Merge tag 'pr-arm32-ti-in-task' of git://git.kernel.org/pub/scm/linux/kernel/git/ardb/linux into devel-stable

ARM: support THREAD_INFO_IN_TASK

Move thread_info off the stack and into the task struct, as is done by
many other architectures. This requires a method to find the task struct
of the task currently running on the CPU, which is provided in this case
by the user space TLS (Thread Local Storage) register. This implies that
the feature is only supported on CPUs that implement this register,
i.e., ARM v6k or later.

Kindly tested by Amit and reviewed by Linus. The first patch is against
the GCC plugins subsystem, but was reviewed by the maintainer and can be
taken through the ARM tree.

20 files changed, 174 insertions, 50 deletions

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index fc196421b2ce..4f61c9789e7f 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -125,6 +125,7 @@ config ARM
 	select PERF_USE_VMALLOC
 	select RTC_LIB
 	select SYS_SUPPORTS_APM_EMULATION
+	select THREAD_INFO_IN_TASK if CURRENT_POINTER_IN_TPIDRURO
 	select TRACE_IRQFLAGS_SUPPORT if !CPU_V7M
 	# Above selects are sorted alphabetically; please add new ones
 	# according to that.  Thanks.
@@ -1157,6 +1158,11 @@ config SMP_ON_UP
 
 	  If you don't know what to do here, say Y.
 
+
+config CURRENT_POINTER_IN_TPIDRURO
+	def_bool y
+	depends on SMP && CPU_32v6K && !CPU_V6
+
 config ARM_CPU_TOPOLOGY
 	bool "Support cpu topology definition"
 	depends on SMP && CPU_V7
@@ -1600,7 +1606,7 @@ config XEN
 
 config STACKPROTECTOR_PER_TASK
 	bool "Use a unique stack canary value for each task"
-	depends on GCC_PLUGINS && STACKPROTECTOR && SMP && !XIP_DEFLATED_DATA
+	depends on GCC_PLUGINS && STACKPROTECTOR && THREAD_INFO_IN_TASK && !XIP_DEFLATED_DATA
 	select GCC_PLUGIN_ARM_SSP_PER_TASK
 	default y
 	help
diff --git a/arch/arm/Makefile b/arch/arm/Makefile
index 847c31e7c368..1c540157e283 100644
--- a/arch/arm/Makefile
+++ b/arch/arm/Makefile
@@ -113,6 +113,10 @@ ifeq ($(CONFIG_CC_IS_CLANG),y)
 CFLAGS_ABI	+= -meabi gnu
 endif
 
+ifeq ($(CONFIG_CURRENT_POINTER_IN_TPIDRURO),y)
+CFLAGS_ABI	+= -mtp=cp15
+endif
+
 # Accept old syntax despite ".syntax unified"
 AFLAGS_NOWARN	:=$(call as-option,-Wa$(comma)-mno-warn-deprecated,-Wa$(comma)-W)
 
@@ -273,11 +277,8 @@ ifeq ($(CONFIG_STACKPROTECTOR_PER_TASK),y)
 prepare: stack_protector_prepare
 stack_protector_prepare: prepare0
 	$(eval SSP_PLUGIN_CFLAGS := \
-		-fplugin-arg-arm_ssp_per_task_plugin-tso=$(shell	\
-			awk '{if ($$2 == "THREAD_SZ_ORDER") print $$3;}'\
-				include/generated/asm-offsets.h)	\
 		-fplugin-arg-arm_ssp_per_task_plugin-offset=$(shell	\
-			awk '{if ($$2 == "TI_STACK_CANARY") print $$3;}'\
+			awk '{if ($$2 == "TSK_STACK_CANARY") print $$3;}'\
 				include/generated/asm-offsets.h))
 	$(eval KBUILD_CFLAGS += $(SSP_PLUGIN_CFLAGS))
 	$(eval GCC_PLUGINS_CFLAGS += $(SSP_PLUGIN_CFLAGS))
diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h
index e2b1fd558bf3..7d23d4bb2168 100644
--- a/arch/arm/include/asm/assembler.h
+++ b/arch/arm/include/asm/assembler.h
@@ -199,14 +199,43 @@
 	.endm
 	.endr
 
