Re: [tip:x86/asm] x86/syscalls: Remove __SYSCALL_COMMON and __SYSCALL_X32

[H. Peter Anvin]

On January 29, 2016 3:34:44 AM PST, tip-bot for Andy Lutomirski <tipbot@xxxxxxxxx> wrote:
>Commit-ID:  32324ce15ea8cb4c8acc28acb2fd36fabf73e9db
>Gitweb:    
>http://git.kernel.org/tip/32324ce15ea8cb4c8acc28acb2fd36fabf73e9db
>Author:     Andy Lutomirski <luto@xxxxxxxxxx>
>AuthorDate: Thu, 28 Jan 2016 15:11:22 -0800
>Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
>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 <luto@xxxxxxxxxx>
>Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
>Cc: Borislav Petkov <bp@xxxxxxxxx>
>Cc: Brian Gerst <brgerst@xxxxxxxxx>
>Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
>Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
>Cc: H. Peter Anvin <hpa@xxxxxxxxx>
>Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
>Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
>Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
>Link:
>http://lkml.kernel.org/r/58d4a95f40e43b894f93288b4a3633963d0ee22e.1454022279.git.luto@xxxxxxxxxx
>Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
>---
> 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
>--- 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 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
>--- 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>
> };

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.
-- 
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