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 #include <asm/cacheflush.h>
  12
  13 #include <linux/module.h>
  14
  15 static int no_alternatives;
  16 static int __init setup_no_alternatives(char *str)
  17 {
  18         no_alternatives = 1;
  19         return 1;
  20 }
  21 __setup("no-alternatives", setup_no_alternatives);
  22
  23 void __init_or_module apply_alternatives(struct alt_instr *start,
  24                  struct alt_instr *end, const char *module_name)
  25 {
  26         struct alt_instr *entry;
  27         int index = 0, applied = 0;
  28         int num_cpus = num_present_cpus();
  29         u16 cond_check;
  30
  31         cond_check = ALT_COND_ALWAYS |
  32                 ((num_cpus == 1) ? ALT_COND_NO_SMP : 0) |
  33                 ((cache_info.dc_size == 0) ? ALT_COND_NO_DCACHE : 0) |
  34                 ((cache_info.ic_size == 0) ? ALT_COND_NO_ICACHE : 0) |
  35                 (running_on_qemu ? ALT_COND_RUN_ON_QEMU : 0) |
  36                 ((split_tlb == 0) ? ALT_COND_NO_SPLIT_TLB : 0) |
  37                 /*
  38                  * If the PDC_MODEL capabilities has Non-coherent IO-PDIR bit
  39                  * set (bit #61, big endian), we have to flush and sync every
  40                  * time IO-PDIR is changed in Ike/Astro.
  41                  */
  42                 (((boot_cpu_data.cpu_type > pcxw_) &&
  43                   ((boot_cpu_data.pdc.capabilities & PDC_MODEL_IOPDIR_FDC) == 0))
  44                         ? ALT_COND_NO_IOC_FDC : 0);
  45
  46         for (entry = start; entry < end; entry++, index++) {
  47
  48                 u32 *from, replacement;
  49                 u16 cond;
  50                 s16 len;
  51
  52                 from = (u32 *)((ulong)&entry->orig_offset + entry->orig_offset);
  53                 len = entry->len;
  54                 cond = entry->cond;
  55                 replacement = entry->replacement;
  56
  57                 WARN_ON(!cond);
  58
  59                 if ((cond & ALT_COND_ALWAYS) == 0 && no_alternatives)
  60                         continue;
  61
  62                 pr_debug("Check %d: Cond 0x%x, Replace %02d instructions @ 0x%px with 0x%08x\n",
  63                         index, cond, len, from, replacement);
  64
  65                 /* Bounce out if none of the conditions are true. */
  66                 if ((cond & cond_check) == 0)
  67                         continue;
  68
  69                 /* Want to replace pdtlb by a pdtlb,l instruction? */
  70                 if (replacement == INSN_PxTLB) {
  71                         replacement = *from;
  72                         if (boot_cpu_data.cpu_type >= pcxu) /* >= pa2.0 ? */
  73                                 replacement |= (1 << 10); /* set el bit */
  74                 }
  75
  76                 /*
  77                  * Replace instruction with NOPs?
  78                  * For long distance insert a branch instruction instead.
  79                  */
  80                 if (replacement == INSN_NOP && len > 1)
  81                         replacement = 0xe8000002 + (len-2)*8; /* "b,n .+8" */
  82
  83                 pr_debug("ALTERNATIVE %3d: Cond %2x, Replace %2d instructions to 0x%08x @ 0x%px (%pS)\n",
  84                         index, cond, len, replacement, from, from);
  85
  86                 if (len < 0) {
  87                         /* Replace multiple instruction by new code */
  88                         u32 *source;
  89                         len = -len;
  90                         source = (u32 *)((ulong)&entry->replacement + entry->replacement);
  91                         memcpy(from, source, 4 * len);
  92                 } else {
  93                         /* Replace by one instruction */
  94                         *from = replacement;
  95                 }
  96                 applied++;
  97         }
  98
  99         pr_info("%s%salternatives: applied %d out of %d patches\n",
 100                 module_name ? : "", module_name ? " " : "",
 101                 applied, index);
 102 }
 103
 104
 105 void __init apply_alternatives_all(void)
 106 {
 107         set_kernel_text_rw(1);
 108
 109         apply_alternatives((struct alt_instr *) &__alt_instructions,
 110                 (struct alt_instr *) &__alt_instructions_end, NULL);
 111
 112         if (cache_info.dc_size == 0 && cache_info.ic_size == 0) {
 113                 pr_info("alternatives: optimizing cache-flushes.\n");
 114                 static_branch_disable(&parisc_has_cache);
 115         }
 116         if (cache_info.dc_size == 0)
 117                 static_branch_disable(&parisc_has_dcache);
 118         if (cache_info.ic_size == 0)
 119                 static_branch_disable(&parisc_has_icache);
 120
 121         set_kernel_text_rw(0);
 122 }