perf/bpf: Remove unneeded uses_default_overflow_handler()

Now that struct perf_event's orig_overflow_handler is gone, there's no need
for the functions and macros to support looking past overflow_handler to
orig_overflow_handler.

This patch is solely a refactoring and results in no behavior change.
Signed-off-by: Kyle Huey <khuey@kylehuey.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240412015019.7060-6-khuey@kylehuey.com

arch/arm/kernel/hw_breakpoint.c

@@ -626,7 +626,7 @@ int hw_breakpoint_arch_parse(struct perf_event *bp,
 	hw->address &= ~alignment_mask;
 	hw->ctrl.len <<= offset;
 
-	if (uses_default_overflow_handler(bp)) {
+	if (is_default_overflow_handler(bp)) {
 		/*
 		 * Mismatch breakpoints are required for single-stepping
 		 * breakpoints.
@@ -798,7 +798,7 @@ static void watchpoint_handler(unsigned long addr, unsigned int fsr,
 		 * Otherwise, insert a temporary mismatch breakpoint so that
 		 * we can single-step over the watchpoint trigger.
 		 */
-		if (!uses_default_overflow_handler(wp))
+		if (!is_default_overflow_handler(wp))
 			continue;
 step:
 		enable_single_step(wp, instruction_pointer(regs));
@@ -811,7 +811,7 @@ static void watchpoint_handler(unsigned long addr, unsigned int fsr,
 		info->trigger = addr;
 		pr_debug("watchpoint fired: address = 0x%x\n", info->trigger);
 		perf_bp_event(wp, regs);
-		if (uses_default_overflow_handler(wp))
+		if (is_default_overflow_handler(wp))
 			enable_single_step(wp, instruction_pointer(regs));
 	}
 
@@ -886,7 +886,7 @@ static void breakpoint_handler(unsigned long unknown, struct pt_regs *regs)
 			info->trigger = addr;
 			pr_debug("breakpoint fired: address = 0x%x\n", addr);
 			perf_bp_event(bp, regs);
-			if (uses_default_overflow_handler(bp))
+			if (is_default_overflow_handler(bp))
 				enable_single_step(bp, addr);
 			goto unlock;
 		}

arch/arm64/kernel/hw_breakpoint.c

@@ -655,7 +655,7 @@ static int breakpoint_handler(unsigned long unused, unsigned long esr,
 		perf_bp_event(bp, regs);
 
 		/* Do we need to handle the stepping? */
-		if (uses_default_overflow_handler(bp))
+		if (is_default_overflow_handler(bp))
 			step = 1;
 unlock:
 		rcu_read_unlock();
@@ -734,7 +734,7 @@ static u64 get_distance_from_watchpoint(unsigned long addr, u64 val,
 static int watchpoint_report(struct perf_event *wp, unsigned long addr,
 			     struct pt_regs *regs)
 {
-	int step = uses_default_overflow_handler(wp);
+	int step = is_default_overflow_handler(wp);
 	struct arch_hw_breakpoint *info = counter_arch_bp(wp);
 
 	info->trigger = addr;

include/linux/perf_event.h

@@ -1345,8 +1345,10 @@ extern int perf_event_output(struct perf_event *event,
 			     struct pt_regs *regs);
 
 static inline bool
-__is_default_overflow_handler(perf_overflow_handler_t overflow_handler)
+is_default_overflow_handler(struct perf_event *event)
 {
+	perf_overflow_handler_t overflow_handler = event->overflow_handler;
+
 	if (likely(overflow_handler == perf_event_output_forward))
 		return true;
 	if (unlikely(overflow_handler == perf_event_output_backward))
@@ -1354,19 +1356,6 @@ __is_default_overflow_handler(perf_overflow_handler_t overflow_handler)
 	return false;
 }
 
-#define is_default_overflow_handler(event) \
-	__is_default_overflow_handler((event)->overflow_handler)
-
-#ifdef CONFIG_BPF_SYSCALL
-static inline bool uses_default_overflow_handler(struct perf_event *event)
-{
-	return is_default_overflow_handler(event);
-}
-#else
-#define uses_default_overflow_handler(event) \
-	is_default_overflow_handler(event)
-#endif
-
 extern void
 perf_event_header__init_id(struct perf_event_header *header,
 			   struct perf_sample_data *data,