+	.macro	get_current, rd
+#ifdef CONFIG_CURRENT_POINTER_IN_TPIDRURO
+	mrc	p15, 0, \rd, c13, c0, 3		@ get TPIDRURO register
+#else
+	get_thread_info \rd
+	ldr	\rd, [\rd, #TI_TASK]
+#endif
+	.endm
+
+	.macro	set_current, rn
+#ifdef CONFIG_CURRENT_POINTER_IN_TPIDRURO
+	mcr	p15, 0, \rn, c13, c0, 3		@ set TPIDRURO register
+#endif
+	.endm
+
+	.macro	reload_current, t1:req, t2:req
+#ifdef CONFIG_CURRENT_POINTER_IN_TPIDRURO
+	adr_l	\t1, __entry_task		@ get __entry_task base address
+	mrc	p15, 0, \t2, c13, c0, 4		@ get per-CPU offset
+	ldr	\t1, [\t1, \t2]			@ load variable
+	mcr	p15, 0, \t1, c13, c0, 3		@ store in TPIDRURO
+#endif
+	.endm
+
 /*
  * Get current thread_info.
  */
 	.macro	get_thread_info, rd
+#ifdef CONFIG_THREAD_INFO_IN_TASK
+	/* thread_info is the first member of struct task_struct */
+	get_current \rd
+#else
  ARM(	mov	\rd, sp, lsr #THREAD_SIZE_ORDER + PAGE_SHIFT	)
  THUMB(	mov	\rd, sp			)
  THUMB(	lsr	\rd, \rd, #THREAD_SIZE_ORDER + PAGE_SHIFT	)
 	mov	\rd, \rd, lsl #THREAD_SIZE_ORDER + PAGE_SHIFT
+#endif
 	.endm
 
 /*
diff --git a/arch/arm/include/asm/current.h b/arch/arm/include/asm/current.h
new file mode 100644
index 000000000000..1d472fa7697b
--- /dev/null
+++ b/arch/arm/include/asm/current.h
@@ -0,0 +1,50 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2021 Keith Packard <[email protected]>
+ * Copyright (c) 2021 Google, LLC <[email protected]>
+ */
+
+#ifndef _ASM_ARM_CURRENT_H
+#define _ASM_ARM_CURRENT_H
+
+#ifndef __ASSEMBLY__
+
+struct task_struct;
+
+static inline void set_current(struct task_struct *cur)
+{
+	if (!IS_ENABLED(CONFIG_CURRENT_POINTER_IN_TPIDRURO))
+		return;
+
+	/* Set TPIDRURO */
+	asm("mcr p15, 0, %0, c13, c0, 3" :: "r"(cur) : "memory");
+}
+
+#ifdef CONFIG_CURRENT_POINTER_IN_TPIDRURO
+
+static inline struct task_struct *get_current(void)
+{
+	struct task_struct *cur;
+
+#if __has_builtin(__builtin_thread_pointer)
+	/*
+	 * Use the __builtin helper when available - this results in better
+	 * code, especially when using GCC in combination with the per-task
+	 * stack protector, as the compiler will recognize that it needs to
+	 * load the TLS register only once in every function.
+	 */
+	cur = __builtin_thread_pointer();
+#else
+	asm("mrc p15, 0, %0, c13, c0, 3" : "=r"(cur));
+#endif
+	return cur;
+}
+
+#define current get_current()
+#else
+#include <asm-generic/current.h>
+#endif /* CONFIG_CURRENT_POINTER_IN_TPIDRURO */
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* _ASM_ARM_CURRENT_H */
diff --git a/arch/arm/include/asm/smp.h b/arch/arm/include/asm/smp.h
index 5d508f5d56c4..f16cbbd5cda4 100644
--- a/arch/arm/include/asm/smp.h
+++ b/arch/arm/include/asm/smp.h
@@ -48,7 +48,7 @@ extern void set_smp_ipi_range(int ipi_base, int nr_ipi);
  * Called from platform specific assembly code, this is the
  * secondary CPU entry point.
  */
-asmlinkage void secondary_start_kernel(void);
+asmlinkage void secondary_start_kernel(struct task_struct *task);
 
