From: Ingo Molnar <mingo@kernel.org>
To: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Jeff Dike <jdike@addtoit.com>,
Richard Weinberger <richard@nod.at>,
Guan Xuetao <gxt@mprc.pku.edu.cn>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, Arnd Bergmann <arnd@arndb.de>,
linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
linux-s390@vger.kernel.org,
user-mode-linux-devel@lists.sourceforge.net,
user-mode-linux-user@lists.sourceforge.net,
linux-arch@vger.kernel.org, linux-mm@kvack.org,
cov@codeaurora.org, criu@openvz.org
Subject: Re: [PATCH v4 2/2] powerpc/mm: Tracking vDSO remap
Date: Thu, 26 Mar 2015 19:55:50 +0100 [thread overview]
Message-ID: <20150326185550.GA25547@gmail.com> (raw)
In-Reply-To: <7fdae652993cf88bdd633d65e5a8f81c7ad8a1e3.1427390952.git.ldufour@linux.vnet.ibm.com>
* Laurent Dufour <ldufour@linux.vnet.ibm.com> wrote:
> +{
> + unsigned long vdso_end, vdso_start;
> +
> + if (!mm->context.vdso_base)
> + return;
> + vdso_start = mm->context.vdso_base;
> +
> +#ifdef CONFIG_PPC64
> + /* Calling is_32bit_task() implies that we are dealing with the
> + * current process memory. If there is a call path where mm is not
> + * owned by the current task, then we'll have need to store the
> + * vDSO size in the mm->context.
> + */
> + BUG_ON(current->mm != mm);
> + if (is_32bit_task())
> + vdso_end = vdso_start + (vdso32_pages << PAGE_SHIFT);
> + else
> + vdso_end = vdso_start + (vdso64_pages << PAGE_SHIFT);
> +#else
> + vdso_end = vdso_start + (vdso32_pages << PAGE_SHIFT);
> +#endif
> + vdso_end += (1<<PAGE_SHIFT); /* data page */
> +
> + /* Check if the vDSO is in the range of the remapped area */
> + if ((vdso_start <= old_start && old_start < vdso_end) ||
> + (vdso_start < old_end && old_end <= vdso_end) ||
> + (old_start <= vdso_start && vdso_start < old_end)) {
> + /* Update vdso_base if the vDSO is entirely moved. */
> + if (old_start == vdso_start && old_end == vdso_end &&
> + (old_end - old_start) == (new_end - new_start))
> + mm->context.vdso_base = new_start;
> + else
> + mm->context.vdso_base = 0;
> + }
> +}
Oh my, that really looks awfully complex, as you predicted, and right
in every mremap() call.
I'm fine with your original, imperfect, KISS approach. Sorry about
this detour ...
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Thanks,
Ingo
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next prev parent reply other threads:[~2015-03-26 18:55 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-20 15:53 [PATCH 0/2] Tracking user space vDSO remaping Laurent Dufour
2015-03-20 15:53 ` [PATCH 1/2] mm: Introducing arch_remap hook Laurent Dufour
2015-03-20 23:19 ` Richard Weinberger
2015-03-23 8:52 ` Ingo Molnar
2015-03-23 9:11 ` Laurent Dufour
2015-03-25 11:06 ` [PATCH v2 0/2] Tracking user space vDSO remaping Laurent Dufour
2015-03-25 11:06 ` [PATCH v2 1/2] mm: Introducing arch_remap hook Laurent Dufour
2015-03-25 11:06 ` [PATCH v2 2/2] powerpc/mm: Tracking vDSO remap Laurent Dufour
2015-03-25 12:11 ` Ingo Molnar
2015-03-25 13:25 ` Laurent Dufour
2015-03-25 13:53 ` [PATCH v3 0/2] Tracking user space vDSO remaping Laurent Dufour
2015-03-25 13:53 ` [PATCH v3 1/2] mm: Introducing arch_remap hook Laurent Dufour
2015-03-25 13:53 ` [PATCH v3 2/2] powerpc/mm: Tracking vDSO remap Laurent Dufour
2015-03-25 18:33 ` Ingo Molnar
2015-03-25 18:36 ` Ingo Molnar
2015-03-25 21:11 ` Benjamin Herrenschmidt
2015-03-26 9:43 ` Ingo Molnar
2015-03-26 10:37 ` Laurent Dufour
2015-03-26 14:17 ` Ingo Molnar
2015-03-26 14:32 ` Laurent Dufour
2015-03-26 17:37 ` [PATCH v4 0/2] Tracking user space vDSO remaping Laurent Dufour
2015-03-26 17:37 ` [PATCH v4 1/2] mm: Introducing arch_remap hook Laurent Dufour
2015-03-26 17:37 ` [PATCH v4 2/2] powerpc/mm: Tracking vDSO remap Laurent Dufour
2015-03-26 18:55 ` Ingo Molnar [this message]
2015-03-27 11:02 ` Laurent Dufour
2015-03-26 23:23 ` [PATCH v3 " Benjamin Herrenschmidt
2015-03-25 21:09 ` Benjamin Herrenschmidt
2015-03-26 9:48 ` Ingo Molnar
2015-03-26 10:13 ` Laurent Dufour
2015-03-20 15:53 ` [PATCH " Laurent Dufour
2016-03-02 12:13 ` [PATCH 0/2] Tracking user space vDSO remaping Christopher Covington
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