kernel/linux.git/lib, branch v4.9.166

lib/int_sqrt: optimize small argument

2019-03-27T05:13:04+00:00

commit 3f3295709edea6268ff1609855f498035286af73 upstream. The current int_sqrt() computation is sub-optimal for the case of small @x. Which is the interesting case when we're going to do cumulative distribution functions on idle times, which we assume to be a random variable, where the target residency of the deepest idle state gives an upper bound on the variable (5e6ns on recent Intel chips). In the case of small @x, the compute loop: while (m != 0) { b = y + m; y >>= 1; if (x >= b) { x -= b; y += m; } m >>= 2; } can be reduced to: while (m > x) m >>= 2; Because y==0, b==m and until x>=m y will remain 0. And while this is computationally equivalent, it runs much faster because there's less code, in particular less branches. cycles: branches: branch-misses: OLD: hot: 45.109444 +- 0.044117 44.333392 +- 0.002254 0.018723 +- 0.000593 cold: 187.737379 +- 0.156678 44.333407 +- 0.002254 6.272844 +- 0.004305 PRE: hot: 67.937492 +- 0.064124 66.999535 +- 0.000488 0.066720 +- 0.001113 cold: 232.004379 +- 0.332811 66.999527 +- 0.000488 6.914634 +- 0.006568 POST: hot: 43.633557 +- 0.034373 45.333132 +- 0.002277 0.023529 +- 0.000681 cold: 207.438411 +- 0.125840 45.333132 +- 0.002277 6.976486 +- 0.004219 Averages computed over all values <128k using a LFSR to generate order. Cold numbers have a LFSR based branch trace buffer 'confuser' ran between each int_sqrt() invocation. Link: http://lkml.kernel.org/r/20171020164644.876503355@infradead.org Fixes: 30493cc9dddb ("lib/int_sqrt.c: optimize square root algorithm") Signed-off-by: Peter Zijlstra (Intel) Suggested-by: Anshul Garg Acked-by: Linus Torvalds Cc: Davidlohr Bueso Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Will Deacon Cc: Joe Perches Cc: David Miller Cc: Matthew Wilcox Cc: Kees Cook Cc: Michael Davidson Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Arnd Bergmann Signed-off-by: Greg Kroah-Hartman

assoc_array: Fix shortcut creation

2019-03-23T12:19:42+00:00

[ Upstream commit bb2ba2d75a2d673e76ddaf13a9bd30d6a8b1bb08 ] Fix the creation of shortcuts for which the length of the index key value is an exact multiple of the machine word size. The problem is that the code that blanks off the unused bits of the shortcut value malfunctions if the number of bits in the last word equals machine word size. This is due to the "<<" operator being given a shift of zero in this case, and so the mask that should be all zeros is all ones instead. This causes the subsequent masking operation to clear everything rather than clearing nothing. Ordinarily, the presence of the hash at the beginning of the tree index key makes the issue very hard to test for, but in this case, it was encountered due to a development mistake that caused the hash output to be either 0 (keyring) or 1 (non-keyring) only. This made it susceptible to the keyctl/unlink/valid test in the keyutils package. The fix is simply to skip the blanking if the shift would be 0. For example, an index key that is 64 bits long would produce a 0 shift and thus a 'blank' of all 1s. This would then be inverted and AND'd onto the index_key, incorrectly clearing the entire last word. Fixes: 3cb989501c26 ("Add a generic associative array implementation.") Signed-off-by: David Howells Signed-off-by: James Morris Signed-off-by: Sasha Levin

seq_buf: Make seq_buf_puts() null-terminate the buffer

2019-02-12T18:44:57+00:00

[ Upstream commit 0464ed24380905d640030d368cd84a4e4d1e15e2 ] Currently seq_buf_puts() will happily create a non null-terminated string for you in the buffer. This is particularly dangerous if the buffer is on the stack. For example: char buf[8]; char secret = "secret"; struct seq_buf s; seq_buf_init(&s, buf, sizeof(buf)); seq_buf_puts(&s, "foo"); printk("Message is %s\n", buf); Can result in: Message is fooªªªªªsecret We could require all users to memset() their buffer to zero before use. But that seems likely to be forgotten and lead to bugs. Instead we can change seq_buf_puts() to always leave the buffer in a null-terminated state. The only downside is that this makes the buffer 1 character smaller for seq_buf_puts(), but that seems like a good trade off. Link: http://lkml.kernel.org/r/20181019042109.8064-1-mpe@ellerman.id.au Acked-by: Kees Cook Signed-off-by: Michael Ellerman Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Sasha Levin

