Conceptually very similar to timingsafe_bcmp(), but with comparison
logic inspired by Elijah Stone's fancy memcmp. A baseline (SSE)
implementation was omitted this time as I was not able to get it to
perform adequately. Best I got was 8% over the scalar version for
long inputs, but slower for short inputs.
Sponsored by: The FreeBSD Foundation
Approved by: security (cperciva)
Inspired by: https://github.com/moon-chilled/fancy-memcmp
Differential Revision: https://reviews.freebsd.org/D41696
Very straightforward and similar to memcmp(3). The code has
been written to use only instructions specified as having
data operand independent timing by Intel.
Sponsored by: The FreeBSD Foundation
Approved by: security (cperciva)
Differential Revision: https://reviews.freebsd.org/D41673
POSIX has accepted a proposal[1] to add glibc-compatible ptsname_r. It
indicates an error by returning the error number, rather than returning
-1 and setting errno. Update RETURN VALUES in ptsname_r's man page now
to encourage folks to test that the return value != 0 rather than == -1.
[1] https://www.austingroupbugs.net/bug_view_page.php?bug_id=508
Reported by: Collin Funk
Reviewed by: kib
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D42204
The man page had `kern.ktrace.geniosize` but the sysctl node contains an
underscore.
PR: 274274
Reported by: Ivan Rozhuk
Sponsored by: The FreeBSD Foundation
The four functions more or less perform the same operation.
Reuse the same unit test with slight changes so we can cover
them all. Constant-time operation is not verified for the
timingsafe_* functions.
Sponsored by: The FreeBSD Foundation
Approved by: ngie
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D41528
Extend the tests to permit loading an external memcmp function
and testing it over using the libc version. This was added by the
example of other tests in the test suite doing the same thing and
helped tremendously in development.
This change was originally part of D41442 but was taken out to
permit separate review as extrapolated from @ngie's request in
D41349.
Sponsored by: FreeBSD Foundation
Approved by: ngie
Differential Revision: https://reviews.freebsd.org/D41528
Compiler memory barriers do not prevent the CPU from executing the code
out of order. Switch to C11 atomics. This also lets us get rid of the
mutex; instead, loop until the compare_exchange succeeds.
While here, change the return value of at_quick_exit() on failure to
the more traditional -1, matching atexit().
Sponsored by: Klara, Inc.
Reviewed by: Olivier Certner, kevans, kib
Differential Revision: https://reviews.freebsd.org/D41936
- cast GETNEXT to unsigned where it is being promoted to int to prevent
sign-extension (really it would have been better for PEEK*() and
GETNEXT() to return unsigned char; this would have removed a ton of
(uch) casts, but it is too intrusive for now).
- fix an isalpha that should have been iswalpha
PR: 264275, 274032
Reviewed by: kevans, eugen (previous version)
Obtained from: NetBSD
Differential Revision: https://reviews.freebsd.org/D41947
This extends the strcspn() unit tests to catch mistakes in the
implementation that only appear when a mismatch occurs in a certain
position of the string against a certain position of the set.
See also: 52d4a4d4e0
Sponsored by: The FreeBSD Foundation
Approved by: imp
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D41821
When memcmp(a, b, len) (or equally, bcmp) is called with a phony length
such that a + len < a, the code would malfunction and not compare the
two buffers correctly. While such arguments are illegal (buffers do not
wrap around the end of the address space), it is neverthless conceivable
that people try things like memcmp(a, b, SIZE_MAX) to compare a and b
until the first mismatch, in the knowledge that such a mismatch exists,
expecting memcmp() to stop comparing somewhere around the mismatch.
While memcmp() is usually written to confirm to this assumption, no
version of ISO/IEC 9899 guarantees this behaviour (in contrast to
memchr() for which it is).
Neverthless it appears sensible to at least not grossly misbehave on
phony lengths. This change hardens memcmp() against this case by
comparing at least until the end of the address space if a + len
overflows a 64 bit integer.
Sponsored by: The FreeBSD Foundation
Approved by: mjg (blanket, via IRC)
See also: b2618b651b
MFC after: 1 week
When a string is matched against a set of 17--32 characters, each chunk
of the string is matched first against the first 16 characters of the
set and then against the remaining characters. We also check at the
same time if the string has a nul byte in the current chunk, terminating
the search if it does.
Due to misconceived logic, the order of checks was "first half of set,
nul byte, second half of set", meaning that a match with the second half
of the set was ignored when the string ended in the same 16 bytes.
Reverse the order of checks to fix this problem.
Sponsored by: The FreeBSD Foundation
Approved by: mjg (blanket, via IRC)
MFC after: 1 week
MFC to: stable/14
When memchr(buf, c, len) is called with a phony len (say, SIZE_MAX),
buf + len overflows and we have buf + len < buf. This confuses the
implementation and makes it return incorrect results. Neverthless we
must support this case as memchr() is guaranteed to work even with
phony buffer lengths, as long as a match is found before the buffer
actually ends.
