2 files changed, 107 insertions, 0 deletions

diff --git a/arch/x86/kernel/Makefile_32 b/arch/x86/kernel/Makefile_32
index a7bc93c27662..5f87f32ada6f 100644
--- a/arch/x86/kernel/Makefile_32
+++ b/arch/x86/kernel/Makefile_32
@@ -49,6 +49,9 @@ obj-y				+= pcspeaker.o
 
 obj-$(CONFIG_SCx200)            += scx200_32.o
 
+obj-$(CONFIG_FEATHER_TRACE)     += ft_event.o
+
+
 # vsyscall_32.o contains the vsyscall DSO images as __initdata.
 # We must build both images before we can assemble it.
 # Note: kbuild does not track this dependency due to usage of .incbin
diff --git a/arch/x86/kernel/ft_event.c b/arch/x86/kernel/ft_event.c
new file mode 100644
index 000000000000..b1d80c52d793
--- /dev/null
+++ b/arch/x86/kernel/ft_event.c
@@ -0,0 +1,104 @@
+#include <linux/types.h>
+
+#include <litmus/feather_trace.h>
+
+/* the feather trace management functions assume
+ * exclusive access to the event table
+ */
+
+
+#define BYTE_JUMP      0xeb
+#define BYTE_JUMP_LEN  0x02
+
+/* for each event, there is an entry in the event table */
+struct trace_event {
+        long    id;
+        long    count;
+        long    start_addr;
+        long    end_addr;
+};
+
+extern struct trace_event  __start___event_table[];
+extern struct trace_event  __stop___event_table[];
+
+int ft_enable_event(unsigned long id)
+{
+        struct trace_event* te = __start___event_table;
+        int count = 0;
+        char* delta;
+        unsigned char* instr;
+
+        while (te < __stop___event_table) {
+                if (te->id == id && ++te->count == 1) {
+                        instr  = (unsigned char*) te->start_addr;
+                        /* make sure we don't clobber something wrong */
+                        if (*instr == BYTE_JUMP) {
+                                delta  = (((unsigned char*) te->start_addr) + 1);
+                                *delta = 0;
+                        }
+                }
+                if (te->id == id)
+                        count++;
+                te++;
+        }
+        return count;
+}
+
+int ft_disable_event(unsigned long id)
+{
+        struct trace_event* te = __start___event_table;
+        int count = 0;
+        char* delta;
+        unsigned char* instr;
+
+        while (te < __stop___event_table) {
+                if (te->id == id && --te->count == 0) {
+                        instr  = (unsigned char*) te->start_addr;
+                        if (*instr == BYTE_JUMP) {
+                                delta  = (((unsigned char*) te->start_addr) + 1);
+                                *delta = te->end_addr - te->start_addr -
+                                        BYTE_JUMP_LEN;
+                        }
+                }
+                if (te->id == id)
+                        count++;
+                te++;
+        }
+        return count;
+}
+
+int ft_disable_all_events(void)
+{
+        struct trace_event* te = __start___event_table;
+        int count = 0;
+        char* delta;
+        unsigned char* instr;
+
+        while (te < __stop___event_table) {
+                if (te->count) {
+                        instr  = (unsigned char*) te->start_addr;
+                        if (*instr == BYTE_JUMP) {
+                                delta  = (((unsigned char*) te->start_addr)
+                                          + 1);
+                                *delta = te->end_addr - te->start_addr -
+                                        BYTE_JUMP_LEN;
+                                te->count = 0;
+                                count++;
+                        }
+                }
+                te++;
+        }
+        return count;
+}
+
+int ft_is_event_enabled(unsigned long id)
+{
+        struct trace_event* te = __start___event_table;
+
+        while (te < __stop___event_table) {
+                if (te->id == id)
+                        return te->count;
+                te++;
+        }
+        return 0;
+}