hw-breakpoints: ftrace plugin for kernel symbol tracing using HW Breakpoint interfaces

This patch adds an ftrace plugin to detect and profile memory access over kernel
variables. It uses HW Breakpoint interfaces to 'watch memory addresses.

Signed-off-by: K.Prasad <prasad@linux.vnet.ibm.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index a508b9d2adb8..d7f01e6e8ba5 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -314,6 +314,27 @@ config POWER_TRACER
           power management decisions, specifically the C-state and P-state
           behavior.
 
+config KSYM_TRACER
+        bool "Trace read and write access on kernel memory locations"
+        depends on HAVE_HW_BREAKPOINT
+        select TRACING
+        help
+          This tracer helps find read and write operations on any given kernel
+          symbol i.e. /proc/kallsyms.
+
+config PROFILE_KSYM_TRACER
+        bool "Profile all kernel memory accesses on 'watched' variables"
+        depends on KSYM_TRACER
+        help
+          This tracer profiles kernel accesses on variables watched through the
+          ksym tracer ftrace plugin. Depending upon the hardware, all read
+          and write operations on kernel variables can be monitored for
+          accesses.
+
+          The results will be displayed in:
+          /debugfs/tracing/profile_ksym
+
+          Say N if unsure.
 
 config STACK_TRACER
         bool "Trace max stack"