19 files changed, 140 insertions, 173 deletions

diff --git a/arch/um/include/asm/Kbuild b/arch/um/include/asm/Kbuild
index 18f902da8e99..428f2c5158c2 100644
--- a/arch/um/include/asm/Kbuild
+++ b/arch/um/include/asm/Kbuild
@@ -1,7 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 generic-y += bug.h
 generic-y += compat.h
-generic-y += current.h
 generic-y += device.h
 generic-y += dma-mapping.h
 generic-y += emergency-restart.h
diff --git a/arch/um/include/asm/current.h b/arch/um/include/asm/current.h
new file mode 100644
index 000000000000..de64e032d66c
--- /dev/null
+++ b/arch/um/include/asm/current.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_CURRENT_H
+#define __ASM_CURRENT_H
+
+#include <linux/compiler.h>
+#include <linux/threads.h>
+
+#ifndef __ASSEMBLY__
+
+struct task_struct;
+extern struct task_struct *cpu_tasks[NR_CPUS];
+
+static __always_inline struct task_struct *get_current(void)
+{
+	return cpu_tasks[0];
+}
+
+
+#define current get_current()
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* __ASM_CURRENT_H */
diff --git a/arch/um/include/asm/page.h b/arch/um/include/asm/page.h
index 834313ecd3d6..3d516f3ca9c7 100644
--- a/arch/um/include/asm/page.h
+++ b/arch/um/include/asm/page.h
@@ -29,51 +29,35 @@ struct page;
 #define clear_user_page(page, vaddr, pg)	clear_page(page)
 #define copy_user_page(to, from, vaddr, pg)	copy_page(to, from)
 
-#if defined(CONFIG_3_LEVEL_PGTABLES) && !defined(CONFIG_64BIT)
-
 typedef struct { unsigned long pte; } pte_t;
-typedef struct { unsigned long pmd; } pmd_t;
 typedef struct { unsigned long pgd; } pgd_t;
-#define pte_val(p) ((p).pte)
 
-#define pte_get_bits(p, bits) ((p).pte & (bits))
-#define pte_set_bits(p, bits) ((p).pte |= (bits))
-#define pte_clear_bits(p, bits) ((p).pte &= ~(bits))
-#define pte_copy(to, from) ({ (to).pte = (from).pte; })
-#define pte_is_zero(p) (!((p).pte & ~_PAGE_NEWPAGE))
-#define pte_set_val(p, phys, prot) \
-	({ (p).pte = (phys) | pgprot_val(prot); })
+#if CONFIG_PGTABLE_LEVELS > 2
 
+typedef struct { unsigned long pmd; } pmd_t;
 #define pmd_val(x)	((x).pmd)
 #define __pmd(x) ((pmd_t) { (x) } )
 
-typedef unsigned long long phys_t;
+#if CONFIG_PGTABLE_LEVELS > 3
 
-#else
-
-typedef struct { unsigned long pte; } pte_t;
-typedef struct { unsigned long pgd; } pgd_t;
+typedef struct { unsigned long pud; } pud_t;
+#define pud_val(x)	((x).pud)
+#define __pud(x) ((pud_t) { (x) } )
 
-#ifdef CONFIG_3_LEVEL_PGTABLES
-typedef struct { unsigned long pmd; } pmd_t;
-#define pmd_val(x)	((x).pmd)
-#define __pmd(x) ((pmd_t) { (x) } )
-#endif
+#endif /* CONFIG_PGTABLE_LEVELS > 3 */
+#endif /* CONFIG_PGTABLE_LEVELS > 2 */
 
 #define pte_val(x)	((x).pte)
 
-
 #define pte_get_bits(p, bits) ((p).pte & (bits))
 #define pte_set_bits(p, bits) ((p).pte |= (bits))
 #define pte_clear_bits(p, bits) ((p).pte &= ~(bits))
 #define pte_copy(to, from) ((to).pte = (from).pte)
-#define pte_is_zero(p) (!((p).pte & ~_PAGE_NEWPAGE))
+#define pte_is_zero(p) (!((p).pte & ~_PAGE_NEEDSYNC))
 #define pte_set_val(p, phys, prot) (p).pte = (phys | pgprot_val(prot))
 
 typedef unsigned long phys_t;
 
-#endif
-
 typedef struct { unsigned long pgprot; } pgprot_t;
 
 typedef struct page *pgtable_t;
diff --git a/arch/um/include/asm/pgalloc.h b/arch/um/include/asm/pgalloc.h
index de5e31c64793..04fb4e6969a4 100644
--- a/arch/um/include/asm/pgalloc.h
+++ b/arch/um/include/asm/pgalloc.h
@@ -31,7 +31,7 @@ do {								\
 	tlb_remove_page_ptdesc((tlb), (page_ptdesc(pte)));	\
 } while (0)
 
