LXR linux/arch/parisc/kernel/alternative.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 *    Alternative live-patching for parisc.
   4 *    Copyright (C) 2018 Helge Deller <deller@gmx.de>
   5 *
   6 */
   7
   8#include <asm/processor.h>
   9#include <asm/sections.h>
  10#include <asm/alternative.h>
  11
  12#include <linux/module.h>
  13
  14static int no_alternatives;
  15static int __init setup_no_alternatives(char *str)
  16{
  17        no_alternatives = 1;
  18        return 1;
  19}
  20__setup("no-alternatives", setup_no_alternatives);
  21
  22void __init_or_module apply_alternatives(struct alt_instr *start,
  23                 struct alt_instr *end, const char *module_name)
  24{
  25        struct alt_instr *entry;
  26        int index = 0, applied = 0;
  27        int num_cpus = num_online_cpus();
  28        u32 cond_check;
  29
  30        cond_check = ALT_COND_ALWAYS |
  31                ((num_cpus == 1) ? ALT_COND_NO_SMP : 0) |
  32                ((cache_info.dc_size == 0) ? ALT_COND_NO_DCACHE : 0) |
  33                ((cache_info.ic_size == 0) ? ALT_COND_NO_ICACHE : 0) |
  34                (running_on_qemu ? ALT_COND_RUN_ON_QEMU : 0) |
  35                ((split_tlb == 0) ? ALT_COND_NO_SPLIT_TLB : 0) |
  36                /*
  37                 * If the PDC_MODEL capabilities has Non-coherent IO-PDIR bit
  38                 * set (bit #61, big endian), we have to flush and sync every
  39                 * time IO-PDIR is changed in Ike/Astro.
  40                 */
  41                (((boot_cpu_data.cpu_type > pcxw_) &&
  42                  ((boot_cpu_data.pdc.capabilities & PDC_MODEL_IOPDIR_FDC) == 0))
  43                        ? ALT_COND_NO_IOC_FDC : 0);
  44
  45        for (entry = start; entry < end; entry++, index++) {
  46
  47                u32 *from, cond, replacement;
  48                s32 len;
  49
  50                from = (u32 *)((ulong)&entry->orig_offset + entry->orig_offset);
  51                len = entry->len;
  52                cond = entry->cond;
  53                replacement = entry->replacement;
  54
  55                WARN_ON(!cond);
  56
  57                if ((cond & ALT_COND_ALWAYS) == 0 && no_alternatives)
  58                        continue;
  59
  60                pr_debug("Check %d: Cond 0x%x, Replace %02d instructions @ 0x%px with 0x%08x\n",
  61                        index, cond, len, from, replacement);
  62
  63                /* Bounce out if none of the conditions are true. */
  64                if ((cond & cond_check) == 0)
  65                        continue;
  66
  67                /* Want to replace pdtlb by a pdtlb,l instruction? */
  68                if (replacement == INSN_PxTLB) {
  69                        replacement = *from;
  70                        if (boot_cpu_data.cpu_type >= pcxu) /* >= pa2.0 ? */
  71                                replacement |= (1 << 10); /* set el bit */
  72                }
  73
  74                /*
  75                 * Replace instruction with NOPs?
  76                 * For long distance insert a branch instruction instead.
  77                 */
  78                if (replacement == INSN_NOP && len > 1)
  79                        replacement = 0xe8000002 + (len-2)*8; /* "b,n .+8" */
  80
  81                pr_debug("ALTERNATIVE %3d: Cond %2x, Replace %2d instructions to 0x%08x @ 0x%px (%pS)\n",
  82                        index, cond, len, replacement, from, from);
  83
  84                if (len < 0) {
  85                        /* Replace multiple instruction by new code */
  86                        u32 *source;
  87                        len = -len;
  88                        source = (u32 *)((ulong)&entry->replacement + entry->replacement);
  89                        memcpy(from, source, 4 * len);
  90                } else {
  91                        /* Replace by one instruction */
  92                        *from = replacement;
  93                }
  94                applied++;
  95        }
  96
  97        pr_info("%s%salternatives: applied %d out of %d patches\n",
  98                module_name ? : "", module_name ? " " : "",
  99                applied, index);
 100}
 101
 102
 103void __init apply_alternatives_all(void)
 104{
 105        set_kernel_text_rw(1);
 106
 107        apply_alternatives((struct alt_instr *) &__alt_instructions,
 108                (struct alt_instr *) &__alt_instructions_end, NULL);
 109
 110        set_kernel_text_rw(0);
 111}
 112