 
 /*
@@ -61,6 +61,7 @@ struct secondary_data {
 	};
 	unsigned long swapper_pg_dir;
 	void *stack;
+	struct task_struct *task;
 };
 extern struct secondary_data secondary_data;
 extern void secondary_startup(void);
diff --git a/arch/arm/include/asm/stackprotector.h b/arch/arm/include/asm/stackprotector.h
index 72a20c3a0a90..088d03161be5 100644
--- a/arch/arm/include/asm/stackprotector.h
+++ b/arch/arm/include/asm/stackprotector.h
@@ -39,8 +39,6 @@ static __always_inline void boot_init_stack_canary(void)
 	current->stack_canary = canary;
 #ifndef CONFIG_STACKPROTECTOR_PER_TASK
 	__stack_chk_guard = current->stack_canary;
-#else
-	current_thread_info()->stack_canary = current->stack_canary;
 #endif
 }
 
diff --git a/arch/arm/include/asm/switch_to.h b/arch/arm/include/asm/switch_to.h
index 007d8fea7157..b55c7b2755e4 100644
--- a/arch/arm/include/asm/switch_to.h
+++ b/arch/arm/include/asm/switch_to.h
@@ -23,9 +23,25 @@
  */
 extern struct task_struct *__switch_to(struct task_struct *, struct thread_info *, struct thread_info *);
 
+static inline void set_ti_cpu(struct task_struct *p)
+{
+#ifdef CONFIG_THREAD_INFO_IN_TASK
+	/*
+	 * The core code no longer maintains the thread_info::cpu field once
+	 * CONFIG_THREAD_INFO_IN_TASK is in effect, but we rely on it for
+	 * raw_smp_processor_id(), which cannot access struct task_struct*
+	 * directly for reasons of circular #inclusion hell.
+	 */
+	task_thread_info(p)->cpu = task_cpu(p);
+#endif
+}
+
 #define switch_to(prev,next,last)					\
 do {									\
 	__complete_pending_tlbi();					\
+	set_ti_cpu(next);						\
+	if (IS_ENABLED(CONFIG_CURRENT_POINTER_IN_TPIDRURO))		\
+		__this_cpu_write(__entry_task, next);			\
 	last = __switch_to(prev,task_thread_info(prev), task_thread_info(next));	\
 } while (0)
 
diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h
index 9a18da3e10cc..787511396f3f 100644
--- a/arch/arm/include/asm/thread_info.h
+++ b/arch/arm/include/asm/thread_info.h
@@ -29,6 +29,8 @@
 
 struct task_struct;
 
+DECLARE_PER_CPU(struct task_struct *, __entry_task);
+
 #include <asm/types.h>
 
 struct cpu_context_save {
@@ -52,12 +54,11 @@ struct cpu_context_save {
 struct thread_info {
 	unsigned long		flags;		/* low level flags */
 	int			preempt_count;	/* 0 => preemptable, <0 => bug */
+#ifndef CONFIG_THREAD_INFO_IN_TASK
 	struct task_struct	*task;		/* main task structure */
+#endif
 	__u32			cpu;		/* cpu */
 	__u32			cpu_domain;	/* cpu domain */
-#ifdef CONFIG_STACKPROTECTOR_PER_TASK
-	unsigned long		stack_canary;
-#endif
 	struct cpu_context_save	cpu_context;	/* cpu context */
 	__u32			abi_syscall;	/* ABI type and syscall nr */
 	__u8			used_cp[16];	/* thread used copro */
@@ -71,11 +72,16 @@ struct thread_info {
 
 #define INIT_THREAD_INFO(tsk)						\
 {									\
-	.task		= &tsk,						\
+	INIT_THREAD_INFO_TASK(tsk)					\
 	.flags		= 0,						\
 	.preempt_count	= INIT_PREEMPT_COUNT,				\
 }
 
+#ifdef CONFIG_THREAD_INFO_IN_TASK
+#define INIT_THREAD_INFO_TASK(tsk)
+#else
+#define INIT_THREAD_INFO_TASK(tsk)	.task = &(tsk),
+
 /*
  * how to get the thread information struct from C
  */
@@ -86,6 +92,7 @@ static inline struct thread_info *current_thread_info(void)
 	return (struct thread_info *)
 		(current_stack_pointer & ~(THREAD_SIZE - 1));
 }
+#endif
 
 #define thread_saved_pc(tsk)	\
 	((unsigned long)(task_thread_info(tsk)->cpu_context.pc))
diff --git a/arch/arm/include/asm/tls.h b/arch/arm/include/asm/tls.h
index 5a66c3b13c92..c3296499176c 100644
--- a/arch/arm/include/asm/tls.h
+++ b/arch/arm/include/asm/tls.h
@@ -12,8 +12,8 @@
 
