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 6A5B8C43219 for ; Mon, 17 Oct 2022 14:54:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231230AbiJQOyn (ORCPT ); Mon, 17 Oct 2022 10:54:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58816 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230320AbiJQOx6 (ORCPT ); Mon, 17 Oct 2022 10:53:58 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D1589691AC; Mon, 17 Oct 2022 07:53:45 -0700 (PDT) Date: Mon, 17 Oct 2022 14:53:37 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1666018418; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=fV1/l0X11YiOIK2ib0RRC0WGOOh6xbDnMI8H9/XHTz4=; b=VaW8qTDnK0LmcEguYPGUfOjyOmKWUvSm0Tkg5rpTPv0+kxxTyn1zUVrPGSkOi/5h9866lm GLSoaf8jjsubxjnwlKkL9TFV9kY312BMBCfTgyTPD7SooySeOs5Fvp+aHxkI0dKzOUjj10 JKBka4GEA+crbWVyeU0x5sQ2jVpRRQz6oteah6LUMqOl1JhVYP4CgTDONO6/WScFYN5Y5v Mlk5tKpN77RBabZYP8cxpYuiijFoQMB20ru4j6/KJ6XagJ9dXsH16A/OgxQicjQ+W/0Ef0 5SgeUdwZ/73QlnZmnzDvdXTWVhCkQWfY1LEuJvT/Medy7AxjjxUmqSrC7BQFWg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1666018418; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=fV1/l0X11YiOIK2ib0RRC0WGOOh6xbDnMI8H9/XHTz4=; b=2N33ZBtZpASKvE5Fhs6wJxTLP2QqlDGM08rd6APJPIUAU/3Sd/LS8Ngoqyyej/KmdU9zUO Wekn831hBwLLzzDg== From: "tip-bot2 for Thomas Gleixner" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/core] x86/calldepth: Add ret/call counting for debug Cc: Thomas Gleixner , "Peter Zijlstra (Intel)" , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20220915111148.204285506@infradead.org> References: <20220915111148.204285506@infradead.org> MIME-Version: 1.0 Message-ID: <166601841738.401.8846324922900036711.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the x86/core branch of tip: Commit-ID: f5c1bb2afe93396d41c5cbdcb909b08a75b8dde4 Gitweb: https://git.kernel.org/tip/f5c1bb2afe93396d41c5cbdcb909b08a75b8dde4 Author: Thomas Gleixner AuthorDate: Thu, 15 Sep 2022 13:11:30 +02:00 Committer: Peter Zijlstra CommitterDate: Mon, 17 Oct 2022 16:41:16 +02:00 x86/calldepth: Add ret/call counting for debug 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) Link: https://lore.kernel.org/r/20220915111148.204285506@infradead.org --- 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(-) diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h index 06ba7ca..4771147 100644 --- 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 + #if defined(CONFIG_CALL_DEPTH_TRACKING) && !defined(COMPILE_OFFSETS) #include @@ -75,18 +91,23 @@ #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 @@ -137,7 +158,8 @@ 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 @@ -321,6 +343,12 @@ static inline void x86_set_skl_return_thunk(void) { 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 diff --git a/arch/x86/kernel/callthunks.c b/arch/x86/kernel/callthunks.c index 01f6f6b..dfe7fff 100644 --- 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_calls(struct callthunk_sites *cs, 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 diff --git a/arch/x86/lib/retpoline.S b/arch/x86/lib/retpoline.S index e002060..5f61c65 100644 --- 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