Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

Pull arm64 fixes from Will Deacon:
 "There's more here than we usually have at this stage, but that's
  mainly down to the stacktrace changes which came in slightly too late
  for the merge window.

  Summary:

   - Big bad batch of MAINTAINERS updates

   - Fix handling of SP alignment fault exceptions

   - Fix PSTATE.SSBS handling on heterogeneous systems

   - Fix fallout from moving to the generic vDSO implementation

   - Fix stack unwinding in the face of frame corruption

   - Fix off-by-one in IORT code

   - Minor SVE cleanups"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  ACPI/IORT: Fix off-by-one check in iort_dev_find_its_id()
  arm64: entry: SP Alignment Fault doesn't write to FAR_EL1
  arm64: Force SSBS on context switch
  MAINTAINERS: Update my email address
  MAINTAINERS: Update my email address
  MAINTAINERS: Fix spelling mistake in my name
  MAINTAINERS: Update my email address to @kernel.org
  arm64: mm: Drop pte_huge()
  arm64/sve: Fix a couple of magic numbers for the Z-reg count
  arm64/sve: Factor out FPSIMD to SVE state conversion
  arm64: stacktrace: Better handle corrupted stacks
  arm64: stacktrace: Factor out backtrace initialisation
  arm64: stacktrace: Constify stacktrace.h functions
  arm64: vdso: Cleanup Makefiles
  arm64: vdso: fix flip/flop vdso build bug
  arm64: vdso: Fix population of AT_SYSINFO_EHDR for compat vdso

17 files changed, 219 insertions, 106 deletions

diff --git a/.mailmap b/.mailmap
index 0fef932de3db..acba1a6163f1 100644
--- a/.mailmap
+++ b/.mailmap
@@ -98,6 +98,7 @@ Jason Gunthorpe <jgg@ziepe.ca> <jgunthorpe@obsidianresearch.com>
 Javi Merino <javi.merino@kernel.org> <javi.merino@arm.com>
 <javier@osg.samsung.com> <javier.martinez@collabora.co.uk>
 Jean Tourrilhes <jt@hpl.hp.com>
+<jean-philippe@linaro.org> <jean-philippe.brucker@arm.com>
 Jeff Garzik <jgarzik@pretzel.yyz.us>
 Jeff Layton <jlayton@kernel.org> <jlayton@redhat.com>
 Jeff Layton <jlayton@kernel.org> <jlayton@poochiereds.net>
@@ -116,6 +117,7 @@ John Stultz <johnstul@us.ibm.com>
 Juha Yrjola <at solidboot.com>
 Juha Yrjola <juha.yrjola@nokia.com>
 Juha Yrjola <juha.yrjola@solidboot.com>
+Julien Thierry <julien.thierry.kdev@gmail.com> <julien.thierry@arm.com>
 Kay Sievers <kay.sievers@vrfy.org>
 Kenneth W Chen <kenneth.w.chen@intel.com>
 Konstantin Khlebnikov <koct9i@gmail.com> <k.khlebnikov@samsung.com>
@@ -132,6 +134,7 @@ Linus Lüssing <linus.luessing@c0d3.blue> <linus.luessing@ascom.ch>
 Li Yang <leoyang.li@nxp.com> <leo@zh-kernel.org>
 Li Yang <leoyang.li@nxp.com> <leoli@freescale.com>
 Maciej W. Rozycki <macro@mips.com> <macro@imgtec.com>
+Marc Zyngier <maz@kernel.org> <marc.zyngier@arm.com>
 Marcin Nowakowski <marcin.nowakowski@mips.com> <marcin.nowakowski@imgtec.com>
 Mark Brown <broonie@sirena.org.uk>
 Mark Yao <markyao0591@gmail.com> <mark.yao@rock-chips.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index 4e2a525e22c0..ce6546c02dff 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1194,7 +1194,7 @@ F:	include/uapi/linux/if_arcnet.h
 
 ARM ARCHITECTED TIMER DRIVER
 M:	Mark Rutland <mark.rutland@arm.com>
-M:	Marc Zyngier <marc.zyngier@arm.com>
+M:	Marc Zyngier <maz@kernel.org>
 L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
 S:	Maintained
 F:	arch/arm/include/asm/arch_timer.h
@@ -8490,7 +8490,7 @@ S:	Obsolete
 F:	include/uapi/linux/ipx.h
 
