From 6fc1c7e3d83c4e06b019b041894d9bb25f37ac6c Mon Sep 17 00:00:00 2001
From: Frederic Weisbecker <frederic@kernel.org>
Date: Mon, 20 Sep 2021 12:57:27 +0200
Subject: [PATCH] arm64: Implement HAVE_PREEMPT_DYNAMIC
Patch-mainline: Not yet, debates on arm64 static call implementation
References: jsc#SLE-18857

Provide the static calls for the common preemption points and report
arm64 ability to support dynamic preemption.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Quentin Perret <qperret@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: Kees Cook <keescook@chromium.org>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Frederic Weisbecker <fweisbecker@suse.de>
---
 arch/arm64/Kconfig               |    1 +
 arch/arm64/include/asm/preempt.h |   20 +++++++++++++++++---
 2 files changed, 18 insertions(+), 3 deletions(-)

--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -193,6 +193,7 @@ config ARM64
 	select HAVE_PERF_EVENTS
 	select HAVE_PERF_REGS
 	select HAVE_PERF_USER_STACK_DUMP
+	select HAVE_PREEMPT_DYNAMIC
 	select HAVE_REGS_AND_STACK_ACCESS_API
 	# https://github.com/ClangBuiltLinux/linux/issues/1354
 	select HAVE_STATIC_CALL if !LTO_CLANG_THIN || CLANG_VERSION >= 130000
--- a/arch/arm64/include/asm/preempt.h
+++ b/arch/arm64/include/asm/preempt.h
@@ -82,15 +82,29 @@ static inline bool should_resched(int pr
 
 #ifdef CONFIG_PREEMPTION
 void preempt_schedule(void);
-#define __preempt_schedule() preempt_schedule()
 void preempt_schedule_notrace(void);
-#define __preempt_schedule_notrace() preempt_schedule_notrace()
-#endif /* CONFIG_PREEMPTION */
 
 #ifdef CONFIG_PREEMPT_DYNAMIC
+
+#define __preempt_schedule_func preempt_schedule
+DECLARE_STATIC_CALL(preempt_schedule, __preempt_schedule_func);
+#define __preempt_schedule() static_call(preempt_schedule)()
+
+#define __preempt_schedule_notrace_func preempt_schedule_notrace
+DECLARE_STATIC_CALL(preempt_schedule_notrace, __preempt_schedule_notrace_func);
+#define __preempt_schedule_notrace() static_call(preempt_schedule_notrace)()
+
 void arm64_preempt_schedule_irq(void);
 #define __irqentry_exit_cond_resched_func arm64_preempt_schedule_irq
 DECLARE_STATIC_CALL(irqentry_exit_cond_resched, __irqentry_exit_cond_resched_func);
+
+#else /* !CONFIG_PREEMPT_DYNAMIC */
+
+#define __preempt_schedule() preempt_schedule()
+#define __preempt_schedule_notrace() preempt_schedule_notrace()
+
 #endif /* CONFIG_PREEMPT_DYNAMIC */
 
+#endif /* CONFIG_PREEMPTION */
+
 #endif /* __ASM_PREEMPT_H */