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
262e6ae708 ("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 055f23b74b ("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 ac3b432839 ("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 5409730962 ("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 ac3b432839 ("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
ee88d363d1 ("x86,static_call: Use alternative RET encoding").
I highlight this to reflect and clarify that we haven't seen more fallout
from ac3b432839 ("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 262e6ae708 ("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 055f23b74b
("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 ac3b432839
("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 5409730962
("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
ac3b432839 ("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 ee88d363d1 ("x86,static_call: Use alternative RET
encoding").
I highlight this to reflect and clarify that we haven't seen more
fallout from ac3b432839 ("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
Kernel test robot reported a kallsyms_test failure when clang lto is
enabled (thin or full) and CONFIG_KALLSYMS_SELFTEST is also enabled.
I can reproduce in my local environment with the following error message
with thin lto:
[ 1.877897] kallsyms_selftest: Test for 1750th symbol failed: (tsc_cs_mark_unstable) addr=ffffffff81038090
[ 1.877901] kallsyms_selftest: abort
It appears that commit 8cc32a9bbf ("kallsyms: strip LTO-only suffixes
from promoted global functions") caused the failure. Commit 8cc32a9bbf
changed cleanup_symbol_name() based on ".llvm." instead of '.' where
".llvm." is appended to a before-lto-optimization local symbol name.
We need to propagate such knowledge in kallsyms_selftest.c as well.
Further more, compare_symbol_name() in kallsyms.c needs change as well.
In scripts/kallsyms.c, kallsyms_names and kallsyms_seqs_of_names are used
to record symbol names themselves and index to symbol names respectively.
For example:
kallsyms_names:
...
__amd_smn_rw._entry <== seq 1000
__amd_smn_rw._entry.5 <== seq 1001
__amd_smn_rw.llvm.<hash> <== seq 1002
...
kallsyms_seqs_of_names are sorted based on cleanup_symbol_name() through, so
the order in kallsyms_seqs_of_names actually has
index 1000: seq 1002 <== __amd_smn_rw.llvm.<hash> (actual symbol comparison using '__amd_smn_rw')
index 1001: seq 1000 <== __amd_smn_rw._entry
index 1002: seq 1001 <== __amd_smn_rw._entry.5
Let us say at a particular point, at index 1000, symbol '__amd_smn_rw.llvm.<hash>'
is comparing to '__amd_smn_rw._entry' where '__amd_smn_rw._entry' is the one to
search e.g., with function kallsyms_on_each_match_symbol(). The current implementation
will find out '__amd_smn_rw._entry' is less than '__amd_smn_rw.llvm.<hash>' and
then continue to search e.g., index 999 and never found a match although the actual
index 1001 is a match.
To fix this issue, let us do cleanup_symbol_name() first and then do comparison.
In the above case, comparing '__amd_smn_rw' vs '__amd_smn_rw._entry' and
'__amd_smn_rw._entry' being greater than '__amd_smn_rw', the next comparison will
be > index 1000 and eventually index 1001 will be hit an a match is found.
For any symbols not having '.llvm.' substr, there is no functionality change
for compare_symbol_name().
Fixes: 8cc32a9bbf ("kallsyms: strip LTO-only suffixes from promoted global functions")
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202308232200.1c932a90-oliver.sang@intel.com
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Reviewed-by: Song Liu <song@kernel.org>
Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/r/20230825034659.1037627-1-yonghong.song@linux.dev
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
While debugging a recent kallsyms_selftest failure[1], I needed more
details on what specifically was failing. This adds those details for
each failure state that is checked.
[1] https://lore.kernel.org/all/202308232200.1c932a90-oliver.sang@intel.com/
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Yonghong Song <yhs@meta.com>
Cc: "Erhard F." <erhard_f@mailbox.org>
Cc: Zhen Lei <thunder.leizhen@huawei.com>
Cc: kernel test robot <oliver.sang@intel.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
The parameter 'struct module *' in the hook function associated with
{module_}kallsyms_on_each_symbol() is no longer used. Delete it.
Suggested-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
kallsyms_on_each* may schedule so must not be called with interrupts
disabled. The iteration function could disable interrupts, but this
also changes lookup_symbol() to match the change to the other timing
code.
Reported-by: Erhard F. <erhard_f@mailbox.org>
Link: https://lore.kernel.org/all/bug-216902-206035@https.bugzilla.kernel.org%2F/
Reported-by: kernel test robot <oliver.sang@intel.com>
Link: https://lore.kernel.org/oe-lkp/202212251728.8d0872ff-oliver.sang@intel.com
Fixes: 30f3bb0977 ("kallsyms: Add self-test facility")
Tested-by: "Erhard F." <erhard_f@mailbox.org>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Added test cases for basic functions and performance of functions
kallsyms_lookup_name(), kallsyms_on_each_symbol() and
kallsyms_on_each_match_symbol(). It also calculates the compression rate
of the kallsyms compression algorithm for the current symbol set.
The basic functions test begins by testing a set of symbols whose address
values are known. Then, traverse all symbol addresses and find the
corresponding symbol name based on the address. It's impossible to
determine whether these addresses are correct, but we can use the above
three functions along with the addresses to test each other. Due to the
traversal operation of kallsyms_on_each_symbol() is too slow, only 60
symbols can be tested in one second, so let it test on average once
every 128 symbols. The other two functions validate all symbols.
If the basic functions test is passed, print only performance test
results. If the test fails, print error information, but do not perform
subsequent performance tests.
Start self-test automatically after system startup if
CONFIG_KALLSYMS_SELFTEST=y.
Example of output content: (prefix 'kallsyms_selftest:' is omitted
start
---------------------------------------------------------
| nr_symbols | compressed size | original size | ratio(%) |
|---------------------------------------------------------|
| 107543 | 1357912 | 2407433 | 56.40 |
---------------------------------------------------------
kallsyms_lookup_name() looked up 107543 symbols
The time spent on each symbol is (ns): min=630, max=35295, avg=7353
kallsyms_on_each_symbol() traverse all: 11782628 ns
kallsyms_on_each_match_symbol() traverse all: 9261 ns
finish
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Linus Torvalds
Yonghong Song
Kees Cook
Zhen Lei
Nicholas Piggin
Yang Li