Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 96 insertions, 0 deletions

diff --git a/Documentation/arch/arm64/ptdump.rst b/Documentation/arch/arm64/ptdump.rst
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+======================
+Kernel page table dump
+======================
+
+ptdump is a debugfs interface that provides a detailed dump of the
+kernel page tables. It offers a comprehensive overview of the kernel
+virtual memory layout as well as the attributes associated with the
+various regions in a human-readable format. It is useful to dump the
+kernel page tables to verify permissions and memory types. Examining the
+page table entries and permissions helps identify potential security
+vulnerabilities such as mappings with overly permissive access rights or
+improper memory protections.
+
+Memory hotplug allows dynamic expansion or contraction of available
+memory without requiring a system reboot. To maintain the consistency
+and integrity of the memory management data structures, arm64 makes use
+of the ``mem_hotplug_lock`` semaphore in write mode. Additionally, in
+read mode, ``mem_hotplug_lock`` supports an efficient implementation of
+``get_online_mems()`` and ``put_online_mems()``. These protect the
+offlining of memory being accessed by the ptdump code.
+
+In order to dump the kernel page tables, enable the following
+configurations and mount debugfs::
+
+ CONFIG_GENERIC_PTDUMP=y
+ CONFIG_PTDUMP_CORE=y
+ CONFIG_PTDUMP_DEBUGFS=y
+
+ mount -t debugfs nodev /sys/kernel/debug
+ cat /sys/kernel/debug/kernel_page_tables
+
+On analysing the output of ``cat /sys/kernel/debug/kernel_page_tables``
+one can derive information about the virtual address range of the entry,
+followed by size of the memory region covered by this entry, the
+hierarchical structure of the page tables and finally the attributes
+associated with each page. The page attributes provide information about
+access permissions, execution capability, type of mapping such as leaf
+level PTE or block level PGD, PMD and PUD, and access status of a page
+within the kernel memory. Assessing these attributes can assist in
+understanding the memory layout, access patterns and security
+characteristics of the kernel pages.
+
+Kernel virtual memory layout example::
+
+ start address        end address         size             attributes
+ +---------------------------------------------------------------------------------------+
+ | ---[ Linear Mapping start ]---------------------------------------------------------- |
+ | ..................                                                                    |
+ | 0xfff0000000000000-0xfff0000000210000  2112K PTE RW NX SHD AF  UXN  MEM/NORMAL-TAGGED |
+ | 0xfff0000000210000-0xfff0000001c00000 26560K PTE ro NX SHD AF  UXN  MEM/NORMAL        |
+ | ..................                                                                    |
+ | ---[ Linear Mapping end ]------------------------------------------------------------ |
+ +---------------------------------------------------------------------------------------+
+ | ---[ Modules start ]----------------------------------------------------------------- |
+ | ..................                                                                    |
+ | 0xffff800000000000-0xffff800008000000   128M PTE                                      |
+ | ..................                                                                    |
+ | ---[ Modules end ]------------------------------------------------------------------- |
+ +---------------------------------------------------------------------------------------+
+ | ---[ vmalloc() area ]---------------------------------------------------------------- |
+ | ..................                                                                    |
+ | 0xffff800008010000-0xffff800008200000  1984K PTE ro x  SHD AF       UXN  MEM/NORMAL   |
+ | 0xffff800008200000-0xffff800008e00000    12M PTE ro x  SHD AF  CON  UXN  MEM/NORMAL   |
+ | ..................                                                                    |
+ | ---[ vmalloc() end ]----------------------------------------------------------------- |
+ +---------------------------------------------------------------------------------------+
+ | ---[ Fixmap start ]------------------------------------------------------------------ |
+ | ..................                                                                    |
+ | 0xfffffbfffdb80000-0xfffffbfffdb90000    64K PTE ro x  SHD AF  UXN  MEM/NORMAL        |
+ | 0xfffffbfffdb90000-0xfffffbfffdba0000    64K PTE ro NX SHD AF  UXN  MEM/NORMAL        |
+ | ..................                                                                    |
+ | ---[ Fixmap end ]-------------------------------------------------------------------- |
+ +---------------------------------------------------------------------------------------+
+ | ---[ PCI I/O start ]----------------------------------------------------------------- |
+ | ..................                                                                    |
+ | 0xfffffbfffe800000-0xfffffbffff800000    16M PTE                                      |
+ | ..................                                                                    |
+ | ---[ PCI I/O end ]------------------------------------------------------------------- |
+ +---------------------------------------------------------------------------------------+
+ | ---[ vmemmap start ]----------------------------------------------------------------- |
+ | ..................                                                                    |
+ | 0xfffffc0002000000-0xfffffc0002200000     2M PTE RW NX SHD AF  UXN  MEM/NORMAL        |
+ | 0xfffffc0002200000-0xfffffc0020000000   478M PTE                                      |
+ | ..................                                                                    |
+ | ---[ vmemmap end ]------------------------------------------------------------------- |
+ +---------------------------------------------------------------------------------------+
+
+``cat /sys/kernel/debug/kernel_page_tables`` output::
+
+ 0xfff0000001c00000-0xfff0000080000000     2020M PTE  RW NX SHD AF   UXN    MEM/NORMAL-TAGGED
+ 0xfff0000080000000-0xfff0000800000000       30G PMD
+ 0xfff0000800000000-0xfff0000800700000        7M PTE  RW NX SHD AF   UXN    MEM/NORMAL-TAGGED
+ 0xfff0000800700000-0xfff0000800710000       64K PTE  ro NX SHD AF   UXN    MEM/NORMAL-TAGGED
+ 0xfff0000800710000-0xfff0000880000000  2089920K PTE  RW NX SHD AF   UXN    MEM/NORMAL-TAGGED
+ 0xfff0000880000000-0xfff0040000000000     4062G PMD
+ 0xfff0040000000000-0xffff800000000000     3964T PGD