[PATCH v2 04/10] x86/syscalls: Remove __SYSCALL_COMMON and __SYSCALL_X32

[Andy Lutomirski]

The common/64/x32 distinction has no effect other than determining
which kernels actually support the syscall. Move the logic into
syscalltbl.sh.

Signed-off-by: Andy Lutomirski <lu...@kernel.org>
---
arch/x86/entry/syscall_64.c | 8 --------
arch/x86/entry/syscalls/syscalltbl.sh | 17 ++++++++++++++++-
arch/x86/kernel/asm-offsets_64.c | 6 ------
arch/x86/um/sys_call_table_64.c | 3 ---
arch/x86/um/user-offsets.c | 2 --
5 files changed, 16 insertions(+), 20 deletions(-)

diff --git a/arch/x86/entry/syscall_64.c b/arch/x86/entry/syscall_64.c
index 41283d22be7a..974fd89ac806 100644
--- a/arch/x86/entry/syscall_64.c
+++ b/arch/x86/entry/syscall_64.c
@@ -6,14 +6,6 @@
#include <asm/asm-offsets.h>
#include <asm/syscall.h>

-#define __SYSCALL_COMMON(nr, sym, compat) __SYSCALL_64(nr, sym, compat)
-
-#ifdef CONFIG_X86_X32_ABI
-# define __SYSCALL_X32(nr, sym, compat) __SYSCALL_64(nr, sym, compat)
-#else
-# define __SYSCALL_X32(nr, sym, compat) /* nothing */
-#endif
-
#define __SYSCALL_64(nr, sym, compat) extern asmlinkage long sym(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long) ;
#include <asm/syscalls_64.h>
#undef __SYSCALL_64
diff --git a/arch/x86/entry/syscalls/syscalltbl.sh b/arch/x86/entry/syscalls/syscalltbl.sh
index 167965ee742e..5ebeaf1041e7 100644
--- a/arch/x86/entry/syscalls/syscalltbl.sh
+++ b/arch/x86/entry/syscalls/syscalltbl.sh
@@ -18,6 +18,21 @@ emit() {
grep '^[0-9]' "$in" | sort -n | (
while read nr abi name entry compat; do
abi=`echo "$abi" | tr '[a-z]' '[A-Z]'`
- emit "$abi" "$nr" "$entry" "$compat"
+ if [ "$abi" == "COMMON" -o "$abi" == "64" ]; then
+ # COMMON is the same as 64, except that we don't expect X32
+ # programs to use it. Our expectation has nothing to do with
+ # any generated code, so treat them the same.
+ emit 64 "$nr" "$entry" "$compat"
+ elif [ "$abi" == "X32" ]; then
+ # X32 is equivalent to 64 on an X32-compatible kernel.
+ echo "#ifdef CONFIG_X86_X32_ABI"
+ emit 64 "$nr" "$entry" "$compat"
+ echo "#endif"
+ elif [ "$abi" == "I386" ]; then
+ emit "$abi" "$nr" "$entry" "$compat"
+ else
+ echo "Unknown abi $abi" >&2
+ exit 1
+ fi
done
) > "$out"
diff --git a/arch/x86/kernel/asm-offsets_64.c b/arch/x86/kernel/asm-offsets_64.c
index f2edafb5f24e..29db3b3f550c 100644
--- a/arch/x86/kernel/asm-offsets_64.c
+++ b/arch/x86/kernel/asm-offsets_64.c
@@ -5,12 +5,6 @@
#include <asm/ia32.h>

#define __SYSCALL_64(nr, sym, compat) [nr] = 1,
-#define __SYSCALL_COMMON(nr, sym, compat) [nr] = 1,
-#ifdef CONFIG_X86_X32_ABI
-# define __SYSCALL_X32(nr, sym, compat) [nr] = 1,
-#else
-# define __SYSCALL_X32(nr, sym, compat) /* nothing */
-#endif
static char syscalls_64[] = {
#include <asm/syscalls_64.h>
};
diff --git a/arch/x86/um/sys_call_table_64.c b/arch/x86/um/sys_call_table_64.c
index b74ea6c2c0e7..71a497cde921 100644
--- a/arch/x86/um/sys_call_table_64.c
+++ b/arch/x86/um/sys_call_table_64.c
@@ -35,9 +35,6 @@
#define stub_execveat sys_execveat
#define stub_rt_sigreturn sys_rt_sigreturn

