From: afzal mohammed <afzal.mohd.ma@gmail.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Russell King <linux@armlinux.org.uk>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: ARM: vmsplit 4g/4g
Date: Sun, 7 Jun 2020 18:29:32 +0530 [thread overview]
Message-ID: <20200607125932.GA4576@afzalpc> (raw)
In-Reply-To: <CAK8P3a01FYoWY9sZKU1q=UQ3ut4srwXXUeGRzW6APi+GpoKo1w@mail.gmail.com>
Hi,
On Sat, May 16, 2020 at 09:35:57AM +0200, Arnd Bergmann wrote:
> On Sat, May 16, 2020 at 8:06 AM afzal mohammed <afzal.mohd.ma@gmail.com> wrote:
> > Okay, so the conclusion i take is,
> > 1. VMSPLIT 4G/4G have to live alongside highmem
> > 2. For user space copy, do pinning followed by kmap
> Right, though kmap_atomic() should be sufficient here
> because it is always a short-lived mapping.
get_user_pages_fast() followed by kmap_atomic() & then memcpy() seems
to work in principle for user copy.
Verified in a crude way by pointing TTBR0 to a location that has user
pgd's cleared upon entry to copy_to_user() & restoring TTBR0 to
earlier value after user copying was done and ensuring boot.
Meanwhile more testing w/ kernel static mapping in vmalloc space
revealed a major issue, w/ LPAE it was not booting. There were issues
related to pmd handling, w/ !LPAE those issues were not present as pmd
is in effect equivalent to pgd. The issues has been fixed, though now
LPAE boots, but feel a kind of fragile, will probably have to revisit
it.
Regards
afzal
next prev parent reply other threads:[~2020-06-07 12:59 UTC|newest]
Thread overview: 89+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-31 9:32 [PATCH 0/3] Highmem support for 32-bit RISC-V Eric Lin
2020-03-31 9:32 ` Eric Lin
2020-03-31 9:32 ` [PATCH 1/3] riscv/mm: Add pkmap region and CONFIG_HIGHMEM Eric Lin
2020-03-31 9:32 ` Eric Lin
2020-03-31 9:32 ` [PATCH 2/3] riscv/mm: Implement kmap() and kmap_atomic() Eric Lin
2020-03-31 9:32 ` Eric Lin
2020-03-31 9:32 ` [PATCH 3/3] riscv/mm: Add pkmap in print_vm_layout() Eric Lin
2020-03-31 9:32 ` Eric Lin
2020-04-02 9:31 ` [PATCH 0/3] Highmem support for 32-bit RISC-V Arnd Bergmann
2020-04-02 9:31 ` Arnd Bergmann
2020-04-08 3:51 ` Alan Kao
2020-04-08 3:51 ` Alan Kao
2020-04-08 14:40 ` Arnd Bergmann
2020-04-08 14:40 ` Arnd Bergmann
2020-04-14 15:17 ` afzal mohammed
2020-04-14 15:17 ` afzal mohammed
2020-04-14 19:29 ` Arnd Bergmann
2020-04-14 19:29 ` Arnd Bergmann
2020-04-15 13:54 ` afzal mohammed
2020-04-15 13:54 ` afzal mohammed
2020-05-03 14:50 ` afzal mohammed
2020-05-03 14:50 ` afzal mohammed
2020-05-03 20:20 ` Arnd Bergmann
2020-05-03 20:20 ` Arnd Bergmann
2020-05-04 9:10 ` afzal mohammed
2020-05-04 9:10 ` afzal mohammed
2020-05-04 9:10 ` afzal mohammed
2020-05-04 11:27 ` Arnd Bergmann
2020-05-04 11:27 ` Arnd Bergmann
2020-05-04 11:27 ` Arnd Bergmann
2020-05-11 14:21 ` ARM: static kernel in vmalloc space (was Re: [PATCH 0/3] Highmem support for 32-bit RISC-V) afzal mohammed
2020-05-11 14:21 ` afzal mohammed
2020-05-11 15:29 ` Arnd Bergmann
2020-05-11 15:29 ` Arnd Bergmann
2020-05-12 10:47 ` ARM: static kernel in vmalloc space afzal mohammed
2020-05-12 10:47 ` afzal mohammed
2020-05-12 19:49 ` Arnd Bergmann
2020-05-12 19:49 ` Arnd Bergmann
2020-05-14 11:17 ` afzal mohammed
2020-05-14 11:17 ` afzal mohammed
2020-05-14 12:41 ` Arnd Bergmann
2020-05-14 12:41 ` Arnd Bergmann
2020-05-14 13:35 ` afzal mohammed
2020-05-14 13:35 ` afzal mohammed
2020-05-14 14:44 ` afzal mohammed
2020-05-14 14:44 ` afzal mohammed
2020-05-14 15:32 ` Arnd Bergmann
2020-05-14 15:32 ` Arnd Bergmann
2020-05-16 6:06 ` afzal mohammed
2020-05-16 6:06 ` afzal mohammed
2020-05-16 7:35 ` Arnd Bergmann
2020-05-16 7:35 ` Arnd Bergmann
2020-06-07 12:59 ` afzal mohammed [this message]
2020-06-07 16:11 ` ARM: vmsplit 4g/4g Russell King - ARM Linux admin
2020-06-07 16:11 ` Russell King - ARM Linux admin
2020-06-08 11:09 ` afzal mohammed
2020-06-08 11:09 ` afzal mohammed
2020-06-10 10:10 ` Linus Walleij
2020-06-10 10:10 ` Linus Walleij
2020-06-12 10:25 ` afzal mohammed
2020-06-12 10:25 ` afzal mohammed
2020-06-15 9:11 ` Linus Walleij
2020-06-15 9:11 ` Linus Walleij
2020-06-15 10:01 ` afzal mohammed
2020-06-15 10:01 ` afzal mohammed
2020-06-07 19:26 ` Arnd Bergmann
2020-06-07 19:26 ` Arnd Bergmann
2020-06-08 11:18 ` afzal mohammed
2020-06-08 11:18 ` afzal mohammed
2020-06-08 14:43 ` Arnd Bergmann
2020-06-08 14:43 ` Arnd Bergmann
2020-06-08 15:17 ` afzal mohammed
2020-06-08 15:17 ` afzal mohammed
2020-06-09 12:15 ` afzal mohammed
2020-06-09 12:15 ` afzal mohammed
2020-06-09 14:22 ` Arnd Bergmann
2020-06-09 14:22 ` Arnd Bergmann
2020-05-14 16:25 ` ARM: static kernel in vmalloc space Russell King - ARM Linux admin
2020-05-14 16:25 ` Russell King - ARM Linux admin
2020-05-14 21:12 ` Arnd Bergmann
2020-05-14 21:12 ` Arnd Bergmann
2020-05-14 23:40 ` Russell King - ARM Linux admin
2020-05-14 23:40 ` Russell King - ARM Linux admin
2020-05-15 15:41 ` Arnd Bergmann
2020-05-15 15:41 ` Arnd Bergmann
2020-07-30 9:33 ` Linus Walleij
2020-07-30 9:33 ` Linus Walleij
2020-07-30 10:17 ` Arnd Bergmann
2020-07-30 10:17 ` Arnd Bergmann
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