From: cyril@ti•com (Cyril Chemparathy)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v3 RESEND 01/17] ARM: add mechanism for late code patching
Date: Sat, 22 Sep 2012 17:41:24 -0400 [thread overview]
Message-ID: <505E3084.80307@ti.com> (raw)
In-Reply-To: <alpine.LFD.2.02.1209221037561.6667@xanadu.home>
On 09/22/12 11:10, Nicolas Pitre wrote:
> On Fri, 21 Sep 2012, Cyril Chemparathy wrote:
>
>> The original phys_to_virt/virt_to_phys patching implementation relied on early
>> patching prior to MMU initialization. On PAE systems running out of >4G
>> address space, this would have entailed an additional round of patching after
>> switching over to the high address space.
>>
>> The approach implemented here conceptually extends the original PHYS_OFFSET
>> patching implementation with the introduction of "early" patch stubs. Early
>> patch code is required to be functional out of the box, even before the patch
>> is applied. This is implemented by inserting functional (but inefficient)
>> load code into the .runtime.patch.code init section. Having functional code
>> out of the box then allows us to defer the init time patch application until
>> later in the init sequence.
>>
>> In addition to fitting better with our need for physical address-space
>> switch-over, this implementation should be somewhat more extensible by virtue
>> of its more readable (and hackable) C implementation. This should prove
>> useful for other similar init time specialization needs, especially in light
>> of our multi-platform kernel initiative.
>>
>> This code has been boot tested in both ARM and Thumb-2 modes on an ARMv7
>> (Cortex-A8) device.
>>
>> Note: the obtuse use of stringified symbols in patch_stub() and
>> early_patch_stub() is intentional. Theoretically this should have been
>> accomplished with formal operands passed into the asm block, but this requires
>> the use of the 'c' modifier for instantiating the long (e.g. .long %c0).
>> However, the 'c' modifier has been found to ICE certain versions of GCC, and
>> therefore we resort to stringified symbols here.
>>
>> Signed-off-by: Cyril Chemparathy <cyril@ti•com>
>> Reviewed-by: Nicolas Pitre <nico@linaro•org>
>
> There is another problem with this.
>
> [...]
>> diff --git a/arch/arm/include/asm/runtime-patch.h b/arch/arm/include/asm/runtime-patch.h
>> new file mode 100644
>> index 0000000..366444d
>> --- /dev/null
>> +++ b/arch/arm/include/asm/runtime-patch.h
>> @@ -0,0 +1,208 @@
>> +/*
>> + * arch/arm/include/asm/runtime-patch.h
>> + * Note: this file should not be included by non-asm/.h files
>> + *
>> + * Copyright 2012 Texas Instruments, Inc.
>> + *
>> + * This program is free software; you can redistribute it and/or modify it
>> + * under the terms and conditions of the GNU General Public License,
>> + * version 2, as published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope it will be useful, but WITHOUT
>> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
>> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
>> + * more details.
>> + *
>> + * You should have received a copy of the GNU General Public License along with
>> + * this program. If not, see <http://www.gnu.org/licenses/>.
>> + */
>> +#ifndef __ASM_ARM_RUNTIME_PATCH_H
>> +#define __ASM_ARM_RUNTIME_PATCH_H
>> +
>> +#include <linux/stringify.h>
>> +
>> +#ifndef __ASSEMBLY__
>> +
>> +#ifdef CONFIG_ARM_RUNTIME_PATCH
>> +
>> +struct patch_info {
>> + void *insn;
>> + u16 type;
>> + u8 insn_size;
>> + u8 data_size;
>> + u32 data[0];
>> +};
>
> This causes the following compilation error:
>
> CC sound/core/pcm.o
> In file included from sound/core/pcm.c:293:0:
> include/linux/soundcard.h:223:8: error: redefinition of 'struct patch_info'
> arch/arm/include/asm/runtime-patch.h:28:8: note: originally defined here
> make[2]: *** [sound/core/pcm.o] Error 1
>
> The problem is that asm/runtime-patch.h gets included by asm/memory.h
> and asm/memory.h is included by almost the entire kernel. Something like
> "struct patch_info" is a bit too generic a name to be exported to the
> world as the likelihood of a name collision with some private definition
> in a driver or the like is rather high.
>
> In that context it might be worth moving everything that is not required
> for the patch stub definitions out of asm/runtime-patch.h. For example,
> the definition of struct patch_info, struct patch_info_imm8,
> patch_next() and patch_data() could be moved to runtime-patch.c directly
> instead. And then patch_stub() should be renamed to
> runtime_patch_stub(), early_patch_stub() to early_runtime_patch_stub(),
> patch_imm8() to runtime_patch_imm8(), etc. Even the __IMM8 symbol name
> is rather weak for kernel wide scope.
>
Thanks for trying this out. I'll take this up in the next rev.