 IRQ DOMAINS (IRQ NUMBER MAPPING LIBRARY)
-M:	Marc Zyngier <marc.zyngier@arm.com>
+M:	Marc Zyngier <maz@kernel.org>
 S:	Maintained
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git irq/core
 F:	Documentation/IRQ-domain.txt
@@ -8508,7 +8508,7 @@ F:	kernel/irq/
 IRQCHIP DRIVERS
 M:	Thomas Gleixner <tglx@linutronix.de>
 M:	Jason Cooper <jason@lakedaemon.net>
-M:	Marc Zyngier <marc.zyngier@arm.com>
+M:	Marc Zyngier <maz@kernel.org>
 L:	linux-kernel@vger.kernel.org
 S:	Maintained
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git irq/core
@@ -8828,10 +8828,10 @@ F:	arch/x86/include/asm/svm.h
 F:	arch/x86/kvm/svm.c
 
 KERNEL VIRTUAL MACHINE FOR ARM/ARM64 (KVM/arm, KVM/arm64)
-M:	Marc Zyngier <marc.zyngier@arm.com>
+M:	Marc Zyngier <maz@kernel.org>
 R:	James Morse <james.morse@arm.com>
-R:	Julien Thierry <julien.thierry@arm.com>
-R:	Suzuki K Pouloze <suzuki.poulose@arm.com>
+R:	Julien Thierry <julien.thierry.kdev@gmail.com>
+R:	Suzuki K Poulose <suzuki.poulose@arm.com>
 L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
 L:	kvmarm@lists.cs.columbia.edu
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm.git
@@ -17124,7 +17124,7 @@ F:	drivers/virtio/virtio_input.c
 F:	include/uapi/linux/virtio_input.h
 
 VIRTIO IOMMU DRIVER
-M:	Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
+M:	Jean-Philippe Brucker <jean-philippe@linaro.org>
 L:	virtualization@lists.linux-foundation.org
 S:	Maintained
 F:	drivers/iommu/virtio-iommu.c
diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h
index 3c7037c6ba9b..b618017205a3 100644
--- a/arch/arm64/include/asm/elf.h
+++ b/arch/arm64/include/asm/elf.h
@@ -202,7 +202,7 @@ typedef compat_elf_greg_t		compat_elf_gregset_t[COMPAT_ELF_NGREG];
 ({									\
 	set_thread_flag(TIF_32BIT);					\
  })
-#ifdef CONFIG_GENERIC_COMPAT_VDSO
+#ifdef CONFIG_COMPAT_VDSO
 #define COMPAT_ARCH_DLINFO						\
 do {									\
 	/*								\
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 87a4b2ddc1a1..3f5461f7b560 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -301,7 +301,6 @@ static inline int pte_same(pte_t pte_a, pte_t pte_b)
 /*
  * Huge pte definitions.
  */
-#define pte_huge(pte)		(!(pte_val(pte) & PTE_TABLE_BIT))
 #define pte_mkhuge(pte)		(__pte(pte_val(pte) & ~PTE_TABLE_BIT))
 
 /*
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index fd5b1a4efc70..844e2964b0f5 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -193,6 +193,16 @@ static inline void start_thread_common(struct pt_regs *regs, unsigned long pc)
 		regs->pmr_save = GIC_PRIO_IRQON;
 }
 
+static inline void set_ssbs_bit(struct pt_regs *regs)
+{
+	regs->pstate |= PSR_SSBS_BIT;
+}
+
+static inline void set_compat_ssbs_bit(struct pt_regs *regs)
+{
+	regs->pstate |= PSR_AA32_SSBS_BIT;
+}
+
 static inline void start_thread(struct pt_regs *regs, unsigned long pc,
 				unsigned long sp)
 {
@@ -200,7 +210,7 @@ static inline void start_thread(struct pt_regs *regs, unsigned long pc,
 	regs->pstate = PSR_MODE_EL0t;
 
 	if (arm64_get_ssbd_state() != ARM64_SSBD_FORCE_ENABLE)
-		regs->pstate |= PSR_SSBS_BIT;
+		set_ssbs_bit(regs);
 
 	regs->sp = sp;
 }
@@ -219,7 +229,7 @@ static inline void compat_start_thread(struct pt_regs *regs, unsigned long pc,
 #endif
 
