From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f41.google.com (mail-wm1-f41.google.com [209.85.128.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C892442E01F for ; Tue, 28 Apr 2026 16:05:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.41 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777392313; cv=none; b=jBIg2BZV6GWo5qJZs8zZnUZ2xK84MU04vvPSUauA5OlhSIA/77GFYIgC4xCrzl+mGOUo1EX1z1Tb8xITq8eGNqnhUEJQJJwzFMgQQPgox2FsMBIddBAEEUy3ZXqGkMLBt3Oow99TBQMjyCQqCxwZFd8LZp2DyCTRNGTWBziza6Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777392313; c=relaxed/simple; bh=0Ca/s7bahRNbDvgZ1Y6fc66EVIW3ao+7iwflwRkhRqM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=PiLDpNjbcJi5WRaNR3wbYsUH1hBlWXRAnQbEnBidzQtSole61NE+mj8daT9KiLzPBLXJZaGrQlOPKcWHRFOiH2NH8JaOlqVGXIY2JNK/XO8BX/URHVifQ0ZIKvzcYWbsgyyr1FFRgR2o4BkrjdjYBTmbWJkKt/I/1fT06o5q0Zw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=pdgcv4vg; arc=none smtp.client-ip=209.85.128.41 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="pdgcv4vg" Received: by mail-wm1-f41.google.com with SMTP id 5b1f17b1804b1-483487335c2so112907785e9.2 for ; Tue, 28 Apr 2026 09:05:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1777392310; x=1777997110; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=dbVFgyuWMP84TilCudYaWDaFqgJWBb3TtKL6dyNDnmY=; b=pdgcv4vgSoFPH2vKQLinrpI7tx6zbN2q5HEMw6essxkixSP7kRVRgp1WeAK4Ep3emA T+T9G9cg8d0Pb3/npj0j6CgLbUgRehWv2qvLpqmQIp7nwYlphOVwmhkTtOK/fC5f0tAP JMRt9SBOLQbGki5o7udxJH7T8Zp7MY6WM4aM9r3GqvkS6XtZgAgeH05aDwWF6W3SSbvd 2yD+q5ubU6UWXKxlCR7qpAGAR1ivHJsfeC/+EV9M27qB+lqvT4W7aagsK7XjKOaPI67C dCE5iuM3IIuu1dZoAKoX2n6AWzm72D67XO3JunKoOlyqZ1te6aI0+WDnF2s/7Dx40Vtz 5PMQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1777392310; x=1777997110; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=dbVFgyuWMP84TilCudYaWDaFqgJWBb3TtKL6dyNDnmY=; b=KXEAKQGZhuvPb+2xorPdUB/+TeEFKohoNL6USRo0pJ4fErEV5oQehGgqEB9e4TntAH 9+jTGMP9vYLNsQL33d5DLxnckBoXCeDyCTKTfbfaQ0H9qDjjf1BQ/gCUBxYnxijnkotx Fp4BATWAbjh5HvwFJ1wJoCMIQfydgcHTvFbGj1w8eadJyB/O/jLuN2J5Ui5zC6rANAYY XxzXWS2dZ7dcPXUCuXISW4VlvkTNJOhb45QvpFHRK/+Qz6jGgpgiY4jxYp1NZhkvRZ40 JdP0uGTRNjyEByP+IvLaZflaIobnLvk2J1j1a8GGsGMkM5zwsZsogpoFA1k897gxjWm6 Qk9g== X-Forwarded-Encrypted: i=1; AFNElJ/WRG4XLxn/6mFHTtI+oI69XuEomqIYRHGeUjWbEEWoRSpDYacetdkU6eShpQUfpupzdv0gd3B4ngLQG3w=@vger.kernel.org X-Gm-Message-State: AOJu0Yxf763fkr3NxjORlluAp3HtI1bwPUFK1/reu/v7BLugcRH88nMj ia2y5QnIRpZ6eDsSboiPSI2UffXKTt0cG73/6qwA0winMVKuKtuGaP5q X-Gm-Gg: AeBDiesTWn30UJQFBYCCxfGzTwPLc3/dRnkanmoEHmnOAOsHBo5mSaerFwOXhY3kncj mSVo9jSHMhJIdQKzsCRtLiHjkaQm+J0EKjKVnsoM5rz2OTbHMS2fqwthwzVGMjkukSmGdnc/Cye OjiAt2+K+Dxsse/RhIAHzDnUR4b24n443Ze9lB9SVEsaebNdRUm3oOZf9MVBRX+r2nLQgKBD0d5 D0zxrT5a/tiy0fkzKhfzrySJaapXjOutGzUbqu21b2x03rxiAxJLShbXYWdkLUzY+aqzAMtS8B3 