Sponsored by: The FreeBSD Foundation
Reported by: yuri, des
Tested by: des
Approved by: mjg (blanket, via IRC)
MFC after: 1 week
MFC to: stable/14
PR: 273652
Now that we have an optimised memchr(3), we can use it to implement
strnlen(3) with better perofrmance.
Sponsored by: The FreeBSD Foundation
Approved by: mjg
MFC after: 1 week
MFC to: stable/14
Differential Revision: https://reviews.freebsd.org/D41598
This is conceptually similar to strchr(3), but there are
slight changes to account for the buffer having an explicit
buffer length.
Sponsored by: The FreeBSD Foundation
Approved by: mjg
MFC after: 1 week
MFC to: stable/14
Differential Revision: https://reviews.freebsd.org/D41598
This is conceptually very similar to the strcspn(3) implementations
from D41557, but we can't do the fast paths the same way.
Sponsored by: The FreeBSD Foundation
Approved by: mjg
MFC after: 1 week
MFC to: stable/14
Differential Revision: https://reviews.freebsd.org/D41567
To cover the new optimised amd64 strspn(3) SIMD implementation, extend
the previously written strcspn(3) unit test to also cover strspn(3).
Sponsored by: The FreeBSD Foundation
Approved by: mjg
MFC after: 1 week
MFC to: stable/14
Differential Revision: https://reviews.freebsd.org/D41567
We currently use the NetBSD test suite to cover strcspn(3). It only
contains a very rudimentary test of this function. This all new set
of unit tests for the FreeBSD test suite should cover many more edge
cases relating to alignment issues.
Sponsored by: The FreeBSD Foundation
Approved by: mjg
MFC after: 1 week
MFC to: stable/14
Differential Revision: https://reviews.freebsd.org/D41557
This changeset adds both a scalar and an x86-64-v2 implementation
of the strcspn(3) function to libc. A baseline implementation does not
appear to be feasible given the requirements of the function.
The scalar implementation is similar to the generic libc implementation,
but expands the bit set into a byte set to reduce latency, improving
performance. This approach could probably be backported to the generic
C version to benefit other platforms.
The x86-64-v2 implementation is built around the infamous pcmpistri
instruction. An alternative implementation based on the Muła/Langdale
algorithm [1] was prototyped, but performed worse than the pcmpistri
approach except for sets of more than 16 characters with long input
strings.
All implementations provide special cases for the empty set (reduces to
strlen as well as single-character sets (reduces to strchr). The
x86-64-v2 kernel falls back to the scalar implementation for sets of
more than 32 characters. This limit could be raised by additional
multiples of 16 through the use of additional pcmpistri code paths, but
I consider this case to be too rare to be of importance.
[1]: http://0x80.pl/articles/simd-byte-lookup.html
Sponsored by: The FreeBSD Foundation
Approved by: mjg
MFC after: 1 week
MFC to: stable/14
Differential Revision: https://reviews.freebsd.org/D41557
This adds test cases for %wN and %wfN to the printf(3) and scanf(3) tests.
While here, fix a few nits in the N2630 test cases.
Reviewed by: imp
Differential Revision: https://reviews.freebsd.org/D41743
This adds specific width length modifiers in the form of wN and wfN (where N is 8, 16, 32, or 64) which allow printing intN_t and int_fastN_t without resorting to casts or PRI macros.
Reviewed by: imp, emaste
Differential Revision: https://reviews.freebsd.org/D41725
LIBCSRCDIR is defined in bsd.libnames.mk, which is read in later in the
Makefile than the line:
.if exists(${LIBCSRCDIR}/${MACHINE_ARCH})
so we test to see if /${MARCHIN_ARCH} exists which it usually doesn't
(but did for me since I mounted 13.2R SD image there). Move to defining
our own LIBC_SRCTOP in terms of SRCTOP to treat these uniformily.
Sponsored by: Netflix
Reviewed by: sjg
Differential Revision: https://reviews.freebsd.org/D41661
With the new simd-dispatch framework documented in simd(7),
add cross-references to the new man pages to appropriate places.
Sponsored by: The FreeBSD Foundation
Approved by: emaste
MFC to: stable/14
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D41697
While here, also update a mention of ANSI C.
Sponsored by: Klara, Inc.
Reviewed by: kevans, markj
Differential Revision: https://reviews.freebsd.org/D41686
This will enable alternative mallocs to be included in the tree and
selected by setting LIBC_MALLOC. As there is only one today (jemalloc)
this option does nothing, but we expect to add other implementations
in the future. This will also reduce diffs to CheriBSD.
Reviewed by: emaste
Differential Revision: https://reviews.freebsd.org/D41660
strverscmp(3) and versionsort(3) where first released in 13.2
PR: 273401
Reviewed by: kib
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D41617
