LXR linux/scripts/gcc-plugins/arm_ssp_per_task

   1// SPDX-License-Identifier: GPL-2.0
   2
   3#include "gcc-common.h"
   4
   5__visible int plugin_is_GPL_compatible;
   6
   7static unsigned int sp_mask, canary_offset;
   8
   9static 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 mask, masked_sp;
  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 copy of the stack canary value
  34                 * stored in struct thread_info
  35                 */
  36                mask = GEN_INT(sext_hwi(sp_mask, GET_MODE_PRECISION(Pmode)));
  37                masked_sp = gen_reg_rtx(Pmode);
  38
  39                emit_insn_before(gen_rtx_set(masked_sp,
  40                                             gen_rtx_AND(Pmode,
  41                                                         stack_pointer_rtx,
  42                                                         mask)),
  43                                 insn);
  44
  45                SET_SRC(body) = gen_rtx_PLUS(Pmode, masked_sp,
  46                                             GEN_INT(canary_offset));
  47        }
  48        return 0;
  49}
  50
  51#define PASS_NAME arm_pertask_ssp_rtl
  52
  53#define NO_GATE
  54#include "gcc-generate-rtl-pass.h"
  55
  56#if BUILDING_GCC_VERSION >= 9000
  57static bool no(void)
  58{
  59        return false;
  60}
  61
  62static void arm_pertask_ssp_start_unit(void *gcc_data, void *user_data)
  63{
  64        targetm.have_stack_protect_combined_set = no;
  65        targetm.have_stack_protect_combined_test = no;
  66}
  67#endif
  68
  69__visible int plugin_init(struct plugin_name_args *plugin_info,
  70                          struct plugin_gcc_version *version)
  71{
  72        const char * const plugin_name = plugin_info->base_name;
  73        const int argc = plugin_info->argc;
  74        const struct plugin_argument *argv = plugin_info->argv;
  75        int tso = 0;
  76        int i;
  77
  78        if (!plugin_default_version_check(version, &gcc_version)) {
  79                error(G_("incompatible gcc/plugin versions"));
  80                return 1;
  81        }
  82
  83        for (i = 0; i < argc; ++i) {
  84                if (!strcmp(argv[i].key, "disable"))
  85                        return 0;
  86
  87                /* all remaining options require a value */
  88                if (!argv[i].value) {
  89                        error(G_("no value supplied for option '-fplugin-arg-%s-%s'"),
  90                              plugin_name, argv[i].key);
  91                        return 1;
  92                }
  93
  94                if (!strcmp(argv[i].key, "tso")) {
  95                        tso = atoi(argv[i].value);
  96                        continue;
  97                }
  98
  99                if (!strcmp(argv[i].key, "offset")) {
 100                        canary_offset = atoi(argv[i].value);
 101                        continue;
 102                }
 103                error(G_("unknown option '-fplugin-arg-%s-%s'"),
 104                      plugin_name, argv[i].key);
 105                return 1;
 106        }
 107
 108        /* create the mask that produces the base of the stack */
 109        sp_mask = ~((1U << (12 + tso)) - 1);
 110
 111        PASS_INFO(arm_pertask_ssp_rtl, "expand", 1, PASS_POS_INSERT_AFTER);
 112
 113        register_callback(plugin_info->base_name, PLUGIN_PASS_MANAGER_SETUP,
 114                          NULL, &arm_pertask_ssp_rtl_pass_info);
 115
 116#if BUILDING_GCC_VERSION >= 9000
 117        register_callback(plugin_info->base_name, PLUGIN_START_UNIT,
 118                          arm_pertask_ssp_start_unit, NULL);
 119#endif
 120
 121        return 0;
 122}
 123