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 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 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
 51static bool no(void)
 52{
 53	return false;
 54}
 55
 56static 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}