[PATCH 07/10] x86/entry: Pass irqentry_state_t by reference

[ira.weiny@intel.com]

From: Ira Weiny <ira.weiny@intel.com>

In preparation for adding PKS information to struct irqentry_state_t
change all call sites and usages to pass the struct by reference
instead of by value.

While we are editing the call sites it is a good time to standardize on
the name 'irq_state'.

Signed-off-by: Ira Weiny <ira.weiny@intel.com>

---
Changes from RFC V3
	Clean up @irq_state comments
	Standardize on 'irq_state' for the state variable name
	Refactor based on new patch from Thomas Gleixner
		Also addresses Peter Zijlstra's comment
---
 arch/x86/entry/common.c         |  8 ++++----
 arch/x86/include/asm/idtentry.h | 25 ++++++++++++++----------
 arch/x86/kernel/cpu/mce/core.c  |  4 ++--
 arch/x86/kernel/kvm.c           |  6 +++---
 arch/x86/kernel/nmi.c           |  4 ++--
 arch/x86/kernel/traps.c         | 21 ++++++++++++--------
 arch/x86/mm/fault.c             |  6 +++---
 include/linux/entry-common.h    | 16 ++++++++++------
 kernel/entry/common.c           | 34 +++++++++++++--------------------
 9 files changed, 65 insertions(+), 59 deletions(-)

diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index 18d8f17f755c..87dea56a15d2 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -259,9 +259,9 @@ __visible noinstr void xen_pv_evtchn_do_upcall(struct pt_regs *regs)
 {
 	struct pt_regs *old_regs;
 	bool inhcall;
-	irqentry_state_t state;
+	irqentry_state_t irq_state;
 
-	state = irqentry_enter(regs);
+	irqentry_enter(regs, &irq_state);
 	old_regs = set_irq_regs(regs);
 
 	instrumentation_begin();
@@ -271,13 +271,13 @@ __visible noinstr void xen_pv_evtchn_do_upcall(struct pt_regs *regs)
 	set_irq_regs(old_regs);
 
