From: arnd@arndb•de (Arnd Bergmann)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v6 12/20] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it
Date: Mon, 21 Dec 2015 23:19:05 +0100 [thread overview]
Message-ID: <201512212319.06173.arnd@arndb.de> (raw)
In-Reply-To: <20151221183117.GC24894@e104818-lin.cambridge.arm.com>
On Monday 21 December 2015, Catalin Marinas wrote:
> On Fri, Dec 18, 2015 at 01:47:55PM +0100, Arnd Bergmann wrote:
> > On Friday 18 December 2015 11:42:19 Catalin Marinas wrote:
> > > 2. Follow the PCS up to glibc and get glibc to zero the top part (not
> > > always safe with hand-written assembly, though we already do this for
> > > AArch32 where the PCS only specifies 4 arguments in registers, the
> > > rest go on the stack)
> >
> > I assume this needs special handling for syscalls with 64-bit arguments
> > in both glibc and kernel.
>
> I think glibc only should suffice, if it is its responsibility to zero
> the top 32-bit part.
The kernel still needs to know about whether to call e.g. sys_llseek or
sys_lseek. The default syscall table contains llseek for 32-bit architectures,
but the current patch set uses lseek because that makes more sense when
you have 64-bit registers.
> > > 3. Follow the PCS up to glibc but always pass syscall arguments in W
> > > registers, like AArch32 compat support (the least preferred option,
> > > the only advantage is a single wrapper for all syscalls but it would
> > > be doing unnecessary zeroing even for syscalls where it isn't needed)
> >
> > This would mean we cannot pass 64-bit arguments in registers, right?
>
> Not in a single register but two (like we do on AArch32).
Yes, that's what I mean. Essentially we'd use the unmodified 32-bit API
here.
> > > My preference, as stated above, is (1). You can write the wrappers in C
> > > directly and let the compiler upgrade the types when calling the native
> > > syscall. But any other option would be fine (take some inspiration from
> > > other architectures). Unfortunately we don't have COMPAT_SYSCALL_DEFINE
> > > for all functions that we need to wrap, it would have been easier (so we
> > > need to add them but probably in the arch/arm64 code).
> >
> > It would be nice to have that code architecture-independent, so we can
> > share it with s390 and only need to update one place when new syscalls
> > get added.
>
> We could indeed move things like:
>
> COMPAT_SYSCALL_DEFINE3(s390_read, unsigned int, fd, char __user *, buf, compat_size_t, count)
>
> to the core code and share them between s390 and arm64/ILP32. So let's
> stick to option 1.
Ok.
Arnd
next prev parent reply other threads:[~2015-12-21 22:19 UTC|newest]
Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-15 21:42 [RFC3 PATCH v6 00/20] ILP32 for ARM64 Yury Norov
2015-12-15 21:42 ` [PATCH v6 01/20] arm64: ilp32: add documentation on the ILP32 ABI " Yury Norov
2015-12-15 21:42 ` [PATCH v6 02/20] arm64: ensure the kernel is compiled for LP64 Yury Norov
2015-12-15 21:42 ` [PATCH v6 03/20] arm64: rename COMPAT to AARCH32_EL0 in Kconfig Yury Norov
2015-12-17 11:23 ` Catalin Marinas
2015-12-15 21:42 ` [PATCH v6 04/20] arm64: change some CONFIG_COMPAT over to use CONFIG_AARCH32_EL0 instead Yury Norov
2015-12-23 14:15 ` Yury Norov
2015-12-28 8:43 ` > diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile Bamvor Jian Zhang
2015-12-28 9:01 ` [PATCH v6 04/20] arm64: change some CONFIG_COMPAT over to use CONFIG_AARCH32_EL0 instead Zhangjian (Bamvor)
2015-12-29 12:27 ` Yury Norov
2015-12-29 14:59 ` [PATCH] arm64: compat: fix wrong dependency Bamvor Jian Zhang