 	.macro switch_tls_v6k, base, tp, tpuser, tmp1, tmp2
 	mrc	p15, 0, \tmp2, c13, c0, 2	@ get the user r/w register
-	mcr	p15, 0, \tp, c13, c0, 3		@ set TLS register
-	mcr	p15, 0, \tpuser, c13, c0, 2	@ and the user r/w register
+	@ TLS register update is deferred until return to user space
+	mcr	p15, 0, \tpuser, c13, c0, 2	@ set the user r/w register
 	str	\tmp2, [\base, #TI_TP_VALUE + 4] @ save it
 	.endm
 
@@ -38,18 +38,22 @@
 #ifdef CONFIG_TLS_REG_EMUL
 #define tls_emu		1
 #define has_tls_reg		1
+#define defer_tls_reg_update	0
 #define switch_tls	switch_tls_none
 #elif defined(CONFIG_CPU_V6)
 #define tls_emu		0
 #define has_tls_reg		(elf_hwcap & HWCAP_TLS)
+#define defer_tls_reg_update	0
 #define switch_tls	switch_tls_v6
 #elif defined(CONFIG_CPU_32v6K)
 #define tls_emu		0
 #define has_tls_reg		1
+#define defer_tls_reg_update	1
 #define switch_tls	switch_tls_v6k
 #else
 #define tls_emu		0
 #define has_tls_reg		0
+#define defer_tls_reg_update	0
 #define switch_tls	switch_tls_software
 #endif
 
@@ -77,7 +81,7 @@ static inline void set_tls(unsigned long val)
 	 */
 	barrier();
 
-	if (!tls_emu) {
+	if (!tls_emu && !defer_tls_reg_update) {
 		if (has_tls_reg) {
 			asm("mcr p15, 0, %0, c13, c0, 3"
 			    : : "r" (val));
diff --git a/arch/arm/kernel/asm-offsets.c b/arch/arm/kernel/asm-offsets.c
index a646a3f6440f..645845e4982a 100644
--- a/arch/arm/kernel/asm-offsets.c
+++ b/arch/arm/kernel/asm-offsets.c
@@ -43,7 +43,9 @@ int main(void)
   BLANK();
   DEFINE(TI_FLAGS,		offsetof(struct thread_info, flags));
   DEFINE(TI_PREEMPT,		offsetof(struct thread_info, preempt_count));
+#ifndef CONFIG_THREAD_INFO_IN_TASK
   DEFINE(TI_TASK,		offsetof(struct thread_info, task));
+#endif
   DEFINE(TI_CPU,		offsetof(struct thread_info, cpu));
   DEFINE(TI_CPU_DOMAIN,		offsetof(struct thread_info, cpu_domain));
   DEFINE(TI_CPU_SAVE,		offsetof(struct thread_info, cpu_context));
@@ -63,10 +65,6 @@ int main(void)
 #ifdef CONFIG_IWMMXT
   DEFINE(TI_IWMMXT_STATE,	offsetof(struct thread_info, fpstate.iwmmxt));
 #endif
-#ifdef CONFIG_STACKPROTECTOR_PER_TASK
-  DEFINE(TI_STACK_CANARY,	offsetof(struct thread_info, stack_canary));
-#endif
-  DEFINE(THREAD_SZ_ORDER,	THREAD_SIZE_ORDER);
   BLANK();
   DEFINE(S_R0,			offsetof(struct pt_regs, ARM_r0));
   DEFINE(S_R1,			offsetof(struct pt_regs, ARM_r1));
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 241b73d64df7..a54b5044d406 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -384,6 +384,8 @@ ENDPROC(__fiq_abt)
  ATRAP(	teq	r8, r7)
  ATRAP( mcrne	p15, 0, r8, c1, c0, 0)
 
+	reload_current r7, r8
+
 	@
 	@ Clear FP to mark the first stack frame
 	@
@@ -762,6 +764,8 @@ ENTRY(__switch_to)
 	add	r7, r7, #TSK_STACK_CANARY & ~IMM12_MASK
 	.endif
 	ldr	r7, [r7, #TSK_STACK_CANARY & IMM12_MASK]
+#elif defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO)
+	mov	r7, r2				@ Preserve 'next'
 #endif
 #ifdef CONFIG_CPU_USE_DOMAINS
 	mcr	p15, 0, r6, c3, c0, 0		@ Set domain register
@@ -776,6 +780,7 @@ ENTRY(__switch_to)
 #endif
  THUMB(	mov	ip, r4			   )
 	mov	r0, r5
+	set_current r7
  ARM(	ldmia	r4, {r4 - sl, fp, sp, pc}  )	@ Load all regs saved previously
  THUMB(	ldmia	ip!, {r4 - sl, fp}	   )	@ Load all regs saved previously
  THUMB(	ldr	sp, [ip], #4		   )
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index d9c99db50243..ac86c34682bb 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -170,6 +170,7 @@ ENTRY(vector_swi)
 	str	saved_psr, [sp, #S_PSR]		@ Save CPSR
 	str	r0, [sp, #S_OLD_R0]		@ Save OLD_R0
 #endif
+	reload_current r10, ip
 	zero_fp
 	alignment_trap r10, ip, __cr_alignment
 	asm_trace_hardirqs_on save=0
diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S
index 40db0f9188b6..ae24dd54e9ef 100644
--- a/arch/arm/kernel/entry-header.S
+++ b/arch/arm/kernel/entry-header.S
@@ -292,6 +292,14 @@
 
