arch/s390/kernel/alternative.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/module.h>
   3 #include <linux/cpu.h>
   4 #include <linux/smp.h>
   5 #include <asm/text-patching.h>
   6 #include <asm/alternative.h>
   7 #include <asm/facility.h>
   8 #include <asm/nospec-branch.h>
   9
  10 static int __initdata_or_module alt_instr_disabled;
  11
  12 static int __init disable_alternative_instructions(char *str)
  13 {
  14         alt_instr_disabled = 1;
  15         return 0;
  16 }
  17
  18 early_param("noaltinstr", disable_alternative_instructions);
  19
  20 static void __init_or_module __apply_alternatives(struct alt_instr *start,
  21                                                   struct alt_instr *end)
  22 {
  23         struct alt_instr *a;
  24         u8 *instr, *replacement;
  25
  26         /*
  27          * The scan order should be from start to end. A later scanned
  28          * alternative code can overwrite previously scanned alternative code.
  29          */
  30         for (a = start; a < end; a++) {
  31                 instr = (u8 *)&a->instr_offset + a->instr_offset;
  32                 replacement = (u8 *)&a->repl_offset + a->repl_offset;
  33
  34                 if (!__test_facility(a->facility, alt_stfle_fac_list))
  35                         continue;
  36
  37                 if (unlikely(a->instrlen % 2)) {
  38                         WARN_ONCE(1, "cpu alternatives instructions length is "
  39                                      "odd, skipping patching\n");
  40                         continue;
  41                 }
  42
  43                 s390_kernel_write(instr, replacement, a->instrlen);
  44         }
  45 }
  46
  47 void __init_or_module apply_alternatives(struct alt_instr *start,
  48                                          struct alt_instr *end)
  49 {
  50         if (!alt_instr_disabled)
  51                 __apply_alternatives(start, end);
  52 }
  53
  54 extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
  55 void __init apply_alternative_instructions(void)
  56 {
  57         apply_alternatives(__alt_instructions, __alt_instructions_end);
  58 }
  59
  60 static void do_sync_core(void *info)
  61 {
  62         sync_core();
  63 }
  64
  65 void text_poke_sync(void)
  66 {
  67         on_each_cpu(do_sync_core, NULL, 1);
  68 }
  69
  70 void text_poke_sync_lock(void)
  71 {
  72         cpus_read_lock();
  73         text_poke_sync();
  74         cpus_read_unlock();
  75 }