 	if (arm64_get_ssbd_state() != ARM64_SSBD_FORCE_ENABLE)
-		regs->pstate |= PSR_AA32_SSBS_BIT;
+		set_compat_ssbs_bit(regs);
 
 	regs->compat_sp = sp;
 }
diff --git a/arch/arm64/include/asm/stacktrace.h b/arch/arm64/include/asm/stacktrace.h
index df45af931459..4d9b1f48dc39 100644
--- a/arch/arm64/include/asm/stacktrace.h
+++ b/arch/arm64/include/asm/stacktrace.h
@@ -8,19 +8,12 @@
 #include <linux/percpu.h>
 #include <linux/sched.h>
 #include <linux/sched/task_stack.h>
+#include <linux/types.h>
 
 #include <asm/memory.h>
 #include <asm/ptrace.h>
 #include <asm/sdei.h>
 
-struct stackframe {
-	unsigned long fp;
-	unsigned long pc;
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-	int graph;
-#endif
-};
-
 enum stack_type {
 	STACK_TYPE_UNKNOWN,
 	STACK_TYPE_TASK,
@@ -28,6 +21,7 @@ enum stack_type {
 	STACK_TYPE_OVERFLOW,
 	STACK_TYPE_SDEI_NORMAL,
 	STACK_TYPE_SDEI_CRITICAL,
+	__NR_STACK_TYPES
 };
 
 struct stack_info {
@@ -36,6 +30,37 @@ struct stack_info {
 	enum stack_type type;
 };
 
+/*
+ * A snapshot of a frame record or fp/lr register values, along with some
+ * accounting information necessary for robust unwinding.
+ *
+ * @fp:          The fp value in the frame record (or the real fp)
+ * @pc:          The fp value in the frame record (or the real lr)
+ *
+ * @stacks_done: Stacks which have been entirely unwound, for which it is no
+ *               longer valid to unwind to.
+ *
+ * @prev_fp:     The fp that pointed to this frame record, or a synthetic value
+ *               of 0. This is used to ensure that within a stack, each
+ *               subsequent frame record is at an increasing address.
+ * @prev_type:   The type of stack this frame record was on, or a synthetic
+ *               value of STACK_TYPE_UNKNOWN. This is used to detect a
+ *               transition from one stack to another.
+ *
+ * @graph:       When FUNCTION_GRAPH_TRACER is selected, holds the index of a
+ *               replacement lr value in the ftrace graph stack.
+ */
+struct stackframe {
+	unsigned long fp;
+	unsigned long pc;
+	DECLARE_BITMAP(stacks_done, __NR_STACK_TYPES);
+	unsigned long prev_fp;
+	enum stack_type prev_type;
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+	int graph;
+#endif
+};
+
 extern int unwind_frame(struct task_struct *tsk, struct stackframe *frame);
 extern void walk_stackframe(struct task_struct *tsk, struct stackframe *frame,
 			    int (*fn)(struct stackframe *, void *), void *data);
@@ -64,8 +89,9 @@ static inline bool on_irq_stack(unsigned long sp,
 	return true;
 }
 
-static inline bool on_task_stack(struct task_struct *tsk, unsigned long sp,
-				struct stack_info *info)
+static inline bool on_task_stack(const struct task_struct *tsk,
+				 unsigned long sp,
+				 struct stack_info *info)
 {
 	unsigned long low = (unsigned long)task_stack_page(tsk);
 	unsigned long high = low + THREAD_SIZE;
@@ -112,10 +138,13 @@ static inline bool on_overflow_stack(unsigned long sp,
  * We can only safely access per-cpu stacks from current in a non-preemptible
  * context.
  */
-static inline bool on_accessible_stack(struct task_struct *tsk,
-					unsigned long sp,
-					struct stack_info *info)
+static inline bool on_accessible_stack(const struct task_struct *tsk,
+				       unsigned long sp,
+				       struct stack_info *info)
 {
+	if (info)
+		info->type = STACK_TYPE_UNKNOWN;
+
 	if (on_task_stack(tsk, sp, info))
 		return true;
 	if (tsk != current || preemptible())
@@ -130,4 +159,27 @@ static inline bool on_accessible_stack(struct task_struct *tsk,
 	return false;
 }
 
