scripts/gcc-plugins/arm_ssp_per_task_plugin.c

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 #include "gcc-common.h"
   4
   5 __visible int plugin_is_GPL_compatible;
   6
   7 static unsigned int canary_offset;
   8
   9 static unsigned int arm_pertask_ssp_rtl_execute(void)
  10 {
  11         rtx_insn *insn;
  12
  13         for (insn = get_insns(); insn; insn = NEXT_INSN(insn)) {
  14                 const char *sym;
  15                 rtx body;
  16                 rtx current;
  17
  18                 /*
  19                  * Find a SET insn involving a SYMBOL_REF to __stack_chk_guard
  20                  */
  21                 if (!INSN_P(insn))
  22                         continue;
  23                 body = PATTERN(insn);
  24                 if (GET_CODE(body) != SET ||
  25                     GET_CODE(SET_SRC(body)) != SYMBOL_REF)
  26                         continue;
  27                 sym = XSTR(SET_SRC(body), 0);
  28                 if (strcmp(sym, "__stack_chk_guard"))
  29                         continue;
  30
  31                 /*
  32                  * Replace the source of the SET insn with an expression that
  33                  * produces the address of the current task's stack canary value
  34                  */
  35                 current = gen_reg_rtx(Pmode);
  36
  37                 emit_insn_before(gen_load_tp_hard(current), insn);
  38
  39                 SET_SRC(body) = gen_rtx_PLUS(Pmode, current,
  40                                              GEN_INT(canary_offset));
  41         }
  42         return 0;
  43 }
  44
  45 #define PASS_NAME arm_pertask_ssp_rtl
  46
  47 #define NO_GATE
  48 #include "gcc-generate-rtl-pass.h"
  49
  50 #if BUILDING_GCC_VERSION >= 9000
  51 static bool no(void)
  52 {
  53         return false;
  54 }
  55
  56 static void arm_pertask_ssp_start_unit(void *gcc_data, void *user_data)
  57 {
  58         targetm.have_stack_protect_combined_set = no;
  59         targetm.have_stack_protect_combined_test = no;
  60 }
  61 #endif
  62
  63 __visible int plugin_init(struct plugin_name_args *plugin_info,
  64                           struct plugin_gcc_version *version)
  65 {
  66         const char * const plugin_name = plugin_info->base_name;
  67         const int argc = plugin_info->argc;
  68         const struct plugin_argument *argv = plugin_info->argv;
  69         int i;
  70
  71         if (!plugin_default_version_check(version, &gcc_version)) {
  72                 error(G_("incompatible gcc/plugin versions"));
  73                 return 1;
  74         }
  75
  76         for (i = 0; i < argc; ++i) {
  77                 if (!strcmp(argv[i].key, "disable"))
  78                         return 0;
  79
  80                 /* all remaining options require a value */
  81                 if (!argv[i].value) {
  82                         error(G_("no value supplied for option '-fplugin-arg-%s-%s'"),
  83                               plugin_name, argv[i].key);
  84                         return 1;
  85                 }
  86
  87                 if (!strcmp(argv[i].key, "offset")) {
  88                         canary_offset = atoi(argv[i].value);
  89                         continue;
  90                 }
  91                 error(G_("unknown option '-fplugin-arg-%s-%s'"),
  92                       plugin_name, argv[i].key);
  93                 return 1;
  94         }
  95
  96         PASS_INFO(arm_pertask_ssp_rtl, "expand", 1, PASS_POS_INSERT_AFTER);
  97
  98         register_callback(plugin_info->base_name, PLUGIN_PASS_MANAGER_SETUP,
  99                           NULL, &arm_pertask_ssp_rtl_pass_info);
 100
 101 #if BUILDING_GCC_VERSION >= 9000
 102         register_callback(plugin_info->base_name, PLUGIN_START_UNIT,
 103                           arm_pertask_ssp_start_unit, NULL);
 104 #endif
 105
 106         return 0;
 107 }