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335 Commits

Author SHA1 Message Date
fennecJ
377e63449b Remove kbleds from non-working list 
Since  has fixed the error with kbleds caused by changed timer API,
now it can work again with docker container.
 2021-09-12 11:47:00 +08:00
Jim Huang
c519f57403 Simplify the wording 2021-09-10 14:19:22 +00:00
Jim Huang
0400543038 Improve top-level documentation 
This patch introduced the changes:
- Build instructions
- Strip duplicated commands
- Add more hyperlinks
- Mention nerdctl as Docker CLI replacement
 2021-09-10 14:03:09 +00:00
linD026
62dbb1b7b8
Adapt the timer API Usage () 
Since v4.14 [1], the timer API has been changed to improve memory safety.
The series of improvements ended up at v4.15 [2].

Reference: https://lwn.net/Articles/735887/

Close 

[1] 686fef928b
[2] 841b86f328
 2021-09-10 12:29:48 +08:00
Kellegram
d5c43420c8
Workaround inconsistent text scaling () 
p + pre remains at em as we want to use the parent element here (however rem
could be used too, just requires a bigger value). I am setting it to 110% size,
otherwise some code blocks have relatively small text. The smaller code blocks
do appear bigger.
 2021-09-10 12:08:57 +08:00
Kellegram
3b9a3bd0b8
Improve readability () 
This new foreground + background color maintains the minimum of 7:1 contrast ratio as specified by WCAG (this has 7.36:1) and is the same colors Firefox reading mode uses when choosing the sepia theme. 

Fonts are too small by default, using responsive units (em) let's me increase them, I am unsure where or if there is font-size specified for parent anywhere but it seems to have been manually decreased.

Increased max-width slightly to adjust for new size and more standard line-height, so the doc doesn't feel significantly longer, still maintains good eye travel.
 2021-09-09 11:20:41 +08:00
Jim Huang
4ef3d90ffe suppress warning: no newline at end of file 2021-09-08 22:23:02 +08:00
fennecJ
3fcbb8e182
Improve CI pipeline to automate module testing () 
The script executes insmod/rmmod twice with available kernel modules.

Close
2021-09-08 20:38:50 +08:00
linD026
148fb013ee
Avoid unexpected concurrent access () 
In file {chardev,chardev2,sleep}.c, the variable to determine
the exclusive access was of integer type, which led to race
condition.

This patch rewrote the above with atomic CAS respectively
to eliminate the race.

Close
2021-09-07 23:42:06 +08:00
linD026
9289bfe59c
Fix the warnings raised by Sparse () 
Sparse[1] is a semantic parser, capable of finding out the potential
problems of Linux kernel code. This patch fixed the warnings.

[1] https://www.kernel.org/doc/html/latest/dev-tools/sparse.html
 2021-09-04 17:53:29 +08:00
Jim Huang
21ca08a17e
Merge pull request from ccs100203/master 
Fix Typo
 2021-09-03 23:13:10 +08:00
ccs100203
56c99328b3 Fix Typo 
from "mask" to "masks"
from "quick" to "quickly"
from "a" to "an"
 2021-09-03 23:02:17 +08:00
linD026
d27203ef46
Enforce consistent style for directory "other" () 2021-09-02 16:26:29 +08:00
linD026
eef2bc4395
Enforce Linux kernel coding style () 
The only exception is to indent with four spaces rather than tabs
for sticking to compact layout of source listing.

Close
2021-09-02 15:15:07 +08:00
Jim Huang
6110f8ee3c Rewrite the descriptions about bottom half 2021-09-01 12:07:25 +08:00
Jim Huang
5b953eea75
Merge pull request from linD026/master 
Fix typo
 2021-09-01 09:44:45 +08:00
linzhien
5cd96a80c9 Fix typo 2021-09-01 07:44:40 +08:00
fennecJ
0e11c00e1b
Add GitHub buttons in rendered HTML () 
GitHub buttons are rendered in the generated HTML:
one is GitHub project page; another is PDF download.

Close
2021-08-31 23:49:18 +08:00
linD026
cccc98ab2c
Fix disallowed cr0 write protection and close_fd () 
Since the commit 8dbec27a242cd3e2816eeb98d3237b9f57cf6232 [1]
(kernel version v5.3+ [2]) the sensitive CR0 bits in x86 is pinned,
we need to use the inline asm [3][4] to bypass it.

commit 8dbec27a242cd3e2816eeb98d3237b9f57cf6232 :
> With sensitive CR4 bits pinned now, it's possible that the WP bit for
> CR0 might become a target as well.
>
> Following the same reasoning for the CR4 pinning, pin CR0's WP
> bit. Contrary to the cpu feature dependend CR4 pinning this can be done
> with a constant value.