-#ifdef CONFIG_3_LEVEL_PGTABLES
+#if CONFIG_PGTABLE_LEVELS > 2
 
 #define __pmd_free_tlb(tlb, pmd, address)			\
 do {								\
@@ -39,6 +39,15 @@ do {								\
 	tlb_remove_page_ptdesc((tlb), virt_to_ptdesc(pmd));	\
 } while (0)
 
+#if CONFIG_PGTABLE_LEVELS > 3
+
+#define __pud_free_tlb(tlb, pud, address)			\
+do {								\
+	pagetable_pud_dtor(virt_to_ptdesc(pud));		\
+	tlb_remove_page_ptdesc((tlb), virt_to_ptdesc(pud));	\
+} while (0)
+
+#endif
 #endif
 
 #endif
diff --git a/arch/um/include/asm/pgtable-2level.h b/arch/um/include/asm/pgtable-2level.h
index 8256ecc5b919..ab0c8dd86564 100644
--- a/arch/um/include/asm/pgtable-2level.h
+++ b/arch/um/include/asm/pgtable-2level.h
@@ -31,7 +31,7 @@
         printk("%s:%d: bad pgd %p(%08lx).\n", __FILE__, __LINE__, &(e), \
 	       pgd_val(e))
 
-static inline int pgd_newpage(pgd_t pgd)	{ return 0; }
+static inline int pgd_needsync(pgd_t pgd)	{ return 0; }
 static inline void pgd_mkuptodate(pgd_t pgd)	{ }
 
 #define set_pmd(pmdptr, pmdval) (*(pmdptr) = (pmdval))
diff --git a/arch/um/include/asm/pgtable-3level.h b/arch/um/include/asm/pgtable-4level.h
index 8a5032ec231f..0d279caee93c 100644
--- a/arch/um/include/asm/pgtable-3level.h
+++ b/arch/um/include/asm/pgtable-4level.h
@@ -4,21 +4,25 @@
  * Derived from include/asm-i386/pgtable.h
  */
 
-#ifndef __UM_PGTABLE_3LEVEL_H
-#define __UM_PGTABLE_3LEVEL_H
+#ifndef __UM_PGTABLE_4LEVEL_H
+#define __UM_PGTABLE_4LEVEL_H
 
-#include <asm-generic/pgtable-nopud.h>
+#include <asm-generic/pgtable-nop4d.h>
 
-/* PGDIR_SHIFT determines what a third-level page table entry can map */
+/* PGDIR_SHIFT determines what a fourth-level page table entry can map */
 
-#ifdef CONFIG_64BIT
-#define PGDIR_SHIFT	30
-#else
-#define PGDIR_SHIFT	31
-#endif
+#define PGDIR_SHIFT	39
 #define PGDIR_SIZE	(1UL << PGDIR_SHIFT)
 #define PGDIR_MASK	(~(PGDIR_SIZE-1))
 
+/* PUD_SHIFT determines the size of the area a third-level page table can
+ * map
+ */
+
+#define PUD_SHIFT	30
+#define PUD_SIZE	(1UL << PUD_SHIFT)
+#define PUD_MASK	(~(PUD_SIZE-1))
+
 /* PMD_SHIFT determines the size of the area a second-level page table can
  * map
  */
@@ -32,13 +36,9 @@
  */
 
 #define PTRS_PER_PTE 512
-#ifdef CONFIG_64BIT
 #define PTRS_PER_PMD 512
+#define PTRS_PER_PUD 512
 #define PTRS_PER_PGD 512
-#else
-#define PTRS_PER_PMD 1024
-#define PTRS_PER_PGD 1024
-#endif
 
 #define USER_PTRS_PER_PGD ((TASK_SIZE + (PGDIR_SIZE - 1)) / PGDIR_SIZE)
 
@@ -48,11 +48,14 @@
 #define pmd_ERROR(e) \
         printk("%s:%d: bad pmd %p(%016lx).\n", __FILE__, __LINE__, &(e), \
 	       pmd_val(e))
+#define pud_ERROR(e) \
+        printk("%s:%d: bad pud %p(%016lx).\n", __FILE__, __LINE__, &(e), \
+	       pud_val(e))
 #define pgd_ERROR(e) \
         printk("%s:%d: bad pgd %p(%016lx).\n", __FILE__, __LINE__, &(e), \
 	       pgd_val(e))
 
