From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 456D9ECAAD4 for ; Wed, 31 Aug 2022 15:51:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231715AbiHaPv0 (ORCPT ); Wed, 31 Aug 2022 11:51:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33970 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231551AbiHaPvZ (ORCPT ); Wed, 31 Aug 2022 11:51:25 -0400 Received: from mail-yw1-x112e.google.com (mail-yw1-x112e.google.com [IPv6:2607:f8b0:4864:20::112e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 329AFA2DA6 for ; Wed, 31 Aug 2022 08:51:22 -0700 (PDT) Received: by mail-yw1-x112e.google.com with SMTP id 00721157ae682-3413ad0640dso155906977b3.13 for ; Wed, 31 Aug 2022 08:51:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc; bh=3PvMR/XycqORFlizT6CxByuKDuIxggxJlBTQLJTuWPk=; b=Gmi2UWcvzrmJ8zqM8a6qsIyzbaP0psVzRrmiTQDUFQ+boYUpfinXOhH3kKBy2TxbXZ ygeIkKnogCEEVHtGen8PFLpJpXJGU25o+NTwvzI5jnj72uy5Cjchmk9EqNZ81045MM9h yDzJSkpnZyziYqR1UQHXQzYV+X7WIdCFOpC8nEcu7lVMc9hTpLbs9tE+UmhjTrN9guKQ 3p6amlVDRlBQ5pch2LYuRNd6kUSpn4yqk5Fz4R7rna8xmxeC2DA0L1p+VaF6BXU7aFkO GgWG+nRtC8kNNs87CPZsk886FgCnJcaZKKpO+18aXX3VN29LAEX04NpAfjzZUKRWKsQN tnsw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc; bh=3PvMR/XycqORFlizT6CxByuKDuIxggxJlBTQLJTuWPk=; b=tLVKMlNBmaI15toV/3bMlxCanA2JCBNrimjb35rXZHZKBadayNsAPNC2hSMf0lLvbd WmSSQApk0lzlB/qIWLqQwIiu/dc5Bb9UGP10EcV/VcHLvUvA+ncXcI/vnrMAwNimnrzy nJ1CIF2jAFvbICxAk6wNBWtqAkxsXKEHVm67QOJDLfZ5IhIYcg3Sxzt4TLfWBgVQy3vD jhoKU1hRAJ01yA4Mz29KIdBDFWTvCpkMcCMFfIGbr9ZxyvS3lmtwGM5zpoQOTjJgptBi 0NoS4nu4dKHo+c1iOMlpmew/5dWagCTITYEn/6LquQimRlOLcYITqeHEp9ucru3f9ffA 731w== X-Gm-Message-State: ACgBeo1xpv8ng/N9Ggqdx9fTAxIbewKNv3SzS3q/wAaJtpPQGztMfZw4 uym0kso/B4kR8/ctYGceLGUNgrIvcS69QAFbvBzwFg== X-Google-Smtp-Source: AA6agR4/rLQr0otczemJmDvQiUx5/CSiDqYtOQdmANq0z9zivATwFqNAF4tlP4F5nNTDABcpDpeH4KIX3SY4Iha+WMk= X-Received: by 2002:a0d:cd02:0:b0:341:a401:4630 with SMTP id p2-20020a0dcd02000000b00341a4014630mr4588576ywd.293.1661961081082; Wed, 31 Aug 2022 08:51:21 -0700 (PDT) MIME-Version: 1.0 References: <20220830214919.53220-1-surenb@google.com> <20220830214919.53220-23-surenb@google.com> In-Reply-To: From: Suren Baghdasaryan Date: Wed, 31 Aug 2022 08:51:10 -0700 Message-ID: Subject: Re: [RFC PATCH 22/30] Code tagging based fault injection To: Dmitry Vyukov Cc: Andrew Morton , Kent Overstreet , Michal Hocko , Vlastimil Babka , Johannes Weiner , Roman Gushchin , Mel Gorman , Davidlohr Bueso , Matthew Wilcox , "Liam R. Howlett" , David Vernet , Peter Zijlstra , Juri Lelli , Laurent Dufour , Peter Xu , David Hildenbrand , Jens Axboe , mcgrof@kernel.org, masahiroy@kernel.org, nathan@kernel.org, changbin.du@intel.com, ytcoode@gmail.com, Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Benjamin Segall , Daniel Bristot de Oliveira , Valentin Schneider , Christopher Lameter , Pekka Enberg , Joonsoo Kim , 42.hyeyoo@gmail.com, Alexander Potapenko , Marco Elver , Shakeel Butt , Muchun Song , arnd@arndb.de, jbaron@akamai.com, David Rientjes , Minchan Kim , Kalesh Singh , kernel-team , linux-mm , iommu@lists.linux.dev, kasan-dev@googlegroups.com, io-uring@vger.kernel.org, linux-arch@vger.kernel.org, xen-devel@lists.xenproject.org, linux-bcache@vger.kernel.org, linux-modules@vger.kernel.org, LKML Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Wed, Aug 31, 2022 at 3:37 AM Dmitry Vyukov wrote: > > On Tue, 30 Aug 2022 at 23:50, Suren Baghdasaryan wrote: > > > > From: Kent Overstreet > > > > This adds a new fault injection capability, based on code tagging. > > > > To use, simply insert somewhere in your code > > > > dynamic_fault("fault_class_name") > > > > and check whether it returns true - if so, inject the error. > > For example > > > > if (dynamic_fault("init")) > > return -EINVAL; > > Hi Suren, > > If this is going to be used by mainline kernel, it would be good to > integrate this with fail_nth systematic fault injection: > https://elixir.bootlin.com/linux/latest/source/lib/fault-inject.c#L109 > > Otherwise these dynamic sites won't be tested by testing systems doing > systematic fault injection testing. Hi Dmitry, Thanks for the information! Will look into it and try to integrate. Suren. > > > > There's no need to define faults elsewhere, as with > > include/linux/fault-injection.h. Faults show up in debugfs, under > > /sys/kernel/debug/dynamic_faults, and can be selected based on > > file/module/function/line number/class, and enabled permanently, or in > > oneshot mode, or with a specified frequency. > > > > Signed-off-by: Kent Overstreet > > --- > > include/asm-generic/codetag.lds.h | 3 +- > > include/linux/dynamic_fault.h | 79 +++++++ > > include/linux/slab.h | 3 +- > > lib/Kconfig.debug | 6 + > > lib/Makefile | 2 + > > lib/dynamic_fault.c | 372 ++++++++++++++++++++++++++++++ > > 6 files changed, 463 insertions(+), 2 deletions(-) > > create mode 100644 include/linux/dynamic_fault.h > > create mode 100644 lib/dynamic_fault.c > > > > diff --git a/include/asm-generic/codetag.lds.h b/include/asm-generic/codetag.lds.h > > index 64f536b80380..16fbf74edc3d 100644 > > --- a/include/asm-generic/codetag.lds.h > > +++ b/include/asm-generic/codetag.lds.h > > @@ -9,6 +9,7 @@ > > __stop_##_name = .; > > > > #define CODETAG_SECTIONS() \ > > - SECTION_WITH_BOUNDARIES(alloc_tags) > > + SECTION_WITH_BOUNDARIES(alloc_tags) \ > > + SECTION_WITH_BOUNDARIES(dynamic_fault_tags) > > > > #endif /* __ASM_GENERIC_CODETAG_LDS_H */ > > diff --git a/include/linux/dynamic_fault.h b/include/linux/dynamic_fault.h > > new file mode 100644 > > index 000000000000..526a33209e94 > > --- /dev/null > > +++ b/include/linux/dynamic_fault.h > > @@ -0,0 +1,79 @@ > > +/* SPDX-License-Identifier: GPL-2.0 */ > > + > > +#ifndef _LINUX_DYNAMIC_FAULT_H > > +#define _LINUX_DYNAMIC_FAULT_H > > + > > +/* > > + * Dynamic/code tagging fault injection: > > + * > > + * Originally based on the dynamic debug trick of putting types in a special elf > > + * section, then rewritten using code tagging: > > + * > > + * To use, simply insert a call to dynamic_fault("fault_class"), which will > > + * return true if an error should be injected. > > + * > > + * Fault injection sites may be listed and enabled via debugfs, under > > + * /sys/kernel/debug/dynamic_faults. > > + */ > > + > > +#ifdef CONFIG_CODETAG_FAULT_INJECTION > > + > > +#include > > +#include > > + > > +#define