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Michael Ellerman 434551e9fd powerpc/mm/radix: Fix off-by-one in split mapping logic 
[ Upstream commit 5c6499b704 ]

When we have CONFIG_STRICT_KERNEL_RWX enabled, we try to split the
kernel linear (1:1) mapping so that the kernel text is in a separate
page to kernel data, so we can mark the former read-only.

We could achieve that just by always using 64K pages for the linear
mapping, but we try to be smarter. Instead we use huge pages when
possible, and only switch to smaller pages when necessary.

However we have an off-by-one bug in that logic, which causes us to
calculate the wrong boundary between text and data.

For example with the end of the kernel text at 16M we see:

  radix-mmu: Mapped 0x0000000000000000-0x0000000001200000 with 64.0 KiB pages
  radix-mmu: Mapped 0x0000000001200000-0x0000000040000000 with 2.00 MiB pages
  radix-mmu: Mapped 0x0000000040000000-0x0000000100000000 with 1.00 GiB pages

ie. we mapped from 0 to 18M with 64K pages, even though the boundary
between text and data is at 16M.

With the fix we see we're correctly hitting the 16M boundary:

  radix-mmu: Mapped 0x0000000000000000-0x0000000001000000 with 64.0 KiB pages
  radix-mmu: Mapped 0x0000000001000000-0x0000000040000000 with 2.00 MiB pages
  radix-mmu: Mapped 0x0000000040000000-0x0000000100000000 with 1.00 GiB pages

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-12-01 09:16:44 +01:00
arch powerpc/mm/radix: Fix off-by-one in split mapping logic 2019-12-01 09:16:44 +01:00
block blok, bfq: do not plug I/O if all queues are weight-raised 2019-11-20 18:46:44 +01:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto crypto: testmgr - fix sizeof() on COMP_BUF_SIZE 2019-12-01 09:16:13 +01:00
Documentation net: phy: mdio-bcm-unimac: Allow configuring MDIO clock divider 2019-11-20 18:47:14 +01:00
drivers scsi: hisi_sas: Fix NULL pointer dereference 2019-12-01 09:16:44 +01:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs xfs: clear ail delwri queued bufs on unmount of shutdown fs 2019-12-01 09:16:34 +01:00
include cpuidle: menu: Fix wakeup statistics updates for polling state 2019-11-24 08:20:07 +01:00
init initramfs: don't free a non-existent initrd 2019-10-01 08:26:09 +02:00
ipc ipc/mqueue.c: only perform resource calculation if user valid 2019-08-06 19:06:52 +02:00
kernel swiotlb: do not panic on mapping failures 2019-12-01 09:16:42 +01:00
lib idr: Fix idr_get_next race with idr_remove 2019-11-24 08:19:11 +01:00
LICENSES LICENSES: Remove CC-BY-SA-4.0 license text 2018-10-18 11:28:50 +02:00
mm mm/ksm.c: don't WARN if page is still mapped in remove_stable_node() 2019-12-01 09:16:11 +01:00
net sunrpc: safely reallow resvport min/max inversion 2019-12-01 09:16:41 +01:00
samples mei: samples: fix a signedness bug in amt_host_if_call() 2019-11-24 08:19:50 +01:00
scripts scripts/setlocalversion: Improve -dirty check with git-status --no-optional-locks 2019-11-06 13:05:27 +01:00
security ima: fix freeing ongoing ahash_request 2019-10-11 18:21:11 +02:00
sound ALSA: i2c/cs8427: Fix int to char conversion 2019-12-01 09:16:36 +01:00
tools selftests/bpf: fix file resource leak in load_kallsyms 2019-12-01 09:16:40 +01:00
usr kbuild: clean compressed initramfs image 2019-10-07 18:57:16 +02:00
virt kvm: arm/arm64: Fix stage2_flush_memslot for 4 level page table 2019-11-24 08:19:31 +01:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap libnvdimm-for-4.19_misc 2018-08-25 18:13:10 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS USB: rio500: Remove Rio 500 kernel driver 2019-10-17 13:44:47 -07:00
Makefile Linux 4.19.86 2019-11-24 08:21:09 +01:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.