 
 	.macro	restore_user_regs, fast = 0, offset = 0
+#if defined(CONFIG_CPU_32v6K) && !defined(CONFIG_CPU_V6)
+	@ The TLS register update is deferred until return to user space so we
+	@ can use it for other things while running in the kernel
+	get_thread_info r1
+	ldr	r1, [r1, #TI_TP_VALUE]
+	mcr	p15, 0, r1, c13, c0, 3		@ set TLS register
+#endif
+
 	uaccess_enable r1, isb=0
 #ifndef CONFIG_THUMB2_KERNEL
 	@ ARM mode restore
diff --git a/arch/arm/kernel/head-common.S b/arch/arm/kernel/head-common.S
index 29b2eda136bb..da18e0a17dc2 100644
--- a/arch/arm/kernel/head-common.S
+++ b/arch/arm/kernel/head-common.S
@@ -105,6 +105,11 @@ __mmap_switched:
 	mov	r1, #0
 	bl	__memset			@ clear .bss
 
+#ifdef CONFIG_CURRENT_POINTER_IN_TPIDRURO
+	adr_l	r0, init_task			@ get swapper task_struct
+	set_current r0
+#endif
+
 	ldmia	r4, {r0, r1, r2, r3}
 	str	r9, [r0]			@ Save processor ID
 	str	r7, [r1]			@ Save machine type
diff --git a/arch/arm/kernel/head-nommu.S b/arch/arm/kernel/head-nommu.S
index 0fc814bbc34b..fadfee9e2b45 100644
--- a/arch/arm/kernel/head-nommu.S
+++ b/arch/arm/kernel/head-nommu.S
@@ -115,6 +115,7 @@ ENTRY(secondary_startup)
 	ret	r12
 1:	bl	__after_proc_init
 	ldr	sp, [r7, #12]			@ set up the stack pointer
+	ldr	r0, [r7, #16]			@ set up task pointer
 	mov	fp, #0
 	b	secondary_start_kernel
 ENDPROC(secondary_startup)
diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
index 29070eb8df7d..fa44e2d9f0b0 100644
--- a/arch/arm/kernel/head.S
+++ b/arch/arm/kernel/head.S
@@ -424,8 +424,9 @@ ENDPROC(secondary_startup)
 ENDPROC(secondary_startup_arm)
 
 ENTRY(__secondary_switched)
-	ldr_l	r7, secondary_data + 12		@ get secondary_data.stack
-	mov	sp, r7
+	adr_l	r7, secondary_data + 12		@ get secondary_data.stack
+	ldr	sp, [r7]
+	ldr	r0, [r7, #4]			@ get secondary_data.task
 	mov	fp, #0
 	b	secondary_start_kernel
 ENDPROC(__secondary_switched)
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 0e2d3051741e..30428d756515 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -36,6 +36,10 @@
 
 #include "signal.h"
 
+#ifdef CONFIG_CURRENT_POINTER_IN_TPIDRURO
+DEFINE_PER_CPU(struct task_struct *, __entry_task);
+#endif
+
 #if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_STACKPROTECTOR_PER_TASK)
 #include <linux/stackprotector.h>
 unsigned long __stack_chk_guard __read_mostly;
@@ -269,10 +273,6 @@ int copy_thread(unsigned long clone_flags, unsigned long stack_start,
 
 	thread_notify(THREAD_NOTIFY_COPY, thread);
 
-#ifdef CONFIG_STACKPROTECTOR_PER_TASK
-	thread->stack_canary = p->stack_canary;
-#endif
-
 	return 0;
 }
 
