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From: Andy Lutomirski <luto@kernel.org>
To: Gabriel Krisman Bertazi <krisman@collabora.com>
Cc: Andrew Lutomirski <luto@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Christoph Hellwig <hch@lst.de>, "H. Peter Anvin" <hpa@zytor.com>,
	Borislav Petkov <bp@alien8.de>, Robert Richter <rric@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>, X86 ML <x86@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	kernel@collabora.com
Subject: Re: [PATCH v2 8/9] x86: Convert mmu context ia32_compat into a proper flags field
Date: Thu, 1 Oct 2020 15:09:33 -0700	[thread overview]
Message-ID: <CALCETrXPXxGZBGOf_DnYogamnkp29u8EqY33zDZb-HD+fj9ugg@mail.gmail.com> (raw)
In-Reply-To: <20201001205819.27879-9-krisman@collabora.com>

On Thu, Oct 1, 2020 at 1:59 PM Gabriel Krisman Bertazi
<krisman@collabora.com> wrote:
>
> The ia32_compat attribute is a weird thing.  It mirrors TIF_IA32 and
> TIF_X32 and is used only in two very unrelated places: (1) to decide if
> the vsyscall page is accessible (2) for uprobes to find whether the
> patched instruction is 32 or 64 bit.  In preparation to remove the TI
> flags, we want new values for ia32_compat, but given its odd semantics,
> I'd rather make it a real flags field that configures these specific
> behaviours.  So, set_personality_x64 can ask for the vsyscall page,
> which is not available in x32/ia32 and set_personality_ia32 can
> configure the uprobe code as needed.
>
> uprobe cannot rely on other methods like user_64bit_mode() to decide how
> to patch, so it needs some specific flag like this.

I like this quite a bit, but can you rename MM_CONTEXT_GATE_PAGE to
MM_CONTEXT_HAS_VSYSCALL?

--Andy

  reply	other threads:[~2020-10-01 22:09 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-01 20:58 [PATCH v2 0/9] Reclaim TIF_IA32 and TIF_X32 Gabriel Krisman Bertazi
2020-10-01 20:58 ` [PATCH v2 1/9] x86: events: Avoid TIF_IA32 when checking 64bit mode Gabriel Krisman Bertazi
2020-10-01 20:58 ` [PATCH v2 2/9] x86: Simplify compat syscall userspace allocation Gabriel Krisman Bertazi
2020-10-01 20:58 ` [PATCH v2 3/9] x86: oprofile: Avoid TIF_IA32 when checking 64bit mode Gabriel Krisman Bertazi
2020-10-01 20:58 ` [PATCH v2 4/9] x86: elf: Use e_machine to choose DLINFO in compat Gabriel Krisman Bertazi
2020-10-01 21:46   ` Andy Lutomirski
2020-10-01 20:58 ` [PATCH v2 5/9] x86: elf: Use e_machine to select start_thread for x32 Gabriel Krisman Bertazi
2020-10-01 21:49   ` Andy Lutomirski
2020-10-01 20:58 ` [PATCH v2 6/9] x86: elf: Use e_machine to select setup_additional_pages " Gabriel Krisman Bertazi
2020-10-01 21:50   ` Andy Lutomirski
2020-10-01 20:58 ` [PATCH v2 7/9] x86: Use current USER_CS to setup correct context on vmx entry Gabriel Krisman Bertazi
2020-10-01 21:52   ` Andy Lutomirski
2020-10-02 22:40     ` Sean Christopherson
2020-10-02 23:11       ` Gabriel Krisman Bertazi
2020-10-03  0:15       ` Andy Lutomirski
2020-10-03 23:04         ` Andy Lutomirski
2020-10-05 18:56           ` Andy Lutomirski
2020-10-05 19:54           ` Sean Christopherson
2020-10-01 20:58 ` [PATCH v2 8/9] x86: Convert mmu context ia32_compat into a proper flags field Gabriel Krisman Bertazi
2020-10-01 22:09   ` Andy Lutomirski [this message]
2020-10-01 20:58 ` [PATCH v2 9/9] x86: Reclaim TIF_IA32 and TIF_X32 Gabriel Krisman Bertazi

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