-#define pud_none(x)	(!(pud_val(x) & ~_PAGE_NEWPAGE))
+#define pud_none(x)	(!(pud_val(x) & ~_PAGE_NEEDSYNC))
 #define	pud_bad(x)	((pud_val(x) & (~PAGE_MASK & ~_PAGE_USER)) != _KERNPG_TABLE)
 #define pud_present(x)	(pud_val(x) & _PAGE_PRESENT)
 #define pud_populate(mm, pud, pmd) \
@@ -60,23 +63,40 @@
 
 #define set_pud(pudptr, pudval) (*(pudptr) = (pudval))
 
-static inline int pgd_newpage(pgd_t pgd)
+#define p4d_none(x)	(!(p4d_val(x) & ~_PAGE_NEEDSYNC))
+#define	p4d_bad(x)	((p4d_val(x) & (~PAGE_MASK & ~_PAGE_USER)) != _KERNPG_TABLE)
+#define p4d_present(x)	(p4d_val(x) & _PAGE_PRESENT)
+#define p4d_populate(mm, p4d, pud) \
+	set_p4d(p4d, __p4d(_PAGE_TABLE + __pa(pud)))
+
+#define set_p4d(p4dptr, p4dval) (*(p4dptr) = (p4dval))
+
+
+static inline int pgd_needsync(pgd_t pgd)
 {
-	return(pgd_val(pgd) & _PAGE_NEWPAGE);
+	return pgd_val(pgd) & _PAGE_NEEDSYNC;
 }
 
-static inline void pgd_mkuptodate(pgd_t pgd) { pgd_val(pgd) &= ~_PAGE_NEWPAGE; }
+static inline void pgd_mkuptodate(pgd_t pgd) { pgd_val(pgd) &= ~_PAGE_NEEDSYNC; }
 
 #define set_pmd(pmdptr, pmdval) (*(pmdptr) = (pmdval))
 
 static inline void pud_clear (pud_t *pud)
 {
-	set_pud(pud, __pud(_PAGE_NEWPAGE));
+	set_pud(pud, __pud(_PAGE_NEEDSYNC));
+}
+
+static inline void p4d_clear (p4d_t *p4d)
+{
+	set_p4d(p4d, __p4d(_PAGE_NEEDSYNC));
 }
 
 #define pud_page(pud) phys_to_page(pud_val(pud) & PAGE_MASK)
 #define pud_pgtable(pud) ((pmd_t *) __va(pud_val(pud) & PAGE_MASK))
 
+#define p4d_page(p4d) phys_to_page(p4d_val(p4d) & PAGE_MASK)
+#define p4d_pgtable(p4d) ((pud_t *) __va(p4d_val(p4d) & PAGE_MASK))
+
 static inline unsigned long pte_pfn(pte_t pte)
 {
 	return phys_to_pfn(pte_val(pte));
@@ -97,4 +117,3 @@ static inline pmd_t pfn_pmd(unsigned long page_nr, pgprot_t pgprot)
 }
 
 #endif
-
diff --git a/arch/um/include/asm/pgtable.h b/arch/um/include/asm/pgtable.h
index faab5a2a4b06..0bd60afcc37d 100644
--- a/arch/um/include/asm/pgtable.h
+++ b/arch/um/include/asm/pgtable.h
@@ -11,8 +11,7 @@
 #include <asm/fixmap.h>
 
 #define _PAGE_PRESENT	0x001
-#define _PAGE_NEWPAGE	0x002
-#define _PAGE_NEWPROT	0x004
+#define _PAGE_NEEDSYNC	0x002
 #define _PAGE_RW	0x020
 #define _PAGE_USER	0x040
 #define _PAGE_ACCESSED	0x080
@@ -24,10 +23,12 @@
 /* We borrow bit 10 to store the exclusive marker in swap PTEs. */
 #define _PAGE_SWP_EXCLUSIVE	0x400
 
-#ifdef CONFIG_3_LEVEL_PGTABLES
-#include <asm/pgtable-3level.h>
-#else
+#if CONFIG_PGTABLE_LEVELS == 4
+#include <asm/pgtable-4level.h>
+#elif CONFIG_PGTABLE_LEVELS == 2
 #include <asm/pgtable-2level.h>
+#else
+#error "Unsupported number of page table levels"
 #endif
 
 extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
@@ -78,22 +79,22 @@ extern unsigned long end_iomem;
  */
 #define ZERO_PAGE(vaddr) virt_to_page(empty_zero_page)
 
