Merge branch 'arm64/vmap-stack' of git://git.kernel.org/pub/scm/linux…

…/kernel/git/mark/linux into for-next/core

* 'arm64/vmap-stack' of git://git.kernel.org/pub/scm/linux/kernel/git/mark/linux:
  arm64: add VMAP_STACK overflow detection
  arm64: add on_accessible_stack()
  arm64: add basic VMAP_STACK support
  arm64: use an irq stack pointer
  arm64: assembler: allow adr_this_cpu to use the stack pointer
  arm64: factor out entry stack manipulation
  efi/arm64: add EFI_KIMG_ALIGN
  arm64: move SEGMENT_ALIGN to <asm/memory.h>
  arm64: clean up irq stack definitions
  arm64: clean up THREAD_* definitions
  arm64: factor out PAGE_* and CONT_* definitions
  arm64: kernel: remove {THREAD,IRQ_STACK}_START_SP
  fork: allow arch-override of VMAP stack alignment
  arm64: remove __die()'s stack dump

arch/arm64/Kconfig

@@ -75,6 +75,7 @@ config ARM64
 	select HAVE_ARCH_SECCOMP_FILTER
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
+	select HAVE_ARCH_VMAP_STACK
 	select HAVE_ARM_SMCCC
 	select HAVE_EBPF_JIT
 	select HAVE_C_RECORDMCOUNT

arch/arm64/include/asm/assembler.h

@@ -230,12 +230,18 @@ lr	.req	x30		// link register
 	.endm
 
 	/*
-	 * @dst: Result of per_cpu(sym, smp_processor_id())
+	 * @dst: Result of per_cpu(sym, smp_processor_id()), can be SP for
+	 *       non-module code
 	 * @sym: The name of the per-cpu variable
 	 * @tmp: scratch register
 	 */
 	.macro adr_this_cpu, dst, sym, tmp
+#ifndef MODULE
+	adrp	\tmp, \sym
+	add	\dst, \tmp, #:lo12:\sym
+#else
 	adr_l	\dst, \sym
+#endif
 	mrs	\tmp, tpidr_el1
 	add	\dst, \dst, \tmp
 	.endm

arch/arm64/include/asm/efi.h

@@ -4,6 +4,7 @@
 #include <asm/boot.h>
 #include <asm/cpufeature.h>
 #include <asm/io.h>
+#include <asm/memory.h>
 #include <asm/mmu_context.h>
 #include <asm/neon.h>
 #include <asm/ptrace.h>
@@ -48,6 +49,13 @@ int efi_set_mapping_permissions(struct mm_struct *mm, efi_memory_desc_t *md);
  */
 #define EFI_FDT_ALIGN	SZ_2M   /* used by allocate_new_fdt_and_exit_boot() */
 
+/*
+ * In some configurations (e.g. VMAP_STACK && 64K pages), stacks built into the
+ * kernel need greater alignment than we require the segments to be padded to.
+ */
+#define EFI_KIMG_ALIGN	\
+	(SEGMENT_ALIGN > THREAD_ALIGN ? SEGMENT_ALIGN : THREAD_ALIGN)
+
 /* on arm64, the FDT may be located anywhere in system RAM */
 static inline unsigned long efi_get_max_fdt_addr(unsigned long dram_base)
 {

arch/arm64/include/asm/irq.h

@@ -1,43 +1,18 @@
 #ifndef __ASM_IRQ_H
 #define __ASM_IRQ_H
 
-#define IRQ_STACK_SIZE			THREAD_SIZE
-#define IRQ_STACK_START_SP		THREAD_START_SP
-
 #ifndef __ASSEMBLER__
 
-#include <linux/percpu.h>
-#include <linux/sched/task_stack.h>
-
 #include <asm-generic/irq.h>
-#include <asm/thread_info.h>
 
 struct pt_regs;
 
