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 
arm_pertask_ssp_rtl_execute(void)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
no(void)51 static bool no(void)
52 {
53 	return false;
54 }
55 
arm_pertask_ssp_start_unit(void * gcc_data,void * user_data)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 
plugin_init(struct plugin_name_args * plugin_info,struct plugin_gcc_version * version)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 }
108