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 842427ff2b3c..cde5b6d8bac5 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -153,6 +153,10 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
 	secondary_data.pgdir = virt_to_phys(idmap_pgd);
 	secondary_data.swapper_pg_dir = get_arch_pgd(swapper_pg_dir);
 #endif
+	secondary_data.task = idle;
+	if (IS_ENABLED(CONFIG_THREAD_INFO_IN_TASK))
+		task_thread_info(idle)->cpu = cpu;
+
 	sync_cache_w(&secondary_data);
 
 	/*
@@ -375,9 +379,12 @@ void arch_cpu_idle_dead(void)
 	 */
 	__asm__("mov	sp, %0\n"
 	"	mov	fp, #0\n"
+	"	mov	r0, %1\n"
 	"	b	secondary_start_kernel"
 		:
-		: "r" (task_stack_page(current) + THREAD_SIZE - 8));
+		: "r" (task_stack_page(current) + THREAD_SIZE - 8),
+		  "r" (current)
+		: "r0");
 }
 #endif /* CONFIG_HOTPLUG_CPU */
 
@@ -400,11 +407,13 @@ static void smp_store_cpu_info(unsigned int cpuid)
  * This is the secondary CPU boot entry.  We're using this CPUs
  * idle thread stack, but a set of temporary page tables.
  */
-asmlinkage void secondary_start_kernel(void)
+asmlinkage void secondary_start_kernel(struct task_struct *task)
 {
 	struct mm_struct *mm = &init_mm;
 	unsigned int cpu;
 
+	set_current(task);
+
 	secondary_biglittle_init();
 
 	/*
diff --git a/arch/arm/mm/proc-macros.S b/arch/arm/mm/proc-macros.S
index e2c743aa2eb2..d48ba99d739c 100644
--- a/arch/arm/mm/proc-macros.S
+++ b/arch/arm/mm/proc-macros.S
@@ -30,8 +30,7 @@
  * act_mm - get current->active_mm
  */
 	.macro	act_mm, rd
-	get_thread_info \rd
-	ldr	\rd, [\rd, #TI_TASK]
+	get_current \rd
 	.if (TSK_ACTIVE_MM > IMM12_MASK)
 	add	\rd, \rd, #TSK_ACTIVE_MM & ~IMM12_MASK
 	.endif
diff --git a/scripts/gcc-plugins/arm_ssp_per_task_plugin.c b/scripts/gcc-plugins/arm_ssp_per_task_plugin.c
index 8c1af9bdcb1b..7328d037f975 100644
--- a/scripts/gcc-plugins/arm_ssp_per_task_plugin.c
+++ b/scripts/gcc-plugins/arm_ssp_per_task_plugin.c
@@ -4,7 +4,7 @@
 
 __visible int plugin_is_GPL_compatible;
 
-static unsigned int sp_mask, canary_offset;
+static unsigned int canary_offset;
 
 static unsigned int arm_pertask_ssp_rtl_execute(void)
 {
@@ -13,7 +13,7 @@ static unsigned int arm_pertask_ssp_rtl_execute(void)
 	for (insn = get_insns(); insn; insn = NEXT_INSN(insn)) {
 		const char *sym;
 		rtx body;
-		rtx mask, masked_sp;
+		rtx current;
 
 		/*
 		 * Find a SET insn involving a SYMBOL_REF to __stack_chk_guard
@@ -30,19 +30,13 @@ static unsigned int arm_pertask_ssp_rtl_execute(void)
 
 		/*
 		 * 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
+		 * produces the address of the current task's stack canary value
 		 */
-		mask = GEN_INT(sext_hwi(sp_mask, GET_MODE_PRECISION(Pmode)));
-		masked_sp = gen_reg_rtx(Pmode);
+		current = gen_reg_rtx(Pmode);
 
-		emit_insn_before(gen_rtx_set(masked_sp,
-					     gen_rtx_AND(Pmode,
-							 stack_pointer_rtx,
-							 mask)),
-				 insn);
+		emit_insn_before(gen_load_tp_hard(current), insn);
 
-		SET_SRC(body) = gen_rtx_PLUS(Pmode, masked_sp,
+		SET_SRC(body) = gen_rtx_PLUS(Pmode, current,
 					     GEN_INT(canary_offset));
 	}
 	return 0;
@@ -72,7 +66,6 @@ __visible int plugin_init(struct plugin_name_args *plugin_info,
 	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)) {
@@ -91,11 +84,6 @@ __visible int plugin_init(struct plugin_name_args *plugin_info,
 			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;
@@ -105,9 +93,6 @@ __visible int plugin_init(struct plugin_name_args *plugin_info,
 		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,