-DECLARE_PER_CPU(unsigned long [IRQ_STACK_SIZE/sizeof(long)], irq_stack);
-
 extern void set_handle_irq(void (*handle_irq)(struct pt_regs *));
 
 static inline int nr_legacy_irqs(void)
 {
 	return 0;
 }
 
-static inline bool on_irq_stack(unsigned long sp)
-{
-	unsigned long low = (unsigned long)raw_cpu_ptr(irq_stack);
-	unsigned long high = low + IRQ_STACK_START_SP;
-
-	return (low <= sp && sp <= high);
-}
-
-static inline bool on_task_stack(struct task_struct *tsk, unsigned long sp)
-{
-	unsigned long low = (unsigned long)task_stack_page(tsk);
-	unsigned long high = low + THREAD_SIZE;
-
-	return (low <= sp && sp < high);
-}
-
 #endif /* !__ASSEMBLER__ */
 #endif

arch/arm64/include/asm/memory.h

@@ -25,6 +25,7 @@
 #include <linux/const.h>
 #include <linux/types.h>
 #include <asm/bug.h>
+#include <asm/page-def.h>
 #include <asm/sizes.h>
 
 /*
@@ -103,6 +104,58 @@
 #define KASAN_SHADOW_SIZE	(0)
 #endif
 
+#define MIN_THREAD_SHIFT	14
+
+/*
+ * VMAP'd stacks are allocated at page granularity, so we must ensure that such
+ * stacks are a multiple of page size.
+ */
+#if defined(CONFIG_VMAP_STACK) && (MIN_THREAD_SHIFT < PAGE_SHIFT)
+#define THREAD_SHIFT		PAGE_SHIFT
+#else
+#define THREAD_SHIFT		MIN_THREAD_SHIFT
+#endif
+
+#if THREAD_SHIFT >= PAGE_SHIFT
+#define THREAD_SIZE_ORDER	(THREAD_SHIFT - PAGE_SHIFT)
+#endif
+
+#define THREAD_SIZE		(UL(1) << THREAD_SHIFT)
+
+/*
+ * By aligning VMAP'd stacks to 2 * THREAD_SIZE, we can detect overflow by
+ * checking sp & (1 << THREAD_SHIFT), which we can do cheaply in the entry
+ * assembly.
+ */
+#ifdef CONFIG_VMAP_STACK
+#define THREAD_ALIGN		(2 * THREAD_SIZE)
+#else
+#define THREAD_ALIGN		THREAD_SIZE
+#endif
+
+#define IRQ_STACK_SIZE		THREAD_SIZE
+
+#define OVERFLOW_STACK_SIZE	SZ_4K
+
+/*
+ * Alignment of kernel segments (e.g. .text, .data).
+ */
+#if defined(CONFIG_DEBUG_ALIGN_RODATA)
+/*
+ *  4 KB granule:   1 level 2 entry
+ * 16 KB granule: 128 level 3 entries, with contiguous bit
+ * 64 KB granule:  32 level 3 entries, with contiguous bit
+ */
+#define SEGMENT_ALIGN			SZ_2M
+#else
+/*
+ *  4 KB granule:  16 level 3 entries, with contiguous bit
+ * 16 KB granule:   4 level 3 entries, without contiguous bit
+ * 64 KB granule:   1 level 3 entry
+ */
+#define SEGMENT_ALIGN			SZ_64K
+#endif
+
 /*
  * Memory types available.
  */

arch/arm64/include/asm/page-def.h

@@ -0,0 +1,34 @@
+/*
+ * Based on arch/arm/include/asm/page.h
+ *
+ * Copyright (C) 1995-2003 Russell King
+ * Copyright (C) 2017 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef __ASM_PAGE_DEF_H
+#define __ASM_PAGE_DEF_H
+
+#include <linux/const.h>
+
+/* PAGE_SHIFT determines the page size */
+/* CONT_SHIFT determines the number of pages which can be tracked together  */
+#define PAGE_SHIFT		CONFIG_ARM64_PAGE_SHIFT
+#define CONT_SHIFT		CONFIG_ARM64_CONT_SHIFT
+#define PAGE_SIZE		(_AC(1, UL) << PAGE_SHIFT)
+#define PAGE_MASK		(~(PAGE_SIZE-1))
+
+#define CONT_SIZE		(_AC(1, UL) << (CONT_SHIFT + PAGE_SHIFT))
+#define CONT_MASK		(~(CONT_SIZE-1))
+
+#endif /* __ASM_PAGE_DEF_H */