+static inline void start_backtrace(struct stackframe *frame,
+				   unsigned long fp, unsigned long pc)
+{
+	frame->fp = fp;
+	frame->pc = pc;
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+	frame->graph = 0;
+#endif
+
+	/*
+	 * Prime the first unwind.
+	 *
+	 * In unwind_frame() we'll check that the FP points to a valid stack,
+	 * which can't be STACK_TYPE_UNKNOWN, and the first unwind will be
+	 * treated as a transition to whichever stack that happens to be. The
+	 * prev_fp value won't be used, but we set it to 0 such that it is
+	 * definitely not an accessible stack address.
+	 */
+	bitmap_zero(frame->stacks_done, __NR_STACK_TYPES);
+	frame->prev_fp = 0;
+	frame->prev_type = STACK_TYPE_UNKNOWN;
+}
+
 #endif	/* __ASM_STACKTRACE_H */
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 9cdc4592da3e..320a30dbe35e 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -586,10 +586,8 @@ el1_sync:
 	b.eq	el1_ia
 	cmp	x24, #ESR_ELx_EC_SYS64		// configurable trap
 	b.eq	el1_undef
-	cmp	x24, #ESR_ELx_EC_SP_ALIGN	// stack alignment exception
-	b.eq	el1_sp_pc
 	cmp	x24, #ESR_ELx_EC_PC_ALIGN	// pc alignment exception
-	b.eq	el1_sp_pc
+	b.eq	el1_pc
 	cmp	x24, #ESR_ELx_EC_UNKNOWN	// unknown exception in EL1
 	b.eq	el1_undef
 	cmp	x24, #ESR_ELx_EC_BREAKPT_CUR	// debug exception in EL1
@@ -611,9 +609,11 @@ el1_da:
 	bl	do_mem_abort
 
 	kernel_exit 1
-el1_sp_pc:
+el1_pc:
 	/*
-	 * Stack or PC alignment exception handling
+	 * PC alignment exception handling. We don't handle SP alignment faults,
+	 * since we will have hit a recursive exception when trying to push the
+	 * initial pt_regs.
 	 */
 	mrs	x0, far_el1
 	inherit_daif	pstate=x23, tmp=x2
@@ -732,9 +732,9 @@ el0_sync:
 	ccmp	x24, #ESR_ELx_EC_WFx, #4, ne
 	b.eq	el0_sys
 	cmp	x24, #ESR_ELx_EC_SP_ALIGN	// stack alignment exception
-	b.eq	el0_sp_pc
+	b.eq	el0_sp
 	cmp	x24, #ESR_ELx_EC_PC_ALIGN	// pc alignment exception
-	b.eq	el0_sp_pc
+	b.eq	el0_pc
 	cmp	x24, #ESR_ELx_EC_UNKNOWN	// unknown exception in EL0
 	b.eq	el0_undef
 	cmp	x24, #ESR_ELx_EC_BREAKPT_LOW	// debug exception in EL0
@@ -758,7 +758,7 @@ el0_sync_compat:
 	cmp	x24, #ESR_ELx_EC_FP_EXC32	// FP/ASIMD exception
 	b.eq	el0_fpsimd_exc
 	cmp	x24, #ESR_ELx_EC_PC_ALIGN	// pc alignment exception
-	b.eq	el0_sp_pc
+	b.eq	el0_pc
 	cmp	x24, #ESR_ELx_EC_UNKNOWN	// unknown exception in EL0
 	b.eq	el0_undef
 	cmp	x24, #ESR_ELx_EC_CP15_32	// CP15 MRC/MCR trap
@@ -858,11 +858,15 @@ el0_fpsimd_exc:
 	mov	x1, sp
 	bl	do_fpsimd_exc
 	b	ret_to_user
+el0_sp:
+	ldr	x26, [sp, #S_SP]
+	b	el0_sp_pc
+el0_pc:
+	mrs	x26, far_el1
 el0_sp_pc:
 	/*
 	 * Stack or PC alignment exception handling
 	 */
-	mrs	x26, far_el1
 	gic_prio_kentry_setup tmp=x0
 	enable_da_f
 #ifdef CONFIG_TRACE_IRQFLAGS
diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index eec4776ae5f0..37d3912cfe06 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -406,6 +406,18 @@ static __uint128_t arm64_cpu_to_le128(__uint128_t x)
 