-#define pte_clear(mm,addr,xp) pte_set_val(*(xp), (phys_t) 0, __pgprot(_PAGE_NEWPAGE))
+#define pte_clear(mm, addr, xp) pte_set_val(*(xp), (phys_t) 0, __pgprot(_PAGE_NEEDSYNC))
 
-#define pmd_none(x)	(!((unsigned long)pmd_val(x) & ~_PAGE_NEWPAGE))
+#define pmd_none(x)	(!((unsigned long)pmd_val(x) & ~_PAGE_NEEDSYNC))
 #define	pmd_bad(x)	((pmd_val(x) & (~PAGE_MASK & ~_PAGE_USER)) != _KERNPG_TABLE)
 
 #define pmd_present(x)	(pmd_val(x) & _PAGE_PRESENT)
-#define pmd_clear(xp)	do { pmd_val(*(xp)) = _PAGE_NEWPAGE; } while (0)
+#define pmd_clear(xp)	do { pmd_val(*(xp)) = _PAGE_NEEDSYNC; } while (0)
 
-#define pmd_newpage(x)  (pmd_val(x) & _PAGE_NEWPAGE)
-#define pmd_mkuptodate(x) (pmd_val(x) &= ~_PAGE_NEWPAGE)
+#define pmd_needsync(x)   (pmd_val(x) & _PAGE_NEEDSYNC)
+#define pmd_mkuptodate(x) (pmd_val(x) &= ~_PAGE_NEEDSYNC)
 
-#define pud_newpage(x)  (pud_val(x) & _PAGE_NEWPAGE)
-#define pud_mkuptodate(x) (pud_val(x) &= ~_PAGE_NEWPAGE)
+#define pud_needsync(x)   (pud_val(x) & _PAGE_NEEDSYNC)
+#define pud_mkuptodate(x) (pud_val(x) &= ~_PAGE_NEEDSYNC)
 
-#define p4d_newpage(x)  (p4d_val(x) & _PAGE_NEWPAGE)
-#define p4d_mkuptodate(x) (p4d_val(x) &= ~_PAGE_NEWPAGE)
+#define p4d_needsync(x)   (p4d_val(x) & _PAGE_NEEDSYNC)
+#define p4d_mkuptodate(x) (p4d_val(x) &= ~_PAGE_NEEDSYNC)
 
 #define pmd_pfn(pmd) (pmd_val(pmd) >> PAGE_SHIFT)
 #define pmd_page(pmd) phys_to_page(pmd_val(pmd) & PAGE_MASK)
@@ -144,14 +145,9 @@ static inline int pte_young(pte_t pte)
 	return pte_get_bits(pte, _PAGE_ACCESSED);
 }
 
-static inline int pte_newpage(pte_t pte)
+static inline int pte_needsync(pte_t pte)
 {
-	return pte_get_bits(pte, _PAGE_NEWPAGE);
-}
-
-static inline int pte_newprot(pte_t pte)
-{
-	return(pte_present(pte) && (pte_get_bits(pte, _PAGE_NEWPROT)));
+	return pte_get_bits(pte, _PAGE_NEEDSYNC);
 }
 
 /*
@@ -160,12 +156,6 @@ static inline int pte_newprot(pte_t pte)
  * =================================
  */
 
-static inline pte_t pte_mknewprot(pte_t pte)
-{
-	pte_set_bits(pte, _PAGE_NEWPROT);
-	return(pte);
-}
-
 static inline pte_t pte_mkclean(pte_t pte)
 {
 	pte_clear_bits(pte, _PAGE_DIRTY);
@@ -180,19 +170,14 @@ static inline pte_t pte_mkold(pte_t pte)
 
 static inline pte_t pte_wrprotect(pte_t pte)
 {
-	if (likely(pte_get_bits(pte, _PAGE_RW)))
-		pte_clear_bits(pte, _PAGE_RW);
-	else
-		return pte;
-	return(pte_mknewprot(pte));
+	pte_clear_bits(pte, _PAGE_RW);
+	return pte;
 }
 
 static inline pte_t pte_mkread(pte_t pte)
 {
-	if (unlikely(pte_get_bits(pte, _PAGE_USER)))
-		return pte;
 	pte_set_bits(pte, _PAGE_USER);
-	return(pte_mknewprot(pte));
+	return pte;
 }
 
 static inline pte_t pte_mkdirty(pte_t pte)
@@ -209,23 +194,19 @@ static inline pte_t pte_mkyoung(pte_t pte)
 
 static inline pte_t pte_mkwrite_novma(pte_t pte)
 {
-	if (unlikely(pte_get_bits(pte,  _PAGE_RW)))
-		return pte;
 	pte_set_bits(pte, _PAGE_RW);
-	return(pte_mknewprot(pte));
+	return pte;
 }
 
 static inline pte_t pte_mkuptodate(pte_t pte)
 {
-	pte_clear_bits(pte, _PAGE_NEWPAGE);
-	if(pte_present(pte))
-		pte_clear_bits(pte, _PAGE_NEWPROT);
-	return(pte);
+	pte_clear_bits(pte, _PAGE_NEEDSYNC);
+	return pte;
 }
 