-- Cyril.
next prev parent reply other threads:[~2012-09-22 21:41 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-21 15:55 [PATCH v3 RESEND 00/17] LPAE fixes and extensions for Keystone Cyril Chemparathy
2012-09-21 15:55 ` [PATCH v3 RESEND 01/17] ARM: add mechanism for late code patching Cyril Chemparathy
2012-09-22 15:10 ` Nicolas Pitre
2012-09-22 21:41 ` Cyril Chemparathy [this message]
2012-09-24 12:06 ` Dave Martin
2012-09-24 14:49 ` Cyril Chemparathy
2012-09-24 15:54 ` Dave Martin
2012-09-21 15:56 ` [PATCH v3 RESEND 02/17] ARM: add self test for runtime patch mechanism Cyril Chemparathy
2012-09-21 15:56 ` [PATCH v3 RESEND 03/17] ARM: use late patch framework for phys-virt patching Cyril Chemparathy
2012-09-21 15:56 ` [PATCH v3 RESEND 04/17] ARM: LPAE: use phys_addr_t on virt <--> phys conversion Cyril Chemparathy
2012-09-24 13:09 ` Catalin Marinas
2012-09-24 13:57 ` Cyril Chemparathy
2012-09-21 15:56 ` [PATCH v3 RESEND 05/17] ARM: LPAE: support 64-bit virt_to_phys patching Cyril Chemparathy
2012-09-22 15:24 ` Nicolas Pitre
2012-09-24 15:13 ` Catalin Marinas
2012-09-24 15:56 ` Nicolas Pitre
2012-09-24 20:59 ` Cyril Chemparathy
2012-09-24 21:20 ` Nicolas Pitre
2012-09-24 21:52 ` Catalin Marinas
2012-09-24 22:32 ` Nicolas Pitre
2012-09-24 22:40 ` Russell King - ARM Linux
2012-09-24 22:53 ` Cyril Chemparathy
2012-09-24 23:03 ` Nicolas Pitre
2012-09-24 23:08 ` Russell King - ARM Linux
2012-09-24 22:55 ` Nicolas Pitre
2012-09-25 12:55 ` Dave Martin
2012-09-25 13:53 ` Catalin Marinas
2012-09-24 21:53 ` Cyril Chemparathy
2012-09-24 22:06 ` Russell King - ARM Linux
2012-09-24 16:31 ` Dave Martin
2012-09-24 16:51 ` Nicolas Pitre
2012-09-21 15:56 ` [PATCH v3 RESEND 06/17] ARM: LPAE: use signed arithmetic for mask definitions Cyril Chemparathy
2012-09-24 13:09 ` Catalin Marinas
2012-09-24 13:54 ` Russell King - ARM Linux
2012-09-21 15:56 ` [PATCH v3 RESEND 07/17] ARM: LPAE: use phys_addr_t in alloc_init_pud() Cyril Chemparathy
2012-09-24 13:10 ` Catalin Marinas
2012-09-21 15:56 ` [PATCH v3 RESEND 08/17] ARM: LPAE: use phys_addr_t in free_memmap() Cyril Chemparathy
2012-09-24 13:29 ` Catalin Marinas
2012-09-24 13:41 ` Russell King - ARM Linux
2012-09-24 15:09 ` Cyril Chemparathy
2012-09-24 15:22 ` Russell King - ARM Linux
2012-09-24 16:41 ` Cyril Chemparathy
2012-09-24 16:51 ` Catalin Marinas
2012-09-24 17:06 ` Cyril Chemparathy
2012-09-24 17:14 ` Russell King - ARM Linux
2012-09-25 13:08 ` Catalin Marinas
2012-09-25 13:30 ` Russell King - ARM Linux
2012-09-24 16:55 ` Russell King - ARM Linux
2012-09-24 17:03 ` Catalin Marinas
2012-09-21 15:56 ` [PATCH v3 RESEND 09/17] ARM: LPAE: use phys_addr_t for initrd location and size Cyril Chemparathy
2012-09-24 13:30 ` Catalin Marinas
2012-09-24 13:38 ` Russell King - ARM Linux
2012-09-24 14:00 ` Cyril Chemparathy
2012-09-21 15:56 ` [PATCH v3 RESEND 10/17] ARM: LPAE: use phys_addr_t in switch_mm() Cyril Chemparathy
2012-09-24 14:05 ` Catalin Marinas
2012-09-24 14:32 ` Cyril Chemparathy
2012-09-21 15:56 ` [PATCH v3 RESEND 11/17] ARM: LPAE: use 64-bit accessors for TTBR registers Cyril Chemparathy
2012-09-24 14:10 ` Catalin Marinas
2012-09-21 15:56 ` [PATCH v3 RESEND 12/17] ARM: LPAE: define ARCH_LOW_ADDRESS_LIMIT for bootmem Cyril Chemparathy
2012-09-24 14:16 ` Catalin Marinas
2012-09-21 15:56 ` [PATCH v3 RESEND 13/17] ARM: LPAE: factor out T1SZ and TTBR1 computations Cyril Chemparathy
2012-09-24 14:45 ` Catalin Marinas
2012-09-24 14:58 ` Cyril Chemparathy
2012-09-21 15:56 ` [PATCH v3 RESEND 14/17] ARM: LPAE: accomodate >32-bit addresses for page table base Cyril Chemparathy
2012-09-24 15:17 ` Catalin Marinas
2012-09-21 15:56 ` [PATCH v3 RESEND 15/17] ARM: mm: use physical addresses in highmem sanity checks Cyril Chemparathy
2012-09-24 15:18 ` Catalin Marinas
2012-09-21 15:56 ` [PATCH v3 RESEND 16/17] ARM: mm: cleanup checks for membank overlap with vmalloc area Cyril Chemparathy
2012-09-21 15:56 ` [PATCH v3 RESEND 17/17] ARM: mm: clean up membank size limit checks Cyril Chemparathy
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=505E3084.80307@ti.com \
--to=cyril@ti$(echo .)com \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox