From: Evgeniy Baskov <baskov@ispras.ru>
To: Andrew Cooper <Andrew.Cooper3@citrix.com>
Cc: Ard Biesheuvel <ardb@kernel.org>, Borislav Petkov <bp@alien8.de>,
Andy Lutomirski <luto@kernel.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Alexey Khoroshilov <khoroshilov@ispras.ru>,
lvc-project@linuxtesting.org, x86@kernel.org,
linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-hardening@vger.kernel.org
Subject: Re: [PATCH 03/16] x86/boot: Set cr0 to known state in trampoline
Date: Thu, 20 Oct 2022 16:25:51 +0300 [thread overview]
Message-ID: <e217cff7752088baca2485f691e62d72@ispras.ru> (raw)
In-Reply-To: <7dce2b16-c652-8b6d-5594-d110c8ac4645@citrix.com>
On 2022-10-19 10:44, Andrew Cooper wrote:
> On 06/09/2022 11:41, Evgeniy Baskov wrote:
>> diff --git a/arch/x86/boot/compressed/head_64.S
>> b/arch/x86/boot/compressed/head_64.S
>> index d33f060900d2..5273367283b7 100644
>> --- a/arch/x86/boot/compressed/head_64.S
>> +++ b/arch/x86/boot/compressed/head_64.S
>> @@ -619,9 +619,8 @@ SYM_CODE_START(trampoline_32bit_src)
>> /* Set up new stack */
>> leal TRAMPOLINE_32BIT_STACK_END(%ecx), %esp
>>
>> - /* Disable paging */
>> - movl %cr0, %eax
>> - btrl $X86_CR0_PG_BIT, %eax
>> + /* Disable paging and setup CR0 */
>> + movl $(CR0_STATE & ~X86_CR0_PG), %eax
>
> Why here? WP is ignored when PG is disabled.
>
> ~Andrew
PG is enabled lower in this function, so WP can also be set there,
it should not make any difference. The only important thing is that
WP supposed to be set in trampoline code.
If you think, that it would be more logical to set PG and WP
simultaneously, I can change it to be that way.
Thanks,
Evgeniy Baskov
next prev parent reply other threads:[~2022-10-20 13:26 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-06 10:41 [PATCH 00/16] x86_64: Improvements at compressed kernel stage Evgeniy Baskov
2022-09-06 10:41 ` [PATCH 01/16] x86/boot: Align vmlinuz sections on page size Evgeniy Baskov
2022-10-19 7:01 ` Ard Biesheuvel
2022-10-20 11:13 ` Evgeniy Baskov
2022-09-06 10:41 ` [PATCH 02/16] x86/build: Remove RWX sections and align on 4KB Evgeniy Baskov
2022-10-19 7:04 ` Ard Biesheuvel
2022-10-20 11:15 ` Evgeniy Baskov
2022-09-06 10:41 ` [PATCH 03/16] x86/boot: Set cr0 to known state in trampoline Evgeniy Baskov
2022-10-19 7:06 ` Ard Biesheuvel
2022-10-20 11:23 ` Evgeniy Baskov
2022-10-19 7:44 ` Andrew Cooper
2022-10-20 13:25 ` Evgeniy Baskov [this message]
2022-09-06 10:41 ` [PATCH 04/16] x86/boot: Increase boot page table size Evgeniy Baskov
2022-10-19 7:08 ` Ard Biesheuvel
2022-10-20 11:29 ` Evgeniy Baskov
2022-09-06 10:41 ` [PATCH 05/16] x86/boot: Support 4KB pages for identity mapping Evgeniy Baskov
2022-10-19 7:11 ` Ard Biesheuvel
2022-10-20 11:30 ` Evgeniy Baskov
2022-09-06 10:41 ` [PATCH 06/16] x86/boot: Setup memory protection for bzImage code Evgeniy Baskov
2022-10-19 7:17 ` Ard Biesheuvel
2022-10-20 12:07 ` Evgeniy Baskov
2022-10-19 7:57 ` Andrew Cooper
2022-10-20 13:30 ` Evgeniy Baskov
2022-10-20 16:51 ` Andrew Cooper
2022-09-06 10:41 ` [PATCH 07/16] x86/boot: Map memory explicitly Evgeniy Baskov
2022-09-06 10:41 ` [PATCH 08/16] x86/boot: Remove mapping from page fault handler Evgeniy Baskov
2022-10-19 7:20 ` Ard Biesheuvel
2022-09-06 10:41 ` [PATCH 09/16] efi/libstub: Move helper function to related file Evgeniy Baskov
2022-10-19 7:21 ` Ard Biesheuvel
2022-09-06 10:41 ` [PATCH 10/16] x86/boot: Make console interface more abstract Evgeniy Baskov
2022-10-19 7:23 ` Ard Biesheuvel
2022-10-20 12:10 ` Evgeniy Baskov
2022-09-06 10:41 ` [PATCH 11/16] x86/boot: Split trampoline and pt init code Evgeniy Baskov
2022-09-06 10:41 ` [PATCH 12/16] x86/boot: Add EFI kernel extraction interface Evgeniy Baskov
2022-10-19 7:27 ` Ard Biesheuvel
2022-10-20 12:14 ` Evgeniy Baskov
2022-09-06 10:41 ` [PATCH 13/16] efi/x86: Support extracting kernel from libstub Evgeniy Baskov
2022-10-19 7:35 ` Ard Biesheuvel
2022-10-20 12:36 ` Evgeniy Baskov
2022-09-06 10:41 ` [PATCH 14/16] x86/build: Make generated PE more spec compliant Evgeniy Baskov
2022-10-19 7:39 ` Ard Biesheuvel
2022-10-20 13:07 ` Evgeniy Baskov
2022-09-06 10:41 ` [PATCH 15/16] efi/libstub: Add memory attribute protocol definitions Evgeniy Baskov
2022-10-19 7:39 ` Ard Biesheuvel
2022-09-06 10:41 ` [PATCH 16/16] efi/libstub: Use memory attribute protocol Evgeniy Baskov
2022-10-18 20:51 ` [PATCH] efi/libstub: make memory protection warnings include newlines Peter Jones
2022-10-19 7:44 ` Ard Biesheuvel
2022-10-19 7:42 ` [PATCH 16/16] efi/libstub: Use memory attribute protocol Ard Biesheuvel
2022-10-20 13:13 ` Evgeniy Baskov
2022-10-18 21:04 ` [PATCH 00/16] x86_64: Improvements at compressed kernel stage Peter Jones
2022-10-20 11:05 ` Evgeniy Baskov
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