-static inline pte_t pte_mknewpage(pte_t pte)
+static inline pte_t pte_mkneedsync(pte_t pte)
 {
-	pte_set_bits(pte, _PAGE_NEWPAGE);
+	pte_set_bits(pte, _PAGE_NEEDSYNC);
 	return(pte);
 }
 
@@ -233,13 +214,11 @@ static inline void set_pte(pte_t *pteptr, pte_t pteval)
 {
 	pte_copy(*pteptr, pteval);
 
-	/* If it's a swap entry, it needs to be marked _PAGE_NEWPAGE so
-	 * fix_range knows to unmap it.  _PAGE_NEWPROT is specific to
-	 * mapped pages.
+	/* If it's a swap entry, it needs to be marked _PAGE_NEEDSYNC so
+	 * update_pte_range knows to unmap it.
 	 */
 
-	*pteptr = pte_mknewpage(*pteptr);
-	if(pte_present(*pteptr)) *pteptr = pte_mknewprot(*pteptr);
+	*pteptr = pte_mkneedsync(*pteptr);
 }
 
 #define PFN_PTE_SHIFT		PAGE_SHIFT
@@ -279,7 +258,7 @@ static inline void set_ptes(struct mm_struct *mm, unsigned long addr,
 #define __HAVE_ARCH_PTE_SAME
 static inline int pte_same(pte_t pte_a, pte_t pte_b)
 {
-	return !((pte_val(pte_a) ^ pte_val(pte_b)) & ~_PAGE_NEWPAGE);
+	return !((pte_val(pte_a) ^ pte_val(pte_b)) & ~_PAGE_NEEDSYNC);
 }
 
 /*
@@ -294,8 +273,6 @@ static inline int pte_same(pte_t pte_a, pte_t pte_b)
 	({ pte_t pte;					\
 							\
 	pte_set_val(pte, page_to_phys(page), (pgprot));	\
-	if (pte_present(pte))				\
-		pte_mknewprot(pte_mknewpage(pte));	\
 	pte;})
 
 static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
@@ -329,7 +306,7 @@ extern pte_t *virt_to_pte(struct mm_struct *mm, unsigned long addr);
  *   <--------------- offset ----------------> E < type -> 0 0 0 1 0
  *
  *   E is the exclusive marker that is not stored in swap entries.
- *   _PAGE_NEWPAGE (bit 1) is always set to 1 in set_pte().
+ *   _PAGE_NEEDSYNC (bit 1) is always set to 1 in set_pte().
  */
 #define __swp_type(x)			(((x).val >> 5) & 0x1f)
 #define __swp_offset(x)			((x).val >> 11)
diff --git a/arch/um/include/asm/processor-generic.h b/arch/um/include/asm/processor-generic.h
index bce4595798da..5d6356eafffe 100644
--- a/arch/um/include/asm/processor-generic.h
+++ b/arch/um/include/asm/processor-generic.h
@@ -20,10 +20,7 @@ struct task_struct;
 struct mm_struct;
 
 struct thread_struct {
-	struct pt_regs regs;
 	struct pt_regs *segv_regs;
-	void *fault_addr;
-	jmp_buf *fault_catcher;
 	struct task_struct *prev_sched;
 	struct arch_thread arch;
 	jmp_buf switch_buf;
@@ -33,12 +30,14 @@ struct thread_struct {
 			void *arg;
 		} thread;
 	} request;
+
+	/* Contains variable sized FP registers */
+	struct pt_regs regs;
 };
 
 #define INIT_THREAD \
 { \
 	.regs		   	= EMPTY_REGS,	\
-	.fault_addr		= NULL, \
 	.prev_sched		= NULL, \
 	.arch			= INIT_ARCH_THREAD, \
 	.request		= { } \
diff --git a/arch/um/include/asm/thread_info.h b/arch/um/include/asm/thread_info.h
index c7b4b49826a2..f9ad06fcc991 100644
--- a/arch/um/include/asm/thread_info.h
+++ b/arch/um/include/asm/thread_info.h
@@ -17,35 +17,17 @@
 #include <sysdep/ptrace_user.h>
 
 struct thread_info {
-	struct task_struct	*task;		/* main task structure */
 	unsigned long		flags;		/* low level flags */
 	__u32			cpu;		/* current CPU */
 	int			preempt_count;  /* 0 => preemptable,
 						   <0 => BUG */
-	struct thread_info	*real_thread;    /* Points to non-IRQ stack */
-	unsigned long aux_fp_regs[FP_SIZE];	/* auxiliary fp_regs to save/restore
-						   them out-of-band */
 };
 
 #define INIT_THREAD_INFO(tsk)			\
 {						\
-	.task =		&tsk,			\
 	.flags =		0,		\
 	.cpu =		0,			\
 	.preempt_count = INIT_PREEMPT_COUNT,	\
-	.real_thread = NULL,			\
-}
-
-/* how to get the thread information struct from C */
-static inline struct thread_info *current_thread_info(void)
-{
-	struct thread_info *ti;
-	unsigned long mask = THREAD_SIZE - 1;
-	void *p;
-
-	asm volatile ("" : "=r" (p) : "0" (&ti));
-	ti = (struct thread_info *) (((unsigned long)p) & ~mask);
-	return ti;
 }
 
 #endif
diff --git a/arch/um/include/asm/tlbflush.h b/arch/um/include/asm/tlbflush.h
index db997976b6ea..13a3009942be 100644
--- a/arch/um/include/asm/tlbflush.h
+++ b/arch/um/include/asm/tlbflush.h
@@ -9,8 +9,8 @@
 #include <linux/mm.h>
 
 /*
- * In UML, we need to sync the TLB over by using mmap/munmap/mprotect syscalls
- * from the process handling the MM (which can be the kernel itself).
+ * In UML, we need to sync the TLB over by using mmap/munmap syscalls from
+ * the process handling the MM (which can be the kernel itself).
  *
  * To track updates, we can hook into set_ptes and flush_tlb_*. With set_ptes
  * we catch all PTE transitions where memory that was unusable becomes usable.
diff --git a/arch/um/include/shared/as-layout.h b/arch/um/include/shared/as-layout.h
index 06292fca5a4d..ea65f151bf48 100644
--- a/arch/um/include/shared/as-layout.h
+++ b/arch/um/include/shared/as-layout.h
@@ -30,25 +30,23 @@
 
 #include <sysdep/ptrace.h>
 
-struct cpu_task {
-	void *task;
-};
+struct task_struct;
+extern struct task_struct *cpu_tasks[];
 
-extern struct cpu_task cpu_tasks[];
+extern unsigned long long physmem_size;
 
 extern unsigned long high_physmem;
 extern unsigned long uml_physmem;
 extern unsigned long uml_reserved;
 extern unsigned long end_vm;
 extern unsigned long start_vm;
-extern unsigned long long highmem;
 
 extern unsigned long brk_start;
 
 extern unsigned long host_task_size;
 extern unsigned long stub_start;
 
-extern int linux_main(int argc, char **argv);
+extern int linux_main(int argc, char **argv, char **envp);
 extern void uml_finishsetup(void);
 
 struct siginfo;
diff --git a/arch/um/include/shared/common-offsets.h b/arch/um/include/shared/common-offsets.h
index 579ed946a3a9..73f3a4792ed8 100644
--- a/arch/um/include/shared/common-offsets.h
+++ b/arch/um/include/shared/common-offsets.h
@@ -6,7 +6,6 @@ DEFINE(KERNEL_MADV_REMOVE, MADV_REMOVE);
 DEFINE(UM_KERN_PAGE_SIZE, PAGE_SIZE);
 DEFINE(UM_KERN_PAGE_MASK, PAGE_MASK);
 DEFINE(UM_KERN_PAGE_SHIFT, PAGE_SHIFT);
-DEFINE(UM_NSEC_PER_SEC, NSEC_PER_SEC);
 
 DEFINE(UM_GFP_KERNEL, GFP_KERNEL);
 DEFINE(UM_GFP_ATOMIC, GFP_ATOMIC);
@@ -15,17 +14,3 @@ DEFINE(UM_THREAD_SIZE, THREAD_SIZE);
 
