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Message-ID: <3261d02e8e6175a3cb122467b1fd0063@ispras.ru>
Date: Thu, 20 Oct 2022 14:15:21 +0300
From: Evgeniy Baskov <baskov@...ras.ru>
To: Ard Biesheuvel <ardb@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>, Andy Lutomirski <luto@...nel.org>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Ingo Molnar <mingo@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Thomas Gleixner <tglx@...utronix.de>,
Alexey Khoroshilov <khoroshilov@...ras.ru>,
lvc-project@...uxtesting.org, x86@...nel.org,
linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-hardening@...r.kernel.org
Subject: Re: [PATCH 02/16] x86/build: Remove RWX sections and align on 4KB
On 2022-10-19 10:04, Ard Biesheuvel wrote:
> On Tue, 6 Sept 2022 at 12:41, Evgeniy Baskov <baskov@...ras.ru> wrote:
>>
>> Avoid creating sections with maximal privileges to prepare for W^X
>
> privileges
>
>> implementation. Align sections on page size (4KB) to allow protecting
>> them in page table.
>>
>
> in the page tables.
>
>> Signed-off-by: Evgeniy Baskov <baskov@...ras.ru>
>> ---
>> arch/x86/kernel/vmlinux.lds.S | 15 ++++++++-------
>> 1 file changed, 8 insertions(+), 7 deletions(-)
>>
>> diff --git a/arch/x86/kernel/vmlinux.lds.S
>> b/arch/x86/kernel/vmlinux.lds.S
>> index 15f29053cec4..6587e0201b50 100644
>> --- a/arch/x86/kernel/vmlinux.lds.S
>> +++ b/arch/x86/kernel/vmlinux.lds.S
>> @@ -102,12 +102,11 @@ jiffies = jiffies_64;
>> PHDRS {
>> text PT_LOAD FLAGS(5); /* R_E */
>> data PT_LOAD FLAGS(6); /* RW_ */
>> -#ifdef CONFIG_X86_64
>> -#ifdef CONFIG_SMP
>> +#if defined(CONFIG_X86_64) && defined(CONFIG_SMP)
>> percpu PT_LOAD FLAGS(6); /* RW_ */
>> #endif
>> - init PT_LOAD FLAGS(7); /* RWE */
>> -#endif
>> + inittext PT_LOAD FLAGS(5); /* R_E */
>> + init PT_LOAD FLAGS(6); /* RW_ */
>
> Please explain in the commit log how this change affects X86_32
>
>> note PT_NOTE FLAGS(0); /* ___ */
>> }
>>
>> @@ -226,9 +225,10 @@ SECTIONS
>> #endif
>>
>> INIT_TEXT_SECTION(PAGE_SIZE)
>> -#ifdef CONFIG_X86_64
>> - :init
>> -#endif
>> + :inittext
>> +
>> + . = ALIGN(PAGE_SIZE);
>> +
>>
>> /*
>> * Section for code used exclusively before alternatives are
>> run. All
>> @@ -240,6 +240,7 @@ SECTIONS
>> .altinstr_aux : AT(ADDR(.altinstr_aux) - LOAD_OFFSET) {
>> *(.altinstr_aux)
>> }
>> + :init
>>
>> INIT_DATA_SECTION(16)
>>
>> --
>> 2.35.1
>>
Thanks for pointing you, I'll fix all mentioned nitpicks before sending
this again.
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