From: philipp.tomsich@theobroma-systems.com (Dr. Philipp Tomsich)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC2 nowrap: PATCH v7 00/18] ILP32 for ARM64
Date: Wed, 17 Aug 2016 14:54:59 +0200 [thread overview]
Message-ID: <DF24AFA0-5B5C-47E8-9B78-7C6C8711948E@theobroma-systems.com> (raw)
In-Reply-To: <20160817124822.GA25751@yury-N73SV>
> On 17 Aug 2016, at 14:48, Yury Norov <ynorov@caviumnetworks.com> wrote:
>
> On Wed, Aug 17, 2016 at 02:28:50PM +0200, Alexander Graf wrote:
>>
>>> On 17 Aug 2016, at 13:46, Yury Norov <ynorov@caviumnetworks.com> wrote:
>>>
>>> This series enables aarch64 with ilp32 mode, and as supporting work,
>>> introduces ARCH_32BIT_OFF_T configuration option that is enabled for
>>> existing 32-bit architectures but disabled for new arches (so 64-bit
>>> off_t is is used by new userspace).
>>>
>>> This version is based on kernel v4.8-rc2.
>>> It works with glibc-2.23, and tested with LTP.
>>>
>>> This is RFC because there is still no solid understanding what type of registers
>>> top-halves delousing we prefer. In this patchset, w0-w7 are cleared for each
>>> syscall in assembler entry. The alternative approach is in introducing compat
>>> wrappers which is little faster for natively routed syscalls (~2.6% for syscall
>>> with no payload) but much more complicated.
>>
>> So you?re saying there are 2 options:
>>
>> 1) easy to get right, slightly slower, same ABI to user space as 2
>> 2) harder to get right, minor performance benefit
>
> No, ABI is little different. If 1) we pass off_t in a pair to syscalls,
> if 2) - in a single register. So if 1, we 'd take some wrappers from aarch32.
> See patch 12 here.
>From our experience with ILP32, I?d prefer to have off_t (and similar) in a single register
whenever possible (i.e. option #2). It feels more natural to use the full 64bit registers
whenever possible, as ILP32 on ARMv8 should really be understood as a 64bit ABI with
a 32bit memory model.
Cheers,
Philipp.
next prev parent reply other threads:[~2016-08-17 12:54 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-17 11:46 [RFC2 nowrap: PATCH v7 00/18] ILP32 for ARM64 Yury Norov
2016-08-17 11:46 ` [PATCH 01/18] 32-bit ABI: introduce ARCH_32BIT_OFF_T config option Yury Norov
2016-08-17 11:46 ` [PATCH 02/18] arm64: ilp32: add documentation on the ILP32 ABI for ARM64 Yury Norov
2016-08-17 11:46 ` [PATCH 03/18] arm64: ensure the kernel is compiled for LP64 Yury Norov
2016-08-17 11:46 ` [PATCH 04/18] arm64: rename COMPAT to AARCH32_EL0 in Kconfig Yury Norov
2016-08-17 11:46 ` [PATCH 05/18] arm64:uapi: set __BITS_PER_LONG correctly for ILP32 and LP64 Yury Norov
2016-08-17 11:46 ` [PATCH 06/18] thread: move thread bits accessors to separated file Yury Norov
2016-08-17 11:46 ` [PATCH 07/18] arm64: introduce is_a32_task and is_a32_thread (for AArch32 compat) Yury Norov
2016-08-17 11:46 ` [PATCH 08/18] arm64: ilp32: add is_ilp32_compat_{task, thread} and TIF_32BIT_AARCH64 Yury Norov
2016-08-17 11:46 ` [PATCH 09/18] arm64: introduce binfmt_elf32.c Yury Norov
2016-08-17 11:46 ` [PATCH 10/18] arm64: ilp32: introduce binfmt_ilp32.c Yury Norov
2016-08-17 11:46 ` [PATCH 11/18] arm64: ilp32: share aarch32 syscall handlers Yury Norov
2016-08-17 11:46 ` [PATCH 12/18] arm64: ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Yury Norov
2016-09-02 10:46 ` Bamvor Jian Zhang
2016-09-02 12:55 ` Arnd Bergmann
2016-09-02 13:04 ` Yury Norov
2016-08-17 11:46 ` [PATCH 13/18] arm64: signal: share lp64 signal routines to ilp32 Yury Norov
2016-08-17 11:46 ` [PATCH 14/18] arm64: signal32: move ilp32 and aarch32 common code to separated file Yury Norov
2016-08-17 11:46 ` [PATCH 15/18] arm64: ilp32: introduce ilp32-specific handlers for sigframe and ucontext Yury Norov
2016-08-17 11:46 ` [PATCH 16/18] arm64: ptrace: handle ptrace_request differently for aarch32 and ilp32 Yury Norov
2016-08-17 11:46 ` [PATCH 17/18] arm64:ilp32: add vdso-ilp32 and use for signal return Yury Norov
2016-08-17 13:18 ` Andreas Schwab
2016-08-17 11:46 ` [PATCH 18/18] arm64:ilp32: add ARM64_ILP32 to Kconfig Yury Norov
2016-08-17 12:28 ` [RFC2 nowrap: PATCH v7 00/18] ILP32 for ARM64 Alexander Graf
2016-08-17 12:48 ` Yury Norov
2016-08-17 12:54 ` Dr. Philipp Tomsich [this message]
2016-08-17 14:29 ` Catalin Marinas
2016-08-17 14:32 ` Dr. Philipp Tomsich
2016-08-17 15:26 ` Catalin Marinas
2016-08-18 9:45 ` Yury Norov
2016-09-02 10:20 ` Bamvor Jian Zhang
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