 DEFINE(UM_NSEC_PER_SEC, NSEC_PER_SEC);
 DEFINE(UM_NSEC_PER_USEC, NSEC_PER_USEC);
-
-#ifdef CONFIG_PRINTK
-DEFINE(UML_CONFIG_PRINTK, CONFIG_PRINTK);
-#endif
-#ifdef CONFIG_UML_X86
-DEFINE(UML_CONFIG_UML_X86, CONFIG_UML_X86);
-#endif
-#ifdef CONFIG_64BIT
-DEFINE(UML_CONFIG_64BIT, CONFIG_64BIT);
-#endif
-#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
-DEFINE(UML_CONFIG_UML_TIME_TRAVEL_SUPPORT, CONFIG_UML_TIME_TRAVEL_SUPPORT);
-#endif
-
diff --git a/arch/um/include/shared/kern_util.h b/arch/um/include/shared/kern_util.h
index d8ffd2db168e..f21dc8517538 100644
--- a/arch/um/include/shared/kern_util.h
+++ b/arch/um/include/shared/kern_util.h
@@ -60,7 +60,6 @@ extern unsigned long from_irq_stack(int nested);
 extern int singlestepping(void);
 
 extern void segv_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs);
-extern void bus_handler(int sig, struct siginfo *si, struct uml_pt_regs *regs);
 extern void winch(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs);
 extern void fatal_sigsegv(void) __attribute__ ((noreturn));
 
diff --git a/arch/um/include/shared/mem_user.h b/arch/um/include/shared/mem_user.h
index 11a723a58545..adfa08062f88 100644
--- a/arch/um/include/shared/mem_user.h
+++ b/arch/um/include/shared/mem_user.h
@@ -47,10 +47,9 @@ extern int iomem_size;
 #define ROUND_4M(n) ((((unsigned long) (n)) + (1 << 22)) & ~((1 << 22) - 1))
 
 extern unsigned long find_iomem(char *driver, unsigned long *len_out);
-extern void mem_total_pages(unsigned long physmem, unsigned long iomem,
-		     unsigned long highmem);
+extern void mem_total_pages(unsigned long physmem, unsigned long iomem);
 extern void setup_physmem(unsigned long start, unsigned long usable,
-			  unsigned long len, unsigned long long highmem);
+			  unsigned long len);
 extern void map_memory(unsigned long virt, unsigned long phys,
 		       unsigned long len, int r, int w, int x);
 
diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h
index 9a039d6f1f74..5babad8c5f75 100644
--- a/arch/um/include/shared/os.h
+++ b/arch/um/include/shared/os.h
@@ -145,7 +145,6 @@ extern int os_ioctl_generic(int fd, unsigned int cmd, unsigned long arg);
 extern int os_get_ifname(int fd, char *namebuf);
 extern int os_set_slip(int fd);
 extern int os_mode_fd(int fd, int mode);
-extern int os_fsync_file(int fd);
 
 extern int os_seek_file(int fd, unsigned long long offset);
 extern int os_open_file(const char *file, struct openflags flags, int mode);
@@ -199,15 +198,11 @@ extern int create_mem_file(unsigned long long len);
 extern void report_enomem(void);
 
 /* process.c */
-extern unsigned long os_process_pc(int pid);
-extern int os_process_parent(int pid);
 extern void os_alarm_process(int pid);
-extern void os_stop_process(int pid);
 extern void os_kill_process(int pid, int reap_child);
 extern void os_kill_ptraced_process(int pid, int reap_child);
 
 extern int os_getpid(void);
-extern int os_getpgrp(void);
 
 extern void init_new_thread_signals(void);
 
@@ -220,6 +215,8 @@ extern int os_drop_memory(void *addr, int length);
 extern int can_drop_memory(void);
 extern int os_mincore(void *addr, unsigned long len);
 
+void os_set_pdeathsig(void);
+
 /* execvp.c */
 extern int execvp_noalloc(char *buf, const char *file, char *const argv[]);
 /* helper.c */
@@ -244,7 +241,6 @@ extern void block_signals(void);
 extern void unblock_signals(void);
 extern int um_set_signals(int enable);
 extern int um_set_signals_trace(int enable);
-extern int os_is_signal_stack(void);
 extern void deliver_alarm(void);
 extern void register_pm_wake_signal(void);
 extern void block_signals_hard(void);
@@ -283,13 +279,11 @@ int map(struct mm_id *mm_idp, unsigned long virt,
 	unsigned long len, int prot, int phys_fd,
 	unsigned long long offset);
 int unmap(struct mm_id *mm_idp, unsigned long addr, unsigned long len);
-int protect(struct mm_id *mm_idp, unsigned long addr,
-	    unsigned long len, unsigned int prot);
 
