From 29ce50e078b857977202205394f200a25889636e Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Tue, 12 Mar 2024 20:48:21 -0700 Subject: crypto: remove CONFIG_CRYPTO_STATS Remove support for the "Crypto usage statistics" feature (CONFIG_CRYPTO_STATS). This feature does not appear to have ever been used, and it is harmful because it significantly reduces performance and is a large maintenance burden. Covering each of these points in detail: 1. Feature is not being used Since these generic crypto statistics are only readable using netlink, it's fairly straightforward to look for programs that use them. I'm unable to find any evidence that any such programs exist. For example, Debian Code Search returns no hits except the kernel header and kernel code itself and translations of the kernel header: https://codesearch.debian.net/search?q=CRYPTOCFGA_STAT&literal=1&perpkg=1 The patch series that added this feature in 2018 (https://lore.kernel.org/linux-crypto/1537351855-16618-1-git-send-email-clabbe@baylibre.com/) said "The goal is to have an ifconfig for crypto device." This doesn't appear to have happened. It's not clear that there is real demand for crypto statistics. Just because the kernel provides other types of statistics such as I/O and networking statistics and some people find those useful does not mean that crypto statistics are useful too. Further evidence that programs are not using CONFIG_CRYPTO_STATS is that it was able to be disabled in RHEL and Fedora as a bug fix (https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/2947). Even further evidence comes from the fact that there are and have been bugs in how the stats work, but they were never reported. For example, before Linux v6.7 hash stats were double-counted in most cases. There has also never been any documentation for this feature, so it might be hard to use even if someone wanted to. 2. CONFIG_CRYPTO_STATS significantly reduces performance Enabling CONFIG_CRYPTO_STATS significantly reduces the performance of the crypto API, even if no program ever retrieves the statistics. This primarily affects systems with a large number of CPUs. For example, https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2039576 reported that Lustre client encryption performance improved from 21.7GB/s to 48.2GB/s by disabling CONFIG_CRYPTO_STATS. It can be argued that this means that CONFIG_CRYPTO_STATS should be optimized with per-cpu counters similar to many of the networking counters. But no one has done this in 5+ years. This is consistent with the fact that the feature appears to be unused, so there seems to be little interest in improving it as opposed to just disabling it. It can be argued that because CONFIG_CRYPTO_STATS is off by default, performance doesn't matter. But Linux distros tend to error on the side of enabling options. The option is enabled in Ubuntu and Arch Linux, and until recently was enabled in RHEL and Fedora (see above). So, even just having the option available is harmful to users. 3. CONFIG_CRYPTO_STATS is a large maintenance burden There are over 1000 lines of code associated with CONFIG_CRYPTO_STATS, spread among 32 files. It significantly complicates much of the implementation of the crypto API. After the initial submission, many fixes and refactorings have consumed effort of multiple people to keep this feature "working". We should be spending this effort elsewhere. Acked-by: Ard Biesheuvel Acked-by: Corentin Labbe Signed-off-by: Eric Biggers Signed-off-by: Herbert Xu --- include/crypto/hash.h | 22 ---------------------- 1 file changed, 22 deletions(-) (limited to 'include/crypto/hash.h') diff --git a/include/crypto/hash.h b/include/crypto/hash.h index 5d61f576cfc8..0014bdd81ab7 100644 --- a/include/crypto/hash.h +++ b/include/crypto/hash.h @@ -23,27 +23,8 @@ struct crypto_ahash; * crypto_unregister_shash(). */ -/* - * struct crypto_istat_hash - statistics for has algorithm - * @hash_cnt: number of hash requests - * @hash_tlen: total data size hashed - * @err_cnt: number of error for hash requests - */ -struct crypto_istat_hash { - atomic64_t hash_cnt; - atomic64_t hash_tlen; - atomic64_t