DFAULT_STATES() \ > > + x(disabled) \ > > + x(enabled) \ > > + x(oneshot) > > + > > +enum dfault_enabled { > > +#define x(n) DFAULT_##n, > > + DFAULT_STATES() > > +#undef x > > +}; > > + > > +union dfault_state { > > + struct { > > + unsigned int enabled:2; > > + unsigned int count:30; > > + }; > > + > > + struct { > > + unsigned int v; > > + }; > > +}; > > + > > +struct dfault { > > + struct codetag tag; > > + const char *class; > > + unsigned int frequency; > > + union dfault_state state; > > + struct static_key_false enabled; > > +}; > > + > > +bool __dynamic_fault_enabled(struct dfault *df); > > + > > +#define dynamic_fault(_class) \ > > +({ \ > > + static struct dfault \ > > + __used \ > > + __section("dynamic_fault_tags") \ > > + __aligned(8) df = { \ > > + .tag = CODE_TAG_INIT, \ > > + .class = _class, \ > > + .enabled = STATIC_KEY_FALSE_INIT, \ > > + }; \ > > + \ > > + static_key_false(&df.enabled.key) && \ > > + __dynamic_fault_enabled(&df); \ > > +}) > > + > > +#else > > + > > +#define dynamic_fault(_class) false > > + > > +#endif /* CODETAG_FAULT_INJECTION */ > > + > > +#define memory_fault() dynamic_fault("memory") > > + > > +#endif /* _LINUX_DYNAMIC_FAULT_H */ > > diff --git a/include/linux/slab.h b/include/linux/slab.h > > index 89273be35743..4be5a93ed15a 100644 > > --- a/include/linux/slab.h > > +++ b/include/linux/slab.h > > @@ -17,6 +17,7 @@ > > #include > > #include > > #include > > +#include > > > > > > /* > > @@ -468,7 +469,7 @@ static inline void slab_tag_dec(const void *ptr) {} > > > > #define krealloc_hooks(_p, _do_alloc) \ > > ({ \ > > - void *_res = _do_alloc; \ > > + void *_res = !memory_fault() ? _do_alloc : NULL; \ > > slab_tag_add(_p, _res); \ > > _res; \ > > }) > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > > index 2790848464f1..b7d03afbc808 100644 > > --- a/lib/Kconfig.debug > > +++ b/lib/Kconfig.debug > > @@ -1982,6 +1982,12 @@ config FAULT_INJECTION_STACKTRACE_FILTER > > help > > Provide stacktrace filter for fault-injection capabilities > > > > +config CODETAG_FAULT_INJECTION > > + bool "Code tagging based fault injection" > > + select CODE_TAGGING > > + help > > + Dynamic fault injection based on code tagging > > + > > config ARCH_HAS_KCOV > > bool > > help > > diff --git a/lib/Makefile b/lib/Makefile > > index 99f732156673..489ea000c528 100644 > > --- a/lib/Makefile > > +++ b/lib/Makefile > > @@ -231,6 +231,8 @@ obj-$(CONFIG_CODE_TAGGING) += codetag.o > > obj-$(CONFIG_ALLOC_TAGGING) += alloc_tag.o > > obj-$(CONFIG_PAGE_ALLOC_TAGGING) += pgalloc_tag.o > > > > +obj-$(CONFIG_CODETAG_FAULT_INJECTION) += dynamic_fault.o > > + > > lib-$(CONFIG_GENERIC_BUG) += bug.o > > > > obj-$(CONFIG_HAVE_ARCH_TRACEHOOK) += syscall.o > > diff --git a/lib/dynamic_fault.c b/lib/dynamic_fault.c > > new file mode 100644 > > index 000000000000..4c9cd18686be > > --- /dev/null > > +++ b/lib/dynamic_fault.c > > @@ -0,0 +1,372 @@ > > +// SPDX-License-Identifier: GPL-2.0-only > > + > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > + > > +static struct codetag_type *cttype; > > + > > +bool __dynamic_fault_enabled(struct dfault *df) > > +{ > > + union dfault_state old, new; > > + unsigned int v = df->state.v; > > + bool ret; > > + > > + do { > > + old.v = new.v = v; > > + > > + if (new.enabled == DFAULT_disabled) > > + return false; > > + > > + ret = df->frequency > > + ? ++new.count >= df->frequency > > + : true; > > + if (ret) > > + new.count = 0; > > + if (ret && new.enabled == DFAULT_oneshot) > > + new.enabled = DFAULT_disabled; > > + } while ((v = cmpxchg(&df->state.v, old.v, new.v)) != old.v); > > + > > + if (ret) > > + pr_debug("returned true for %s:%u", df->tag.filename, df->tag.lineno); > > + > > + return ret; > > +} > > +EXPORT_SYMBOL(__dynamic_fault_enabled); > > + > > +static const char * const dfault_state_strs[] = { > > +#define x(n) #n, > > + DFAULT_STATES() > > +#undef x > > + NULL > > +}; > > + > > +static void dynamic_fault_to_text(struct seq_buf *out, struct dfault *df) > > +{ > > + codetag_to_text(out, &df->tag); > > + seq_buf_printf(out, "class:%s %s \"", df->class, > > + dfault_state_strs[df->state.enabled]); > > +} > > + > > +struct dfault_query { > > + struct codetag_query q; > > + > > + bool set_enabled:1; > > + unsigned int enabled:2; > > + > > + bool set_frequency:1; > > + unsigned int frequency; > > +}; > > + > > +/* > > + * Search the tables for _dfault's which match the given > > + * `query' and apply the `flags' and `mask' to them. Tells > > + * the user which dfault's were changed, or whether none > > + * were matched. > > + */ > > +static int dfault_change(struct dfault_query *query) > > +{ > > + struct codetag_iterator ct_iter; > > + struct codetag *ct; > > + unsigned int nfound = 0; > > + > > + codetag_lock_module_list(cttype, true); > > + codetag_init_iter(&ct_iter, cttype); > > + > > + while ((ct = codetag_next_ct(&ct_iter))) { > > + struct dfault *df = container_of(ct, struct dfault, tag); > > + > > + if (!codetag_matches_query(&query->q, ct, ct_iter.cmod, df->class)) > > + continue; > > + > > + if (query->set_enabled && > > + query->enabled != df->state.enabled) { > > + if (query->enabled != DFAULT_disabled) > > + static_key_slow_inc(&df->enabled.key); > > + else if (df->state.enabled != DFAULT_disabled) > > + static_key_slow_dec(&df->enabled.key); > > + > > + df->state.enabled = query->enabled; > > + } > > + > > + if (query->set_frequency) > > + df->frequency = query->frequency; > > + > > + pr_debug("changed %s:%d [%s]%s #%d %s", > > + df->tag.filename, df->tag.lineno, df->tag.modname, > > + df->tag.function, query->q.cur_index, > > + dfault_state_strs[df->state.enabled]); > > + > > + nfound++; > > + } > > + > > + pr_debug("dfault: %u matches", nfound); > > + > > + codetag_lock_module_list(cttype, false); > > + > > + return nfound ? 0 : -ENOENT; > > +} > > + > > +#define DFAULT_TOKENS() \ > > + x(disable, 0) \ > > + x(enable, 0) \ > > + x(oneshot, 0) \ > > + x(frequency, 1) > > + > > +enum dfault_token { > > +#define x(name, nr_args) TOK_##name, > > + DFAULT_TOKENS() > > +#undef x > > +}; > > + > > +static const char * const dfault_token_strs[] = { > > +#define x(name, nr_args) #name, > > + DFAULT_TOKENS() > > +#undef x > > + NULL > > +}; > > + > > +static unsigned int dfault_token_nr_args[] = { > > +#define x(name, nr_args) nr_args, > > + DFAULT_TOKENS() > > +#undef