linux-kernel - Re: [PATCH 20/25] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it

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Message-ID: <57347BD4.8010105@huawei.com>
Date:	Thu, 12 May 2016 20:49:24 +0800
From:	"Zhangjian (Bamvor)" <bamvor.zhangjian@...wei.com>
To:	Arnd Bergmann <arnd@...db.de>,
	Catalin Marinas <catalin.marinas@....com>
CC:	<linux-doc@...r.kernel.org>,
	Andrew Pinski <Andrew.Pinski@...iumnetworks.com>,
	<heiko.carstens@...ibm.com>,
	Yury Norov <ynorov@...iumnetworks.com>,
	Hanjun Guo <guohanjun@...wei.com>, <joseph@...esourcery.com>,
	<linux-arch@...r.kernel.org>, <linux-s390@...r.kernel.org>,
	"jijun (D)" <jijun2@...wei.com>,
	<Prasun.Kapoor@...iumnetworks.com>, <schwab@...e.de>,
	<agraf@...e.de>, <pinskia@...il.com>, <klimov.linux@...il.com>,
	<broonie@...nel.org>, <linux-arm-kernel@...ts.infradead.org>,
	<Nathan_Lynch@...tor.com>, <linux-kernel@...r.kernel.org>,
	Andrew Pinski <apinski@...ium.com>, <schwidefsky@...ibm.com>,
	<christoph.muellner@...obroma-systems.com>,
	"Zhangjian (Bamvor)" <bamvor.zhangjian@...wei.com>
Subject: Re: [PATCH 20/25] arm64:ilp32: add sys_ilp32.c and a separate table
 (in entry.S) to use it

Hi,

On 2016/5/12 17:21, Arnd Bergmann wrote:
> On Thursday 12 May 2016 10:17:58 Catalin Marinas wrote:
>> On Wed, May 11, 2016 at 09:30:07PM +0200, Arnd Bergmann wrote:
>>> On Wednesday 11 May 2016 17:59:01 Catalin Marinas wrote:
>>>
>>> I don't think the shifts are a problem, the main downside would be
>>> the limit to 44 bits of file offsets (16TB files), but it's also
>>> unclear if that is a practical problem at all. If it is, we run
>>> into the same problem on all other 32-bit architectures too.
>>
>> I hope people are seriously thinking of moving to an LP64 ABI if they
>> have such large file offset needs.
>
> Good point. 44 bits of file size is certainly enough for mmap()
> on a 32-bit task: you would only be able to map a very small fraction
> of the file anyway, and if you want to map larger files, and should
> move to 64-bit tasks long before this becomes a limitation.
Hi,

I apply the following patch in order to make use of the REAL mmmap2. LTP
test pass in litle endian. mmap16 successful with segfault in big endian.

BTW, I saw the similar code in tile, mips, microblaze and s390 compat. Should
we merge these code into a common syscall wrapper?

kernel:
diff --git a/arch/arm64/kernel/sys_ilp32.c b/arch/arm64/kernel/sys_ilp32.c
index d85fe94..2cd72eb 100644
--- a/arch/arm64/kernel/sys_ilp32.c
+++ b/arch/arm64/kernel/sys_ilp32.c
@@ -41,7 +41,16 @@
  #define compat_sys_sync_file_range     sys_sync_file_range
  #define compat_sys_truncate64          sys_truncate
  #define sys_llseek                     sys_lseek
-#define sys_mmap2                     sys_mmap
+
+SYSCALL_DEFINE6(mmap2, unsigned long, addr, unsigned long, len,
+       unsigned long, prot, unsigned long, flags, unsigned long, fd,
+       unsigned long, pgoff)
+{
+       if (pgoff & (~PAGE_MASK >> 12))
+               return -EINVAL;
+
+       return sys_mmap_pgoff(addr, len, prot, flags, fd, pgoff >> (PAGE_SHIFT-12));
+}

  asmlinkage long ilp32_sys_rt_sigreturn_wrapper(void);
  #define compat_sys_rt_sigreturn        ilp32_sys_rt_sigreturn_wrapper

glibc:
diff --git a/sysdeps/unix/sysv/linux/aarch64/ilp32/mmap.c b/sysdeps/unix/sysv/linux/aarch64/ilp32/mmap.c
index e69de29..f75e251 100644
--- a/sysdeps/unix/sysv/linux/aarch64/ilp32/mmap.c
+++ b/sysdeps/unix/sysv/linux/aarch64/ilp32/mmap.c
@@ -0,0 +1,2 @@
+#include <sysdeps/unix/sysv/linux/generic/wordsize-32/mmap.c>
+
diff --git a/sysdeps/unix/sysv/linux/aarch64/ilp32/mmap64.c b/sysdeps/unix/sysv/linux/aarch64/ilp32/mmap64.c
index c6c7f1d..6f1a141 100644
--- a/sysdeps/unix/sysv/linux/aarch64/ilp32/mmap64.c
+++ b/sysdeps/unix/sysv/linux/aarch64/ilp32/mmap64.c
@@ -1,29 +1 @@
-#include <errno.h>
-#include <unistd.h>
-#include <sys/mman.h>
-#include <string.h>
-
-#include <sysdep.h>
-#include <sys/syscall.h>
-
-/* mmap is provided by mmap as they are the same. */
-void *__mmap (void *__addr, size_t __len, int __prot,
-                    int __flags, int __fd, __off_t __offset)
-{
-   void *result;
-   result = (void *) INLINE_SYSCALL (mmap2, 6, __addr, __len, __prot, __flags,
-   return result;
-}
-/* mmap64 is provided by mmap as they are the same. */
-void *__mmap64 (void *__addr, size_t __len, int __prot,
-                    int __flags, int __fd, __off64_t __offset)
-{
-   void *result;
-   result = (void *)
-     INLINE_SYSCALL (mmap2, 6, __addr,
-                     __len, __prot, __flags, __fd, __offset);
-   return result;
-}
-weak_alias (__mmap, mmap)
-weak_alias (__mmap64, mmap64)
+#include <sysdeps/unix/sysv/linux/mmap64.c>

Regards

Bamvor
> 	Arnd
>