-#define __SYSCALL_COMMON(nr, sym, compat) __SYSCALL_64(nr, sym, compat)
-#define __SYSCALL_X32(nr, sym, compat) /* Not supported */
-
#define __SYSCALL_64(nr, sym, compat) extern asmlinkage long sym(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long) ;
#include <asm/syscalls_64.h>

diff --git a/arch/x86/um/user-offsets.c b/arch/x86/um/user-offsets.c
index ce7e3607a870..5edf4f4bbf53 100644
--- a/arch/x86/um/user-offsets.c
+++ b/arch/x86/um/user-offsets.c
@@ -15,8 +15,6 @@ static char syscalls[] = {
};
#else
#define __SYSCALL_64(nr, sym, compat) [nr] = 1,
-#define __SYSCALL_COMMON(nr, sym, compat) [nr] = 1,
-#define __SYSCALL_X32(nr, sym, compat) /* Not supported */
static char syscalls[] = {
#include <asm/syscalls_64.h>
};
--
2.5.0

[tip-bot for Andy Lutomirski]

Commit-ID: 32324ce15ea8cb4c8acc28acb2fd36fabf73e9db
Gitweb: http://git.kernel.org/tip/32324ce15ea8cb4c8acc28acb2fd36fabf73e9db
Author: Andy Lutomirski <lu...@kernel.org>
AuthorDate: Thu, 28 Jan 2016 15:11:22 -0800
Committer: Ingo Molnar <mi...@kernel.org>
CommitDate: Fri, 29 Jan 2016 09:46:37 +0100

x86/syscalls: Remove __SYSCALL_COMMON and __SYSCALL_X32

The common/64/x32 distinction has no effect other than
determining which kernels actually support the syscall. Move
the logic into syscalltbl.sh.

Signed-off-by: Andy Lutomirski <lu...@kernel.org>

Cc: Andy Lutomirski <lu...@amacapital.net>
Cc: Borislav Petkov <b...@alien8.de>
Cc: Brian Gerst <brg...@gmail.com>
Cc: Denys Vlasenko <dvla...@redhat.com>
Cc: Frederic Weisbecker <fwei...@gmail.com>
Cc: H. Peter Anvin <h...@zytor.com>
Cc: Linus Torvalds <torv...@linux-foundation.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Thomas Gleixner <tg...@linutronix.de>
Link: http://lkml.kernel.org/r/58d4a95f40e43b894f93288b4a3633...@kernel.org
Signed-off-by: Ingo Molnar <mi...@kernel.org>

---
arch/x86/entry/syscall_64.c | 8 --------
arch/x86/entry/syscalls/syscalltbl.sh | 17 ++++++++++++++++-
arch/x86/kernel/asm-offsets_64.c | 6 ------
arch/x86/um/sys_call_table_64.c | 3 ---
arch/x86/um/user-offsets.c | 2 --
5 files changed, 16 insertions(+), 20 deletions(-)

diff --git a/arch/x86/entry/syscall_64.c b/arch/x86/entry/syscall_64.c

index 41283d2..974fd89 100644

--- a/arch/x86/entry/syscall_64.c
+++ b/arch/x86/entry/syscall_64.c
@@ -6,14 +6,6 @@
#include <asm/asm-offsets.h>
#include <asm/syscall.h>

-#define __SYSCALL_COMMON(nr, sym, compat) __SYSCALL_64(nr, sym, compat)
-
-#ifdef CONFIG_X86_X32_ABI
-# define __SYSCALL_X32(nr, sym, compat) __SYSCALL_64(nr, sym, compat)
-#else
-# define __SYSCALL_X32(nr, sym, compat) /* nothing */
-#endif
-
#define __SYSCALL_64(nr, sym, compat) extern asmlinkage long sym(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long) ;
#include <asm/syscalls_64.h>
#undef __SYSCALL_64
diff --git a/arch/x86/entry/syscalls/syscalltbl.sh b/arch/x86/entry/syscalls/syscalltbl.sh

index 167965e..5ebeaf1 100644

index f2edafb..29db3b3 100644

--- a/arch/x86/kernel/asm-offsets_64.c
+++ b/arch/x86/kernel/asm-offsets_64.c
@@ -5,12 +5,6 @@
#include <asm/ia32.h>

#define __SYSCALL_64(nr, sym, compat) [nr] = 1,
-#define __SYSCALL_COMMON(nr, sym, compat) [nr] = 1,
-#ifdef CONFIG_X86_X32_ABI
-# define __SYSCALL_X32(nr, sym, compat) [nr] = 1,
-#else
-# define __SYSCALL_X32(nr, sym, compat) /* nothing */
-#endif
static char syscalls_64[] = {
#include <asm/syscalls_64.h>
};
diff --git a/arch/x86/um/sys_call_table_64.c b/arch/x86/um/sys_call_table_64.c

index b74ea6c..71a497c 100644

--- a/arch/x86/um/sys_call_table_64.c
+++ b/arch/x86/um/sys_call_table_64.c
@@ -35,9 +35,6 @@
#define stub_execveat sys_execveat
#define stub_rt_sigreturn sys_rt_sigreturn