x > > +}; > > + > > +static enum dfault_token str_to_token(const char *word, unsigned int nr_words) > > +{ > > + int tok = match_string(dfault_token_strs, ARRAY_SIZE(dfault_token_strs), word); > > + > > + if (tok < 0) { > > + pr_debug("unknown keyword \"%s\"", word); > > + return tok; > > + } > > + > > + if (nr_words < dfault_token_nr_args[tok]) { > > + pr_debug("insufficient arguments to \"%s\"", word); > > + return -EINVAL; > > + } > > + > > + return tok; > > +} > > + > > +static int dfault_parse_command(struct dfault_query *query, > > + enum dfault_token tok, > > + char *words[], size_t nr_words) > > +{ > > + unsigned int i = 0; > > + int ret; > > + > > + switch (tok) { > > + case TOK_disable: > > + query->set_enabled = true; > > + query->enabled = DFAULT_disabled; > > + break; > > + case TOK_enable: > > + query->set_enabled = true; > > + query->enabled = DFAULT_enabled; > > + break; > > + case TOK_oneshot: > > + query->set_enabled = true; > > + query->enabled = DFAULT_oneshot; > > + break; > > + case TOK_frequency: > > + query->set_frequency = 1; > > + ret = kstrtouint(words[i++], 10, &query->frequency); > > + if (ret) > > + return ret; > > + > > + if (!query->set_enabled) { > > + query->set_enabled = 1; > > + query->enabled = DFAULT_enabled; > > + } > > + break; > > + } > > + > > + return i; > > +} > > + > > +static int dynamic_fault_store(char *buf) > > +{ > > + struct dfault_query query = { NULL }; > > +#define MAXWORDS 9 > > + char *tok, *words[MAXWORDS]; > > + int ret, nr_words, i = 0; > > + > > + buf = codetag_query_parse(&query.q, buf); > > + if (IS_ERR(buf)) > > + return PTR_ERR(buf); > > + > > + while ((tok = strsep_no_empty(&buf, " \t\r\n"))) { > > + if (nr_words == ARRAY_SIZE(words)) > > + return -EINVAL; /* ran out of words[] before bytes */ > > + words[nr_words++] = tok; > > + } > > + > > + while (i < nr_words) { > > + const char *tok_str = words[i++]; > > + enum dfault_token tok = str_to_token(tok_str, nr_words - i); > > + > > + if (tok < 0) > > + return tok; > > + > > + ret = dfault_parse_command(&query, tok, words + i, nr_words - i); > > + if (ret < 0) > > + return ret; > > + > > + i += ret; > > + BUG_ON(i > nr_words); > > + } > > + > > + pr_debug("q->function=\"%s\" q->filename=\"%s\" " > > + "q->module=\"%s\" q->line=%u-%u\n q->index=%u-%u", > > + query.q.function, query.q.filename, query.q.module, > > + query.q.first_line, query.q.last_line, > > + query.q.first_index, query.q.last_index); > > + > > + ret = dfault_change(&query); > > + if (ret < 0) > > + return ret; > > + > > + return 0; > > +} > > + > > +struct dfault_iter { > > + struct codetag_iterator ct_iter; > > + > > + struct seq_buf buf; > > + char rawbuf[4096]; > > +}; > > + > > +static int dfault_open(struct inode *inode, struct file *file) > > +{ > > + struct dfault_iter *iter; > > + > > + iter = kzalloc(sizeof(*iter), GFP_KERNEL); > > + if (!iter) > > + return -ENOMEM; > > + > > + codetag_lock_module_list(cttype, true); > > + codetag_init_iter(&iter->ct_iter, cttype); > > + codetag_lock_module_list(cttype, false); > > + > > + file->private_data = iter; > > + seq_buf_init(&iter->buf, iter->rawbuf, sizeof(iter->rawbuf)); > > + return 