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gcc-plugins: arm-ssp: Prepare for THREAD_INFO_IN_TASK support
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>
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@ -1600,7 +1600,7 @@ config XEN
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config STACKPROTECTOR_PER_TASK
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config STACKPROTECTOR_PER_TASK
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bool "Use a unique stack canary value for each task"
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bool "Use a unique stack canary value for each task"
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depends on GCC_PLUGINS && STACKPROTECTOR && SMP && !XIP_DEFLATED_DATA
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depends on GCC_PLUGINS && STACKPROTECTOR && THREAD_INFO_IN_TASK && !XIP_DEFLATED_DATA
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select GCC_PLUGIN_ARM_SSP_PER_TASK
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select GCC_PLUGIN_ARM_SSP_PER_TASK
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default y
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default y
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help
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help
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@ -273,11 +273,8 @@ ifeq ($(CONFIG_STACKPROTECTOR_PER_TASK),y)
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prepare: stack_protector_prepare
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prepare: stack_protector_prepare
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stack_protector_prepare: prepare0
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stack_protector_prepare: prepare0
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$(eval SSP_PLUGIN_CFLAGS := \
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$(eval SSP_PLUGIN_CFLAGS := \
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-fplugin-arg-arm_ssp_per_task_plugin-tso=$(shell \
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awk '{if ($$2 == "THREAD_SZ_ORDER") print $$3;}'\
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include/generated/asm-offsets.h) \
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-fplugin-arg-arm_ssp_per_task_plugin-offset=$(shell \
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-fplugin-arg-arm_ssp_per_task_plugin-offset=$(shell \
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awk '{if ($$2 == "TI_STACK_CANARY") print $$3;}'\
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awk '{if ($$2 == "TSK_STACK_CANARY") print $$3;}'\
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include/generated/asm-offsets.h))
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include/generated/asm-offsets.h))
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$(eval KBUILD_CFLAGS += $(SSP_PLUGIN_CFLAGS))
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$(eval KBUILD_CFLAGS += $(SSP_PLUGIN_CFLAGS))
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$(eval GCC_PLUGINS_CFLAGS += $(SSP_PLUGIN_CFLAGS))
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$(eval GCC_PLUGINS_CFLAGS += $(SSP_PLUGIN_CFLAGS))
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@ -39,8 +39,6 @@ static __always_inline void boot_init_stack_canary(void)
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current->stack_canary = canary;
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current->stack_canary = canary;
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#ifndef CONFIG_STACKPROTECTOR_PER_TASK
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#ifndef CONFIG_STACKPROTECTOR_PER_TASK
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__stack_chk_guard = current->stack_canary;
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__stack_chk_guard = current->stack_canary;
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#else
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current_thread_info()->stack_canary = current->stack_canary;
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#endif
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#endif
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}
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}
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@ -55,9 +55,6 @@ struct thread_info {
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struct task_struct *task; /* main task structure */
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struct task_struct *task; /* main task structure */
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__u32 cpu; /* cpu */
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__u32 cpu; /* cpu */
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__u32 cpu_domain; /* cpu domain */
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__u32 cpu_domain; /* cpu domain */
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#ifdef CONFIG_STACKPROTECTOR_PER_TASK
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unsigned long stack_canary;
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#endif
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struct cpu_context_save cpu_context; /* cpu context */
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struct cpu_context_save cpu_context; /* cpu context */
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__u32 abi_syscall; /* ABI type and syscall nr */
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__u32 abi_syscall; /* ABI type and syscall nr */
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__u8 used_cp[16]; /* thread used copro */
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__u8 used_cp[16]; /* thread used copro */
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@ -63,10 +63,6 @@ int main(void)
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#ifdef CONFIG_IWMMXT
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#ifdef CONFIG_IWMMXT
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DEFINE(TI_IWMMXT_STATE, offsetof(struct thread_info, fpstate.iwmmxt));
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DEFINE(TI_IWMMXT_STATE, offsetof(struct thread_info, fpstate.iwmmxt));
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#endif
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#endif
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#ifdef CONFIG_STACKPROTECTOR_PER_TASK
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DEFINE(TI_STACK_CANARY, offsetof(struct thread_info, stack_canary));
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#endif
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DEFINE(THREAD_SZ_ORDER, THREAD_SIZE_ORDER);
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BLANK();
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BLANK();
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DEFINE(S_R0, offsetof(struct pt_regs, ARM_r0));
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DEFINE(S_R0, offsetof(struct pt_regs, ARM_r0));
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DEFINE(S_R1, offsetof(struct pt_regs, ARM_r1));
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DEFINE(S_R1, offsetof(struct pt_regs, ARM_r1));
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@ -269,10 +269,6 @@ int copy_thread(unsigned long clone_flags, unsigned long stack_start,
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thread_notify(THREAD_NOTIFY_COPY, thread);