Y3g21Ys4QAqUxOZybN02tw4p6Qj958aGleaWJ3G7UNmTXCrcFyReP2RFb2zH8vyLDT4d7KqdKAL 08w0KJsoygMtOzJrXsJAmB1eexb5Hm1SejIla50217cp8CTYUYvsHB69k62RwLyUEQvr8f3PIBv LG5pJM8DFVdzZzlfohONcthZTOIwju0DLf/pG/+eurwNPH8t9lC+b7MYBJowrHyx8Ikks/bVksM Pdx1D5/fs2yx6m72ab8LmkkrVYXplqrieN4AxgmMIRW/vvTR0TGxC4= X-Received: by 2002:a05:600c:a110:b0:489:1f3e:5f69 with SMTP id 5b1f17b1804b1-48a77b176f5mr45756435e9.18.1777392309985; Tue, 28 Apr 2026 09:05:09 -0700 (PDT) Received: from fedora ([46.248.82.114]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4464004edc8sm7532923f8f.37.2026.04.28.09.05.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Apr 2026 09:05:09 -0700 (PDT) From: Uros Bizjak To: x86@kernel.org, linux-kernel@vger.kernel.org Cc: Uros Bizjak , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" Subject: [PATCH RESEND -tip v2 5/7] x86/kexec: store segment registers directly to memory in crash_setup_regs() Date: Tue, 28 Apr 2026 18:03:39 +0200 Message-ID: <20260428160443.3593331-5-ubizjak@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260428160443.3593331-1-ubizjak@gmail.com> References: <20260428160443.3593331-1-ubizjak@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit crash_setup_regs() currently moves segment registers (ss, cs, ds, es) into pt_regs via a general purpose register (%eax). Update the code to avoid the intermediate register and store segment registers directly to their destination fields. This reduces the generated code from: 131: 8c d0 mov %ss,%eax 133: 66 89 84 24 a0 00 00 mov %ax,0xa0(%rsp) 13a: 00 13b: 8c c8 mov %cs,%eax 13d: 66 89 84 24 88 00 00 mov %ax,0x88(%rsp) 144: 00 to: 131: 8c 94 24 a0 00 00 00 mov %ss,0xa0(%rsp) 138: 8c 8c 24 88 00 00 00 mov %cs,0x88(%rsp) No functional change intended. Signed-off-by: Uros Bizjak Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: "H. Peter Anvin" --- arch/x86/include/asm/kexec.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h index 5cfb27f26583..ad7ef567452b 100644 --- a/arch/x86/include/asm/kexec.h +++ b/arch/x86/include/asm/kexec.h @@ -106,11 +106,11 @@ static inline void crash_setup_regs(struct pt_regs *newregs, asm volatile("mov %%r14,%0" : "=m"(newregs->r14)); asm volatile("mov %%r15,%0" : "=m"(newregs->r15)); #endif - asm volatile("mov %%ss,%k0" : "=a"(newregs->ss)); - asm volatile("mov %%cs,%k0" : "=a"(newregs->cs)); + asm volatile("mov %%ss,%0" : "=m"(newregs->ss)); + asm volatile("mov %%cs,%0" : "=m"(newregs->cs)); #ifdef CONFIG_X86_32 - asm volatile("mov %%ds,%k0" : "=a"(newregs->ds)); - asm volatile("mov %%es,%k0" : "=a"(newregs->es)); + asm volatile("mov %%ds,%0" : "=m"(newregs->ds)); + asm volatile("mov %%es,%0" : "=m"(newregs->es)); #endif asm volatile("pushf\n\t" "pop %0" : "=m"(newregs->flags)); -- 2.53.0