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Date:   Tue, 3 Dec 2019 15:14:12 +0100
From:   Oleg Nesterov <oleg@redhat.com>
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@alien8.de>,
        Ingo Molnar <mingo@kernel.org>,
        Jan Kratochvil <jan.kratochvil@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Pedro Alves <palves@redhat.com>, Peter Anvin <hpa@zytor.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        linux-kernel@vger.kernel.org, x86@kernel.org
Subject: [PATCH v2 4/4] x86: introduce restart_block->arch_data to kill
 TS_COMPAT_RESTART
Message-ID: <20191203141412.GE30688@redhat.com>
References: <20191126110659.GA14042@redhat.com>
 <20191203141239.GA30688@redhat.com>
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With this patch x86 just saves current_thread_info()->status in the
new restart_block->arch_data field, TS_COMPAT_RESTART can be removed.

Rather than saving "status" we could shift the code from
get_nr_restart_syscall() to arch_set_restart_data() and save the syscall
number in ->arch_data.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
 arch/x86/include/asm/thread_info.h | 12 ++----------
 arch/x86/kernel/signal.c           |  2 +-
 include/linux/restart_block.h      |  1 +
 3 files changed, 4 insertions(+), 11 deletions(-)

diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thre=
ad_info.h
index a4de7aa..75c4a0a 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -233,18 +233,10 @@ static inline int arch_within_stack_frames(const void=
 * const stack,
 #ifndef __ASSEMBLY__
 #ifdef CONFIG_COMPAT
 #define TS_I386_REGS_POKED=090x0004=09/* regs poked by 32-bit ptracer */
-#define TS_COMPAT_RESTART=090x0008
=20
-#define arch_set_restart_data=09arch_set_restart_data
+#define arch_set_restart_data(restart)=09\
+=09do { restart->arch_data =3D current_thread_info()->status; } while (0)
=20
-static inline void arch_set_restart_data(struct restart_block *restart)
-{
-=09struct thread_info *ti =3D current_thread_info();
-=09if (ti->status & TS_COMPAT)
-=09=09ti->status |=3D TS_COMPAT_RESTART;
-=09else
-=09=09ti->status &=3D ~TS_COMPAT_RESTART;
-}
 #endif
=20
 #ifdef CONFIG_X86_32
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 2fdbf5e..2e52767 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -771,7 +771,7 @@ handle_signal(struct ksignal *ksig, struct pt_regs *reg=
s)
 static inline unsigned long get_nr_restart_syscall(const struct pt_regs *r=
egs)
 {
 #ifdef CONFIG_IA32_EMULATION
-=09if (current_thread_info()->status & TS_COMPAT_RESTART)
+=09if (current->restart_block.arch_data & TS_COMPAT)
 =09=09return __NR_ia32_restart_syscall;
 #endif
 #ifdef CONFIG_X86_X32_ABI
diff --git a/include/linux/restart_block.h b/include/linux/restart_block.h
index bba2920..980a655 100644
--- a/include/linux/restart_block.h
+++ b/include/linux/restart_block.h
@@ -23,6 +23,7 @@ enum timespec_type {
  * System call restart block.
  */
 struct restart_block {
+=09unsigned long arch_data;
 =09long (*fn)(struct restart_block *);
 =09union {
 =09=09/* For futex_wait and futex_wait_requeue_pi */
--=20
2.5.0