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 8947CC6FA8A for ; Thu, 15 Sep 2022 11:43:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230404AbiIOLnp (ORCPT ); Thu, 15 Sep 2022 07:43:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39006 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230110AbiIOLlC (ORCPT ); Thu, 15 Sep 2022 07:41:02 -0400 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 66CDC4C615 for ; Thu, 15 Sep 2022 04:40:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Content-Type:MIME-Version:References: Subject:Cc:To:From:Date:Message-ID:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:In-Reply-To; bh=+OpChG5m5Za8mkIkCncS6zKt3a7LKRkg2fN4td+8QnM=; b=haQ/PsSTTcURnEcbbpmp09Qe39 FSsHDS7MY05LLri8lIGqUw1mhGJUlqXCVviJVxBAH1aSqcHjTXuO50jDyX8aHqj+2SuFEzj8FwUCv 6N96yRMczSktCcAigCeBmihbGur7XcmQdoU6iecJQ4Nr8Ly7JZFQKR/+sh2wtExQxr9fffc8LfSLq HUvEobVcA88D600MGWWjYLgTitlbJMgMSe8qtaNDxcLgOoKhgLOH00Swr/uML3h4vwlRxV/OPucba BSdLJyGCsCe3nD98zRDkrlt18txfxVKb8EwebIOybT9Ghcr7X4Yqbfb/jZuESdhc8TJBRw7baIgby P+88wdhA==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1oYnDn-00Cabe-09; Thu, 15 Sep 2022 11:40:00 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 23293302ED7; Thu, 15 Sep 2022 13:39:40 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 0) id 1350129AADBE5; Thu, 15 Sep 2022 13:39:40 +0200 (CEST) Message-ID: <20220915111148.204285506@infradead.org> User-Agent: quilt/0.66 Date: Thu, 15 Sep 2022 13:11:30 +0200 From: Peter Zijlstra To: Thomas Gleixner Cc: linux-kernel@vger.kernel.org, peterz@infradead.org, x86@kernel.org, Linus Torvalds , Tim Chen , Josh Poimboeuf , Andrew Cooper , Pawan Gupta , Johannes Wikner , Alyssa Milburn , Jann Horn , "H.J. Lu" , Joao Moreira , Joseph Nuzman , Steven Rostedt , Juergen Gross , Masami Hiramatsu , Alexei Starovoitov , Daniel Borkmann , K Prateek Nayak , Eric Dumazet Subject: [PATCH v3 51/59] x86/calldepth: Add ret/call counting for debug References: <20220915111039.092790446@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Thomas Gleixner Add a debuigfs mechanism to validate the accounting, e.g. vs. call/ret balance and to gather statistics about the stuffing to call ratio. Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) --- arch/x86/include/asm/nospec-branch.h | 36 +++++++++++++++++++++-- arch/x86/kernel/callthunks.c | 53 +++++++++++++++++++++++++++++++++++ arch/x86/lib/retpoline.S | 7 +++- 3 files changed, 91 insertions(+), 5 deletions(-) --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -57,6 +57,22 @@ #define RET_DEPTH_INIT_FROM_CALL 0xfc00000000000000ULL #define RET_DEPTH_CREDIT 0xffffffffffffffffULL +#ifdef CONFIG_CALL_THUNKS_DEBUG +# define CALL_THUNKS_DEBUG_INC_CALLS \ + incq %gs:__x86_call_count; +# define CALL_THUNKS_DEBUG_INC_RETS \ + incq %gs:__x86_ret_count; +# define CALL_THUNKS_DEBUG_INC_STUFFS \ + incq %gs:__x86_stuffs_count; +# define CALL_THUNKS_DEBUG_INC_CTXSW \ + incq %gs:__x86_ctxsw_count; +#else +# define CALL_THUNKS_DEBUG_INC_CALLS +# define CALL_THUNKS_DEBUG_INC_RETS +# define CALL_THUNKS_DEBUG_INC_STUFFS +# define CALL_THUNKS_DEBUG_INC_CTXSW +#endif + #ifdef CONFIG_CALL_DEPTH_TRACKING #define CREDIT_CALL_DEPTH \ movq $-1, PER_CPU_VAR(pcpu_hot + X86_call_depth); @@ -72,18 +88,23 @@ #define RESET_CALL_DEPTH_FROM_CALL \ mov $0xfc, %rax; \ shl $56, %rax; \ - movq %rax, PER_CPU_VAR(pcpu_hot + X86_call_depth); + movq %rax, PER_CPU_VAR(pcpu_hot + X86_call_depth); \ + CALL_THUNKS_DEBUG_INC_CALLS #define INCREMENT_CALL_DEPTH \ - sarq $5, %gs:pcpu_hot + X86_call_depth; + sarq $5, %gs:pcpu_hot + X86_call_depth; \ + CALL_THUNKS_DEBUG_INC_CALLS #define ASM_INCREMENT_CALL_DEPTH \ - sarq $5, PER_CPU_VAR(pcpu_hot + X86_call_depth); + sarq $5, PER_CPU_VAR(pcpu_hot + X86_call_depth); \ + CALL_THUNKS_DEBUG_INC_CALLS #else #define CREDIT_CALL_DEPTH +#define ASM_CREDIT_CALL_DEPTH #define RESET_CALL_DEPTH #define INCREMENT_CALL_DEPTH +#define ASM_INCREMENT_CALL_DEPTH #define RESET_CALL_DEPTH_FROM_CALL #endif @@ -134,7 +155,8 @@ jnz 771b; \ /* barrier for jnz misprediction */ \ lfence; \ - ASM_CREDIT_CALL_DEPTH + ASM_CREDIT_CALL_DEPTH \ + CALL_THUNKS_DEBUG_INC_CTXSW #else /* * i386 doesn't unconditionally have LFENCE, as such it can't @@ -319,6 +341,12 @@ static inline void x86_set_skl_return_th { x86_return_thunk = &__x86_return_skl; } +#ifdef CONFIG_CALL_THUNKS_DEBUG +DECLARE_PER_CPU(u64, __x86_call_count); +DECLARE_PER_CPU(u64, __x86_ret_count); +DECLARE_PER_CPU(u64, __x86_stuffs_count); +DECLARE_PER_CPU(u64, __x86_ctxsw_count); +#endif #else static inline void x86_set_skl_return_thunk(void) {} #endif --- a/arch/x86/kernel/callthunks.c +++ b/arch/x86/kernel/callthunks.c @@ -2,6 +2,7 @@ #define pr_fmt(fmt) "callthunks: " fmt +#include #include #include #include @@ -35,6 +36,15 @@ static int __init debug_thunks(char *str } __setup("debug-callthunks", debug_thunks); +#ifdef CONFIG_CALL_THUNKS_DEBUG +DEFINE_PER_CPU(u64, __x86_call_count); +DEFINE_PER_CPU(u64, __x86_ret_count); +DEFINE_PER_CPU(u64, __x86_stuffs_count); +DEFINE_PER_CPU(u64, __x86_ctxsw_count); +EXPORT_SYMBOL_GPL(__x86_ctxsw_count); +EXPORT_SYMBOL_GPL(__x86_call_count); +#endif + extern s32 __call_sites[], __call_sites_end[]; struct thunk_desc { @@ -283,3 +293,46 @@ void noinline callthunks_patch_module_ca mutex_unlock(&text_mutex); } #endif /* CONFIG_MODULES */ + +#if defined(CONFIG_CALL_THUNKS_DEBUG) && defined(CONFIG_DEBUG_FS) +static int callthunks_debug_show(struct seq_file *m, void *p) +{ + unsigned long cpu = (unsigned long)m->private; + + seq_printf(m, "C: %16llu R: %16llu S: %16llu X: %16llu\n,", + per_cpu(__x86_call_count, cpu), + per_cpu(__x86_ret_count, cpu), + per_cpu(__x86_stuffs_count, cpu), + per_cpu(__x86_ctxsw_count, cpu)); + return 0; +} + +static int callthunks_debug_open(struct inode *inode, struct file *file) +{ + return single_open(file, callthunks_debug_show, inode->i_private); +} + +static const struct file_operations dfs_ops = { + .open = callthunks_debug_open, + .read = seq_read, + .llseek = seq_lseek, + .release = single_release, +}; + +static int __init callthunks_debugfs_init(void) +{ + struct dentry *dir; + unsigned long cpu; + + dir = debugfs_create_dir("callthunks", NULL); + for_each_possible_cpu(cpu) { + void *arg = (void *)cpu; + char name [10]; + + sprintf(name, "cpu%lu", cpu); + debugfs_create_file(name, 0644, dir, arg, &dfs_ops); + } + return 0; +} +__initcall(callthunks_debugfs_init); +#endif --- a/arch/x86/lib/retpoline.S +++ b/arch/x86/lib/retpoline.S @@ -203,13 +203,18 @@ EXPORT_SYMBOL(__x86_return_thunk) .align 64 SYM_FUNC_START(__x86_return_skl) ANNOTATE_NOENDBR - /* Keep the hotpath in a 16byte I-fetch */ + /* + * Keep the hotpath in a 16byte I-fetch for the non-debug + * case. + */ + CALL_THUNKS_DEBUG_INC_RETS shlq $5, PER_CPU_VAR(pcpu_hot + X86_call_depth) jz 1f ANNOTATE_UNRET_SAFE ret int3 1: + CALL_THUNKS_DEBUG_INC_STUFFS .rept 16 ANNOTATE_INTRA_FUNCTION_CALL call 2f