// SPDX-License-Identifier: GPL-2.0
/*
 *    Alternative live-patching for parisc.
 *    Copyright (C) 2018 Helge Deller <deller@gmx.de>
 *
 */

#include <asm/processor.h>
#include <asm/sections.h>
#include <asm/alternative.h>
#include <asm/cacheflush.h>

#include <linux/module.h>

static int no_alternatives;
static int __init setup_no_alternatives(char *str)
{
        no_alternatives = 1;
        return 1;
}
__setup("no-alternatives", setup_no_alternatives);

void __init_or_module apply_alternatives(struct alt_instr *start,
                 struct alt_instr *end, const char *module_name)
{
        struct alt_instr *entry;
        int index = 0, applied = 0;
        int num_cpus = num_present_cpus();
        u16 cond_check;

        cond_check = ALT_COND_ALWAYS |
                ((num_cpus == 1) ? ALT_COND_NO_SMP : 0) |
                ((cache_info.dc_size == 0) ? ALT_COND_NO_DCACHE : 0) |
                ((cache_info.ic_size == 0) ? ALT_COND_NO_ICACHE : 0) |
                (running_on_qemu ? ALT_COND_RUN_ON_QEMU : 0) |
                ((split_tlb == 0) ? ALT_COND_NO_SPLIT_TLB : 0) |
                /*
                 * If the PDC_MODEL capabilities has Non-coherent IO-PDIR bit
                 * set (bit #61, big endian), we have to flush and sync every
                 * time IO-PDIR is changed in Ike/Astro.
                 */
                (((boot_cpu_data.cpu_type > pcxw_) &&
                  ((boot_cpu_data.pdc.capabilities & PDC_MODEL_IOPDIR_FDC) == 0))
                        ? ALT_COND_NO_IOC_FDC : 0);

        for (entry = start; entry < end; entry++, index++) {

                u32 *from, replacement;
                u16 cond;
                s16 len;

                from = (u32 *)((ulong)&entry->orig_offset + entry->orig_offset);
                len = entry->len;
                cond = entry->cond;
                replacement = entry->replacement;

                WARN_ON(!cond);

                if ((cond & ALT_COND_ALWAYS) == 0 && no_alternatives)
                        continue;

                pr_debug("Check %d: Cond 0x%x, Replace %02d instructions @ 0x%px with 0x%08x\n",
                        index, cond, len, from, replacement);

                /* Bounce out if none of the conditions are true. */
                if ((cond & cond_check) == 0)
                        continue;

                /* Want to replace pdtlb by a pdtlb,l instruction? */
                if (replacement == INSN_PxTLB) {
                        replacement = *from;
                        if (boot_cpu_data.cpu_type >= pcxu) /* >= pa2.0 ? */
                                replacement |= (1 << 10); /* set el bit */
                }

                /*
                 * Replace instruction with NOPs?
                 * For long distance insert a branch instruction instead.
                 */
                if (replacement == INSN_NOP && len > 1)
                        replacement = 0xe8000002 + (len-2)*8; /* "b,n .+8" */

                pr_debug("ALTERNATIVE %3d: Cond %2x, Replace %2d instructions to 0x%08x @ 0x%px (%pS)\n",
                        index, cond, len, replacement, from, from);

                if (len < 0) {
                        /* Replace multiple instruction by new code */
                        u32 *source;
                        len = -len;
                        source = (u32 *)((ulong)&entry->replacement + entry->replacement);
                        memcpy(from, source, 4 * len);
                } else {
                        /* Replace by one instruction */
                        *from = replacement;
                }
                applied++;
        }

        pr_info("%s%salternatives: applied %d out of %d patches\n",
                module_name ? : "", module_name ? " " : "",
                applied, index);
}


void __init apply_alternatives_all(void)
{
        set_kernel_text_rw(1);

        apply_alternatives((struct alt_instr *) &__alt_instructions,
                (struct alt_instr *) &__alt_instructions_end, NULL);

        if (cache_info.dc_size == 0 && cache_info.ic_size == 0) {
                pr_info("alternatives: optimizing cache-flushes.\n");
                static_branch_disable(&parisc_has_cache);
        }
        if (cache_info.dc_size == 0)
                static_branch_disable(&parisc_has_dcache);
        if (cache_info.ic_size == 0)
                static_branch_disable(&parisc_has_icache);

        set_kernel_text_rw(0);
}