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}
108