		return false;

	return true;
}

/*
 * th.dcache.ipa rs1 (invalidate, physical address)
 * | 31 - 25 | 24 - 20 | 19 - 15 | 14 - 12 | 11 - 7 | 6 - 0 |
 *   0000001    01010      rs1       000      00000  0001011
 * th.dcache.iva rs1 (invalidate, virtual address)
 *   0000001    00110      rs1       000      00000  0001011
 *
 * th.dcache.cpa rs1 (clean, physical address)
 * | 31 - 25 | 24 - 20 | 19 - 15 | 14 - 12 | 11 - 7 | 6 - 0 |
 *   0000001    01001      rs1       000      00000  0001011
 * th.dcache.cva rs1 (clean, virtual address)
 *   0000001    00101      rs1       000      00000  0001011
 *
 * th.dcache.cipa rs1 (clean then invalidate, physical address)
 * | 31 - 25 | 24 - 20 | 19 - 15 | 14 - 12 | 11 - 7 | 6 - 0 |
 *   0000001    01011      rs1       000      00000  0001011
 * th.dcache.civa rs1 (clean then invalidate, virtual address)
 *   0000001    00111      rs1       000      00000  0001011
 *
 * th.sync.s (make sure all cache operations finished)
 * | 31 - 25 | 24 - 20 | 19 - 15 | 14 - 12 | 11 - 7 | 6 - 0 |
 *   0000000    11001     00000      000      00000  0001011
 */
#define THEAD_INVAL_A0	".long 0x02a5000b"
#define THEAD_CLEAN_A0	".long 0x0295000b"
#define THEAD_FLUSH_A0	".long 0x02b5000b"
#define THEAD_SYNC_S	".long 0x0190000b"

#define THEAD_CMO_OP(_op, _start, _size, _cachesize)			\
asm volatile("mv a0, %1\n\t"						\
	     "j 2f\n\t"							\
	     "3:\n\t"							\
	     THEAD_##_op##_A0 "\n\t"					\
	     "add a0, a0, %0\n\t"					\
	     "2:\n\t"							\
	     "bltu a0, %2, 3b\n\t"					\
	     THEAD_SYNC_S						\
	     : : "r"(_cachesize),					\
		 "r"((unsigned long)(_start) & ~((_cachesize) - 1UL)),	\
		 "r"((unsigned long)(_start) + (_size))			\
	     : "a0")

static void thead_errata_cache_inv(phys_addr_t paddr, size_t size)
{
	THEAD_CMO_OP(INVAL, paddr, size, riscv_cbom_block_size);
}

static void thead_errata_cache_wback(phys_addr_t paddr, size_t size)
{
	THEAD_CMO_OP(CLEAN, paddr, size, riscv_cbom_block_size);
}

static void thead_errata_cache_wback_inv(phys_addr_t paddr, size_t size)
{
	THEAD_CMO_OP(FLUSH, paddr, size, riscv_cbom_block_size);
}

static const struct riscv_nonstd_cache_ops thead_errata_cmo_ops = {
	.wback = &thead_errata_cache_wback,
	.inv = &thead_errata_cache_inv,
	.wback_inv = &thead_errata_cache_wback_inv,
};

static bool errata_probe_cmo(unsigned int stage,
			     unsigned long arch_id, unsigned long impid)
{
	if (!IS_ENABLED(CONFIG_ERRATA_THEAD_CMO))
		return false;

	if (arch_id != 0 || impid != 0)
		return false;

	if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
		return false;

	if (stage == RISCV_ALTERNATIVES_BOOT) {
		riscv_cbom_block_size = L1_CACHE_BYTES;
		riscv_noncoherent_supported();
		riscv_noncoherent_register_cache_ops(&thead_errata_cmo_ops);
	}

	return true;
}

static bool errata_probe_pmu(unsigned int stage,
			     unsigned long arch_id, unsigned long impid)
{
	if (!IS_ENABLED(CONFIG_ERRATA_THEAD_PMU))
		return false;

	/* target-c9xx cores report arch_id and impid as 0 */
	if (arch_id != 0 || impid != 0)
		return false;

	if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
		return false;

	return true;
}

static bool errata_probe_ghostwrite(unsigned int stage,
				    unsigned long arch_id, unsigned long impid)
{
	if (!IS_ENABLED(CONFIG_ERRATA_THEAD_GHOSTWRITE))
		return false;

	/*
	 * target-c9xx cores report arch_id and impid as 0
	 *
	 * While ghostwrite may not affect all c9xx cores that implement
	 * xtheadvector, there is no futher granularity than c9xx. Assume
	 * vulnerable for this entire class of processors when xtheadvector is
	 * enabled.
	 */
	if (arch_id != 0 || impid != 0)
		return false;

	if (stage != RISCV_ALTERNATIVES_EARLY_BOOT)
		return false;

	ghostwrite_set_vulnerable();

	return true;
}

static u32 thead_errata_probe(unsigned int stage,
			      unsigned long archid, unsigned long impid)
{
	u32 cpu_req_errata = 0;

	if (errata_probe_mae(stage, archid, impid))
		cpu_req_errata |= BIT(ERRATA_THEAD_MAE);

	errata_probe_cmo(stage, archid, impid);

	if (errata_probe_pmu(stage, archid, impid))
		cpu_req_errata |= BIT(ERRATA_THEAD_PMU);

	errata_probe_ghostwrite(stage, archid, impid);

	return cpu_req_errata;
}

void thead_errata_patch_func(struct alt_entry *begin, struct alt_entry *end,
			     unsigned long archid, unsigned long impid,
			     unsigned int stage)
{
	struct alt_entry *alt;
	u32 cpu_req_errata = thead_errata_probe(stage, archid, impid);
	u32 tmp;
	void *oldptr, *altptr;

	BUILD_BUG_ON(ERRATA_THEAD_NUMBER >= RISCV_VENDOR_EXT_ALTERNATIVES_BASE);

	for (alt = begin; alt < end; alt++) {
		if (alt->vendor_id != THEAD_VENDOR_ID)
			continue;
		if (alt->patch_id >= ERRATA_THEAD_NUMBER)
			continue;

		tmp = (1U << alt->patch_id);
		if (cpu_req_errata & tmp) {
			oldptr = ALT_OLD_PTR(alt);
			altptr = ALT_ALT_PTR(alt);

			/* On vm-alternatives, the mmu isn't running yet */
			if (stage == RISCV_ALTERNATIVES_EARLY_BOOT) {
				memcpy(oldptr, altptr, alt->alt_len);
			} else {
				mutex_lock(&text_mutex);
				patch_text_nosync(oldptr, altptr, alt->alt_len);
				mutex_unlock(&text_mutex);
			}
		}
	}

	if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
		local_flush_icache_all();
}