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daa22f5a78
Summary of the changes worth highlighting from most interesting to boring below:
* Christoph Hellwig's symbol_get() fix to Nvidia's efforts to circumvent the
protection he put in place in year 2020 to prevent proprietary modules from
using GPL only symbols, and also ensuring proprietary modules which export
symbols grandfather their taint. That was done through year 2020 commit
262e6ae7081d ("modules: inherit TAINT_PROPRIETARY_MODULE"). Christoph's new
fix is done by clarifing __symbol_get() was only ever intended to prevent
module reference loops by Linux kernel modules and so making it only find
symbols exported via EXPORT_SYMBOL_GPL(). The circumvention tactic used
by Nvidia was to use symbol_get() to purposely swift through proprietary
module symbols and completley bypass our traditional EXPORT_SYMBOL*()
annotations and community agreed upon restrictions.
A small set of preamble patches fix up a few symbols which just needed
adjusting for this on two modules, the rtc ds1685 and the networking enetc
module. Two other modules just needed some build fixing and removal of use
of __symbol_get() as they can't ever be modular, as was done by Arnd on
the ARM pxa module and Christoph did on the mmc au1xmmc driver.
This is a good reminder to us that symbol_get() is just a hack to address
things which should be fixed through Kconfig at build time as was done in
the later patches, and so ultimately it should just go.
* Extremely late minor fix for old module layout 055f23b74b20 ("module: check
for exit sections in layout_sections() instead of module_init_section()") by
James Morse for arm64. Note that this layout thing is old, it is *not*
Song Liu's commit ac3b43283923 ("module: replace module_layout with
module_memory"). The issue however is very odd to run into and so there was
no hurry to get this in fast.
* Although the fix did not go through the modules tree I'd like to highlight
the fix by Peter Zijlstra in commit 54097309620e ("x86/static_call: Fix
__static_call_fixup()") now merged in your tree which came out of what
was originally suspected to be a fallout of the the newer module layout
changes by Song Liu commit ac3b43283923 ("module: replace module_layout
with module_memory") instead of module_init_section()"). Thanks to the report
by Christian Bricart and the debugging by Song Liu & Peter that turned to
be noted as a kernel regression in place since v5.19 through commit
ee88d363d156 ("x86,static_call: Use alternative RET encoding").
I highlight this to reflect and clarify that we haven't seen more fallout
from ac3b43283923 ("module: replace module_layout with module_memory").
* RISC-V toolchain got mapping symbol support which prefix symbols with "$"
to help with alignment considerations for disassembly. This is used to
differentiate between incompatible instruction encodings when disassembling.
RISC-V just matches what ARM/AARCH64 did for alignment considerations and
Palmer Dabbelt extended is_mapping_symbol() to accept these symbols for
RISC-V. We already had support for this for all architectures but it also
checked for the second character, the RISC-V check Dabbelt added was just
for the "$". After a bit of testing and fallout on linux-next and based on
feedback from Masahiro Yamada it was decided to simplify the check and treat
the first char "$" as unique for all architectures, and so we no make
is_mapping_symbol() for all archs if the symbol starts with "$".
The most relevant commit for this for RISC-V on binutils was:
https://sourceware.org/pipermail/binutils/2021-July/117350.html
* A late fix by Andrea Righi (today) to make module zstd decompression use
vmalloc() instead of kmalloc() to account for large compressed modules. I
suspect we'll see similar things for other decompression algorithms soon.
* samples/hw_breakpoint minor fixes by Rong Tao, Arnd Bergmann and Chen Jiahao
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Merge tag 'modules-6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux
Pull modules updates from Luis Chamberlain:
"Summary of the changes worth highlighting from most interesting to
boring below:
- Christoph Hellwig's symbol_get() fix to Nvidia's efforts to
circumvent the protection he put in place in year 2020 to prevent
proprietary modules from using GPL only symbols, and also ensuring
proprietary modules which export symbols grandfather their taint.