 	inhcall = get_and_clear_inhcall();
-	if (inhcall && !WARN_ON_ONCE(state.exit_rcu)) {
+	if (inhcall && !WARN_ON_ONCE(irq_state.exit_rcu)) {
 		instrumentation_begin();
 		irqentry_exit_cond_resched();
 		instrumentation_end();
 		restore_inhcall(inhcall);
 	} else {
-		irqentry_exit(regs, state);
+		irqentry_exit(regs, &irq_state);
 	}
 }
 #endif /* CONFIG_XEN_PV */
diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h
index 247a60a47331..282d2413b6a1 100644
--- a/arch/x86/include/asm/idtentry.h
+++ b/arch/x86/include/asm/idtentry.h
@@ -49,12 +49,13 @@ static __always_inline void __##func(struct pt_regs *regs);		\
 									\
 __visible noinstr void func(struct pt_regs *regs)			\
 {									\
-	irqentry_state_t state = irqentry_enter(regs);			\
+	irqentry_state_t irq_state;						\
 									\
+	irqentry_enter(regs, &irq_state);					\
 	instrumentation_begin();					\
 	__##func (regs);						\
 	instrumentation_end();						\
-	irqentry_exit(regs, state);					\
+	irqentry_exit(regs, &irq_state);					\
 }									\
 									\
 static __always_inline void __##func(struct pt_regs *regs)
@@ -96,12 +97,13 @@ static __always_inline void __##func(struct pt_regs *regs,		\
 __visible noinstr void func(struct pt_regs *regs,			\
 			    unsigned long error_code)			\
 {									\
-	irqentry_state_t state = irqentry_enter(regs);			\
+	irqentry_state_t irq_state;						\
 									\
+	irqentry_enter(regs, &irq_state);					\
 	instrumentation_begin();					\
 	__##func (regs, error_code);					\
 	instrumentation_end();						\
-	irqentry_exit(regs, state);					\
+	irqentry_exit(regs, &irq_state);					\
 }									\
 									\
 static __always_inline void __##func(struct pt_regs *regs,		\
@@ -192,15 +194,16 @@ static __always_inline void __##func(struct pt_regs *regs, u8 vector);	\
 __visible noinstr void func(struct pt_regs *regs,			\
 			    unsigned long error_code)			\
 {									\
-	irqentry_state_t state = irqentry_enter(regs);			\
+	irqentry_state_t irq_state;						\
 									\
+	irqentry_enter(regs, &irq_state);					\
 	instrumentation_begin();					\
 	irq_enter_rcu();						\
 	kvm_set_cpu_l1tf_flush_l1d();					\
 	__##func (regs, (u8)error_code);				\
 	irq_exit_rcu();							\
 	instrumentation_end();						\
-	irqentry_exit(regs, state);					\
+	irqentry_exit(regs, &irq_state);					\
 }									\
 									\
 static __always_inline void __##func(struct pt_regs *regs, u8 vector)
@@ -234,15 +237,16 @@ static void __##func(struct pt_regs *regs);				\
 									\
 __visible noinstr void func(struct pt_regs *regs)			\
 {									\
-	irqentry_state_t state = irqentry_enter(regs);			\
+	irqentry_state_t irq_state;						\
 									\
+	irqentry_enter(regs, &irq_state);					\
 	instrumentation_begin();					\
 	irq_enter_rcu();						\
 	kvm_set_cpu_l1tf_flush_l1d();					\
 	run_sysvec_on_irqstack_cond(__##func, regs);			\
 	irq_exit_rcu();							\
 	instrumentation_end();						\
-	irqentry_exit(regs, state);					\
+	irqentry_exit(regs, &irq_state);					\
 }									\
 									\
 static noinline void __##func(struct pt_regs *regs)
@@ -263,15 +267,16 @@ static __always_inline void __##func(struct pt_regs *regs);		\
 									\
 __visible noinstr void func(struct pt_regs *regs)			\
 {									\
-	irqentry_state_t state = irqentry_enter(regs);			\
+	irqentry_state_t irq_state;						\
 									\
+	irqentry_enter(regs, &irq_state);					\
 	instrumentation_begin();					\
 	__irq_enter_raw();						\
 	kvm_set_cpu_l1tf_flush_l1d();					\
 	__##func (regs);						\
 	__irq_exit_raw();						\
 	instrumentation_end();						\
-	irqentry_exit(regs, state);					\
+	irqentry_exit(regs, &irq_state);					\
 }									\
 									\
 static __always_inline void __##func(struct pt_regs *regs)
diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index eb3338c0bbc1..f90f2163e366 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -1995,7 +1995,7 @@ static __always_inline void exc_machine_check_kernel(struct pt_regs *regs)
 	    mce_check_crashing_cpu())
 		return;
 
-	irq_state = irqentry_nmi_enter(regs);
+	irqentry_nmi_enter(regs, &irq_state);
 	/*
 	 * The call targets are marked noinstr, but objtool can't figure
 	 * that out because it's an indirect call. Annotate it.
@@ -2006,7 +2006,7 @@ static __always_inline void exc_machine_check_kernel(struct pt_regs *regs)
 	if (regs->flags & X86_EFLAGS_IF)
 		trace_hardirqs_on_prepare();
 	instrumentation_end();
-	irqentry_nmi_exit(regs, irq_state);
+	irqentry_nmi_exit(regs, &irq_state);
 }
 
 static __always_inline void exc_machine_check_user(struct pt_regs *regs)
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 1c0f2560a41c..78416af3d3a0 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -238,12 +238,12 @@ EXPORT_SYMBOL_GPL(kvm_read_and_reset_apf_flags);
 noinstr bool __kvm_handle_async_pf(struct pt_regs *regs, u32 token)
 {
 	u32 flags = kvm_read_and_reset_apf_flags();
-	irqentry_state_t state;
+	irqentry_state_t irq_state;
 
 	if (!flags)
 		return false;
 
