From nobody Sun Feb 8 18:24:40 2026 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7B9BC1FBEB9; Tue, 4 Mar 2025 08:27:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741076872; cv=none; b=j5ag9FA5JT+NU+pTbQIyeapNYqxWaMUSLGhfTmBoQAXBL+qXfu8vrSzpub4e0F935+PbSDz+J/Uom1UYl328/Bkzlt+vIFhQAIDeuqPueuDo2Z2xR8a+I7k+MdgbSjf54QJJuBp8NxwB2m/nlMWrY9W9UL8zC+yn9z0QcCkH/Lw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741076872; c=relaxed/simple; bh=EH4Ns7RGVUwvPNPq415WG7MXhhwqqmCfRwGWkfGL4bQ=; h=Date:From:To:Subject:Cc:In-Reply-To:References:MIME-Version: Message-ID:Content-Type; b=h5uB7oEapJF0aLdD2O72waLVL0aCMDxv6c/oPosViyvU3nsk5AOpPDXWl6jKdWmOiv6+ASn7NgRCPDl2Y1yv231+iEuBlKWqmYCcCT5qY5+8tOhv1tPMjcRp/PP67AUQuP2zdLZw7fAtOVrOGDGEcwz6CTUpGafepOIe/Zxtfz8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=pAxJskcN; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=WDznIPeJ; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="pAxJskcN"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="WDznIPeJ" Date: Tue, 04 Mar 2025 08:27:48 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1741076868; 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=Jp6bCnZBpNShy0/dkxT8SVr+AanNcMDDnJUzsy0bQ5o=; b=pAxJskcNxP5jWru9C9NlnbdD2pgfCkvwUYw0KPE5Rn5CHsNy3ljph14l7dHoV+1okXJ+bD nGcxibyJId+ACnBabLD9bTRek7h2dFt3Ju9c5ZlEZzVMy5KFn9zwa423ekhF51rl2A0NFR +6k4n+afvqbirjoktg0mlRpu8CD61qw18ZSBODa21EMgBVcFOEHkFR1Vd5WsSHiyuGTAZK BgUzQ2AUAQYruekkrg9voZrkzZp3tgvVqRh52+BvAH9RFSh+Q3wGpQpNuQ90b/LiaodKYa H2NMARqyv0y1dFyXdARTTu1t3vNa1zZ/pZ/9cut/ugz+pu8F7E9YmIF4RWrtQA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1741076868; 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=Jp6bCnZBpNShy0/dkxT8SVr+AanNcMDDnJUzsy0bQ5o=; b=WDznIPeJppJdshZgKkvqT7o2vxXNvA+UmuhtrTRhZIIssQmnOkZjzmGpaRAJdl/yBgjao1 0uwwUxm5wGvq+YAA== From: "tip-bot2 for Brian Gerst" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/core] x86/retbleed: Move call depth to percpu hot section Cc: Brian Gerst , Ingo Molnar , Uros Bizjak , Linus Torvalds , Peter Zijlstra , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20250303165246.2175811-6-brgerst@gmail.com> References: <20250303165246.2175811-6-brgerst@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <174107686802.14745.1591483482446970377.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The following commit has been merged into the x86/core branch of tip: Commit-ID: e836c9cd89d097603e80a1a0d1c90d887f573129 Gitweb: https://git.kernel.org/tip/e836c9cd89d097603e80a1a0d1c90d887= f573129 Author: Brian Gerst AuthorDate: Mon, 03 Mar 2025 11:52:40 -05:00 Committer: Ingo Molnar CommitterDate: Mon, 03 Mar 2025 21:37:41 +01:00 x86/retbleed: Move call depth to percpu hot section No functional change. Signed-off-by: Brian Gerst Signed-off-by: Ingo Molnar Acked-by: Uros Bizjak Cc: Linus Torvalds Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20250303165246.2175811-6-brgerst@gmail.com --- arch/x86/include/asm/current.h | 3 --- arch/x86/include/asm/nospec-branch.h | 11 ++++++----- arch/x86/kernel/asm-offsets.c | 3 --- arch/x86/kernel/cpu/common.c | 8 ++++++++ arch/x86/lib/retpoline.S | 2 +- 5 files changed, 15 insertions(+), 12 deletions(-) diff --git