lib/interval_tree_test.c: allow users to limit scope of endpoint

2018-12-21T13:11:30+00:00

[ Upstream commit a8ec14d4f6aa8e245efacc992c8ee6ea0464ce2a ] Add a 'max_endpoint' parameter such that users may easily limit the size of the intervals that are randomly generated. Link: http://lkml.kernel.org/r/20170518174936.20265-4-dave@stgolabs.net Signed-off-by: Davidlohr Bueso Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

lib/rbtree-test: lower default params

2018-12-21T13:11:30+00:00

[ Upstream commit 0b548e33e6cb2bff240fdaf1783783be15c29080 ] Fengguang reported soft lockups while running the rbtree and interval tree test modules. The logic for these tests all occur in init phase, and we currently are pounding with the default values for number of nodes and number of iterations of each test. Reduce the latter by two orders of magnitude. This does not influence the value of the tests in that one thousand times by default is enough to get the picture. Link: http://lkml.kernel.org/r/20171109161715.xai2dtwqw2frhkcm@linux-n805 Signed-off-by: Davidlohr Bueso Reported-by: Fengguang Wu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

lib/rbtree_test.c: make input module parameters

2018-12-21T13:11:30+00:00

[ Upstream commit 223f8911eace60c787f8767c25148b80ece9732a ] Allows for more flexible debugging. Link: http://lkml.kernel.org/r/20170719014603.19029-5-dave@stgolabs.net Signed-off-by: Davidlohr Bueso Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

lib/interval_tree_test.c: allow full tree search

2018-12-21T13:11:30+00:00

[ Upstream commit c46ecce431ebe6b1a9551d1f530eb432dae5c39b ] ... such that a user can specify visiting all the nodes in the tree (intersects with the world). This is a nice opposite from the very basic default query which is a single point. Link: http://lkml.kernel.org/r/20170518174936.20265-5-dave@stgolabs.net Signed-off-by: Davidlohr Bueso Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

lib/interval_tree_test.c: make test options module parameters

2018-12-21T13:11:29+00:00

[ Upstream commit a54dae0338b7f01eb0f9c7571fb9b74f791d1c6b ] Allows for more flexible debugging. Link: http://lkml.kernel.org/r/20170518174936.20265-3-dave@stgolabs.net Signed-off-by: Davidlohr Bueso Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

debugobjects: avoid recursive calls with kmemleak

2018-12-17T08:38:35+00:00

[ Upstream commit 8de456cf87ba863e028c4dd01bae44255ce3d835 ] CONFIG_DEBUG_OBJECTS_RCU_HEAD does not play well with kmemleak due to recursive calls. fill_pool kmemleak_ignore make_black_object put_object __call_rcu (kernel/rcu/tree.c) debug_rcu_head_queue debug_object_activate debug_object_init fill_pool kmemleak_ignore make_black_object ... So add SLAB_NOLEAKTRACE to kmem_cache_create() to not register newly allocated debug objects at all. Link: http://lkml.kernel.org/r/20181126165343.2339-1-cai@gmx.us Signed-off-by: Qian Cai Suggested-by: Catalin Marinas Acked-by: Waiman Long Acked-by: Catalin Marinas Cc: Thomas Gleixner Cc: Yang Shi Cc: Arnd Bergmann Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

swiotlb: clean up reporting

2018-12-13T08:20:29+00:00

commit 7d63fb3af87aa67aa7d24466e792f9d7c57d8e79 upstream. This removes needless use of '%p', and refactors the printk calls to use pr_*() helpers instead. Signed-off-by: Kees Cook Reviewed-by: Konrad Rzeszutek Wilk Signed-off-by: Christoph Hellwig [bwh: Backported to 4.9: - Adjust filename - Remove "swiotlb: " prefix from an additional log message] Signed-off-by: Ben Hutchings Signed-off-by: Sasha Levin