Commit 8d4826cc8a ("vsnprintf: collapse the number format state into
one single state") changed the format specification decoding to be a bit
more straightforward but in the process ended up also resetting the
number base to zero for formats that aren't clearly numerical.
Now, the number base obviously doesn't matter for something like '%s',
so this wasn't all that obvious. But some of our specialized pointer
extension formatting (ie, things like "print out IPv6 address") did up
depending on the default base-10 setting, and when they then tried to
print out numbers in "base zero", things didn't work out so well.
Most pointer formatting (including things like the default raw hex value
conversion) didn't have this issue, because they used helpers that
explicitly set the base.
Reported-and-tested-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202501131352.e226f995-lkp@intel.com
Fixes: 8d4826cc8a ("vsnprintf: collapse the number format state into one single state")
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Stephen Rothwell reports that I missed fixing up the documentation when
the argument names changed in commit 938df695e9 ("vsprintf: associate
the format state with the format pointer"), resulting in htmldoc
warnings like
lib/vsprintf.c:2760: warning: Function parameter or struct member 'fmt_str' not described in 'vsnprintf'
lib/vsprintf.c:2760: warning: Excess function parameter 'fmt' description in 'vsnprintf'
...
which I didn't notice because the doc build takes longer than the whole
"real" kernel build for me, so I never bother (and judging by the other
warnings, pretty much nobody else does either).
I guess the bigger issues won't be fixed until the doc build is much
faster (narrator: "That isn's in the cards") but at least linux-next
finds the new cases.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Fixes: 938df695e9 ("vsprintf: associate the format state with the format pointer")
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The strange vbin_printf / bstr_printf interface used to save one- and
two-byte printf numerical arguments into their packed format.
That's more than a bit strange since the argument buffer is supposed to
be an array of 'u32' words, and it's also very different from how the
source of the data (varargs) work - which always do the normal integer
type conversions, so 'char' and 'short' are always passed as int-sized
anyway.
This odd packing causes extra code complexity, and it really isn't worth
it, since the space savings are simply not there: it only happens for
formats like '%hd' (short) and '%hhd' (char), which are very rare
indeed.
In fact, the only other user of this interface seems to be the bpf
helper code (bpf_bprintf_prepare()), and Alexei points out that that
case doesn't support those truncated integer formatting options at all
in the first place.
As a result, bpf_bprintf_prepare() doesn't need any changes for this,
and TRACE_BPRINT uses 'vbin_printf()' -> 'bstr_printf()' for the
formatting and hopefully doesn't expose the odd packing any other way
(knock wood).
Link: https://lore.kernel.org/all/CAADnVQJy65oOubjxM-378O3wDfhuwg8TGa9hc-cTv6NmmUSykQ@mail.gmail.com/
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We'll squirrel away the size of the number in 'struct fmt' instead.
We have two fairly separate state structures: the 'decode state' is in
'struct fmt', while the 'printout format' is in 'printf_spec'. Both
structures are small enough to pass around in registers even across
function boundaries (ie two words), even on 32-bit machines.
The goal here is to avoid the case statements on the format states,
which generate either deep conditionals or jump tables, while also
keeping the state size manageable.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Make the format_decode() code generation easier to look at by getting
the strange and unlikely cases out of line.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
At some point skip_atoi() had been marked 'noinline_for_stack', but it
turns out that this is now a pessimization, and not inlining it actually
results in a stack frame in format decoding due to the call and thus
hurts stack usage rather than helping.
With the simplistic atoi function inlined, the format decoding now needs
no frame at all.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We did the flags as an array earlier, they had simpler rules. The final
format specifiers are a bit more complex since they have more fields to
deal with, and we want to handle the length modifiers at the same time.
But like the flags, we're better off just making it a data-driven table
rather than some case statement.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Rather than a case statement, just look up the printf format flags
(justification, zero-padding etc) using a small table.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The vsnprintf() code is written as a state machine as it walks the
format pointer, but for various historical reasons the state is oddly
named and was encoded as the 'type' field in the 'struct printf_spec'.
That naming came from the fact that the states used to not just encode
the state of the state machine, but also the various integer types that
would then be printed out.
Let's make the state machine more obvious, and actually call it 'state',
and associate it with the format pointer itself, rather than the
'printf_spec' that contains the currently decoded formatting specs.
This also removes the bit packing from printf_spec, which makes it much
easier on the compiler.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Every single caller wants to know what the next format location is, but
instead the function returned the length of the processed part and so
every single return statement in the format_decode() function was
instead subtracting the start of the format string.
The callers that that did want to know the length (in addition to the
end of the format processing) already had to save off the start of the
format string anyway. So this was all just doing extra processing both
on the caller and callee sides.
