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 X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 09666C43603 for ; Thu, 5 Dec 2019 00:52:57 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A0EB52465A for ; Thu, 5 Dec 2019 00:52:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="DTj3lCfv" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A0EB52465A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 52A886B0DDA; Wed, 4 Dec 2019 19:52:56 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 48D016B0DDC; Wed, 4 Dec 2019 19:52:56 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 32D086B0DDD; Wed, 4 Dec 2019 19:52:56 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0148.hostedemail.com [216.40.44.148]) by kanga.kvack.org (Postfix) with ESMTP id 1674D6B0DDA for ; Wed, 4 Dec 2019 19:52:56 -0500 (EST) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with SMTP id CE85952DE for ; Thu, 5 Dec 2019 00:52:55 +0000 (UTC) X-FDA: 76229263110.10.cloth30_1988ff27fd523 X-HE-Tag: cloth30_1988ff27fd523 X-Filterd-Recvd-Size: 11689 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf12.hostedemail.com (Postfix) with ESMTP for ; Thu, 5 Dec 2019 00:52:55 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 59CE32465F; Thu, 5 Dec 2019 00:52:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1575507174; bh=frRKDKvi7Fe0VIUqcyQuX4vQ+LCQzC+wP4pAv0srig8=; h=Date:From:To:Subject:In-Reply-To:From; b=DTj3lCfv2xUYAoj88Osbh3JCIiBZ0w5rP1ZiT+BWnji7lazhpw7Uz0O99eek66As2 N0brCDVw1SlCtNXxHHNiDj9Iu/NZNFk4Tvjvsax8u8JDBH8dSix9ymhZLvWHzTrB8/ 2UE8feDc1oR7c/Tf0fMMNtsuQJREoHBMQeZW5BrE= Date: Wed, 04 Dec 2019 16:52:53 -0800 From: Andrew Morton To: akpm@linux-foundation.org, andre.przywara@arm.com, aryabinin@virtuozzo.com, bigeasy@linutronix.de, julien.grall@arm.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, rostedt@goodmis.org, tglx@linutronix.de, torvalds@linux-foundation.org Subject: [patch 59/86] lib/ubsan: don't serialize UBSAN report Message-ID: <20191205005253.kA5BhdOHk%akpm@linux-foundation.org> In-Reply-To: <20191204164858.fe4ed8886e34ad9f3b34ea00@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Julien Grall Subject: lib/ubsan: don't serialize UBSAN report At the moment, UBSAN report will be serialized using a spin_lock(). On RT-systems, spinlocks are turned to rt_spin_lock and may sleep. This will result to the following splat if the undefined behavior is in a context that can sleep: [ 6951.484876] BUG: sleeping function called from invalid context at /src/linux/kernel/locking/rtmutex.c:968 [ 6951.484882] in_atomic(): 1, irqs_disabled(): 128, pid: 3447, name: make [ 6951.484884] 1 lock held by make/3447: [ 6951.484885] #0: 000000009a966332 (&mm->mmap_sem){++++}, at: do_page_fault+0x140/0x4f8 [ 6951.484895] irq event stamp: 6284 [ 6951.484896] hardirqs last enabled at (6283): [] _raw_spin_unlock_irqrestore+0x90/0xa0 [ 6951.484901] hardirqs last disabled at (6284): [] _raw_spin_lock_irqsave+0x30/0x78 [ 6951.484902] softirqs last enabled at (2430): [] fpsimd_restore_current_state+0x60/0xe8 [ 6951.484905] softirqs last disabled at (2427): [] fpsimd_restore_current_state+0x28/0xe8 [ 6951.484907] Preemption disabled at: [ 6951.484907] [] rt_mutex_futex_unlock+0x4c/0xb0 [ 6951.484911] CPU: 3 PID: 3447 Comm: make Tainted: G W 5.2.14-rt7-01890-ge6e057589653 #911 [ 6951.484913] Call trace: [ 6951.484913] dump_backtrace+0x0/0x148 [ 6951.484915] show_stack+0x14/0x20 [ 6951.484917] dump_stack+0xbc/0x104 [ 6951.484919] ___might_sleep+0x154/0x210 [ 6951.484921] rt_spin_lock+0x68/0xa0 [ 6951.484922] ubsan_prologue+0x30/0x68 [ 6951.484924] handle_overflow+0x64/0xe0 [ 6951.484926] __ubsan_handle_add_overflow+0x10/0x18 [ 6951.484927] __lock_acquire+0x1c28/0x2a28 [ 6951.484929] lock_acquire+0xf0/0x370 [ 6951.484931] _raw_spin_lock_irqsave+0x58/0x78 [ 6951.484932] rt_mutex_futex_unlock+0x4c/0xb0 [ 6951.484933] rt_spin_unlock+0x28/0x70 [ 6951.484934] get_page_from_freelist+0x428/0x2b60 [ 6951.484936] __alloc_pages_nodemask+0x174/0x1708 [ 6951.484938] alloc_pages_vma+0x1ac/0x238 [ 6951.484940] __handle_mm_fault+0x4ac/0x10b0 [ 6951.484941] handle_mm_fault+0x1d8/0x3b0 [ 6951.484942] do_page_fault+0x1c8/0x4f8 [ 6951.484943] do_translation_fault+0xb8/0xe0 [ 6951.484945] do_mem_abort+0x3c/0x98 [ 6951.484946] el0_da+0x20/0x24 The spin_lock() will protect against multiple CPUs to output a report together, I guess to prevent them from being interleaved. However, they can still interleave with other messages (and even splat from __might_sleep). So the lock usefulness seems pretty limited. Rather than trying to accomodate RT-system by switching to a raw_spin_lock(), the lock is now completely dropped. Link: http://lkml.kernel.org/r/20190920100835.14999-1-julien.grall@arm.com Signed-off-by: Julien Grall Reported-by: Andre Przywara Acked-by: Andrey Ryabinin Cc: Thomas Gleixner Cc: Sebastian Andrzej Siewior Cc: Steven Rostedt Signed-off-by: Andrew Morton --- lib/ubsan.c | 64 +++++++++++++++++--------------------------------- 1 file changed, 23 insertions(+), 41 deletions(-) --- a/lib/ubsan.c~lib-ubsan-dont-seralize-ubsan-report +++ a/lib/ubsan.c @@ -140,25 +140,21 @@ static void val_to_string(char *str, siz } } -static DEFINE_SPINLOCK(report_lock); - -static void ubsan_prologue(struct source_location *location, - unsigned long *flags) +static void ubsan_prologue(struct source_location *location) { current->in_ubsan++; - spin_lock_irqsave(&report_lock, *flags); pr_err("========================================" "========================================\n"); print_source_location("UBSAN: Undefined behaviour in", location); } -static void ubsan_epilogue(unsigned long *flags) +static void ubsan_epilogue(void) { dump_stack(); pr_err("========================================" "========================================\n"); - spin_unlock_irqrestore(&report_lock, *flags); + current->in_ubsan--; } @@ -167,14 +163,13 @@ static void handle_overflow(struct overf { struct type_descriptor *type = data->type; - unsigned long flags; char lhs_val_str[VALUE_LENGTH]; char rhs_val_str[VALUE_LENGTH]; if (suppress_report(&data->location)) return; - ubsan_prologue(&data->location, &flags); + ubsan_prologue(&data->location); val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs); val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs); @@ -186,7 +181,7 @@ static void handle_overflow(struct overf rhs_val_str, type->type_name); - ubsan_epilogue(&flags); + ubsan_epilogue(); } void __ubsan_handle_add_overflow(struct overflow_data *data, @@ -214,20 +209,19 @@ EXPORT_SYMBOL(__ubsan_handle_mul_overflo void __ubsan_handle_negate_overflow(struct overflow_data *data, void *old_val) { - unsigned long flags; char old_val_str[VALUE_LENGTH]; if (suppress_report(&data->location)) return; - ubsan_prologue(&data->location, &flags); + ubsan_prologue(&data->location); val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val); pr_err("negation of %s cannot be represented in type %s:\n", old_val_str, data->type->type_name); - ubsan_epilogue(&flags); + ubsan_epilogue(); } EXPORT_SYMBOL(__ubsan_handle_negate_overflow); @@ -235,13 +229,12 @@ EXPORT_SYMBOL(__ubsan_handle_negate_over void __ubsan_handle_divrem_overflow(struct overflow_data *data, void *lhs, void *rhs) { - unsigned long flags; char rhs_val_str[VALUE_LENGTH]; if (suppress_report(&data->location)) return; - ubsan_prologue(&data->location, &flags); + ubsan_prologue(&data->location); val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs); @@ -251,58 +244,52 @@ void __ubsan_handle_divrem_overflow(stru else pr_err("division by