That was done through year 2020 commit 262e6ae7081d ("modules:
inherit TAINT_PROPRIETARY_MODULE"). Christoph's new fix is done by
clarifing __symbol_get() was only ever intended to prevent module
reference loops by Linux kernel modules and so making it only find
symbols exported via EXPORT_SYMBOL_GPL(). The circumvention tactic
used by Nvidia was to use symbol_get() to purposely swift through
proprietary module symbols and completely bypass our traditional
EXPORT_SYMBOL*() annotations and community agreed upon
restrictions.
A small set of preamble patches fix up a few symbols which just
needed adjusting for this on two modules, the rtc ds1685 and the
networking enetc module. Two other modules just needed some build
fixing and removal of use of __symbol_get() as they can't ever be
modular, as was done by Arnd on the ARM pxa module and Christoph
did on the mmc au1xmmc driver.
This is a good reminder to us that symbol_get() is just a hack to
address things which should be fixed through Kconfig at build time
as was done in the later patches, and so ultimately it should just
go.
- Extremely late minor fix for old module layout 055f23b74b20
("module: check for exit sections in layout_sections() instead of
module_init_section()") by James Morse for arm64. Note that this
layout thing is old, it is *not* Song Liu's commit ac3b43283923
("module: replace module_layout with module_memory"). The issue
however is very odd to run into and so there was no hurry to get
this in fast.
- Although the fix did not go through the modules tree I'd like to
highlight the fix by Peter Zijlstra in commit 54097309620e
("x86/static_call: Fix __static_call_fixup()") now merged in your
tree which came out of what was originally suspected to be a
fallout of the the newer module layout changes by Song Liu commit
ac3b43283923 ("module: replace module_layout with module_memory")
instead of module_init_section()"). Thanks to the report by
Christian Bricart and the debugging by Song Liu & Peter that turned
to be noted as a kernel regression in place since v5.19 through
commit ee88d363d156 ("x86,static_call: Use alternative RET
encoding").
I highlight this to reflect and clarify that we haven't seen more
fallout from ac3b43283923 ("module: replace module_layout with
module_memory").
- RISC-V toolchain got mapping symbol support which prefix symbols
with "$" to help with alignment considerations for disassembly.
This is used to differentiate between incompatible instruction
encodings when disassembling. RISC-V just matches what ARM/AARCH64
did for alignment considerations and Palmer Dabbelt extended
is_mapping_symbol() to accept these symbols for RISC-V. We already
had support for this for all architectures but it also checked for
the second character, the RISC-V check Dabbelt added was just for
the "$". After a bit of testing and fallout on linux-next and based
on feedback from Masahiro Yamada it was decided to simplify the
check and treat the first char "$" as unique for all architectures,
and so we no make is_mapping_symbol() for all archs if the symbol
starts with "$".
The most relevant commit for this for RISC-V on binutils was:
https://sourceware.org/pipermail/binutils/2021-July/117350.html
- A late fix by Andrea Righi (today) to make module zstd
decompression use vmalloc() instead of kmalloc() to account for
large compressed modules. I suspect we'll see similar things for
other decompression algorithms soon.
- samples/hw_breakpoint minor fixes by Rong Tao, Arnd Bergmann and
Chen Jiahao"
* tag 'modules-6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux:
module/decompress: use vmalloc() for zstd decompression workspace
kallsyms: Add more debug output for selftest
ARM: module: Use module_init_layout_section() to spot init sections
arm64: module: Use module_init_layout_section() to spot init sections
module: Expose module_init_layout_section()
modules: only allow symbol_get of EXPORT_SYMBOL_GPL modules
rtc: ds1685: use EXPORT_SYMBOL_GPL for ds1685_rtc_poweroff
net: enetc: use EXPORT_SYMBOL_GPL for enetc_phc_index
mmc: au1xmmc: force non-modular build and remove symbol_get usage
ARM: pxa: remove use of symbol_get()
samples/hw_breakpoint: mark sample_hbp as static
samples/hw_breakpoint: fix building without module unloading
samples/hw_breakpoint: Fix kernel BUG 'invalid opcode: 0000'
modpost, kallsyms: Treat add '$'-prefixed symbols as mapping symbols
kernel: params: Remove unnecessary ‘0’ values from err
module: Ignore RISC-V mapping symbols too
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.