From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 4AF8E4D8B6; Mon, 10 Jun 2024 20:48:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718052526; cv=none; b=ZGgV2zVjVIKnmp+MMTo6b89Fv237vz2YT6dNp6hLV2dUJmhc5Ofm3FYH3Os+TU8DG2bWf4Qlao6CfskpUx5j4AGi9ElKKkQkDe0Aye7VTPexEybmc8Jonhucaif9SSPvohmUSFnGlvdmp7NZSdvfI4/YPT9e4K7lTXB9/An5oS8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718052526; c=relaxed/simple; bh=FOi86UUldJ0DWqgv3J6xhcGdiAK6DXsRyDRsaDmLflk=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=UqEh5NgkDJqJI7T6eg0Lqs40u4O+jES4KJ3eBMS8cLmWpcMEdc377x/uphAZEUotRpBF9EeGxRs5tsovtufzehu8gsrR5nKukiHV6nQ8CsyczjVP9YiuHWQd6ubTB9uV0f9N3RLIZcUjvmi7ovKX+5fCC5lKHc0xGbfFtWh0a1s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=JbjctN5u; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="JbjctN5u" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 86479C32789; Mon, 10 Jun 2024 20:48:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1718052525; bh=FOi86UUldJ0DWqgv3J6xhcGdiAK6DXsRyDRsaDmLflk=; h=From:To:Cc:Subject:Date:From; b=JbjctN5ukgqDo74t/mtIe3qdJp7NLV6bNy0d+r9Tl9X8W2pffb0HzTbX9bcA2WglY u3t5dDKfR3wnUKv9jy5lrQ7feHQUisP+6OvaVf+J0CmAu+oZQQoF9dp3n+rGQNrnT9 lhBQcb81GuKAGvcYAlquAO2mDYX4s1hUdkY5t/M8= From: Linus Torvalds To: Peter Anvin , Ingo Molnar , Borislav Petkov , Thomas Gleixner , Rasmus Villemoes , Josh Poimboeuf , Catalin Marinas , Will Deacon Cc: Linux Kernel Mailing List , the arch/x86 maintainers , linux-arm-kernel@lists.infradead.org, linux-arch , Linus Torvalds Subject: [PATCH 0/7] arm64 / x86-64: low-level code generation issues Date: Mon, 10 Jun 2024 13:48:14 -0700 Message-ID: <20240610204821.230388-1-torvalds@linux-foundation.org> X-Mailer: git-send-email 2.45.1.209.gc6f12300df Precedence: bulk X-Mailing-List: linux-arch@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit So this is the result of me doing some profiling on my 128-core Altra box. I've sent out versions of this before, but they've all been fairly ugly partial series. This is the full cleaned-up series with patches split up to be logical, and with fixes from some of the commentary from previous patches. The first four patches are for the 'runtime constant' code, where I did the initial implementation on x86-64 just because I was more comfy with that, and the arm64 version of it came once I had the x86-64 side working. The horror that is __d_lookup_rcu() shows up a lot more on my Altra box because of the relatively pitiful caches, but it's something that I've wanted on x86-64 before. The arm64 numbers just made me bite the bullet on the whole runtime constant thing. The last three patches are purely arm64-specific, and just fix up some nasty code generation in the user access functions. I just noticed that I will need to implement 'user_access_save()' for KCSAN now that I do the unsafe user access functions. Anyway, that 'user_access_save/restore()' issue only shows up with KCSAN. And it would be a no-op thanks to arm64 doing SMAP the right way (pet peeve: arm64 did what I told the x86 designers to do originally, but they claimed was too hard, so we ended up with that CLAC/STAC instead)... Sadly that "no-op for KCSAN" would is except for the horrid CONFIG_ARM64_SW_TTBR0_PAN case, which is why I'm not touching it. I'm hoping some hapless^Whelpful arm64 person is willing to tackle this (or maybe make KCSAN and ARM64_SW_TTBR0_PAN incompatible in the Kconfig). Note: the final access_ok() change in 7/7 is a API relaxation and cleanup, and as such much more worrisome than the other patches. It's _simpler_ than the other patches, but the others aren't intended to really change behavior. That one does. Linus Torvalds (7): vfs: dcache: move hashlen_hash() from callers into d_hash() add default dummy 'runtime constant' infrastructure x86: add 'runtime constant' support arm64: add 'runtime constant' support arm64: start using 'asm goto' for get_user() when available arm64: start using 'asm goto' for put_user() when available arm64: access_ok() optimization arch/arm64/include/asm/runtime-const.h | 75 ++++++++++ arch/arm64/include/asm/uaccess.h | 191 +++++++++++++++++-------- arch/arm64/kernel/mte.c | 12 +- arch/arm64/kernel/vmlinux.lds.S | 3 + arch/x86/include/asm/runtime-const.h | 61 ++++++++ arch/x86/kernel/vmlinux.lds.S | 3 + fs/dcache.c | 17 ++- include/asm-generic/Kbuild | 1 + include/asm-generic/runtime-const.h | 15 ++ include/asm-generic/vmlinux.lds.h | 8 ++ 10 files changed, 319 insertions(+), 67 deletions(-) create mode 100644 arch/arm64/include/asm/runtime-const.h create mode 100644 arch/x86/include/asm/runtime-const.h create mode 100644 include/asm-generic/runtime-const.h -- 2.45.1.209.gc6f12300df