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 <[email protected]>
   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
  14 static int no_alternatives;
  15 static int __init setup_no_alternatives(char *str)
  16 {
  17         no_alternatives = 1;
  18         return 1;
  19 }
  20 __setup("no-alternatives", setup_no_alternatives);
  21
  22 void __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
  29         for (entry = start; entry < end; entry++, index++) {
  30
  31                 u32 *from, len, cond, replacement;
  32
  33                 from = (u32 *)((ulong)&entry->orig_offset + entry->orig_offset);
  34                 len = entry->len;
  35                 cond = entry->cond;
  36                 replacement = entry->replacement;
  37
  38                 WARN_ON(!cond);
  39
  40                 if (cond != ALT_COND_ALWAYS && no_alternatives)
  41                         continue;
  42
  43                 pr_debug("Check %d: Cond 0x%x, Replace %02d instructions @ 0x%px with 0x%08x\n",
  44                         index, cond, len, from, replacement);
  45
  46                 if ((cond & ALT_COND_NO_SMP) && (num_cpus != 1))
  47                         continue;
  48                 if ((cond & ALT_COND_NO_DCACHE) && (cache_info.dc_size != 0))
  49                         continue;
  50                 if ((cond & ALT_COND_NO_ICACHE) && (cache_info.ic_size != 0))
  51                         continue;
  52
  53                 /*
  54                  * If the PDC_MODEL capabilities has Non-coherent IO-PDIR bit
  55                  * set (bit #61, big endian), we have to flush and sync every
  56                  * time IO-PDIR is changed in Ike/Astro.
  57                  */
  58                 if ((cond & ALT_COND_NO_IOC_FDC) &&
  59                         (boot_cpu_data.pdc.capabilities & PDC_MODEL_IOPDIR_FDC))
  60                         continue;
  61
  62                 /* Want to replace pdtlb by a pdtlb,l instruction? */
  63                 if (replacement == INSN_PxTLB) {
  64                         replacement = *from;
  65                         if (boot_cpu_data.cpu_type >= pcxu) /* >= pa2.0 ? */
  66                                 replacement |= (1 << 10); /* set el bit */
  67                 }
  68
  69                 /*
  70                  * Replace instruction with NOPs?
  71                  * For long distance insert a branch instruction instead.
  72                  */
  73                 if (replacement == INSN_NOP && len > 1)
  74                         replacement = 0xe8000002 + (len-2)*8; /* "b,n .+8" */
  75
  76                 pr_debug("Do    %d: Cond 0x%x, Replace %02d instructions @ 0x%px with 0x%08x\n",
  77                         index, cond, len, from, replacement);
  78
  79                 /* Replace instruction */
  80                 *from = replacement;
  81                 applied++;
  82         }
  83
  84         pr_info("%s%salternatives: applied %d out of %d patches\n",
  85                 module_name ? : "", module_name ? " " : "",
  86                 applied, index);
  87 }
  88
  89
  90 void __init apply_alternatives_all(void)
  91 {
  92         set_kernel_text_rw(1);
  93
  94         apply_alternatives((struct alt_instr *) &__alt_instructions,
  95                 (struct alt_instr *) &__alt_instructions_end, NULL);
  96
  97         set_kernel_text_rw(0);
  98 }