tracing/perf: Add interrupt_context_level() helper

Now that there are three different instances of doing the addition trick
to the preempt_count() and NMI_MASK, HARDIRQ_MASK and SOFTIRQ_OFFSET
macros, it deserves a helper function defined in the preempt.h header.

Add the interrupt_context_level() helper and replace the three instances
that do that logic with it.

Link: https://lore.kernel.org/all/20211015142541.4badd8a9@gandalf.local.home/
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/include/linux/preempt.h b/include/linux/preempt.h
index 4d244e2..b32e3da 100644 (file)
--- a/include/linux/preempt.h
+++ b/include/linux/preempt.h
@@ -77,6 +77,27 @@
 /* preempt_count() and related functions, depends on PREEMPT_NEED_RESCHED */
 #include <asm/preempt.h>
 
+/**
+ * interrupt_context_level - return interrupt context level
+ *
+ * Returns the current interrupt context level.
+ *  0 - normal context
+ *  1 - softirq context
+ *  2 - hardirq context
+ *  3 - NMI context
+ */
+static __always_inline unsigned char interrupt_context_level(void)
+{
+       unsigned long pc = preempt_count();
+       unsigned char level = 0;
+
+       level += !!(pc & (NMI_MASK));
+       level += !!(pc & (NMI_MASK | HARDIRQ_MASK));
+       level += !!(pc & (NMI_MASK | HARDIRQ_MASK | SOFTIRQ_OFFSET));
+
+       return level;
+}
+
 #define nmi_count()    (preempt_count() & NMI_MASK)
 #define hardirq_count()        (preempt_count() & HARDIRQ_MASK)
 #ifdef CONFIG_PREEMPT_RT

diff --git a/include/linux/trace_recursion.h b/include/linux/trace_recursion.h
index f6da7a0..1d8cce0 100644 (file)
--- a/include/linux/trace_recursion.h
+++ b/include/linux/trace_recursion.h
@@ -136,12 +136,7 @@ enum {
 
 static __always_inline int trace_get_context_bit(void)
 {
-       unsigned long pc = preempt_count();
-       unsigned char bit = 0;
-
-       bit += !!(pc & (NMI_MASK));
-       bit += !!(pc & (NMI_MASK | HARDIRQ_MASK));
-       bit += !!(pc & (NMI_MASK | HARDIRQ_MASK | SOFTIRQ_OFFSET));
+       unsigned char bit = interrupt_context_level();
 
        return TRACE_CTX_NORMAL - bit;
 }

diff --git a/kernel/events/internal.h b/kernel/events/internal.h
index 228801e..0828327 100644 (file)
--- a/kernel/events/internal.h
+++ b/kernel/events/internal.h
@@ -205,12 +205,7 @@ DEFINE_OUTPUT_COPY(__output_copy_user, arch_perf_out_copy_user)
 
 static inline int get_recursion_context(int *recursion)
 {
-       unsigned int pc = preempt_count();
-       unsigned char rctx = 0;
-
-       rctx += !!(pc & (NMI_MASK));
-       rctx += !!(pc & (NMI_MASK | HARDIRQ_MASK));
-       rctx += !!(pc & (NMI_MASK | HARDIRQ_MASK | SOFTIRQ_OFFSET));
+       unsigned char rctx = interrupt_context_level();
 
        if (recursion[rctx])
                return -1;

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 15d4380..f6520d0 100644 (file)
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -3167,12 +3167,7 @@ static __always_inline int
 trace_recursive_lock(struct ring_buffer_per_cpu *cpu_buffer)
 {
        unsigned int val = cpu_buffer->current_context;
-       unsigned long pc = preempt_count();
-       int bit = 0;
-
-       bit += !!(pc & (NMI_MASK));
-       bit += !!(pc & (NMI_MASK | HARDIRQ_MASK));
-       bit += !!(pc & (NMI_MASK | HARDIRQ_MASK | SOFTIRQ_OFFSET));
+       int bit = interrupt_context_level();
 
        bit = RB_CTX_NORMAL - bit;