a/arch/x86/include/asm/current.h b/arch/x86/include/asm/current.h index f988462..8ba2c0f 100644 --- a/arch/x86/include/asm/current.h +++ b/arch/x86/include/asm/current.h @@ -14,9 +14,6 @@ struct task_struct; =20 struct pcpu_hot { struct task_struct *current_task; -#ifdef CONFIG_MITIGATION_CALL_DEPTH_TRACKING - u64 call_depth; -#endif unsigned long top_of_stack; void *hardirq_stack_ptr; u16 softirq_pending; diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/no= spec-branch.h index 7e8bf78..a560205 100644 --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -12,7 +12,6 @@ #include #include #include -#include =20 /* * Call depth tracking for Intel SKL CPUs to address the RSB underflow @@ -78,21 +77,21 @@ #include =20 #define CREDIT_CALL_DEPTH \ - movq $-1, PER_CPU_VAR(pcpu_hot + X86_call_depth); + movq $-1, PER_CPU_VAR(__x86_call_depth); =20 #define RESET_CALL_DEPTH \ xor %eax, %eax; \ bts $63, %rax; \ - movq %rax, PER_CPU_VAR(pcpu_hot + X86_call_depth); + movq %rax, PER_CPU_VAR(__x86_call_depth); =20 #define RESET_CALL_DEPTH_FROM_CALL \ movb $0xfc, %al; \ shl $56, %rax; \ - movq %rax, PER_CPU_VAR(pcpu_hot + X86_call_depth); \ + movq %rax, PER_CPU_VAR(__x86_call_depth); \ CALL_THUNKS_DEBUG_INC_CALLS =20 #define INCREMENT_CALL_DEPTH \ - sarq $5, PER_CPU_VAR(pcpu_hot + X86_call_depth); \ + sarq $5, PER_CPU_VAR(__x86_call_depth); \ CALL_THUNKS_DEBUG_INC_CALLS =20 #else @@ -388,6 +387,8 @@ extern void call_depth_return_thunk(void); __stringify(INCREMENT_CALL_DEPTH), \ X86_FEATURE_CALL_DEPTH) =20 +DECLARE_PER_CPU_CACHE_HOT(u64, __x86_call_depth); + #ifdef CONFIG_CALL_THUNKS_DEBUG DECLARE_PER_CPU(u64, __x86_call_count); DECLARE_PER_CPU(u64, __x86_ret_count); diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c index a98020b..6fae88f 100644 --- a/arch/x86/kernel/asm-offsets.c +++ b/arch/x86/kernel/asm-offsets.c @@ -109,9 +109,6 @@ static void __used common(void) OFFSET(TSS_sp2, tss_struct, x86_tss.sp2); OFFSET(X86_top_of_stack, pcpu_hot, top_of_stack); OFFSET(X86_current_task, pcpu_hot, current_task); -#ifdef CONFIG_MITIGATION_CALL_DEPTH_TRACKING - OFFSET(X86_call_depth, pcpu_hot, call_depth); -#endif #if IS_ENABLED(CONFIG_CRYPTO_ARIA_AESNI_AVX_X86_64) /* Offset for fields in aria_ctx */ BLANK(); diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index c479d3c..ffa291c 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -2058,6 +2058,14 @@ DEFINE_PER_CPU_CACHE_HOT(int, __preempt_count) =3D I= NIT_PREEMPT_COUNT; EXPORT_PER_CPU_SYMBOL(__preempt_count); =20 #ifdef CONFIG_X86_64 +/* + * Note: Do not make this dependant on CONFIG_MITIGATION_CALL_DEPTH_TRACKI= NG + * so that this space is reserved in the hot cache section even when the + * mitigation is disabled. + */ +DEFINE_PER_CPU_CACHE_HOT(u64, __x86_call_depth); +EXPORT_PER_CPU_SYMBOL(__x86_call_depth); + static void wrmsrl_cstar(unsigned long val) { /* diff --git a/arch/x86/lib/retpoline.S b/arch/x86/lib/retpoline.S index 038f49a..a26c43a 100644 --- a/arch/x86/lib/retpoline.S +++ b/arch/x86/lib/retpoline.S @@ -343,7 +343,7 @@ SYM_FUNC_START(call_depth_return_thunk) * case. */ CALL_THUNKS_DEBUG_INC_RETS - shlq $5, PER_CPU_VAR(pcpu_hot + X86_call_depth) + shlq $5, PER_CPU_VAR(__x86_call_depth) jz 1f ANNOTATE_UNRET_SAFE ret