zero\n"); - ubsan_epilogue(&flags); + ubsan_epilogue(); } EXPORT_SYMBOL(__ubsan_handle_divrem_overflow); static void handle_null_ptr_deref(struct type_mismatch_data_common *data) { - unsigned long flags; - if (suppress_report(data->location)) return; - ubsan_prologue(data->location, &flags); + ubsan_prologue(data->location); pr_err("%s null pointer of type %s\n", type_check_kinds[data->type_check_kind], data->type->type_name); - ubsan_epilogue(&flags); + ubsan_epilogue(); } static void handle_misaligned_access(struct type_mismatch_data_common *data, unsigned long ptr) { - unsigned long flags; - if (suppress_report(data->location)) return; - ubsan_prologue(data->location, &flags); + ubsan_prologue(data->location); pr_err("%s misaligned address %p for type %s\n", type_check_kinds[data->type_check_kind], (void *)ptr, data->type->type_name); pr_err("which requires %ld byte alignment\n", data->alignment); - ubsan_epilogue(&flags); + ubsan_epilogue(); } static void handle_object_size_mismatch(struct type_mismatch_data_common *data, unsigned long ptr) { - unsigned long flags; - if (suppress_report(data->location)) return; - ubsan_prologue(data->location, &flags); + ubsan_prologue(data->location); pr_err("%s address %p with insufficient space\n", type_check_kinds[data->type_check_kind], (void *) ptr); pr_err("for an object of type %s\n", data->type->type_name); - ubsan_epilogue(&flags); + ubsan_epilogue(); } static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data, @@ -351,25 +338,23 @@ EXPORT_SYMBOL(__ubsan_handle_type_mismat void __ubsan_handle_out_of_bounds(struct out_of_bounds_data *data, void *index) { - unsigned long flags; char index_str[VALUE_LENGTH]; if (suppress_report(&data->location)) return; - ubsan_prologue(&data->location, &flags); + ubsan_prologue(&data->location); val_to_string(index_str, sizeof(index_str), data->index_type, index); pr_err("index %s is out of range for type %s\n", index_str, data->array_type->type_name); - ubsan_epilogue(&flags); + ubsan_epilogue(); } EXPORT_SYMBOL(__ubsan_handle_out_of_bounds); void __ubsan_handle_shift_out_of_bounds(struct shift_out_of_bounds_data *data, void *lhs, void *rhs) { - unsigned long flags; struct type_descriptor *rhs_type = data->rhs_type; struct type_descriptor *lhs_type = data->lhs_type; char rhs_str[VALUE_LENGTH]; @@ -379,7 +364,7 @@ void __ubsan_handle_shift_out_of_bounds( if (suppress_report(&data->location)) goto out; - ubsan_prologue(&data->location, &flags); + ubsan_prologue(&data->location); val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs); val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs); @@ -402,7 +387,7 @@ void __ubsan_handle_shift_out_of_bounds( lhs_str, rhs_str, lhs_type->type_name); - ubsan_epilogue(&flags); + ubsan_epilogue(); out: user_access_restore(ua_flags); } @@ -411,11 +396,9 @@ EXPORT_SYMBOL(__ubsan_handle_shift_out_o void __ubsan_handle_builtin_unreachable(struct unreachable_data *data) { - unsigned long flags; - - ubsan_prologue(&data->location, &flags); + ubsan_prologue(&data->location); pr_err("calling __builtin_unreachable()\n"); - ubsan_epilogue(&flags); + ubsan_epilogue(); panic("can't return from __builtin_unreachable()"); } EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable); @@ -423,19 +406,18 @@ EXPORT_SYMBOL(__ubsan_handle_builtin_unr void __ubsan_handle_load_invalid_value(struct invalid_value_data *data, void *val) { - unsigned long flags; char val_str[VALUE_LENGTH]; if (suppress_report(&data->location)) return; - ubsan_prologue(&data->location, &flags); + ubsan_prologue(&data->location); val_to_string(val_str, sizeof(val_str), data->type, val); pr_err("load of value %s is not a valid value for type %s\n", val_str, data->type->type_name); - ubsan_epilogue(&flags); + ubsan_epilogue(); } EXPORT_SYMBOL(__ubsan_handle_load_invalid_value); _