Merge branch 'akpm' (patches from Andrew)

Merge even more updates from Andrew Morton:

 - a kernel-wide sweep of show_stack()

 - pagetable cleanups

 - abstract out accesses to mmap_sem - prep for mmap_sem scalability work

 - hch's user acess work

Subsystems affected by this patch series: debug, mm/pagemap, mm/maccess,
mm/documentation.

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (93 commits)
  include/linux/cache.h: expand documentation over __read_mostly
  maccess: return -ERANGE when probe_kernel_read() fails
  x86: use non-set_fs based maccess routines
  maccess: allow architectures to provide kernel probing directly
  maccess: move user access routines together
  maccess: always use strict semantics for probe_kernel_read
  maccess: remove strncpy_from_unsafe
  tracing/kprobes: handle mixed kernel/userspace probes better
  bpf: rework the compat kernel probe handling
  bpf:bpf_seq_printf(): handle potentially unsafe format string better
  bpf: handle the compat string in bpf_trace_copy_string better
  bpf: factor out a bpf_trace_copy_string helper
  maccess: unify the probe kernel arch hooks
  maccess: remove probe_read_common and probe_write_common
  maccess: rename strnlen_unsafe_user to strnlen_user_nofault
  maccess: rename strncpy_from_unsafe_strict to strncpy_from_kernel_nofault
  maccess: rename strncpy_from_unsafe_user to strncpy_from_user_nofault
  maccess: update the top of file comment
  maccess: clarify kerneldoc comments
  maccess: remove duplicate kerneldoc comments
  ...

1 files changed, 122 insertions, 6 deletions

diff --git a/include/asm-generic/pgtable.h b/include/linux/pgtable.h
index 0a9329656ae6..32b6c52d41b9 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/linux/pgtable.h
@@ -1,8 +1,9 @@
 /* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _ASM_GENERIC_PGTABLE_H
-#define _ASM_GENERIC_PGTABLE_H
+#ifndef _LINUX_PGTABLE_H
+#define _LINUX_PGTABLE_H
 
 #include <linux/pfn.h>
+#include <asm/pgtable.h>
 
 #ifndef __ASSEMBLY__
 #ifdef CONFIG_MMU
@@ -27,6 +28,121 @@
 #define USER_PGTABLES_CEILING	0UL
 #endif
 