Also, getting "sys_call_table" [8] from the symbol lookup by using the address
of "close_fd" does not work for v5.11+ [5][6]. The reason is the entry of
"sys_call_table[__NR_close]" is not the address of "close_fd", actually
it is "__x64_sys_close" in x86.

Two solutions were proposed: using "kallsyms_lookup_name" [7] or just specifying
the address into the module. The symbol "kallsyms_lookup_name"  is unexported
since v5.7; the address of "sys_call_table" can be found in
"/boot/System.map" or "/proc/kallsyms".

Since v5.7, the manual symbol lookup is not guaranteed to work
because of control-flow integrity (or control-flow enforcement [9][10]) is added
[11] for x86, but it is disabled since v5.11 [12][13]. To make sure manual symbol
lookup work, it only uses up to v5.4.

Reference:
[1] 8dbec27a24
[2] https://outflux.net/blog/archives/2019/11/14/security-things-in-linux-v5-3/
[3] https://patchwork.kernel.org/project/linux-kbuild/patch/20200903203053.3411268-3-samitolvanen@google.com/
[4] https://stackoverflow.com/questions/58512430/how-to-write-to-protected-pages-in-the-linux-kernel
[5] https://lore.kernel.org/bpf/20201120231441.29911-21-ebiederm@xmission.com/
[6] https://lore.kernel.org/bpf/87blj83ysq.fsf@x220.int.ebiederm.org/
[7] 0bd476e6c6
[8] 8f27766a88
[9] https://lore.kernel.org/lkml/20200204171425.28073-1-yu-cheng.yu@intel.com/
[10] https://lore.kernel.org/linux-doc/20201110162211.9207-1-yu-cheng.yu@intel.com/T/
[11] 5790921bc1
[12] 20bf2b3787
[13] https://lore.kernel.org/bpf/20210128123842.c9e33949e62f504b84bfadf5@gmail.com/
 2021-08-31 11:07:01 +08:00
Jim Huang
d3bde7daed print_string: Validate tty before accessing its operations 
Close
2021-08-30 01:41:57 +08:00
Jim Huang
b990049715
Merge pull request from xatier/patch-1 
Update Arch Linux kernel headers information
 2021-08-26 11:14:11 +08:00
xatier
1f9f201940
Update Archlinux kernel headers instructions 
`linux-libre-headers` has been moved to AUR [1]. We can simply install `linux-headers` [2] instead.

[1] https://aur.archlinux.org/packages/linux-libre-headers/
[2] https://archlinux.org/packages/core/x86_64/linux-headers/
 2021-08-25 20:11:27 -07:00
linD026
06b75942cc
Fix incorrect major number registration in chardev () 
chardev2.c demonstrates the ioctl operation with static major
number MAJOR_NUM, but there also exists "Major," the dynamic
one, which results in registration and deregistration on different
device. Once the module remove, it cannot insert again:

  $ sudo insmod chardev2.ko
  $ sudo rmmod chardev2
  $ cat /proc/devices
  Character devices:
  ...
  100 char_dev
  $ sudo insmod chardev2.ko
  insmod: ERROR: could not insert module chardev2.ko: Device or resource busy

This patch removed the use of dynamic major number.
 2021-08-26 03:16:17 +08:00
Jim Huang
c97348d2d5
Merge pull request from tuckerpo/fix/errno_assignment 
Fix: errno assignment should be comparison.
 2021-08-24 23:22:32 +08:00
Tucker Polomik
a183cc72f0 Fix: errno assignment should be comparison. 2021-08-24 11:16:25 -04:00
Jim Huang
ecfe9606de Get rid of the initial 0 that shows up in every (sub)section 
Every section and subsection number can be eliminated by adding the
renewcommand.

