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6ccdc91d6a
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Linus Torvalds 6ccdc91d6a x86: mm: remove architecture-specific 'access_ok()' define 
There's already a generic definition of 'access_ok()' in the
asm-generic/access_ok.h header file, and the only difference bwteen that
and the x86-specific one is the added check for WARN_ON_IN_IRQ().

And it turns out that the reason for that check is long gone: it used to
use a "user_addr_max()" inline function that depended on the current
thread, and caused problems in non-thread contexts.

For details, see commits 7c4788950b ("x86/uaccess, sched/preempt:
Verify access_ok() context") and in particular commit ae31fe51a3
("perf/x86: Restore TASK_SIZE check on frame pointer") about how and why
this came to be.

But that "current task" issue was removed in the big set_fs() removal by
Christoph Hellwig in commit 47058bb54b ("x86: remove address space
overrides using set_fs()").

So the reason for the test and the architecture-specific access_ok()
define no longer exists, and is actually harmful these days.  For
example, it led various 'copy_from_user_nmi()' games (eg using
__range_not_ok() instead, and then later converted to __access_ok() when
that became ok).

And that in turn meant that LAM was broken for the frame following
before this series, because __access_ok() used to not do the address
untagging.

Accessing user state still needs care in many contexts, but access_ok()
is not the place for this test.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Linus Torvalds torvalds@linux-foundation.org>
2023-05-03 10:37:22 -07:00
arch x86: mm: remove architecture-specific 'access_ok()' define 2023-05-03 10:37:22 -07:00
block Driver core changes for 6.4-rc1 2023-04-27 11:53:57 -07:00
certs KEYS: Add missing function documentation 2023-04-24 16:15:52 +03:00
crypto modules-6.4-rc1 2023-04-27 16:36:55 -07:00
Documentation Pin control bulk changes for the v6.4 kernel: 2023-05-02 15:40:41 -07:00
drivers Pin control bulk changes for the v6.4 kernel: 2023-05-02 15:40:41 -07:00
fs afs: Avoid endless loop if file is larger than expected 2023-05-02 17:23:50 +01:00
include VFIO updates for v6.4-rc1 2023-05-02 11:56:43 -07:00
init Objtool changes for v6.4: 2023-04-28 14:02:54 -07:00
io_uring Networking changes for 6.4. 2023-04-26 16:07:23 -07:00
ipc Merge branch 'work.namespace' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2023-02-24 19:20:07 -08:00
kernel IOMMU Updates for Linux 6.4 2023-04-30 13:00:38 -07:00
lib s390 updates for the 6.4 merge window 2023-04-30 11:43:31 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm x86-64: make access_ok() independent of LAM 2023-05-03 10:37:22 -07:00
net NFSD 6.4 Release Notes 2023-04-29 11:04:14 -07:00
rust Rust changes for v6.4 2023-04-30 11:20:22 -07:00
samples Rust changes for v6.4 2023-04-30 11:20:22 -07:00
scripts Kbuild updates for v6.4 2023-04-30 11:32:53 -07:00
security integrity-v6.4 2023-04-29 10:11:32 -07:00
sound Mainly singleton patches all over the place. Series of note are: 2023-04-27 19:57:00 -07:00
tools s390: 2023-05-01 12:06:20 -07:00
usr initramfs: Check negative timestamp to prevent broken cpio archive 2023-04-16 17:37:01 +09:00
virt s390: 2023-05-01 12:06:20 -07:00
.clang-format cxl for v6.4 2023-04-30 11:51:51 -07:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for *.dtso files 2023-02-26 15:28:23 +09:00
.gitignore linux-kselftest-kunit-6.4-rc1 2023-04-24 12:31:32 -07:00
.mailmap Mainly singleton patches all over the place. Series of note are: 2023-04-27 19:57:00 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS Char/Misc drivers for 6.4-rc1 2023-04-27 12:07:50 -07:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Pin control bulk changes for the v6.4 kernel: 2023-05-02 15:40:41 -07:00
Makefile Kbuild updates for v6.4 2023-04-30 11:32:53 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -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.

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.