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thread_notify(THREAD_NOTIFY_COPY, thread);
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#ifdef CONFIG_STACKPROTECTOR_PER_TASK
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thread->stack_canary = p->stack_canary;
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#endif
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return 0;
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return 0;
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}
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}
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@ -4,7 +4,7 @@
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__visible int plugin_is_GPL_compatible;
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__visible int plugin_is_GPL_compatible;
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static unsigned int sp_mask, canary_offset;
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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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static unsigned int arm_pertask_ssp_rtl_execute(void)
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{
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{
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@ -13,7 +13,7 @@ static unsigned int arm_pertask_ssp_rtl_execute(void)
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for (insn = get_insns(); insn; insn = NEXT_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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const char *sym;
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rtx body;
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rtx body;
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rtx mask, masked_sp;
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rtx current;
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/*
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/*
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* Find a SET insn involving a SYMBOL_REF to __stack_chk_guard
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* Find a SET insn involving a SYMBOL_REF to __stack_chk_guard
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@ -30,19 +30,13 @@ static unsigned int arm_pertask_ssp_rtl_execute(void)
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/*
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/*
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* Replace the source of the SET insn with an expression that
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* Replace the source of the SET insn with an expression that
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* produces the address of the copy of the stack canary value
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* produces the address of the current task's stack canary value
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* stored in struct thread_info
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*/
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*/
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mask = GEN_INT(sext_hwi(sp_mask, GET_MODE_PRECISION(Pmode)));
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current = gen_reg_rtx(Pmode);
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masked_sp = gen_reg_rtx(Pmode);
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emit_insn_before(gen_rtx_set(masked_sp,
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emit_insn_before(gen_load_tp_hard(current), insn);
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gen_rtx_AND(Pmode,
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stack_pointer_rtx,
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mask)),
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insn);
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SET_SRC(body) = gen_rtx_PLUS(Pmode, masked_sp,
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SET_SRC(body) = gen_rtx_PLUS(Pmode, current,
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GEN_INT(canary_offset));
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GEN_INT(canary_offset));
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}
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}
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return 0;
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return 0;
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@ -72,7 +66,6 @@ __visible int plugin_init(struct plugin_name_args *plugin_info,
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const char * const plugin_name = plugin_info->base_name;
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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 int argc = plugin_info->argc;
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const struct plugin_argument *argv = plugin_info->argv;
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const struct plugin_argument *argv = plugin_info->argv;
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int tso = 0;
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int i;
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int i;
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if (!plugin_default_version_check(version, &gcc_version)) {
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if (!plugin_default_version_check(version, &gcc_version)) {
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@ -91,11 +84,6 @@ __visible int plugin_init(struct plugin_name_args *plugin_info,
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return 1;
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return 1;
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}
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}
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if (!strcmp(argv[i].key, "tso")) {
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tso = atoi(argv[i].value);
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continue;
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}
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if (!strcmp(argv[i].key, "offset")) {
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if (!strcmp(argv[i].key, "offset")) {
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canary_offset = atoi(argv[i].value);
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canary_offset = atoi(argv[i].value);
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continue;
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continue;
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@ -105,9 +93,6 @@ __visible int plugin_init(struct plugin_name_args *plugin_info,
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return 1;
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return 1;
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}
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}
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/* create the mask that produces the base of the stack */
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sp_mask = ~((1U << (12 + tso)) - 1);
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PASS_INFO(arm_pertask_ssp_rtl, "expand", 1, PASS_POS_INSERT_AFTER);
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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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register_callback(plugin_info->base_name, PLUGIN_PASS_MANAGER_SETUP,
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