-	state = irqentry_enter(regs);
+	irqentry_enter(regs, &irq_state);
 	instrumentation_begin();
 
 	/*
@@ -264,7 +264,7 @@ noinstr bool __kvm_handle_async_pf(struct pt_regs *regs, u32 token)
 	}
 
 	instrumentation_end();
-	irqentry_exit(regs, state);
+	irqentry_exit(regs, &irq_state);
 	return true;
 }
 
diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index bf250a339655..1fd7780e99dd 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -502,14 +502,14 @@ DEFINE_IDTENTRY_RAW(exc_nmi)
 
 	this_cpu_write(nmi_dr7, local_db_save());
 
-	irq_state = irqentry_nmi_enter(regs);
+	irqentry_nmi_enter(regs, &irq_state);
 
 	inc_irq_stat(__nmi_count);
 
 	if (!ignore_nmis)
 		default_do_nmi(regs);
 
-	irqentry_nmi_exit(regs, irq_state);
+	irqentry_nmi_exit(regs, &irq_state);
 
 	local_db_restore(this_cpu_read(nmi_dr7));
 
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index bffbbe29fc8c..5566a0a38f63 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -245,7 +245,7 @@ static noinstr bool handle_bug(struct pt_regs *regs)
 
 DEFINE_IDTENTRY_RAW(exc_invalid_op)
 {
-	irqentry_state_t state;
+	irqentry_state_t irq_state;
 
 	/*
 	 * We use UD2 as a short encoding for 'CALL __WARN', as such
@@ -255,11 +255,11 @@ DEFINE_IDTENTRY_RAW(exc_invalid_op)
 	if (!user_mode(regs) && handle_bug(regs))
 		return;
 
-	state = irqentry_enter(regs);
+	irqentry_enter(regs, &irq_state);
 	instrumentation_begin();
 	handle_invalid_op(regs);
 	instrumentation_end();
-	irqentry_exit(regs, state);
+	irqentry_exit(regs, &irq_state);
 }
 
 DEFINE_IDTENTRY(exc_coproc_segment_overrun)
@@ -343,6 +343,7 @@ __visible void __noreturn handle_stack_overflow(const char *message,
  */
 DEFINE_IDTENTRY_DF(exc_double_fault)
 {
+	irqentry_state_t irq_state;
 	static const char str[] = "double fault";
 	struct task_struct *tsk = current;
 
@@ -405,7 +406,7 @@ DEFINE_IDTENTRY_DF(exc_double_fault)
 	}
 #endif
 
-	irqentry_nmi_enter(regs);
+	irqentry_nmi_enter(regs, &irq_state);
 	instrumentation_begin();
 	notify_die(DIE_TRAP, str, regs, error_code, X86_TRAP_DF, SIGSEGV);
 
@@ -651,13 +652,15 @@ DEFINE_IDTENTRY_RAW(exc_int3)
 		instrumentation_end();
 		irqentry_exit_to_user_mode(regs);
 	} else {
-		irqentry_state_t irq_state = irqentry_nmi_enter(regs);
+		irqentry_state_t irq_state;
+
+		irqentry_nmi_enter(regs, &irq_state);
 
 		instrumentation_begin();
 		if (!do_int3(regs))
 			die("int3", regs, 0);
 		instrumentation_end();
-		irqentry_nmi_exit(regs, irq_state);
+		irqentry_nmi_exit(regs, &irq_state);
 	}
 }
 
@@ -865,7 +868,9 @@ static __always_inline void exc_debug_kernel(struct pt_regs *regs,
 	 * includes the entry stack is excluded for everything.
 	 */
 	unsigned long dr7 = local_db_save();
-	irqentry_state_t irq_state = irqentry_nmi_enter(regs);
+	irqentry_state_t irq_state;
+
+	irqentry_nmi_enter(regs, &irq_state);
 	instrumentation_begin();
 
