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From:   Sven Schnelle <svens@linux.ibm.com>
To:     Thomas Gleixner <tglx@linutronix.de>
Cc:     linux-kernel@vger.kernel.org, hca@linux.ibm.com,
        Sven Schnelle <svens@linux.ibm.com>
Subject: [PATCH] entry: split lockdep and syscall work functions
Date:   Tue,  1 Dec 2020 09:35:53 +0100
Message-Id: <20201201083553.50996-2-svens@linux.ibm.com>
In-Reply-To: <20201201083553.50996-1-svens@linux.ibm.com>
References: <20201201083553.50996-1-svens@linux.ibm.com>
Precedence: bulk

On s390, we can not call one function which sets lockdep
state and do the syscall work at the same time. There add
make enter_from_user_mode() and exit_to_user_mode() public, and
add syscall_exit_to_user_mode1() which does the same as
syscall_exit_to_user_mode() but skips the final exit_to_user_mode().

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
---
 include/linux/entry-common.h |  4 +++-
 kernel/entry/common.c        | 35 +++++++++++++++++++++++++++--------
 2 files changed, 30 insertions(+), 9 deletions(-)

diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index 474f29638d2c..496c9a47eab4 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -124,7 +124,7 @@ static inline __must_check int arch_syscall_enter_tracehook(struct pt_regs *regs
  * to be done between establishing state and handling user mode entry work.
  */
 void syscall_enter_from_user_mode_prepare(struct pt_regs *regs);
-
+void enter_from_user_mode(struct pt_regs *regs);
 /**
  * syscall_enter_from_user_mode_work - Check and handle work before invoking
  *				       a syscall
@@ -311,6 +311,8 @@ static inline void arch_syscall_exit_tracehook(struct pt_regs *regs, bool step)
  *     arch_exit_to_user_mode() to handle e.g. speculation mitigations
  */
 void syscall_exit_to_user_mode(struct pt_regs *regs);
+void syscall_exit_to_user_mode1(struct pt_regs *regs);
+void exit_to_user_mode(void);
 
 /**
  * irqentry_enter_from_user_mode - Establish state before invoking the irq handler
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index e9e2df3f3f9e..3ad462ebfa15 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -18,7 +18,7 @@
  * 2) Invoke context tracking if enabled to reactivate RCU
  * 3) Trace interrupts off state
  */
-static __always_inline void enter_from_user_mode(struct pt_regs *regs)
+static __always_inline void __enter_from_user_mode(struct pt_regs *regs)
 {
 	arch_check_user_regs(regs);
 	lockdep_hardirqs_off(CALLER_ADDR0);
@@ -31,6 +31,11 @@ static __always_inline void enter_from_user_mode(struct pt_regs *regs)
 	instrumentation_end();
 }
 
+void noinstr enter_from_user_mode(struct pt_regs *regs)
+{
+	__enter_from_user_mode(regs);
+}
+
 static inline void syscall_enter_audit(struct pt_regs *regs, long syscall)
 {
 	if (unlikely(audit_context())) {
@@ -92,7 +97,7 @@ noinstr long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall)
 {
 	long ret;
 
-	enter_from_user_mode(regs);
+	__enter_from_user_mode(regs);
 
 	instrumentation_begin();
 	local_irq_enable();
@@ -104,14 +109,14 @@ noinstr long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall)
 
 noinstr void syscall_enter_from_user_mode_prepare(struct pt_regs *regs)
 {
-	enter_from_user_mode(regs);
+	__enter_from_user_mode(regs);
 	instrumentation_begin();
 	local_irq_enable();
 	instrumentation_end();
 }
 
 /**
- * exit_to_user_mode - Fixup state when exiting to user mode
+ * __exit_to_user_mode - Fixup state when exiting to user mode
  *
  * Syscall/interupt exit enables interrupts, but the kernel state is
  * interrupts disabled when this is invoked. Also tell RCU about it.
@@ -122,7 +127,7 @@ noinstr void syscall_enter_from_user_mode_prepare(struct pt_regs *regs)
  *    mitigations, etc.
  * 4) Tell lockdep that interrupts are enabled
  */
-static __always_inline void exit_to_user_mode(void)
+static __always_inline void __exit_to_user_mode(void)
 {
 	instrumentation_begin();
 	trace_hardirqs_on_prepare();
@@ -134,6 +139,11 @@ static __always_inline void exit_to_user_mode(void)
 	lockdep_hardirqs_on(CALLER_ADDR0);
 }
 
+void noinstr exit_to_user_mode(void)
+{
+	__exit_to_user_mode();
+}
+
 /* Workaround to allow gradual conversion of architecture code */
 void __weak arch_do_signal(struct pt_regs *regs) { }
 
@@ -265,12 +275,21 @@ __visible noinstr void syscall_exit_to_user_mode(struct pt_regs *regs)
 	local_irq_disable_exit_to_user();
 	exit_to_user_mode_prepare(regs);
 	instrumentation_end();
-	exit_to_user_mode();
+	__exit_to_user_mode();
+}
+
+__visible noinstr void syscall_exit_to_user_mode1(struct pt_regs *regs)
+{
+	instrumentation_begin();
+	syscall_exit_to_user_mode_prepare(regs);
+	local_irq_disable_exit_to_user();
+	exit_to_user_mode_prepare(regs);
+	instrumentation_end();
 }
 
 noinstr void irqentry_enter_from_user_mode(struct pt_regs *regs)
 {
-	enter_from_user_mode(regs);
+	__enter_from_user_mode(regs);
 }
 
 noinstr void irqentry_exit_to_user_mode(struct pt_regs *regs)
@@ -278,7 +297,7 @@ noinstr void irqentry_exit_to_user_mode(struct pt_regs *regs)
 	instrumentation_begin();
 	exit_to_user_mode_prepare(regs);
 	instrumentation_end();
-	exit_to_user_mode();
+	__exit_to_user_mode();
 }
 
 noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs)
-- 
2.17.1