0; > > +} > > + > > +static int dfault_release(struct inode *inode, struct file *file) > > +{ > > + struct dfault_iter *iter = file->private_data; > > + > > + kfree(iter); > > + return 0; > > +} > > + > > +struct user_buf { > > + char __user *buf; /* destination user buffer */ > > + size_t size; /* size of requested read */ > > + ssize_t ret; /* bytes read so far */ > > +}; > > + > > +static int flush_ubuf(struct user_buf *dst, struct seq_buf *src) > > +{ > > + if (src->len) { > > + size_t bytes = min_t(size_t, src->len, dst->size); > > + int err = copy_to_user(dst->buf, src->buffer, bytes); > > + > > + if (err) > > + return err; > > + > > + dst->ret += bytes; > > + dst->buf += bytes; > > + dst->size -= bytes; > > + src->len -= bytes; > > + memmove(src->buffer, src->buffer + bytes, src->len); > > + } > > + > > + return 0; > > +} > > + > > +static ssize_t dfault_read(struct file *file, char __user *ubuf, > > + size_t size, loff_t *ppos) > > +{ > > + struct dfault_iter *iter = file->private_data; > > + struct user_buf buf = { .buf = ubuf, .size = size }; > > + struct codetag *ct; > > + struct dfault *df; > > + int err; > > + > > + codetag_lock_module_list(iter->ct_iter.cttype, true); > > + while (1) { > > + err = flush_ubuf(&buf, &iter->buf); > > + if (err || !buf.size) > > + break; > > + > > + ct = codetag_next_ct(&iter->ct_iter); > > + if (!ct) > > + break; > > + > > + df = container_of(ct, struct dfault, tag); > > + dynamic_fault_to_text(&iter->buf, df); > > + seq_buf_putc(&iter->buf, '\n'); > > + } > > + codetag_lock_module_list(iter->ct_iter.cttype, false); > > + > > + return err ?: buf.ret; > > +} > > + > > +/* > > + * File_ops->write method for /dynamic_fault/conrol. Gathers the > > + * command text from userspace, parses and executes it. > > + */ > > +static ssize_t dfault_write(struct file *file, const char __user *ubuf, > > + size_t len, loff_t *offp) > > +{ > > + char tmpbuf[256]; > > + > > + if (len == 0) > > + return 0; > > + /* we don't check *offp -- multiple writes() are allowed */ > > + if (len > sizeof(tmpbuf)-1) > > + return -E2BIG; > > + if (copy_from_user(tmpbuf, ubuf, len)) > > + return -EFAULT; > > + tmpbuf[len] = '\0'; > > + pr_debug("read %zu bytes from userspace", len); > > + > > + dynamic_fault_store(tmpbuf); > > + > > + *offp += len; > > + return len; > > +} > > + > > +static const struct file_operations dfault_ops = { > > + .owner = THIS_MODULE, > > + .open = dfault_open, > > + .release = dfault_release, > > + .read = dfault_read, > > + .write = dfault_write > > +}; > > + > > +static int __init dynamic_fault_init(void) > > +{ > > + const struct codetag_type_desc desc = { > > + .section = "dynamic_fault_tags", > > + .tag_size = sizeof(struct dfault), > > + }; > > + struct dentry *debugfs_file; > > + > > + cttype = codetag_register_type(&desc); > > + if (IS_ERR_OR_NULL(cttype)) > > + return PTR_ERR(cttype); > > + > > + debugfs_file = debugfs_create_file("dynamic_faults", 0666, NULL, NULL, &dfault_ops); > > + if (IS_ERR(debugfs_file)) > > + return PTR_ERR(debugfs_file); > > + > > + return 0; > > +} > > +module_init(dynamic_fault_init); > > -- > > 2.37.2.672.g94769d06f0-goog > >