2015-12-29 13:12 ` [PATCH v6 04/20] arm64: change some CONFIG_COMPAT over to use CONFIG_AARCH32_EL0 instead Yury Norov
2015-12-15 21:42 ` [PATCH v6 05/20] arm64:uapi: set __BITS_PER_LONG correctly for ILP32 and LP64 Yury Norov
2015-12-15 21:42 ` [PATCH v6 06/20] thread: move thread bits accessors to separated file Yury Norov
2015-12-15 21:42 ` [PATCH v6 07/20] arm64: introduce is_a32_task and is_a32_thread (for AArch32 compat) Yury Norov
2015-12-17 11:38 ` Catalin Marinas
2015-12-15 21:42 ` [PATCH v6 08/20] arm64: ilp32: add is_ilp32_compat_{task, thread} and TIF_32BIT_AARCH64 Yury Norov
2015-12-17 11:41 ` Catalin Marinas
2015-12-18 14:11 ` Yury Norov
2015-12-18 14:44 ` Yury Norov
2015-12-21 17:42 ` Catalin Marinas
2015-12-15 21:42 ` [PATCH v6 09/20] arm64:ilp32: share HWCAP between LP64 and ILP32 Yury Norov
2015-12-16 15:54 ` Arnd Bergmann
2015-12-16 16:58 ` Catalin Marinas
2015-12-16 17:19 ` Catalin Marinas
2015-12-16 19:17 ` Arnd Bergmann
2015-12-17 10:54 ` Catalin Marinas
2015-12-17 13:56 ` Arnd Bergmann
2015-12-15 21:42 ` [PATCH v6 10/20] arm64:ilp32 use the native LP64 'start_thread' for ILP32 threads Yury Norov
2015-12-16 15:50 ` Arnd Bergmann
2015-12-18 13:57 ` Yury Norov
2015-12-15 21:42 ` [PATCH v6 11/20] arm64:ilp32: support core dump generation for ILP32 Yury Norov
2015-12-17 14:05 ` Catalin Marinas
2015-12-15 21:42 ` [PATCH v6 12/20] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Yury Norov
2015-12-16 16:07 ` Arnd Bergmann
2015-12-17 18:27 ` Catalin Marinas
2015-12-17 20:10 ` Arnd Bergmann
2015-12-17 20:14 ` Andrew Pinski
2015-12-17 20:50 ` Arnd Bergmann
2016-01-05 15:26 ` Yury Norov
2016-01-05 21:12 ` Arnd Bergmann
2016-01-06 17:10 ` Catalin Marinas
2016-01-07 14:13 ` Arnd Bergmann
2016-01-07 15:42 ` Yury Norov
2016-01-07 17:23 ` Catalin Marinas
2015-12-18 11:42 ` Catalin Marinas
2015-12-18 12:47 ` Arnd Bergmann
2015-12-21 18:31 ` Catalin Marinas
2015-12-21 22:19 ` Arnd Bergmann [this message]
2015-12-21 18:39 ` Dr. Philipp Tomsich
2015-12-21 22:13 ` Arnd Bergmann
2015-12-21 22:31 ` Arnd Bergmann
2015-12-23 18:31 ` Yury Norov
2015-12-23 21:48 ` Arnd Bergmann
2015-12-15 21:42 ` [PATCH v6 13/20] arm64: ilp32: share aarch32 syscall wrappers to ilp32 Yury Norov
2015-12-17 14:38 ` Andreas Schwab
2015-12-18 13:49 ` Yury Norov
2015-12-22 12:25 ` Catalin Marinas
2015-12-22 21:44 ` Arnd Bergmann
2015-12-23 13:37 ` Catalin Marinas
2015-12-23 20:41 ` Arnd Bergmann
2015-12-30 17:29 ` Yury Norov
2015-12-30 22:36 ` Arnd Bergmann
2015-12-23 4:21 ` Yury Norov
2015-12-15 21:42 ` [PATCH v6 14/20] arm64: signal: wrap struct ucontext, fp and lr with struct sigframe Yury Norov
2015-12-15 21:42 ` [PATCH v6 15/20] arm64: signal: move ilp32 and lp64 common code to separated file Yury Norov
2015-12-16 16:08 ` Arnd Bergmann
2015-12-18 13:48 ` Yury Norov
2015-12-18 14:09 ` Arnd Bergmann
2015-12-22 17:11 ` Catalin Marinas
2015-12-15 21:42 ` [PATCH v6 16/20] arm64: signal32: move ilp32 and aarch32 " Yury Norov
2015-12-22 14:29 ` Catalin Marinas
2015-12-15 21:42 ` [PATCH v6 17/20] arm64: ilp32: introduce ilp32-specific handlers for sigframe Yury Norov
2015-12-22 17:08 ` Catalin Marinas
2015-12-15 21:42 ` [PATCH v6 18/20] arm64:ilp32: add vdso-ilp32 and use for signal return Yury Norov
2015-12-15 21:42 ` [PATCH v6 19/20] arm64:ilp32: change COMPAT_ELF_PLATFORM to report a a subplatform for ILP32 Yury Norov
2015-12-15 21:42 ` [PATCH v6 20/20] arm64:ilp32: add ARM64_ILP32 to Kconfig Yury Norov
2015-12-16 16:24 ` [RFC3 PATCH v6 00/20] ILP32 for ARM64 Arnd Bergmann
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