 #define arm64_le128_to_cpu(x) arm64_cpu_to_le128(x)
 
+static void __fpsimd_to_sve(void *sst, struct user_fpsimd_state const *fst,
+			    unsigned int vq)
+{
+	unsigned int i;
+	__uint128_t *p;
+
+	for (i = 0; i < SVE_NUM_ZREGS; ++i) {
+		p = (__uint128_t *)ZREG(sst, vq, i);
+		*p = arm64_cpu_to_le128(fst->vregs[i]);
+	}
+}
+
 /*
  * Transfer the FPSIMD state in task->thread.uw.fpsimd_state to
  * task->thread.sve_state.
@@ -423,17 +435,12 @@ static void fpsimd_to_sve(struct task_struct *task)
 	unsigned int vq;
 	void *sst = task->thread.sve_state;
 	struct user_fpsimd_state const *fst = &task->thread.uw.fpsimd_state;
-	unsigned int i;
-	__uint128_t *p;
 
 	if (!system_supports_sve())
 		return;
 
 	vq = sve_vq_from_vl(task->thread.sve_vl);
-	for (i = 0; i < 32; ++i) {
-		p = (__uint128_t *)ZREG(sst, vq, i);
-		*p = arm64_cpu_to_le128(fst->vregs[i]);
-	}
+	__fpsimd_to_sve(sst, fst, vq);
 }
 
 /*
@@ -459,7 +466,7 @@ static void sve_to_fpsimd(struct task_struct *task)
 		return;
 
 	vq = sve_vq_from_vl(task->thread.sve_vl);
-	for (i = 0; i < 32; ++i) {
+	for (i = 0; i < SVE_NUM_ZREGS; ++i) {
 		p = (__uint128_t const *)ZREG(sst, vq, i);
 		fst->vregs[i] = arm64_le128_to_cpu(*p);
 	}
@@ -550,8 +557,6 @@ void sve_sync_from_fpsimd_zeropad(struct task_struct *task)
 	unsigned int vq;
 	void *sst = task->thread.sve_state;
 	struct user_fpsimd_state const *fst = &task->thread.uw.fpsimd_state;
-	unsigned int i;
-	__uint128_t *p;
 
 	if (!test_tsk_thread_flag(task, TIF_SVE))
 		return;
@@ -559,11 +564,7 @@ void sve_sync_from_fpsimd_zeropad(struct task_struct *task)
 	vq = sve_vq_from_vl(task->thread.sve_vl);
 
 	memset(sst, 0, SVE_SIG_REGS_SIZE(vq));
-
-	for (i = 0; i < 32; ++i) {
-		p = (__uint128_t *)ZREG(sst, vq, i);
-		*p = arm64_cpu_to_le128(fst->vregs[i]);
-	}
+	__fpsimd_to_sve(sst, fst, vq);
 }
 
 int sve_set_vector_length(struct task_struct *task,
diff --git a/arch/arm64/kernel/perf_callchain.c b/arch/arm64/kernel/perf_callchain.c
index 9d63514b9836..b0e03e052dd1 100644
--- a/arch/arm64/kernel/perf_callchain.c
+++ b/arch/arm64/kernel/perf_callchain.c
@@ -154,12 +154,7 @@ void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 		return;
 	}
 
-	frame.fp = regs->regs[29];
-	frame.pc = regs->pc;
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-	frame.graph = 0;
-#endif
-
+	start_backtrace(&frame, regs->regs[29], regs->pc);
 	walk_stackframe(current, &frame, callchain_trace, entry);
 }
 
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 6a869d9f304f..f674f28df663 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -398,7 +398,7 @@ int copy_thread(unsigned long clone_flags, unsigned long stack_start,
 			childregs->pstate |= PSR_UAO_BIT;
 
 		if (arm64_get_ssbd_state() == ARM64_SSBD_FORCE_DISABLE)
-			childregs->pstate |= PSR_SSBS_BIT;
+			set_ssbs_bit(childregs);
 
 		if (system_uses_irq_prio_masking())
 			childregs->pmr_save = GIC_PRIO_IRQON;
@@ -443,6 +443,32 @@ void uao_thread_switch(struct task_struct *next)
 }
 
