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authorLinus Torvalds <torvalds@linux-foundation.org>2018-12-27 11:19:07 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2018-12-27 11:19:07 -0800
commitc6f1b355d451680a45d63ce66cea67057c938a87 (patch)
tree413ed05d88e6a59d33a8b2034cfffdae1862e7b8 /scripts/gcc-plugins
parentc06e9ef6918b1a6d183f1fef78ebc66f054a7b5a (diff)
parent189af4657186da08a2e79fb8e906cfd82b2ccddc (diff)
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Merge tag 'gcc-plugins-v4.21-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull gcc-plugins update from Kees Cook: "Both arm and arm64 are gaining per-task stack canaries (to match x86), but arm is being done with a gcc plugin, hence it going through the gcc-plugins tree. New gcc-plugin: - Enable per-task stack protector for ARM (Ard Biesheuvel)" * tag 'gcc-plugins-v4.21-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: ARM: smp: add support for per-task stack canaries
Diffstat (limited to 'scripts/gcc-plugins')
-rw-r--r--scripts/gcc-plugins/Kconfig4
-rw-r--r--scripts/gcc-plugins/arm_ssp_per_task_plugin.c103
2 files changed, 107 insertions, 0 deletions
diff --git a/scripts/gcc-plugins/Kconfig b/scripts/gcc-plugins/Kconfig
index 0d5c799688f0..d45f7f36b859 100644
--- a/scripts/gcc-plugins/Kconfig
+++ b/scripts/gcc-plugins/Kconfig
@@ -190,4 +190,8 @@ config STACKLEAK_RUNTIME_DISABLE
runtime to control kernel stack erasing for kernels built with
CONFIG_GCC_PLUGIN_STACKLEAK.
+config GCC_PLUGIN_ARM_SSP_PER_TASK
+ bool
+ depends on GCC_PLUGINS && ARM
+
endif
diff --git a/scripts/gcc-plugins/arm_ssp_per_task_plugin.c b/scripts/gcc-plugins/arm_ssp_per_task_plugin.c
new file mode 100644
index 000000000000..de70b8470971
--- /dev/null
+++ b/scripts/gcc-plugins/arm_ssp_per_task_plugin.c
@@ -0,0 +1,103 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "gcc-common.h"
+
+__visible int plugin_is_GPL_compatible;
+
+static unsigned int sp_mask, canary_offset;
+
+static unsigned int arm_pertask_ssp_rtl_execute(void)
+{
+ rtx_insn *insn;
+
+ for (insn = get_insns(); insn; insn = NEXT_INSN(insn)) {
+ const char *sym;
+ rtx body;
+ rtx masked_sp;
+
+ /*
+ * Find a SET insn involving a SYMBOL_REF to __stack_chk_guard
+ */
+ if (!INSN_P(insn))
+ continue;
+ body = PATTERN(insn);
+ if (GET_CODE(body) != SET ||
+ GET_CODE(SET_SRC(body)) != SYMBOL_REF)
+ continue;
+ sym = XSTR(SET_SRC(body), 0);
+ if (strcmp(sym, "__stack_chk_guard"))
+ continue;
+
+ /*
+ * Replace the source of the SET insn with an expression that
+ * produces the address of the copy of the stack canary value
+ * stored in struct thread_info
+ */
+ masked_sp = gen_reg_rtx(Pmode);
+
+ emit_insn_before(gen_rtx_SET(masked_sp,
+ gen_rtx_AND(Pmode,
+ stack_pointer_rtx,
+ GEN_INT(sp_mask))),
+ insn);
+
+ SET_SRC(body) = gen_rtx_PLUS(Pmode, masked_sp,
+ GEN_INT(canary_offset));
+ }
+ return 0;
+}
+
+#define PASS_NAME arm_pertask_ssp_rtl
+
+#define NO_GATE
+#include "gcc-generate-rtl-pass.h"
+
+__visible int plugin_init(struct plugin_name_args *plugin_info,
+ struct plugin_gcc_version *version)
+{
+ const char * const plugin_name = plugin_info->base_name;
+ const int argc = plugin_info->argc;
+ const struct plugin_argument *argv = plugin_info->argv;
+ int tso = 0;
+ int i;
+
+ if (!plugin_default_version_check(version, &gcc_version)) {
+ error(G_("incompatible gcc/plugin versions"));
+ return 1;
+ }
+
+ for (i = 0; i < argc; ++i) {
+ if (!strcmp(argv[i].key, "disable"))
+ return 0;
+
+ /* all remaining options require a value */
+ if (!argv[i].value) {
+ error(G_("no value supplied for option '-fplugin-arg-%s-%s'"),
+ plugin_name, argv[i].key);
+ return 1;
+ }
+
+ if (!strcmp(argv[i].key, "tso")) {
+ tso = atoi(argv[i].value);
+ continue;
+ }
+
+ if (!strcmp(argv[i].key, "offset")) {
+ canary_offset = atoi(argv[i].value);
+ continue;
+ }
+ error(G_("unknown option '-fplugin-arg-%s-%s'"),
+ plugin_name, argv[i].key);
+ return 1;
+ }
+
+ /* create the mask that produces the base of the stack */
+ sp_mask = ~((1U << (12 + tso)) - 1);
+
+ PASS_INFO(arm_pertask_ssp_rtl, "expand", 1, PASS_POS_INSERT_AFTER);
+
+ register_callback(plugin_info->base_name, PLUGIN_PASS_MANAGER_SETUP,
+ NULL, &arm_pertask_ssp_rtl_pass_info);
+
+ return 0;
+}