-#define __SYSCALL_COMMON(nr, sym, compat) __SYSCALL_64(nr, sym, compat)
-#define __SYSCALL_X32(nr, sym, compat) /* Not supported */
-
#define __SYSCALL_64(nr, sym, compat) extern asmlinkage long sym(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long) ;
#include <asm/syscalls_64.h>

diff --git a/arch/x86/um/user-offsets.c b/arch/x86/um/user-offsets.c

index ce7e360..5edf4f4 100644

[H. Peter Anvin]

I am really unhappy about this change. syscalltbl.sh is written so that other architectures can use it, and so I would really prefer for it to stay arch-neutral and encourage other arches to use it, too.
--
Sent from my Android device with K-9 Mail. Please excuse brevity and formatting.

[Brian Gerst]

We could use a qualifier (ie. /x32 or /x32ptregs) instead.

--
Brian Gerst

[Andy Lutomirski]

No combinatorial explosion, please. We could use __SYSCALL(nr, sym,
abi, qual), though.

--Andy

[Ingo Molnar]

* Andy Lutomirski <lu...@amacapital.net> wrote:

> >>>+ if [ "$abi" == "COMMON" -o "$abi" == "64" ]; then
> >>>+ # COMMON is the same as 64, except that we don't expect X32
> >>>+ # programs to use it. Our expectation has nothing to do with
> >>>+ # any generated code, so treat them the same.
> >>>+ emit 64 "$nr" "$entry" "$compat"
> >>>+ elif [ "$abi" == "X32" ]; then
> >>>+ # X32 is equivalent to 64 on an X32-compatible kernel.
> >>>+ echo "#ifdef CONFIG_X86_X32_ABI"
> >>>+ emit 64 "$nr" "$entry" "$compat"
> >>>+ echo "#endif"
> >>>+ elif [ "$abi" == "I386" ]; then
> >>>+ emit "$abi" "$nr" "$entry" "$compat"
> >>>+ else
> >>>+ echo "Unknown abi $abi" >&2
> >>>+ exit 1
> >>>+ fi

> No combinatorial explosion, please. We could use __SYSCALL(nr, sym,
> abi, qual), though.

Mind fixing it, so that we get back the arch-neutral property?

Thanks,

Ingo

[Andy Lutomirski]

I need some guidance as to the goal to do a good job.

In the version in -tip, I have this thing:

if [ "$abi" == "64" -a -n "$compat" ]; then
echo "a compat entry for a 64-bit syscall makes no sense" >&2
exit 1
fi

Moving that outside the script will either be impossible or an
exercise in really awful C preprocessor hacks. We could keep that
under the theory that it's arch-neutral.

It might be nice to add a similar warning that a compat entry for an
x32 syscall makes so sense. That's a little less arch-neutral,
although it wouldn't be actively harmful on any architecture, since
"x32" wouldn't occur in the first place.

Other than that, I could add a little header called
syscall_abi_mapping.h containing something like:

#ifndef __SYSCALL_ABI_MAPPING_H
#define __SYSCALL_ABI_MAPPING_H

#ifdef CONFIG_X86_32

/* Only I386 entries should ever be compiled into 32-bit kernels. */
#define __SYSCALL_ABI_I386(nr, entry, qual, compat, compat_qual)
__SYSCALL_I386(nr, entry, qual)

#else

/* I386 entries on 64-bit kernels use the compat entry point. */
#define __SYSCALL_ABI_I386(nr, entry, qual, compat, compat_qual)
__SYSCALL_I386(nr, compat, compat_qual)

#define __SYSCALL_ABI_common(nr, entry, compat, qual)
#define __SYSCALL_ABI_64(nr, entry, qual, compat, compat_qual)
__SYSCALL_64(nr, entry, qual)
#ifdef CONFIG_X86_X32
#define __SYSCALL_ABI_x32(nr, entry, qual, compat, compat_qual)
__SYSCALL_64(nr, entry, qual)
#else
#define __SYSCALL_ABI_x32(nr, entry, qual, compat, compat_qual)
__SYSCALL_64(nr, entry, qual)
#endif

#endif

#endif

and teach syscalltbl.sh to emit #include <asm/syscall_abi_mapping.h>
at the beginning of syscalls_32.h and syscalls_64.h and to reference
those macros.

hpa, would that meet your requirements?

IMO this is quite a bit messier than the code in -tip, and I'm
honestly not convinced it's an improvement.

--Andy

[H. Peter Anvin]

I like that idea much better.

[H. Peter Anvin]

Something like that... however, I can't look at in detail right now.