 /*
+ * Force SSBS state on context-switch, since it may be lost after migrating
+ * from a CPU which treats the bit as RES0 in a heterogeneous system.
+ */
+static void ssbs_thread_switch(struct task_struct *next)
+{
+	struct pt_regs *regs = task_pt_regs(next);
+
+	/*
+	 * Nothing to do for kernel threads, but 'regs' may be junk
+	 * (e.g. idle task) so check the flags and bail early.
+	 */
+	if (unlikely(next->flags & PF_KTHREAD))
+		return;
+
+	/* If the mitigation is enabled, then we leave SSBS clear. */
+	if ((arm64_get_ssbd_state() == ARM64_SSBD_FORCE_ENABLE) ||
+	    test_tsk_thread_flag(next, TIF_SSBD))
+		return;
+
+	if (compat_user_mode(regs))
+		set_compat_ssbs_bit(regs);
+	else if (user_mode(regs))
+		set_ssbs_bit(regs);
+}
+
+/*
  * We store our current task in sp_el0, which is clobbered by userspace. Keep a
  * shadow copy so that we can restore this upon entry from userspace.
  *
@@ -471,6 +497,7 @@ __notrace_funcgraph struct task_struct *__switch_to(struct task_struct *prev,
 	entry_task_switch(next);
 	uao_thread_switch(next);
 	ptrauth_thread_switch(next);
+	ssbs_thread_switch(next);
 
 	/*
 	 * Complete any pending TLB or cache maintenance on this CPU in case
@@ -498,11 +525,8 @@ unsigned long get_wchan(struct task_struct *p)
 	if (!stack_page)
 		return 0;
 
-	frame.fp = thread_saved_fp(p);
-	frame.pc = thread_saved_pc(p);
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-	frame.graph = 0;
-#endif
+	start_backtrace(&frame, thread_saved_fp(p), thread_saved_pc(p));
+
 	do {
 		if (unwind_frame(p, &frame))
 			goto out;
diff --git a/arch/arm64/kernel/return_address.c b/arch/arm64/kernel/return_address.c
index b21cba90f82d..c4ae647d2306 100644
--- a/arch/arm64/kernel/return_address.c
+++ b/arch/arm64/kernel/return_address.c
@@ -38,12 +38,9 @@ void *return_address(unsigned int level)
 	data.level = level + 2;
 	data.addr = NULL;
 
-	frame.fp = (unsigned long)__builtin_frame_address(0);
-	frame.pc = (unsigned long)return_address; /* dummy */
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-	frame.graph = 0;
-#endif
-
+	start_backtrace(&frame,
+			(unsigned long)__builtin_frame_address(0),
+			(unsigned long)return_address);
 	walk_stackframe(current, &frame, save_return_addr, &data);
 
 	if (!data.level)
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index 62d395151abe..2b160ae594eb 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -29,9 +29,18 @@
  *	ldp	x29, x30, [sp]
  *	add	sp, sp, #0x10
  */
+
+/*
+ * Unwind from one frame record (A) to the next frame record (B).
+ *
+ * We terminate early if the location of B indicates a malformed chain of frame
+ * records (e.g. a cycle), determined based on the location and fp value of A
+ * and the location (but not the fp value) of B.
+ */
 int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame)
 {
 	unsigned long fp = frame->fp;
+	struct stack_info info;
 
 	if (fp & 0xf)
 		return -EINVAL;
@@ -39,11 +48,40 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame)
 	if (!tsk)
 		tsk = current;
 
-	if (!on_accessible_stack(tsk, fp, NULL))
+	if (!on_accessible_stack(tsk, fp, &info))
+		return -EINVAL;
+
+	if (test_bit(info.type, frame->stacks_done))
 		return -EINVAL;
 