 /* skas/process.c */
 extern int is_skas_winch(int pid, int fd, void *data);
 extern int start_userspace(unsigned long stub_stack);
-extern void userspace(struct uml_pt_regs *regs, unsigned long *aux_fp_regs);
+extern void userspace(struct uml_pt_regs *regs);
 extern void new_thread(void *stack, jmp_buf *buf, void (*handler)(void));
 extern void switch_threads(jmp_buf *me, jmp_buf *you);
 extern int start_idle_thread(void *stack, jmp_buf *switch_buf);
@@ -329,9 +323,6 @@ extern int __ignore_sigio_fd(int fd);
 /* tty.c */
 extern int get_pty(void);
 
-/* sys-$ARCH/task_size.c */
-extern unsigned long os_get_top_address(void);
-
 long syscall(long number, ...);
 
 /* irqflags tracing */
diff --git a/arch/um/include/shared/registers.h b/arch/um/include/shared/registers.h
index a0450326521c..7d81b2339a48 100644
--- a/arch/um/include/shared/registers.h
+++ b/arch/um/include/shared/registers.h
@@ -8,12 +8,6 @@
 
 #include <sysdep/ptrace.h>
 
-extern int save_i387_registers(int pid, unsigned long *fp_regs);
-extern int restore_i387_registers(int pid, unsigned long *fp_regs);
-extern int save_fp_registers(int pid, unsigned long *fp_regs);
-extern int restore_fp_registers(int pid, unsigned long *fp_regs);
-extern int save_fpx_registers(int pid, unsigned long *fp_regs);
-extern int restore_fpx_registers(int pid, unsigned long *fp_regs);
 extern int init_pid_registers(int pid);
 extern void get_safe_registers(unsigned long *regs, unsigned long *fp_regs);
 extern int get_fp_registers(int pid, unsigned long *regs);
diff --git a/arch/um/include/shared/skas/stub-data.h b/arch/um/include/shared/skas/stub-data.h
index 2b6b44759dfa..81a4cace032c 100644
--- a/arch/um/include/shared/skas/stub-data.h
+++ b/arch/um/include/shared/skas/stub-data.h
@@ -12,6 +12,17 @@
 #include <as-layout.h>
 #include <sysdep/tls.h>
 
+struct stub_init_data {
+	unsigned long stub_start;
+
+	int stub_code_fd;
+	unsigned long stub_code_offset;
+	int stub_data_fd;
+	unsigned long stub_data_offset;
+
+	unsigned long segv_handler;
+};
+
 #define STUB_NEXT_SYSCALL(s) \
 	((struct stub_syscall *) (((unsigned long) s) + (s)->cmd_len))
 
@@ -19,7 +30,6 @@ enum stub_syscall_type {
 	STUB_SYSCALL_UNSET = 0,
 	STUB_SYSCALL_MMAP,
 	STUB_SYSCALL_MUNMAP,
-	STUB_SYSCALL_MPROTECT,
 };
 
 struct stub_syscall {
diff --git a/arch/um/include/shared/timetravel.h b/arch/um/include/shared/timetravel.h
index c8db2f213dba..7c2b277b7eb0 100644
--- a/arch/um/include/shared/timetravel.h
+++ b/arch/um/include/shared/timetravel.h
@@ -12,14 +12,13 @@ enum time_travel_mode {
 	TT_MODE_EXTERNAL,
 };
 
-#if defined(UML_CONFIG_UML_TIME_TRAVEL_SUPPORT) || \
-    defined(CONFIG_UML_TIME_TRAVEL_SUPPORT)
+#if IS_ENABLED(CONFIG_UML_TIME_TRAVEL_SUPPORT)
 extern enum time_travel_mode time_travel_mode;
 extern int time_travel_should_print_bc_msg;
 #else
 #define time_travel_mode TT_MODE_OFF
 #define time_travel_should_print_bc_msg 0
-#endif /* (UML_)CONFIG_UML_TIME_TRAVEL_SUPPORT */
+#endif /* CONFIG_UML_TIME_TRAVEL_SUPPORT */
 
 void _time_travel_print_bc_msg(void);
 static inline void time_travel_print_bc_msg(void)
diff --git a/arch/um/include/shared/user.h b/arch/um/include/shared/user.h
index bbab79c0c074..139eb78a4767 100644
--- a/arch/um/include/shared/user.h
+++ b/arch/um/include/shared/user.h
@@ -38,7 +38,7 @@ extern void panic(const char *fmt, ...)
 #define UM_KERN_DEBUG	KERN_DEBUG
 #define UM_KERN_CONT	KERN_CONT
 
-#ifdef UML_CONFIG_PRINTK
+#if IS_ENABLED(CONFIG_PRINTK)
 #define printk(...) _printk(__VA_ARGS__)
 extern int _printk(const char *fmt, ...)
 	__attribute__ ((format (printf, 1, 2)));