MIPS: kprobe: Add support.

This patch is based on previous work by Sony and Himanshu Chauhan.

I have done some cleanup and implemented JProbes and KRETPROBES.  The
KRETPROBES part is pretty much copied verbatim from powerpc.  A possible
future enhance might be to factor out the common code.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Cc: Himanshu Chauhan <hschauhan@nulltrace.org>
To: linux-mips@linux-mips.org
To: ananth@in.ibm.com,
To: anil.s.keshavamurthy@intel.com
To: davem@davemloft.net
To: masami.hiramatsu.pt@hitachi.com
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/1525/
Patchwork: https://patchwork.linux-mips.org/patch/1530/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 21 insertions, 1 deletions

diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 1515b673179d..4c6079f24958 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -25,6 +25,7 @@
 #include <linux/ptrace.h>
 #include <linux/kgdb.h>
 #include <linux/kdebug.h>
+#include <linux/kprobes.h>
 #include <linux/notifier.h>
 #include <linux/kdb.h>
 
@@ -334,7 +335,7 @@ void show_regs(struct pt_regs *regs)
         __show_regs((struct pt_regs *)regs);
 }
 
-void show_registers(const struct pt_regs *regs)
+void show_registers(struct pt_regs *regs)
 {
         const int field = 2 * sizeof(unsigned long);
 
@@ -783,6 +784,25 @@ asmlinkage void do_bp(struct pt_regs *regs)
         if (bcode >= (1 << 10))
                 bcode >>= 10;
 
+        /*
+         * notify the kprobe handlers, if instruction is likely to
+         * pertain to them.
+         */
+        switch (bcode) {
+        case BRK_KPROBE_BP:
+                if (notify_die(DIE_BREAK, "debug", regs, bcode, 0, 0) == NOTIFY_STOP)
+                        return;
+                else
+                        break;
+        case BRK_KPROBE_SSTEPBP:
+                if (notify_die(DIE_SSTEPBP, "single_step", regs, bcode, 0, 0) == NOTIFY_STOP)
+                        return;
+                else
+                        break;
+        default:
+                break;
+        }
+
         do_trap_or_bp(regs, bcode, "Break");
         return;