+	/*
+	 * As stacks grow downward, any valid record on the same stack must be
+	 * at a strictly higher address than the prior record.
+	 *
+	 * Stacks can nest in several valid orders, e.g.
+	 *
+	 * TASK -> IRQ -> OVERFLOW -> SDEI_NORMAL
+	 * TASK -> SDEI_NORMAL -> SDEI_CRITICAL -> OVERFLOW
+	 *
+	 * ... but the nesting itself is strict. Once we transition from one
+	 * stack to another, it's never valid to unwind back to that first
+	 * stack.
+	 */
+	if (info.type == frame->prev_type) {
+		if (fp <= frame->prev_fp)
+			return -EINVAL;
+	} else {
+		set_bit(frame->prev_type, frame->stacks_done);
+	}
+
+	/*
+	 * Record this frame record's values and location. The prev_fp and
+	 * prev_type are only meaningful to the next unwind_frame() invocation.
+	 */
 	frame->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp));
 	frame->pc = READ_ONCE_NOCHECK(*(unsigned long *)(fp + 8));
+	frame->prev_fp = fp;
+	frame->prev_type = info.type;
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 	if (tsk->ret_stack &&
@@ -122,12 +160,7 @@ void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
 	data.skip = trace->skip;
 	data.no_sched_functions = 0;
 
-	frame.fp = regs->regs[29];
-	frame.pc = regs->pc;
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-	frame.graph = 0;
-#endif
-
+	start_backtrace(&frame, regs->regs[29], regs->pc);
 	walk_stackframe(current, &frame, save_trace, &data);
 }
 EXPORT_SYMBOL_GPL(save_stack_trace_regs);
@@ -146,17 +179,15 @@ static noinline void __save_stack_trace(struct task_struct *tsk,
 	data.no_sched_functions = nosched;
 
 	if (tsk != current) {
-		frame.fp = thread_saved_fp(tsk);
-		frame.pc = thread_saved_pc(tsk);
+		start_backtrace(&frame, thread_saved_fp(tsk),
+				thread_saved_pc(tsk));
 	} else {
 		/* We don't want this function nor the caller */
 		data.skip += 2;
-		frame.fp = (unsigned long)__builtin_frame_address(0);
-		frame.pc = (unsigned long)__save_stack_trace;
+		start_backtrace(&frame,
+				(unsigned long)__builtin_frame_address(0),
+				(unsigned long)__save_stack_trace);
 	}
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-	frame.graph = 0;
-#endif
 
 	walk_stackframe(tsk, &frame, save_trace, &data);
 
diff --git a/arch/arm64/kernel/time.c b/arch/arm64/kernel/time.c
index 9f25aedeac9d..0b2946414dc9 100644
--- a/arch/arm64/kernel/time.c
+++ b/arch/arm64/kernel/time.c
@@ -38,11 +38,8 @@ unsigned long profile_pc(struct pt_regs *regs)
 	if (!in_lock_functions(regs->pc))
 		return regs->pc;
 
-	frame.fp = regs->regs[29];
-	frame.pc = regs->pc;
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-	frame.graph = 0;
-#endif
+	start_backtrace(&frame, regs->regs[29], regs->pc);
+
 	do {
 		int ret = unwind_frame(NULL, &frame);
 		if (ret < 0)
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 8c03456dade6..d3313797cca9 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -100,18 +100,17 @@ void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
 		return;
 
 	if (tsk == current) {
-		frame.fp = (unsigned long)__builtin_frame_address(0);
-		frame.pc = (unsigned long)dump_backtrace;
+		start_backtrace(&frame,
+				(unsigned long)__builtin_frame_address(0),
+				(unsigned long)dump_backtrace);
 	} else {
 		/*
 		 * task blocked in __switch_to
 		 */
-		frame.fp = thread_saved_fp(tsk);
-		frame.pc = thread_saved_pc(tsk);
+		start_backtrace(&frame,
+				thread_saved_fp(tsk),
+				thread_saved_pc(tsk));
 	}
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-	frame.graph = 0;
-#endif
 
 	printk("Call trace:\n");
 	do {
diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
index 4ab863045188..dd2514bb1511 100644
--- a/arch/arm64/kernel/vdso/Makefile
+++ b/arch/arm64/kernel/vdso/Makefile
@@ -32,10 +32,10 @@ UBSAN_SANITIZE			:= n
 OBJECT_FILES_NON_STANDARD	:= y
 KCOV_INSTRUMENT			:= n
 
-ifeq ($(c-gettimeofday-y),)
 CFLAGS_vgettimeofday.o = -O2 -mcmodel=tiny
-else
-CFLAGS_vgettimeofday.o = -O2 -mcmodel=tiny -include $(c-gettimeofday-y)
+
+ifneq ($(c-gettimeofday-y),)
+  CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y)
 endif
 
