From: Thomas Gleixner <tglx@linutronix.de>
To: Wei Yang <richard.weiyang@gmail.com>,
mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
Wei Yang <richard.weiyang@gmail.com>,
Vivek Goyal <vgoyal@in.ibm.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
Ingo Molnar <mingo@kernel.org>, Steve Wahl <steve.wahl@hpe.com>,
Borislav Petkov <bp@suse.de>
Subject: Re: [PATCH] x86/head/64: level2_kernel_pgt's kernel area is built with _PAGE_PRESENT set
Date: Wed, 22 May 2024 11:58:01 +0200 [thread overview]
Message-ID: <87jzjmgod2.ffs@tglx> (raw)
In-Reply-To: <20240323232621.10400-1-richard.weiyang@gmail.com>
On Sat, Mar 23 2024 at 23:26, Wei Yang wrote:
> The code is first introduced in 'commit 1ab60e0f72f7 ("[PATCH] x86-64:
> Relocatable Kernel Support")'. Then 'commit c88d71508e36b
> ("x86/boot/64: Rewrite startup_64() in C")', convert it to c. And
> 'commit 2aa85f246c181 ("x86/boot/64: Make level2_kernel_pgt pages
> invalid outside kernel area")' limit the range from _text to _end.
>
> Originally, it does the check because the loop iterate the whole
> level2_kernel_pgt, while currently it just fixup the kernel area. This
> area is built with _PAGE_PRESENT set.
What's the actual problem you are trying to solve?
> /* fixup pages that are part of the kernel image */
> for (; i <= pmd_index((unsigned long)_end); i++)
> - if (pmd[i] & _PAGE_PRESENT)
> - pmd[i] += load_delta;
> + pmd[i] += load_delta;
Fixing up non-present PMDs is a pointless exercise.
Thanks,
tglx
next prev parent reply other threads:[~2024-05-22 9:58 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-23 23:26 [PATCH] x86/head/64: level2_kernel_pgt's kernel area is built with _PAGE_PRESENT set Wei Yang
2024-05-22 7:34 ` Wei Yang
2024-05-22 9:58 ` Thomas Gleixner [this message]
2024-05-22 14:06 ` Wei Yang
2024-05-22 20:33 ` Thomas Gleixner
2024-05-23 7:43 ` Wei Yang
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