arch/arm64/include/asm/page.h

@@ -19,17 +19,7 @@
 #ifndef __ASM_PAGE_H
 #define __ASM_PAGE_H
 
-#include <linux/const.h>
-
-/* PAGE_SHIFT determines the page size */
-/* CONT_SHIFT determines the number of pages which can be tracked together  */
-#define PAGE_SHIFT		CONFIG_ARM64_PAGE_SHIFT
-#define CONT_SHIFT		CONFIG_ARM64_CONT_SHIFT
-#define PAGE_SIZE		(_AC(1, UL) << PAGE_SHIFT)
-#define PAGE_MASK		(~(PAGE_SIZE-1))
-
-#define CONT_SIZE		(_AC(1, UL) << (CONT_SHIFT + PAGE_SHIFT))
-#define CONT_MASK		(~(CONT_SIZE-1))
+#include <asm/page-def.h>
 
 #ifndef __ASSEMBLY__
 

arch/arm64/include/asm/processor.h

@@ -159,7 +159,7 @@ extern struct task_struct *cpu_switch_to(struct task_struct *prev,
 					 struct task_struct *next);
 
 #define task_pt_regs(p) \
-	((struct pt_regs *)(THREAD_START_SP + task_stack_page(p)) - 1)
+	((struct pt_regs *)(THREAD_SIZE + task_stack_page(p)) - 1)
 
 #define KSTK_EIP(tsk)	((unsigned long)task_pt_regs(tsk)->pc)
 #define KSTK_ESP(tsk)	user_stack_pointer(task_pt_regs(tsk))

arch/arm64/include/asm/stacktrace.h

@@ -16,7 +16,12 @@
 #ifndef __ASM_STACKTRACE_H
 #define __ASM_STACKTRACE_H
 
-struct task_struct;
+#include <linux/percpu.h>
+#include <linux/sched.h>
+#include <linux/sched/task_stack.h>
+
+#include <asm/memory.h>
+#include <asm/ptrace.h>
 
 struct stackframe {
 	unsigned long fp;
@@ -31,4 +36,57 @@ extern void walk_stackframe(struct task_struct *tsk, struct stackframe *frame,
 			    int (*fn)(struct stackframe *, void *), void *data);
 extern void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk);
 
+DECLARE_PER_CPU(unsigned long *, irq_stack_ptr);
+
+static inline bool on_irq_stack(unsigned long sp)
+{
+	unsigned long low = (unsigned long)raw_cpu_read(irq_stack_ptr);
+	unsigned long high = low + IRQ_STACK_SIZE;
+
+	if (!low)
+		return false;
+
+	return (low <= sp && sp < high);
+}
+
+static inline bool on_task_stack(struct task_struct *tsk, unsigned long sp)
+{
+	unsigned long low = (unsigned long)task_stack_page(tsk);
+	unsigned long high = low + THREAD_SIZE;
+
+	return (low <= sp && sp < high);
+}
+
+#ifdef CONFIG_VMAP_STACK
+DECLARE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], overflow_stack);
+
+static inline bool on_overflow_stack(unsigned long sp)
+{
+	unsigned long low = (unsigned long)raw_cpu_ptr(overflow_stack);
+	unsigned long high = low + OVERFLOW_STACK_SIZE;
+
+	return (low <= sp && sp < high);
+}
+#else
+static inline bool on_overflow_stack(unsigned long sp) { return false; }
+#endif
+
+/*
+ * 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)
+{
+	if (on_task_stack(tsk, sp))
+		return true;
+	if (tsk != current || preemptible())
+		return false;
+	if (on_irq_stack(sp))
+		return true;
+	if (on_overflow_stack(sp))
+		return true;
+
+	return false;
+}
+
 #endif	/* __ASM_STACKTRACE_H */

arch/arm64/include/asm/thread_info.h

@@ -23,19 +23,11 @@
 
 #include <linux/compiler.h>
 
-#ifdef CONFIG_ARM64_4K_PAGES
-#define THREAD_SIZE_ORDER	2
-#elif defined(CONFIG_ARM64_16K_PAGES)
-#define THREAD_SIZE_ORDER	0
-#endif
-
-#define THREAD_SIZE		16384
-#define THREAD_START_SP		(THREAD_SIZE - 16)
-
 #ifndef __ASSEMBLY__
 
 struct task_struct;
 
+#include <asm/memory.h>
 #include <asm/stack_pointer.h>
 #include <asm/types.h>