 # Clang versions less than 8 do not support -mcmodel=tiny
@@ -57,8 +57,7 @@ $(obj)/vdso.o : $(obj)/vdso.so
 
 # Link rule for the .so file, .lds has to be first
 $(obj)/vdso.so.dbg: $(obj)/vdso.lds $(obj-vdso) FORCE
-	$(call if_changed,ld)
-	$(call if_changed,vdso_check)
+	$(call if_changed,vdsold_and_vdso_check)
 
 # Strip rule for the .so file
 $(obj)/%.so: OBJCOPYFLAGS := -S
@@ -74,8 +73,8 @@ include/generated/vdso-offsets.h: $(obj)/vdso.so.dbg FORCE
 	$(call if_changed,vdsosym)
 
 # Actual build commands
-quiet_cmd_vdsocc = VDSOCC   $@
-      cmd_vdsocc = $(CC) $(a_flags) $(c_flags) -c -o $@ $<
+quiet_cmd_vdsold_and_vdso_check = LD      $@
+      cmd_vdsold_and_vdso_check = $(cmd_ld); $(cmd_vdso_check)
 
 # Install commands for the unstripped file
 quiet_cmd_vdso_install = INSTALL $@
diff --git a/arch/arm64/kernel/vdso32/Makefile b/arch/arm64/kernel/vdso32/Makefile
index 60a4c6239712..1fba0776ed40 100644
--- a/arch/arm64/kernel/vdso32/Makefile
+++ b/arch/arm64/kernel/vdso32/Makefile
@@ -144,8 +144,7 @@ $(obj)/vdso.so.dbg: $(obj)/vdso.so.raw $(obj)/$(munge) FORCE
 
 # Link rule for the .so file, .lds has to be first
 $(obj)/vdso.so.raw: $(src)/vdso.lds $(obj-vdso) FORCE
-	$(call if_changed,vdsold)
-	$(call if_changed,vdso_check)
+	$(call if_changed,vdsold_and_vdso_check)
 
 # Compilation rules for the vDSO sources
 $(c-obj-vdso): %.o: %.c FORCE
@@ -156,14 +155,17 @@ $(asm-obj-vdso): %.o: %.S FORCE
 	$(call if_changed_dep,vdsoas)
 
 # Actual build commands
-quiet_cmd_vdsold = VDSOL   $@
+quiet_cmd_vdsold_and_vdso_check = LD32    $@
+      cmd_vdsold_and_vdso_check = $(cmd_vdsold); $(cmd_vdso_check)
+
+quiet_cmd_vdsold = LD32    $@
       cmd_vdsold = $(COMPATCC) -Wp,-MD,$(depfile) $(VDSO_LDFLAGS) \
                    -Wl,-T $(filter %.lds,$^) $(filter %.o,$^) -o $@
-quiet_cmd_vdsocc = VDSOC   $@
+quiet_cmd_vdsocc = CC32    $@
       cmd_vdsocc = $(COMPATCC) -Wp,-MD,$(depfile) $(VDSO_CFLAGS) -c -o $@ $<
-quiet_cmd_vdsocc_gettimeofday = VDSOC_GTD   $@
+quiet_cmd_vdsocc_gettimeofday = CC32    $@
       cmd_vdsocc_gettimeofday = $(COMPATCC) -Wp,-MD,$(depfile) $(VDSO_CFLAGS) $(VDSO_CFLAGS_gettimeofday_o) -c -o $@ $<
-quiet_cmd_vdsoas = VDSOA   $@
+quiet_cmd_vdsoas = AS32    $@
       cmd_vdsoas = $(COMPATCC) -Wp,-MD,$(depfile) $(VDSO_AFLAGS) -c -o $@ $<
 
 quiet_cmd_vdsomunge = MUNGE   $@
diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index d4551e33fa71..8569b79e8b58 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c
@@ -611,8 +611,8 @@ static int iort_dev_find_its_id(struct device *dev, u32 req_id,
 
 	/* Move to ITS specific data */
 	its = (struct acpi_iort_its_group *)node->node_data;
-	if (idx > its->its_count) {
-		dev_err(dev, "requested ITS ID index [%d] is greater than available [%d]\n",
+	if (idx >= its->its_count) {
+		dev_err(dev, "requested ITS ID index [%d] overruns ITS entries [%d]\n",
 			idx, its->its_count);
 		return -ENXIO;
 	}