From nobody Sun Feb 8 11:11:43 2026 Received: from out203-205-221-205.mail.qq.com (out203-205-221-205.mail.qq.com [203.205.221.205]) (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 F085F2AD31 for ; Wed, 8 Oct 2025 14:43:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=203.205.221.205 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759934612; cv=none; b=tk/2DBn88PFvTW6hhcUF/FGVf+pcaX1JU9lFzA4y8TTDev7O3VeiltLY7TYxYKum+aonxgZCOF3VMlPa8IxKxgAdLvrvpF8oaz/nDTuQPcg/iU0WCcikQE1hc1Pu2fjmnSTw+2tOD9LXLWB8YCbzcz7AvVnq18TRzEKYSRk56E8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759934612; c=relaxed/simple; bh=+Mwd6O/6R0+UhWbbwOh4kyOOOxzLz+tRUgxLNNbpuYc=; h=From:To:Cc:Subject:Mime-Version:Content-Type:Date:Message-ID; b=qzbHiKBwolWBKJHS82UgfUKktAoQ751ZXUATtLScVM8c6vVJTR4aJgOqBbEhDnY3e8EMg74/0DQ677v5jFdMy2lZQsEuhFifBnxi680o060RsMQxs1U+85819wL4eEsjhNPg8xmoMCApLf21ViGGOjCKCjt25whx4Fg0xb66nhE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=qq.com; spf=pass smtp.mailfrom=qq.com; dkim=pass (1024-bit key) header.d=qq.com header.i=@qq.com header.b=JWcf1aol; arc=none smtp.client-ip=203.205.221.205 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=qq.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=qq.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=qq.com header.i=@qq.com header.b="JWcf1aol" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=qq.com; s=s201512; t=1759934601; bh=+Mwd6O/6R0+UhWbbwOh4kyOOOxzLz+tRUgxLNNbpuYc=; h=From:To:Cc:Subject:Date; b=JWcf1aolFnCsggqCCK5ov//c3DoKQMZ1+AQUlBHC+YbssHBkFlqhnPeEXrmWgxsb6 S+k9IxmyF7ThX2SYYCvoUU6Uwz8Uexi80YT1dJLC4wkS76eeXWoZIg+3yJ+599Zz3E tnLoD07X7iIVLSge6/djpZNmLqWx3SyKuGHmu8uk= X-QQ-XMRINFO: Mp0Kj//9VHAxr69bL5MkOOs= X-QQ-XMAILINFO: NNde6qybtQwECC0vR34hGWq6wGRWwpT8CnG+b7xWG5a7I0wtAcX9HXtHcDZsM3 0R3XkOnXIC17HgETTaw9RxA64lNgpy67X6PtJcRuh6d4GigJuIPeuc9HTYokPZgpnbKWQLIFJyJ4p JWXB93o1A96WlgtYtCY9DDZNlVtXAW2Wi5AAVHfHcgqOGReWHdBRIoNTzmdLw0JhDvYVYmpr4LnGU fFqNaLdJ8tWUYmWN50uxEPAluAH65lzDq1jKj1+ndocW0qHXMCc5LpDShcKDQJUietHvLa4Vwymh1 M9+9eSMS5Kyv8DaOSEkI+D8Np47QK+sUpoaQzZi+u8SNqu4O+JTW2jwJP/Olcq2vbaNyOnnX4xeF7 z8VI2ate8Mr/UWIWQcQ2tDXEOYI98GgZDhTTFmPbvyx9b8+vYlLIlV/u63Dz6LetQ/T1JOz5PnJZg ETU8NtK+BKY/EAfNTcIwJ/xPJnh9rTB/FGE3gtYLnGZNIDv25uRZAmkiCycmzUrTsa1ApqVLaBa/N i+nHR+M5ywjBsJOv6zhnaYfV0+8UGr91BgfagBIbj/oVOE0H34BkIplX8nxDg4sreHpIXitCqLY0T UxT+TL9WrCr2kwWGysdw7k8DrmI4nWBfhBpNWrnW3mzcV9BwcgSpJVAmUDsryrcb+mprAeHfr6hrY jjhCFWIvBajPx2FKdhTubl+U+SgRSijA5N1nyRLpAR5moQKRV3zmEO8m5TzB08Hkp2Ow8EdN+EEFf PBTdZLBcn+vXtYvzxrm4AUAeHEJyBUIvZ4ju0Szj/yRqwEGRQ0DKcfU4aOP52NZ7yAoVYuDw7lqVN rILkTf0jEq0Th5FxEI/z97Jzm2tIQz0nGSGqdkAW/N7xCwwLxg4S2A25aO/ndYOoNmvswrbFaDt9L ZVCxEKXKNXcZoiWLBvolGelToP1zuRRyvrO3cJ5LGsGA8OMbVzAGzkH0l1V0y5rM0X3s0TEuhHmHT dAao+4PuPym16lLrWJpnQ/O0siwU/vo5aybKotzjMjxNXwSepB65am8EWPws9wuZFU38Cxc/mmSJH g4AoNjBFUDBRMX69sfV43wMzP5gjjarA4tWrqK9xmq2svqZgBD0hFLfOArTvvBH/VEbvf From: "=?utf-8?B?c2hlbmdtaW5naHU1MTI=?=" To: "=?utf-8?B?dGdseA==?=" , "=?utf-8?B?bWluZ28=?=" , "=?utf-8?B?YnA=?=" , "=?utf-8?B?ZGF2ZS5oYW5zZW4=?=" , "=?utf-8?B?eDg2?=" Cc: "=?utf-8?B?aHBh?=" , "=?utf-8?B?YnJvb25pZQ==?=" , "=?utf-8?B?bGludXgta2VybmVs?=" , "=?utf-8?B?emhhbmcucnVu?=" , "=?utf-8?B?aHUuc2hlbmdtaW5n?=" Subject: [PATCH v1] x86/boot: Use pgd_index(__START_KERNEL_map) instead of hardcoded 511 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Date: Wed, 8 Oct 2025 22:43:00 +0800 X-Priority: 3 Message-ID: X-QQ-MIME: TCMime 1.0 by Tencent X-Mailer: QQMail 2.x X-QQ-Mailer: QQMail 2.x X-QQ-mid: xmsezc43-1t1759934580tulx4ocqe Content-Type: text/plain; charset="utf-8" From: Shengming Hu Date: Wed, 8 Oct 2025 21:46:03 +0800 Subject: [PATCH v1] x86/boot: Use pgd_index(__START_KERNEL_map) instead of hardcoded 511 The index 511 is used to set up the kernel high mapping in the top-level page table.=20 Replacing the magic number with pgd_index(__START_KERNEL_map)=20 improves code readability and future-proofs the code against=20 possible changes in paging structure. Signed-off-by: Shengming Hu --- arch/x86/kernel/head64.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index fd28b53db..65d4c485a 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -286,7 +286,9 @@ asmlinkage __visible void __init __noreturn x86_64_star= t_kernel(char * real_mode load_ucode_bsp(); =20 /* set init_top_pgt kernel high mapping*/ - init_top_pgt[511] =3D early_top_pgt[511]; + unsigned int kernel_pgd =3D pgd_index(__START_KERNEL_map); + + init_top_pgt[kernel_pgd] =3D early_top_pgt[kernel_pgd]; =20 x86_64_start_reservations(real_mode_data); } --=20 2.34.1