 	/*
@@ -908,7 +913,7 @@ static __always_inline void exc_debug_kernel(struct pt_regs *regs,
 		regs->flags &= ~X86_EFLAGS_TF;
 out:
 	instrumentation_end();
-	irqentry_nmi_exit(regs, irq_state);
+	irqentry_nmi_exit(regs, &irq_state);
 
 	local_db_restore(dr7);
 }
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 42606a04ae85..5e3fd7763315 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -1441,7 +1441,7 @@ handle_page_fault(struct pt_regs *regs, unsigned long error_code,
 DEFINE_IDTENTRY_RAW_ERRORCODE(exc_page_fault)
 {
 	unsigned long address = read_cr2();
-	irqentry_state_t state;
+	irqentry_state_t irq_state;
 
 	prefetchw(&current->mm->mmap_lock);
 
@@ -1476,11 +1476,11 @@ DEFINE_IDTENTRY_RAW_ERRORCODE(exc_page_fault)
 	 * code reenabled RCU to avoid subsequent wreckage which helps
 	 * debugability.
 	 */
-	state = irqentry_enter(regs);
+	irqentry_enter(regs, &irq_state);
 
 	instrumentation_begin();
 	handle_page_fault(regs, error_code, address);
 	instrumentation_end();
 
-	irqentry_exit(regs, state);
+	irqentry_exit(regs, &irq_state);
 }
diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index 47f9a0658acf..b79704af744f 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -352,6 +352,8 @@ typedef struct irqentry_state {
 /**
  * irqentry_enter - Handle state tracking on ordinary interrupt entries
  * @regs:	Pointer to pt_regs of interrupted context
+ * @irq_state:	Pointer to state information; to be passed back to
+ *              irqentry_exit()
  *
  * Invokes:
  *  - lockdep irqflag state tracking as low level ASM entry disabled
@@ -380,7 +382,7 @@ typedef struct irqentry_state {
  *
  * Returns: An opaque object that must be passed to idtentry_exit()
  */
-irqentry_state_t noinstr irqentry_enter(struct pt_regs *regs);
+void noinstr irqentry_enter(struct pt_regs *regs, irqentry_state_t *irq_state);
 
 /**
  * irqentry_exit_cond_resched - Conditionally reschedule on return from interrupt
@@ -392,7 +394,7 @@ void irqentry_exit_cond_resched(void);
 /**
  * irqentry_exit - Handle return from exception that used irqentry_enter()
  * @regs:	Pointer to pt_regs (exception entry regs)
- * @state:	Return value from matching call to irqentry_enter()
+ * @irq_state:	Pointer to state information passed to irqentry_enter()
  *
  * Depending on the return target (kernel/user) this runs the necessary
  * preemption and work checks if possible and reguired and returns to
@@ -403,25 +405,27 @@ void irqentry_exit_cond_resched(void);
  *
  * Counterpart to irqentry_enter().
  */
-void noinstr irqentry_exit(struct pt_regs *regs, irqentry_state_t state);
+void noinstr irqentry_exit(struct pt_regs *regs, irqentry_state_t *irq_state);
 
 /**
  * irqentry_nmi_enter - Handle NMI entry
  * @regs:	Pointer to currents pt_regs
+ * @irq_state:	Pointer to state information; to be passed back to
+ *              irqentry_nmi_exit()
  *
  * Similar to irqentry_enter() but taking care of the NMI constraints.
  */
-irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs);
+void noinstr irqentry_nmi_enter(struct pt_regs *regs, irqentry_state_t *irq_state);
 
 /**
  * irqentry_nmi_exit - Handle return from NMI handling
  * @regs:	Pointer to pt_regs (NMI entry regs)
- * @irq_state:	Return value from matching call to irqentry_nmi_enter()
+ * @irq_state:	Pointer to state information passed to irqentry_nmi_enter()
  *
  * Last action before returning to the low level assmenbly code.
  *
  * Counterpart to irqentry_nmi_enter().
  */
-void noinstr irqentry_nmi_exit(struct pt_regs *regs, irqentry_state_t irq_state);
+void noinstr irqentry_nmi_exit(struct pt_regs *regs, irqentry_state_t *irq_state);
 