err_cnt; -}; - -#ifdef CONFIG_CRYPTO_STATS -#define HASH_ALG_COMMON_STAT struct crypto_istat_hash stat; -#else -#define HASH_ALG_COMMON_STAT -#endif - /* * struct hash_alg_common - define properties of message digest - * @stat: Statistics for hash algorithm. * @digestsize: Size of the result of the transformation. A buffer of this size * must be available to the @final and @finup calls, so they can * store the resulting hash into it. For various predefined sizes, @@ -60,8 +41,6 @@ struct crypto_istat_hash { * information. */ #define HASH_ALG_COMMON { \ - HASH_ALG_COMMON_STAT \ - \ unsigned int digestsize; \ unsigned int statesize; \ \ @@ -243,7 +222,6 @@ struct shash_alg { }; }; #undef HASH_ALG_COMMON -#undef HASH_ALG_COMMON_STAT struct crypto_ahash { bool using_shash; /* Underlying algorithm is shash, not ahash */ -- cgit v1.2.3 From 2c321f3f70bc284510598f712b702ce8d60c4d14 Mon Sep 17 00:00:00 2001 From: Suren Baghdasaryan Date: Sun, 14 Apr 2024 19:07:31 -0700 Subject: mm: change inlined allocation helpers to account at the call site Main goal of memory allocation profiling patchset is to provide accounting that is cheap enough to run in production. To achieve that we inject counters using codetags at the allocation call sites to account every time allocation is made. This injection allows us to perform accounting efficiently because injected counters are immediately available as opposed to the alternative methods, such as using _RET_IP_, which would require counter lookup and appropriate locking that makes accounting much more expensive. This method requires all allocation functions to inject separate counters at their call sites so that their callers can be individually accounted. Counter injection is implemented by allocation hooks which should wrap all allocation functions. Inlined functions which perform allocations but do not use allocation hooks are directly charged for the allocations they perform. In most cases these functions are just specialized allocation wrappers used from multiple places to allocate objects of a specific type. It would be more useful to do the accounting at their call sites instead. Instrument these helpers to do accounting at the call site. Simple inlined allocation wrappers are converted directly into macros. More complex allocators or allocators with documentation are converted into _noprof versions and allocation hooks are added. This allows memory allocation profiling mechanism to charge allocations to the callers of these functions. Link: https://lkml.kernel.org/r/20240415020731.1152108-1-surenb@google.com Signed-off-by: Suren Baghdasaryan Acked-by: Jan Kara [jbd2] Cc: Anna Schumaker Cc: Arnd Bergmann Cc: Benjamin Tissoires Cc: Christoph Lameter Cc: David Rientjes Cc: David S. Miller Cc: Dennis Zhou Cc: Eric Dumazet Cc: Herbert Xu Cc: Jakub Kicinski Cc: Jakub Sitnicki Cc: Jiri Kosina Cc: Joerg Roedel Cc: Joonsoo Kim Cc: Kent Overstreet Cc: Matthew Wilcox (Oracle) Cc: Paolo Abeni Cc: Pekka Enberg Cc: Tejun Heo Cc: Theodore Ts'o Cc: Trond Myklebust Cc: Vlastimil Babka Cc: Will Deacon Signed-off-by: Andrew Morton --- include/crypto/hash.h | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'include/crypto/hash.h') diff --git a/include/crypto/hash.h b/include/crypto/hash.h index 5d61f576cfc8..e5181cc9b7c5 100644 --- a/include/crypto/hash.h +++ b/include/crypto/hash.h @@ -578,19 +578,20 @@ static inline void ahash_request_set_tfm(struct ahash_request *req, * * Return: allocated request handle in case of success, or NULL if out of memory */ -static inline struct ahash_request *ahash_request_alloc( +static inline struct ahash_request *ahash_request_alloc_noprof( struct crypto_ahash *tfm, gfp_t gfp) { struct ahash_request *req; - req = kmalloc(sizeof(struct ahash_request) + - crypto_ahash_reqsize(tfm), gfp); + req = kmalloc_noprof(sizeof(struct ahash_request) + + crypto_ahash_reqsize(tfm), gfp); if (likely(req)) ahash_request_set_tfm(req, tfm); return req; } +#define ahash_request_alloc(...) alloc_hooks(ahash_request_alloc_noprof(__VA_ARGS__)) /** * ahash_request_free() - zeroize and free the request data structure -- cgit v1.2.3