Suggested by Lars Engebretsen.
 2021-08-24 19:02:16 +08:00
Jim Huang
9d39f658c7
Merge pull request from brdbkr/master 
Fixed typo
 2021-08-24 14:08:24 +08:00
Brad Baker
8012508508 Fixing typo 2021-08-24 00:15:47 -04:00
Jim Huang
fe3db9f939
Merge pull request from fennecJ/patch 
Adapt recent kernel changes
 2021-08-24 03:41:14 +08:00
fennecJ
870b26fa2d Update several example code for newer kernel 
Known issues with current example code:
If you using newer kernel(e.g linux 5.11.x) to compile the example code,
you may meet following error:
1. syscall.c:83:50: error: ‘ksys_close’ undeclared;
2. cryptosk.c:17:24: error: field ‘sg’ has incomplete type
3. cryptosk.c:143:9: error: implicit declaration of function
‘get_random_bytes’
4. error: macro "DECLARE_TASKLET" passed 3 arguments, but takes just 2

Solutions/workaround:
1. In syscall.c, replace #include <linux/syscalls.h> with
#include <linux/fdtable.h> and replace  ksys_close with close_fd
if the kernel version >= 5.11. [1][2]
2. Add #include <linux/scatterlist.h> into cryptosk.c
3. Add #include <linux/random.h> into cryptosk.c
4. In bottomhalf.c and example_tasklet.c, replace DECLARE_TASKLET
with DECLARE_TASKLET_OLD and dispose third argument(0L). [3]

[1] - https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1572bfdf21d4d50e51941498ffe0b56c2289f783
[2] - https://www.mail-archive.com/meta-arago@arago-project.org//msg11939.html
[3] - https://patchwork.kernel.org/project/kernel-hardening/patch/20200716030847.1564131-3-keescook@chromium.org/
 2021-08-23 21:30:43 +08:00
Jim Huang
bd8342bc14
Merge pull request from gagachang/master 
Update path to kernel v5.x
 2021-08-21 19:27:08 +08:00
gagachang
9827e32e4d Update some file path to kernel v5.x+ in example/kbleds.c 
1. drivers/char/vt_ioctl.c -> drivers/tty/vt/vt_ioctl.c
2. drivers/char/keyboard.c -> drivers/tty/vt/keyboard.c
 2021-08-21 14:51:37 +08:00
Jim Huang
22e50f3ce9 Use recent kernel build messages 2021-08-20 01:05:51 +08:00
Jim Huang
f7e2186e6b Revise the version magic descriptions for recent kernels 2021-08-20 01:02:20 +08:00
Jim Huang
3c742b0c7c Fix wording 2021-08-20 00:29:43 +08:00
Jim Huang
e47258cd19 Neither latexmk nor dvipng is required 
The package texlive-bin from extra also contains a dvipng binary.

Close
2021-08-18 20:43:51 +08:00
Jim Huang
9a19fde915
Merge pull request from fennecJ/master 
Add pdf download link in html only
 2021-08-17 17:37:08 +08:00
fennecj
fe8dd00e2c Add PDF download link in html only 
Close
2021-08-17 17:35:36 +08:00
Jim Huang
2db805da2c Check coding style in CI 2021-08-17 13:07:06 +08:00
Jim Huang
48cb100473
Merge pull request from CyrilBrulebois/master 
Proofreading and small improvements
 2021-08-17 08:56:55 +08:00
Cyril Brulebois
98aa78e4d2 Adjust link to ioctl-number.rst 2021-08-16 21:54:03 +02:00
Cyril Brulebois
c43c01db31 Improve wording (avoid a send/sent repetition along the way) 2021-08-16 21:54:03 +02:00
Cyril Brulebois
08b6de2cde Use an https:// link for LWN 2021-08-16 21:54:03 +02:00
Cyril Brulebois
8861d1ead7 Improve wording (statistics seem gathered, not stat-ed) 2021-08-16 21:54:03 +02:00
Cyril Brulebois
4d5649fc08 Improve wording (there's only one kernel) 2021-08-16 21:54:03 +02:00
Cyril Brulebois
3e05439b6d Add emphasis for the y/m values 2021-08-16 21:54:03 +02:00
Cyril Brulebois
b5ab7c5e88 Fix various typos 2021-08-16 21:54:03 +02:00
Cyril Brulebois
d85944d107 Mention pr_info() rather than KERN_INFO 
The latter might have been used along with printk() in an earlier
version, but pr_info() is getting used consistently so adjust the
#include comments accordingly.

For the avoidance of doubt, pr_info() actually comes from printk.h,
which gets #include'd by kernel.h.
 2021-08-16 21:53:22 +02:00
fennecJ
467cc83cc7
Improve the descriptions about reference count () 
The term "reference count" would be better than "use count."
In addition, the usage of module_refcount(THIS_MODULE) was appended
for the reference counter query.
 2021-08-17 00:23:22 +08:00
Jim Huang
53d071eb16
Merge pull request from fennecJ/patch2 
Fix typo
 2021-08-17 00:11:37 +08:00