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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Date:	Sat, 14 May 2016 15:49:50 +0300
From:	Yury Norov <ynorov@...iumnetworks.com>
To:	Arnd Bergmann <arnd@...db.de>
CC:	"Zhangjian (Bamvor)" <bamvor.zhangjian@...wei.com>,
	Catalin Marinas <catalin.marinas@....com>,
	<linux-doc@...r.kernel.org>,
	Andrew Pinski <Andrew.Pinski@...iumnetworks.com>,
	<heiko.carstens@...ibm.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>,
	<jan.dakinevich@...il.com>
Subject: Re: [PATCH 20/25] arm64:ilp32: add sys_ilp32.c and a separate table
 (in entry.S) to use it

On Thu, May 12, 2016 at 04:19:48PM +0300, Yury Norov wrote:

[...]

> > I think that's a good idea. The function used to be slightly different
> > for each architecture, but now it seems we have a significant number
> > of identical implementations that we could just merge them together
> > into one.
> > 
> > sys_mmap_pgoff was originally introduced as the common implementation
> > and it reduced the amount of duplication a lot, but as its units
> > are based on PAGE_SIZE rather than hardwired 4096 bytes, it's
> > not as useful.
> > 
> 
> microblaze and mips (twice) are doing like this. And aarh32 as well,
> in arch/arm64/kernel/entry32.S
> 
> In previous submissions it was a patch that shares aarch32 code to
> ilp32. If we decided turn around again, I think, we'd pick up that patch.
> 
> The other option is to make this hack generic, as so many arches use it.

Hi again,

I picked up that old patch from Jan, and found that it doesn't delouse
addr and length, which is wrong for ilp32. So now I think we'd pick
Bamvor version.

Jan's patch (rebased) is attached for reference.

Yury.


>From 02ad258662c40d457ac041634e67e1cbdbb800f3 Mon Sep 17 00:00:00 2001
From: Jan Dakinevich <jan.dakinevich@...il.com>
Date: Tue, 3 Nov 2015 02:30:41 +0300
Subject: ilp32: common 32-bit wrappers

Signed-off-by: Jan Dakinevich <jan.dakinevich@...il.com>
Signed-off-by: Yury Norov <ynorov@...iumnetworks.com>

diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index 9dfdf86..2319042 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -30,6 +30,7 @@ arm64-obj-$(CONFIG_AARCH32_EL0)		+= sys32.o kuser32.o signal32.o 	\
 					   ../../arm/kernel/opcodes.o binfmt_elf32.o
 arm64-obj-$(CONFIG_ARM64_ILP32)		+= binfmt_ilp32.o
 arm64-obj-$(CONFIG_FUNCTION_TRACER)	+= ftrace.o entry-ftrace.o
+arm64-obj-$(CONFIG_COMPAT)		+= entry32-common.o
 arm64-obj-$(CONFIG_MODULES)		+= arm64ksyms.o module.o
 arm64-obj-$(CONFIG_ARM64_MODULE_PLTS)	+= module-plts.o
 arm64-obj-$(CONFIG_PERF_EVENTS)		+= perf_regs.o perf_callchain.o
diff --git a/arch/arm64/kernel/entry32-common.S b/arch/arm64/kernel/entry32-common.S
new file mode 100644
index 0000000..1a0abe3
--- /dev/null
+++ b/arch/arm64/kernel/entry32-common.S
@@ -0,0 +1,23 @@
+#include <linux/linkage.h>
+#include <linux/const.h>
+
+#include <asm/assembler.h>
+#include <asm/asm-offsets.h>
+#include <asm/errno.h>
+#include <asm/page.h>
+
+/*
+ * Note: off_4k (w5) is always in units of 4K. If we can't do the
+ * requested offset because it is not page-aligned, we return -EINVAL.
+ */
+ENTRY(compat_sys_mmap2_wrapper)
+#if PAGE_SHIFT > 12
+	tst	w5, #~PAGE_MASK >> 12
+	b.ne	1f
+	lsr	w5, w5, #PAGE_SHIFT - 12
+#endif
+	b	sys_mmap_pgoff
+1:	mov	x0, #-EINVAL
+	ret
+ENDPROC(compat_sys_mmap2_wrapper)
+
diff --git a/arch/arm64/kernel/entry32.S b/arch/arm64/kernel/entry32.S
index f332d5d..58cb5b0 100644
--- a/arch/arm64/kernel/entry32.S
+++ b/arch/arm64/kernel/entry32.S
@@ -55,21 +55,6 @@ ENTRY(compat_sys_fstatfs64_wrapper)
 ENDPROC(compat_sys_fstatfs64_wrapper)
 
 /*
- * Note: off_4k (w5) is always in units of 4K. If we can't do the
- * requested offset because it is not page-aligned, we return -EINVAL.
- */
-ENTRY(compat_sys_mmap2_wrapper)
-#if PAGE_SHIFT > 12
-	tst	w5, #~PAGE_MASK >> 12
-	b.ne	1f
-	lsr	w5, w5, #PAGE_SHIFT - 12
-#endif
-	b	sys_mmap_pgoff
-1:	mov	x0, #-EINVAL
-	ret
-ENDPROC(compat_sys_mmap2_wrapper)
-
-/*
  * Wrappers for AArch32 syscalls that either take 64-bit parameters
  * in registers or that take 32-bit parameters which require sign
  * extension.