Just change the calling convention to return the end of the format
processing, making everything simpler (and preparing for yet more
simplification to come).
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now that we have simplified the number format types, the top-level
switch table can easily just handle all the remaining cases, and we
don't need to have a case statement with a conditional on the same
expression as the switch statement.
We do want to fall through to the common 'number()' case, but that's
trivially done by making the other case statements use 'continue'
instead of 'break'. They are just looping back to the top, after all.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Instead of dealing with all the different special types (size_t,
unsigned char, ptrdiff_t..) just deal with the size of the integer type
and the sign.
This avoids a lot of unnecessary case statements, and the games we play
with the value of the 'SIGN' flags value
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
asm/unaligned.h is always an include of asm-generic/unaligned.h;
might as well move that thing to linux/unaligned.h and include
that - there's nothing arch-specific in that header.
auto-generated by the following:
for i in `git grep -l -w asm/unaligned.h`; do
sed -i -e "s/asm\/unaligned.h/linux\/unaligned.h/" $i
done
for i in `git grep -l -w asm-generic/unaligned.h`; do
sed -i -e "s/asm-generic\/unaligned.h/linux\/unaligned.h/" $i
done
git mv include/asm-generic/unaligned.h include/linux/unaligned.h
git mv tools/include/asm-generic/unaligned.h tools/include/linux/unaligned.h
sed -i -e "/unaligned.h/d" include/asm-generic/Kbuild
sed -i -e "s/__ASM_GENERIC/__LINUX/" include/linux/unaligned.h tools/include/linux/unaligned.h
We only had a couple of array[] declarations, and changing them to just
use 'MAX()' instead of 'max()' fixes the issue.
This will allow us to simplify our min/max macros enormously, since they
can now unconditionally use temporary variables to avoid using the
argument values multiple times.
Cc: David Laight <David.Laight@aculab.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
A refcount issue can appeared in __fwnode_link_del() due to the
pr_debug() call:
WARNING: CPU: 0 PID: 901 at lib/refcount.c:25 refcount_warn_saturate+0xe5/0x110
Call Trace:
<TASK>
...
of_node_get+0x1e/0x30
of_fwnode_get+0x28/0x40
fwnode_full_name_string+0x34/0x90
fwnode_string+0xdb/0x140
...
vsnprintf+0x17b/0x630
...
__fwnode_link_del+0x25/0xa0
fwnode_links_purge+0x39/0xb0
of_node_release+0xd9/0x180
...
Indeed, an fwnode (of_node) is being destroyed and so, of_node_release()
is called because the of_node refcount reached 0.
From of_node_release() several function calls are done and lead to
a pr_debug() calls with %pfwf to print the fwnode full name.
The issue is not present if we change %pfwf to %pfwP.
To print the full name, %pfwf iterates over the current node and its
parents and obtain/drop a reference to all nodes involved.
In order to allow to print the full name (%pfwf) of a node while it is
being destroyed, do not obtain/drop a reference to this current node.
Fixes: a92eb7621b ("lib/vsprintf: Make use of fwnode API to obtain node names and separators")
Cc: stable@vger.kernel.org
Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20231114152655.409331-1-herve.codina@bootlin.com
* uninline simple_strntoull(),
gcc overinlines and this function is not performance critical
* reorder arguments, so that appending INT_MAX as 4th argument
generates very efficient tail call
Space savings:
add/remove: 1/0 grow/shrink: 0/3 up/down: 27/-179 (-152)
Function old new delta
simple_strntoll - 27 +27
simple_strtoull 15 10 -5
simple_strtoll 41 7 -34
vsscanf 1930 1790 -140
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/all/82a2af6e-9b6c-4a09-89d7-ca90cc1cdad1@p183/
Pull MM updates from Andrew Morton:
- Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of
switching from a user process to a kernel thread.
- More folio conversions from Kefeng Wang, Zhang Peng and Pankaj
Raghav.
- zsmalloc performance improvements from Sergey Senozhatsky.
- Yue Zhao has found and fixed some data race issues around the
alteration of memcg userspace tunables.
- VFS rationalizations from Christoph Hellwig:
- removal of most of the callers of write_one_page()
- make __filemap_get_folio()'s return value more useful
- Luis Chamberlain has changed tmpfs so it no longer requires swap
backing. Use `mount -o noswap'.
- Qi Zheng has made the slab shrinkers operate locklessly, providing
some scalability benefits.
- Keith Busch has improved dmapool's performance, making part of its
operations O(1) rather than O(n).
- Peter Xu adds the UFFD_FEATURE_WP_UNPOPULATED feature to userfaultd,
permitting userspace to wr-protect anon memory unpopulated ptes.
- Kirill Shutemov has changed MAX_ORDER's meaning to be inclusive
rather than exclusive, and has fixed a bunch of errors which were
caused by its unintuitive meaning.
- Axel Rasmussen give userfaultfd the UFFDIO_CONTINUE_MODE_WP feature,
which causes minor faults to install a write-protected pte.
- Vlastimil Babka has done some maintenance work on vma_merge():
cleanups to the kernel code and improvements to our userspace test
harness.
- Cleanups to do_fault_around() by Lorenzo Stoakes.
- Mike Rapoport has moved a lot of initialization code out of various
mm/ files and into mm/mm_init.c.
- Lorenzo Stoakes removd vmf_insert_mixed_prot(), which was added for
DRM, but DRM doesn't use it any more.
- Lorenzo has also coverted read_kcore() and vread() to use iterators
and has thereby removed the use of bounce buffers in some cases.
- Lorenzo has also contributed further cleanups of vma_merge().
- Chaitanya Prakash provides some fixes to the mmap selftesting code.
- Matthew Wilcox changes xfs and afs so they no longer take sleeping
locks in ->map_page(), a step towards RCUification of pagefaults.
- Suren Baghdasaryan has improved mmap_lock scalability by switching to
per-VMA locking.
- Frederic Weisbecker has reworked the percpu cache draining so that it
no longer causes latency glitches on cpu isolated workloads.
- Mike Rapoport cleans up and corrects the ARCH_FORCE_MAX_ORDER Kconfig
logic.
- Liu Shixin has changed zswap's initialization so we no longer waste a
chunk of memory if zswap is not being used.
- Yosry Ahmed has improved the performance of memcg statistics
flushing.
- David Stevens has fixed several issues involving khugepaged,
userfaultfd and shmem.
- Christoph Hellwig has provided some cleanup work to zram's IO-related
code paths.
- David Hildenbrand has fixed up some issues in the selftest code's
testing of our pte state changing.
- Pankaj Raghav has made page_endio() unneeded and has removed it.
- Peter Xu contributed some rationalizations of the userfaultfd
selftests.
- Yosry Ahmed has fixed an issue around memcg's page recalim
accounting.
- Chaitanya Prakash has fixed some arm-related issues in the
selftests/mm code.
- Longlong Xia has improved the way in which KSM handles hwpoisoned
pages.
- Peter Xu fixes a few issues with uffd-wp at fork() time.
- Stefan Roesch has changed KSM so that it may now be used on a
per-process and per-cgroup basis.
* tag 'mm-stable-2023-04-27-15-30' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (369 commits)
mm,unmap: avoid flushing TLB in batch if PTE is inaccessible
shmem: restrict noswap option to initial user namespace
mm/khugepaged: fix conflicting mods to collapse_file()
sparse: remove unnecessary 0 values from rc
mm: move 'mmap_min_addr' logic from callers into vm_unmapped_area()
hugetlb: pte_alloc_huge() to replace huge pte_alloc_map()
maple_tree: fix allocation in mas_sparse_area()
mm: do not increment pgfault stats when page fault handler retries
zsmalloc: allow only one active pool compaction context
selftests/mm: add new selftests for KSM
mm: add new KSM process and sysfs knobs
mm: add new api to enable ksm per process
mm: shrinkers: fix debugfs file permissions
mm: don't check VMA write permissions if the PTE/PMD indicates write permissions
migrate_pages_batch: fix statistics for longterm pin retry
userfaultfd: use helper function range_in_vma()
lib/show_mem.c: use for_each_populated_zone() simplify code
mm: correct arg in reclaim_pages()/reclaim_clean_pages_from_list()
fs/buffer: convert create_page_buffers to folio_create_buffers
fs/buffer: add folio_create_empty_buffers helper
...
%pGp format is used to display 'flags' field of a struct page. However,
some page flags (i.e. PG_buddy, see page-flags.h for more details) are
stored in page_type field. To display human-readable output of page_type,
introduce %pGt format.
It is important to note the meaning of bits are different in page_type.
if page_type is 0xffffffff, no flags are set. Setting PG_buddy
(0x00000080) flag results in a page_type of 0xffffff7f. Clearing a bit
actually means setting a flag. Bits in page_type are inverted when
displaying type names.
Only values for which page_type_has_type() returns true are considered as
page_type, to avoid confusion with mapcount values. if it returns false,
only raw values are displayed and not page type names.
Link: https://lkml.kernel.org/r/20230130042514.2418-3-42.hyeyoo@gmail.com
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Reviewed-by: Petr Mladek <pmladek@suse.com> [vsprintf part]
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