 #endif
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index 5cc2e4174d7c..e4f745b3a229 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -282,15 +282,13 @@ noinstr void irqentry_exit_to_user_mode(struct pt_regs *regs)
 	exit_to_user_mode();
 }
 
-noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs)
+noinstr void irqentry_enter(struct pt_regs *regs, irqentry_state_t *irq_state)
 {
-	irqentry_state_t ret = {
-		.exit_rcu = false,
-	};
+	irq_state->exit_rcu = false;
 
 	if (user_mode(regs)) {
 		irqentry_enter_from_user_mode(regs);
-		return ret;
+		return;
 	}
 
 	/*
@@ -328,8 +326,8 @@ noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs)
 		trace_hardirqs_off_finish();
 		instrumentation_end();
 
-		ret.exit_rcu = true;
-		return ret;
+		irq_state->exit_rcu = true;
+		return;
 	}
 
 	/*
@@ -343,8 +341,6 @@ noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs)
 	/* Use the combo lockdep/tracing function */
 	trace_hardirqs_off();
 	instrumentation_end();
-
-	return ret;
 }
 
 void irqentry_exit_cond_resched(void)
@@ -359,7 +355,7 @@ void irqentry_exit_cond_resched(void)
 	}
 }
 
-noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t state)
+noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t *irq_state)
 {
 	lockdep_assert_irqs_disabled();
 
@@ -372,7 +368,7 @@ noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t state)
 		 * carefully and needs the same ordering of lockdep/tracing
 		 * and RCU as the return to user mode path.
 		 */
-		if (state.exit_rcu) {
+		if (irq_state->exit_rcu) {
 			instrumentation_begin();
 			/* Tell the tracer that IRET will enable interrupts */
 			trace_hardirqs_on_prepare();
@@ -394,16 +390,14 @@ noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t state)
 		 * IRQ flags state is correct already. Just tell RCU if it
 		 * was not watching on entry.
 		 */
-		if (state.exit_rcu)
+		if (irq_state->exit_rcu)
 			rcu_irq_exit();
 	}
 }
 
-irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs)
+void noinstr irqentry_nmi_enter(struct pt_regs *regs, irqentry_state_t *irq_state)
 {
-	irqentry_state_t irq_state;
-
-	irq_state.lockdep = lockdep_hardirqs_enabled();
+	irq_state->lockdep = lockdep_hardirqs_enabled();
 
 	__nmi_enter();
 	lockdep_hardirqs_off(CALLER_ADDR0);
@@ -414,15 +408,13 @@ irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs)
 	trace_hardirqs_off_finish();
 	ftrace_nmi_enter();
 	instrumentation_end();
-
-	return irq_state;
 }
 
-void noinstr irqentry_nmi_exit(struct pt_regs *regs, irqentry_state_t irq_state)
+void noinstr irqentry_nmi_exit(struct pt_regs *regs, irqentry_state_t *irq_state)
 {
 	instrumentation_begin();
 	ftrace_nmi_exit();
-	if (irq_state.lockdep) {
+	if (irq_state->lockdep) {
 		trace_hardirqs_on_prepare();
 		lockdep_hardirqs_on_prepare(CALLER_ADDR0);
 	}
@@ -430,7 +422,7 @@ void noinstr irqentry_nmi_exit(struct pt_regs *regs, irqentry_state_t irq_state)
 
 	rcu_nmi_exit();
 	lockdep_hardirq_exit();
-	if (irq_state.lockdep)
+	if (irq_state->lockdep)
 		lockdep_hardirqs_on(CALLER_ADDR0);
 	__nmi_exit();
 }
-- 
2.28.0.rc0.12.gb6a658bd00c9