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 11877ECAAD1 for ; Wed, 31 Aug 2022 10:37:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230054AbiHaKhe (ORCPT ); Wed, 31 Aug 2022 06:37:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53700 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230193AbiHaKhc (ORCPT ); Wed, 31 Aug 2022 06:37:32 -0400 Received: from mail-lf1-x12a.google.com (mail-lf1-x12a.google.com [IPv6:2a00:1450:4864:20::12a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 935CCBFE8C for ; Wed, 31 Aug 2022 03:37:28 -0700 (PDT) Received: by mail-lf1-x12a.google.com with SMTP id z29so10751279lfb.13 for ; Wed, 31 Aug 2022 03:37:28 -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=WJL9T2x+a2YdG1AthmK6UN7443yAuiR2WAuOKZxAW8E=; b=rgCPeyAfJg5zG0rMpAkkqGHUcmJAJmkadgznfo2KJH0hFTEHV5Gxz6AJC26ltFRX6v k4enm+y4fV0atHzlz7gc9VjH3AU5RSOSAJTC66alWPnPjVO6rBMw2NC2EeGmx7YnHNY6 GjQO9PdG4cDd7tRoWdCryVseQQ440mjDBSgy28tBCS1Uw4G19h707SJ/Ab0K3OQwGwit zKTxtnc0aM6C1C2rmGbfILemVtoBFRqOYs4sHdPtie4yVS3pCaxJLvDL5dshz1izePtd hX8EFP2fkIOo1VJvyrhF4t2T4kd9Q30ypdy4DGBAP3OX9btdUI+yxt70XDEkvIOxEoZG iYCQ== 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=WJL9T2x+a2YdG1AthmK6UN7443yAuiR2WAuOKZxAW8E=; b=NdW3drZ55OJOmqNfG2xlW8OVnK+7zmX4Gp8GgTFFhA0qjtt8+A1rUYCZqBxRk7EHuj jWprHA5vio8hdgNik33Q9g7QG3AsQmz+THr+SRKRnF6DwCk5O5Fi95HlIIMS5kDp4Ig+ WcvEjRLK5PLGV2Er30GuavNhs+4Wx3FxmfIS5HT/p37zX/eXTkZR+Pio8doE6XEfrfRN yC9is3wgUs1Qc9gL+lHrlTyoN3HPCej7P7Snbuxifrp6lF7QVv4zG739DbY8m9MoWcRH pea1eFm2+jixHKO+1+qFG0QNrDSCbpEOzDA6yrFLScuattc8R20e7aqQmH3em+HHR9Qk kmaA== X-Gm-Message-State: ACgBeo2s5HkUIzuYO2P30JBu4l15siTE+AtVTPoIfvc5l1R6dth4Qnfi yers7Yrrl5FsQ+ygMuq4M+Ozz8TPEu7yFmex7o/9XQ== X-Google-Smtp-Source: AA6agR4pT/CTaEizCaURhQyuAEAI0lYFzrOzS9I6rHKULsX8mlMRlMiADaWRoKYoVd+PXABbNzSjv7+KWE13JNHqVwE= X-Received: by 2002:a05:6512:2203:b0:492:e57d:7c24 with SMTP id h3-20020a056512220300b00492e57d7c24mr8795828lfu.540.1661942246538; Wed, 31 Aug 2022 03:37:26 -0700 (PDT) MIME-Version: 1.0 References: <20220830214919.53220-1-surenb@google.com> <20220830214919.53220-23-surenb@google.com> In-Reply-To: <20220830214919.53220-23-surenb@google.com> From: Dmitry Vyukov Date: Wed, 31 Aug 2022 12:37:14 +0200 Message-ID: Subject: Re: [RFC PATCH 22/30] Code tagging based fault injection To: Suren Baghdasaryan Cc: akpm@linux-foundation.org, kent.overstreet@linux.dev, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, roman.gushchin@linux.dev, mgorman@suse.de, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, void@manifault.com, peterz@infradead.org, juri.lelli@redhat.com, ldufour@linux.ibm.com, peterx@redhat.com, david@redhat.com, axboe@kernel.dk, mcgrof@kernel.org, masahiroy@kernel.org, nathan@kernel.org, changbin.du@intel.com, ytcoode@gmail.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, bristot@redhat.com, vschneid@redhat.com, cl@linux.com, penberg@kernel.org, iamjoonsoo.kim@lge.com, 42.hyeyoo@gmail.com, glider@google.com, elver@google.com, shakeelb@google.com, songmuchun@bytedance.com, arnd@arndb.de, jbaron@akamai.com, rientjes@google.com, minchan@google.com, kaleshsingh@google.com, kernel-team@android.com, linux-mm@kvack.org, 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, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-bcache@vger.kernel.org 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. > 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 >