diff mbox series

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

Message ID 20201022222701.887660-8-ira.weiny@intel.com (mailing list archive)
State New
Headers show
Series PKS: Add Protection Keys Supervisor (PKS) support | expand

Commit Message

Ira Weiny Oct. 22, 2020, 10:26 p.m. UTC 
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(-)

Comments

Thomas Gleixner Oct. 23, 2020, 9:56 p.m. UTC | #1 
On Thu, Oct 22 2020 at 15:26, ira weiny wrote:
> 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.

This still does not explain WHY you need to do that. 'Preparation' is a
pretty useless information.

What is the actual reason for this? Just because PKS information feels
better that way?

Also what is PKS information? Changelogs have to make sense on their own
and not only in the context of a larger series of changes.

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

  While at it change all usage sites to consistently use the variable
  name 'irq_state'.

Or something like that. See Documentation/process/...

Thanks,

        tglx
Ira Weiny Oct. 27, 2020, 7:11 a.m. UTC | #2 
On Fri, Oct 23, 2020 at 11:56:33PM +0200, Thomas Gleixner wrote:
> On Thu, Oct 22 2020 at 15:26, ira weiny wrote:
> > 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.
> 
> This still does not explain WHY you need to do that. 'Preparation' is a
> pretty useless information.
> 
> What is the actual reason for this? Just because PKS information feels
> better that way?
> 
> Also what is PKS information? Changelogs have to make sense on their own
> and not only in the context of a larger series of changes.

I've reworded this to explain the addition of new members which would make
passing by value less efficient with additional structure changes being added
later in the series.

> 
> > While we are editing the call sites it is a good time to standardize on
> > the name 'irq_state'.
> 
>   While at it change all usage sites to consistently use the variable
>   name 'irq_state'.
> 
> Or something like that. See Documentation/process/...

Sorry, bad habit.

Fixed.

Thanks,
Ira

> 
> Thanks,
> 
>         tglx
>
diff mbox series

Patch

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();
 }