linux-kernel - [PATCH V9 24/45] entry: Split up irqentry_exit_cond

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Date:   Thu, 10 Mar 2022 09:19:58 -0800
From:   ira.weiny@...el.com
To:     Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Dan Williams <dan.j.williams@...el.com>
Cc:     Ira Weiny <ira.weiny@...el.com>, Fenghua Yu <fenghua.yu@...el.com>,
        Rick Edgecombe <rick.p.edgecombe@...el.com>,
        "Shankar, Ravi V" <ravi.v.shankar@...el.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH V9 24/45] entry: Split up irqentry_exit_cond_resched()

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

Auxiliary pt_regs space needs to be manipulated by the generic
entry/exit code.

Normally irqentry_exit() would take care of handling any auxiliary
pt_regs on exit.  Unfortunately, the call to
irqentry_exit_cond_resched() from xen_pv_evtchn_do_upcall() bypasses the
normal irqentry_exit() call.  Because of this bypass
irqentry_exit_cond_resched() will be required to handle any auxiliary
pt_regs exit handling.  However, this prevents irqentry_exit() from
being able to call irqentry_exit_cond_resched() and while maintaining
control of the auxiliary pt_regs.

Separate out the common functionality of irqentry_exit_cond_resched() so
that functionality can be used by irqentry_exit().  Add a pt_regs
parameter in anticipation of having irqentry_exit_cond_resched() handle
the auxiliary pt_regs separately from irqentry_exit().

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

---
Changes for V9
	Update commit message

Changes for V8
	New Patch
---
 arch/x86/entry/common.c      | 2 +-
 include/linux/entry-common.h | 3 ++-
 kernel/entry/common.c        | 9 +++++++--
 3 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index 6c2826417b33..f1ba770d035d 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -309,7 +309,7 @@ __visible noinstr void xen_pv_evtchn_do_upcall(struct pt_regs *regs)
 
 	inhcall = get_and_clear_inhcall();
 	if (inhcall && !WARN_ON_ONCE(state.exit_rcu)) {
-		irqentry_exit_cond_resched();
+		irqentry_exit_cond_resched(regs);
 		instrumentation_end();
 		restore_inhcall(inhcall);
 	} else {
diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index ddaffc983e62..14fd329847e7 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -451,10 +451,11 @@ irqentry_state_t noinstr irqentry_enter(struct pt_regs *regs);
 
 /**
  * irqentry_exit_cond_resched - Conditionally reschedule on return from interrupt
+ * @regs:	Pointer to pt_regs of interrupted context
  *
  * Conditional reschedule with additional sanity checks.
  */
-void irqentry_exit_cond_resched(void);
+void irqentry_exit_cond_resched(struct pt_regs *regs);
 
 void __irqentry_exit_cond_resched(void);
 #ifdef CONFIG_PREEMPT_DYNAMIC
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index 490442a48332..f4210a7fc84d 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -395,7 +395,7 @@ void __irqentry_exit_cond_resched(void)
 DEFINE_STATIC_CALL(__irqentry_exit_cond_resched, __irqentry_exit_cond_resched);
 #endif
 
-void irqentry_exit_cond_resched(void)
+static void exit_cond_resched(void)
 {
 	if (IS_ENABLED(CONFIG_PREEMPTION)) {
 #ifdef CONFIG_PREEMPT_DYNAMIC
@@ -406,6 +406,11 @@ void irqentry_exit_cond_resched(void)
 	}
 }
 
+void irqentry_exit_cond_resched(struct pt_regs *regs)
+{
+	exit_cond_resched();
+}
+
 noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t state)
 {
 	lockdep_assert_irqs_disabled();
@@ -431,7 +436,7 @@ noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t state)
 		}
 
 		instrumentation_begin();
-		irqentry_exit_cond_resched();
+		exit_cond_resched();
 		/* Covers both tracing and lockdep */
 		trace_hardirqs_on();
 		instrumentation_end();
-- 
2.35.1