tracing/function-graph-tracer: add a new .irqentry.text section

Impact: let the function-graph-tracer be aware of the irq entrypoints

Add a new .irqentry.text section to store the irq entrypoints functions
inside the same section. This way, the tracer will be able to signal
an interrupts triggering on output by recognizing these entrypoints.

Also, make this section recordable for dynamic tracing.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

3 files changed, 12 insertions, 0 deletions

diff --git a/arch/x86/kernel/vmlinux_64.lds.S b/arch/x86/kernel/vmlinux_64.lds.S
index 46e05447405b..1a614c0e6bef 100644
--- a/arch/x86/kernel/vmlinux_64.lds.S
+++ b/arch/x86/kernel/vmlinux_64.lds.S
@@ -35,6 +35,7 @@ SECTIONS
         SCHED_TEXT
         LOCK_TEXT
         KPROBES_TEXT
+        IRQENTRY_TEXT
         *(.fixup)
         *(.gnu.warning)
         _etext = .;             /* End of text section */
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index eba835a2c2cd..c61fab1dd2f8 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -288,6 +288,16 @@
                 *(.kprobes.text)                                        \
                 VMLINUX_SYMBOL(__kprobes_text_end) = .;
 
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+#define IRQENTRY_TEXT                                                   \
+                ALIGN_FUNCTION();                                       \
+                VMLINUX_SYMBOL(__irqentry_text_start) = .;              \
+                *(.irqentry.text)                                       \
+                VMLINUX_SYMBOL(__irqentry_text_end) = .;
+#else
+#define IRQENTRY_TEXT
+#endif
+
 /* Section used for early init (in .S files) */
 #define HEAD_TEXT  *(.head.text)
 
diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
index 0b1dc9f9bb06..fe831412bea9 100755
--- a/scripts/recordmcount.pl
+++ b/scripts/recordmcount.pl
@@ -114,6 +114,7 @@ my %text_sections = (
      ".text" => 1,
      ".sched.text" => 1,
      ".spinlock.text" => 1,
+     ".irqentry.text" => 1,
 );
 
 $objdump = "objdump" if ((length $objdump) == 0);