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dfbdcda280
We will be enabling THREAD_INFO_IN_TASK support for ARM, which means that we can no longer load the stack canary value by masking the stack pointer and taking the copy that lives in thread_info. Instead, we will be able to load it from the task_struct directly, by using the TPIDRURO register which will hold the current task pointer when THREAD_INFO_IN_TASK is in effect. This is much more straight-forward, and allows us to declutter this code a bit while at it. Note that this means that ARMv6 (non-v6K) SMP systems can no longer use this feature, but those are quite rare to begin with, so this is a reasonable trade off. Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Tested-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
107 lines
2.4 KiB
C
107 lines
2.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include "gcc-common.h"
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__visible int plugin_is_GPL_compatible;
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static unsigned int canary_offset;
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static unsigned int arm_pertask_ssp_rtl_execute(void)
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{
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rtx_insn *insn;
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for (insn = get_insns(); insn; insn = NEXT_INSN(insn)) {
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const char *sym;
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rtx body;
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rtx current;
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/*
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* Find a SET insn involving a SYMBOL_REF to __stack_chk_guard
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*/
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if (!INSN_P(insn))
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continue;
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body = PATTERN(insn);
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if (GET_CODE(body) != SET ||
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GET_CODE(SET_SRC(body)) != SYMBOL_REF)
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continue;
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sym = XSTR(SET_SRC(body), 0);
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if (strcmp(sym, "__stack_chk_guard"))
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continue;
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/*
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* Replace the source of the SET insn with an expression that
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* produces the address of the current task's stack canary value
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*/
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current = gen_reg_rtx(Pmode);
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emit_insn_before(gen_load_tp_hard(current), insn);
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SET_SRC(body) = gen_rtx_PLUS(Pmode, current,
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GEN_INT(canary_offset));
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}
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return 0;
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}
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#define PASS_NAME arm_pertask_ssp_rtl
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#define NO_GATE
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#include "gcc-generate-rtl-pass.h"
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#if BUILDING_GCC_VERSION >= 9000
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static bool no(void)
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{
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return false;
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}
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static void arm_pertask_ssp_start_unit(void *gcc_data, void *user_data)
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{
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targetm.have_stack_protect_combined_set = no;
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targetm.have_stack_protect_combined_test = no;
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}
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#endif
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__visible int plugin_init(struct plugin_name_args *plugin_info,
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struct plugin_gcc_version *version)
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{
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const char * const plugin_name = plugin_info->base_name;
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const int argc = plugin_info->argc;
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const struct plugin_argument *argv = plugin_info->argv;
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int i;
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if (!plugin_default_version_check(version, &gcc_version)) {
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error(G_("incompatible gcc/plugin versions"));
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return 1;
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}
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for (i = 0; i < argc; ++i) {
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if (!strcmp(argv[i].key, "disable"))
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return 0;
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/* all remaining options require a value */
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if (!argv[i].value) {
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error(G_("no value supplied for option '-fplugin-arg-%s-%s'"),
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plugin_name, argv[i].key);
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return 1;
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}
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if (!strcmp(argv[i].key, "offset")) {
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canary_offset = atoi(argv[i].value);
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continue;
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}
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error(G_("unknown option '-fplugin-arg-%s-%s'"),
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plugin_name, argv[i].key);
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return 1;
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}
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PASS_INFO(arm_pertask_ssp_rtl, "expand", 1, PASS_POS_INSERT_AFTER);
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register_callback(plugin_info->base_name, PLUGIN_PASS_MANAGER_SETUP,
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NULL, &arm_pertask_ssp_rtl_pass_info);
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#if BUILDING_GCC_VERSION >= 9000
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register_callback(plugin_info->base_name, PLUGIN_START_UNIT,
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arm_pertask_ssp_start_unit, NULL);
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#endif
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return 0;
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}
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