ARM: smp: add support for per-task stack canaries
[muen/linux.git] / 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 sp_mask, 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 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                 masked_sp = gen_reg_rtx(Pmode);
37
38                 emit_insn_before(gen_rtx_SET(masked_sp,
39                                              gen_rtx_AND(Pmode,
40                                                          stack_pointer_rtx,
41                                                          GEN_INT(sp_mask))),
42                                  insn);
43
44                 SET_SRC(body) = gen_rtx_PLUS(Pmode, masked_sp,
45                                              GEN_INT(canary_offset));
46         }
47         return 0;
48 }
49
50 #define PASS_NAME arm_pertask_ssp_rtl
51
52 #define NO_GATE
53 #include "gcc-generate-rtl-pass.h"
54
55 __visible int plugin_init(struct plugin_name_args *plugin_info,
56                           struct plugin_gcc_version *version)
57 {
58         const char * const plugin_name = plugin_info->base_name;
59         const int argc = plugin_info->argc;
60         const struct plugin_argument *argv = plugin_info->argv;
61         int tso = 0;
62         int i;
63
64         if (!plugin_default_version_check(version, &gcc_version)) {
65                 error(G_("incompatible gcc/plugin versions"));
66                 return 1;
67         }
68
69         for (i = 0; i < argc; ++i) {
70                 if (!strcmp(argv[i].key, "disable"))
71                         return 0;
72
73                 /* all remaining options require a value */
74                 if (!argv[i].value) {
75                         error(G_("no value supplied for option '-fplugin-arg-%s-%s'"),
76                               plugin_name, argv[i].key);
77                         return 1;
78                 }
79
80                 if (!strcmp(argv[i].key, "tso")) {
81                         tso = atoi(argv[i].value);
82                         continue;
83                 }
84
85                 if (!strcmp(argv[i].key, "offset")) {
86                         canary_offset = atoi(argv[i].value);
87                         continue;
88                 }
89                 error(G_("unknown option '-fplugin-arg-%s-%s'"),
90                       plugin_name, argv[i].key);
91                 return 1;
92         }
93
94         /* create the mask that produces the base of the stack */
95         sp_mask = ~((1U << (12 + tso)) - 1);
96
97         PASS_INFO(arm_pertask_ssp_rtl, "expand", 1, PASS_POS_INSERT_AFTER);
98
99         register_callback(plugin_info->base_name, PLUGIN_PASS_MANAGER_SETUP,
100                           NULL, &arm_pertask_ssp_rtl_pass_info);
101
102         return 0;
103 }