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
  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, cond, replacement;
  32                 s32 len;
  33
  34                 from = (u32 *)((ulong)&entry->orig_offset + entry->orig_offset);
  35                 len = entry->len;
  36                 cond = entry->cond;
  37                 replacement = entry->replacement;
  38
  39                 WARN_ON(!cond);
  40
  41                 if (cond != ALT_COND_ALWAYS && no_alternatives)
  42                         continue;
  43
  44                 pr_debug("Check %d: Cond 0x%x, Replace %02d instructions @ 0x%px with 0x%08x\n",
  45                         index, cond, len, from, replacement);
  46
  47                 if ((cond & ALT_COND_NO_SMP) && (num_cpus != 1))
  48                         continue;
  49                 if ((cond & ALT_COND_NO_DCACHE) && (cache_info.dc_size != 0))
  50                         continue;
  51                 if ((cond & ALT_COND_NO_ICACHE) && (cache_info.ic_size != 0))
  52                         continue;
  53                 if ((cond & ALT_COND_RUN_ON_QEMU) && !running_on_qemu)
  54                         continue;
  55
  56                 /*
  57                  * If the PDC_MODEL capabilities has Non-coherent IO-PDIR bit
  58                  * set (bit #61, big endian), we have to flush and sync every
  59                  * time IO-PDIR is changed in Ike/Astro.
  60                  */
  61                 if ((cond & ALT_COND_NO_IOC_FDC) &&
  62                         ((boot_cpu_data.cpu_type <= pcxw_) ||
  63                          (boot_cpu_data.pdc.capabilities & PDC_MODEL_IOPDIR_FDC)))
  64                         continue;
  65
  66                 /* Want to replace pdtlb by a pdtlb,l instruction? */
  67                 if (replacement == INSN_PxTLB) {
  68                         replacement = *from;
  69                         if (boot_cpu_data.cpu_type >= pcxu) /* >= pa2.0 ? */
  70                                 replacement |= (1 << 10); /* set el bit */
  71                 }
  72
  73                 /*
  74                  * Replace instruction with NOPs?
  75                  * For long distance insert a branch instruction instead.
  76                  */
  77                 if (replacement == INSN_NOP && len > 1)
  78                         replacement = 0xe8000002 + (len-2)*8; /* "b,n .+8" */
  79
  80                 pr_debug("ALTERNATIVE %3d: Cond %2x, Replace %2d instructions to 0x%08x @ 0x%px (%pS)\n",
  81                         index, cond, len, replacement, from, from);
  82
  83                 if (len < 0) {
  84                         /* Replace multiple instruction by new code */
  85                         u32 *source;
  86                         len = -len;
  87                         source = (u32 *)((ulong)&entry->replacement + entry->replacement);
  88                         memcpy(from, source, 4 * len);
  89                 } else {
  90                         /* Replace by one instruction */
  91                         *from = replacement;
  92                 }
  93                 applied++;
  94         }
  95
  96         pr_info("%s%salternatives: applied %d out of %d patches\n",
  97                 module_name ? : "", module_name ? " " : "",
  98                 applied, index);
  99 }
 100
 101
 102 void __init apply_alternatives_all(void)
 103 {
 104         set_kernel_text_rw(1);
 105
 106         apply_alternatives((struct alt_instr *) &__alt_instructions,
 107                 (struct alt_instr *) &__alt_instructions_end, NULL);
 108
 109         set_kernel_text_rw(0);
 110 }