+/*
+ * A page table page can be thought of an array like this: pXd_t[PTRS_PER_PxD]
+ *
+ * The pXx_index() functions return the index of the entry in the page
+ * table page which would control the given virtual address
+ *
+ * As these functions may be used by the same code for different levels of
+ * the page table folding, they are always available, regardless of
+ * CONFIG_PGTABLE_LEVELS value. For the folded levels they simply return 0
+ * because in such cases PTRS_PER_PxD equals 1.
+ */
+
+static inline unsigned long pte_index(unsigned long address)
+{
+	return (address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
+}
+
+#ifndef pmd_index
+static inline unsigned long pmd_index(unsigned long address)
+{
+	return (address >> PMD_SHIFT) & (PTRS_PER_PMD - 1);
+}
+#define pmd_index pmd_index
+#endif
+
+#ifndef pud_index
+static inline unsigned long pud_index(unsigned long address)
+{
+	return (address >> PUD_SHIFT) & (PTRS_PER_PUD - 1);
+}
+#define pud_index pud_index
+#endif
+
+#ifndef pgd_index
+/* Must be a compile-time constant, so implement it as a macro */
+#define pgd_index(a)  (((a) >> PGDIR_SHIFT) & (PTRS_PER_PGD - 1))
+#endif
+
+#ifndef pte_offset_kernel
+static inline pte_t *pte_offset_kernel(pmd_t *pmd, unsigned long address)
+{
+	return (pte_t *)pmd_page_vaddr(*pmd) + pte_index(address);
+}
+#define pte_offset_kernel pte_offset_kernel
+#endif
+
+#if defined(CONFIG_HIGHPTE)
+#define pte_offset_map(dir, address)				\
+	((pte_t *)kmap_atomic(pmd_page(*(dir))) +		\
+	 pte_index((address)))
+#define pte_unmap(pte) kunmap_atomic((pte))
+#else
+#define pte_offset_map(dir, address)	pte_offset_kernel((dir), (address))
+#define pte_unmap(pte) ((void)(pte))	/* NOP */
+#endif
+
+/* Find an entry in the second-level page table.. */
+#ifndef pmd_offset
+static inline pmd_t *pmd_offset(pud_t *pud, unsigned long address)
+{
+	return (pmd_t *)pud_page_vaddr(*pud) + pmd_index(address);
+}
+#define pmd_offset pmd_offset
+#endif
+
+#ifndef pud_offset
+static inline pud_t *pud_offset(p4d_t *p4d, unsigned long address)
+{
+	return (pud_t *)p4d_page_vaddr(*p4d) + pud_index(address);
+}
+#define pud_offset pud_offset
+#endif
+
+static inline pgd_t *pgd_offset_pgd(pgd_t *pgd, unsigned long address)
+{
+	return (pgd + pgd_index(address));
+};
+
+/*
+ * a shortcut to get a pgd_t in a given mm
+ */
+#ifndef pgd_offset
+#define pgd_offset(mm, address)		pgd_offset_pgd((mm)->pgd, (address))
+#endif
+
+/*
+ * a shortcut which implies the use of the kernel's pgd, instead
+ * of a process's
+ */
+#define pgd_offset_k(address)		pgd_offset(&init_mm, (address))
+
+/*
+ * In many cases it is known that a virtual address is mapped at PMD or PTE
+ * level, so instead of traversing all the page table levels, we can get a
+ * pointer to the PMD entry in user or kernel page table or translate a virtual
+ * address to the pointer in the PTE in the kernel page tables with simple
+ * helpers.
+ */
+static inline pmd_t *pmd_off(struct mm_struct *mm, unsigned long va)
+{
+	return pmd_offset(pud_offset(p4d_offset(pgd_offset(mm, va), va), va), va);
+}
+
+static inline pmd_t *pmd_off_k(unsigned long va)
+{
+	return pmd_offset(pud_offset(p4d_offset(pgd_offset_k(va), va), va), va);
+}
+
+static inline pte_t *virt_to_kpte(unsigned long vaddr)
+{
+	pmd_t *pmd = pmd_off_k(vaddr);
+
+	return pmd_none(*pmd) ? NULL : pte_offset_kernel(pmd, vaddr);
+}
+
 #ifndef __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
 extern int ptep_set_access_flags(struct vm_area_struct *vma,
 				 unsigned long address, pte_t *ptep,
@@ -1018,11 +1134,11 @@ static inline pmd_t pmd_read_atomic(pmd_t *pmdp)
 #endif
 /*
  * This function is meant to be used by sites walking pagetables with
- * the mmap_sem hold in read mode to protect against MADV_DONTNEED and
+ * the mmap_lock held in read mode to protect against MADV_DONTNEED and
  * transhuge page faults. MADV_DONTNEED can convert a transhuge pmd
  * into a null pmd and the transhuge page fault can convert a null pmd
  * into an hugepmd or into a regular pmd (if the hugepage allocation
- * fails). While holding the mmap_sem in read mode the pmd becomes
+ * fails). While holding the mmap_lock in read mode the pmd becomes
  * stable and stops changing under us only if it's not null and not a
  * transhuge pmd. When those races occurs and this function makes a
  * difference vs the standard pmd_none_or_clear_bad, the result is
@@ -1032,7 +1148,7 @@ static inline pmd_t pmd_read_atomic(pmd_t *pmdp)
  *
  * For 32bit kernels with a 64bit large pmd_t this automatically takes
  * care of reading the pmd atomically to avoid SMP race conditions
- * against pmd_populate() when the mmap_sem is hold for reading by the
+ * against pmd_populate() when the mmap_lock is hold for reading by the
  * caller (a special atomic read not done by "gcc" as in the generic
  * version above, is also needed when THP is disabled because the page
  * fault can populate the pmd from under us).
@@ -1319,4 +1435,4 @@ typedef unsigned int pgtbl_mod_mask;
 #define pmd_leaf(x)	0
 #endif
 
-#endif /* _ASM_GENERIC_PGTABLE_H */
+#endif /* _LINUX_PGTABLE_H */