tile: support kprobes on tilegx

This change includes support for Kprobes, Jprobes and Return Probes.

Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Tony Lu <zlu@tilera.com>
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

1 files changed, 44 insertions, 1 deletions

diff --git a/arch/tile/kernel/traps.c b/arch/tile/kernel/traps.c
index a1bbc5de4d00..cfff6f958d58 100644
--- a/arch/tile/kernel/traps.c
+++ b/arch/tile/kernel/traps.c
@@ -15,6 +15,7 @@
 #include <linux/sched.h>
 #include <linux/kernel.h>
 #include <linux/kprobes.h>
+#include <linux/kdebug.h>
 #include <linux/module.h>
 #include <linux/reboot.h>
 #include <linux/uaccess.h>
@@ -214,6 +215,43 @@ static const char *const int_name[] = {
 #endif
 };
 
+static int do_bpt(struct pt_regs *regs)
+{
+        unsigned long bundle, bcode, bpt;
+
+        bundle = *(unsigned long *)instruction_pointer(regs);
+
+        /*
+         * bpt shoule be { bpt; nop }, which is 0x286a44ae51485000ULL.
+         * we encode the unused least significant bits for other purpose.
+         */
+        bpt = bundle & ~((1ULL << 12) - 1);
+        if (bpt != TILE_BPT_BUNDLE)
+                return 0;
+
+        bcode = bundle & ((1ULL << 12) - 1);
+        /*
+         * notify the kprobe handlers, if instruction is likely to
+         * pertain to them.
+         */
+        switch (bcode) {
+        /* breakpoint_insn */
+        case 0:
+                notify_die(DIE_BREAK, "debug", regs, bundle,
+                        INT_ILL, SIGTRAP);
+                break;
+        /* breakpoint2_insn */
+        case DIE_SSTEPBP:
+                notify_die(DIE_SSTEPBP, "single_step", regs, bundle,
+                        INT_ILL, SIGTRAP);
+                break;
+        default:
+                return 0;
+        }
+
+        return 1;
+}
+
 void __kprobes do_trap(struct pt_regs *regs, int fault_num,
                        unsigned long reason)
 {
@@ -221,6 +259,11 @@ void __kprobes do_trap(struct pt_regs *regs, int fault_num,
         int signo, code;
         unsigned long address = 0;
         bundle_bits instr;
+        int is_kernel = !user_mode(regs);
+
+        /* Handle breakpoints, etc. */
+        if (is_kernel && fault_num == INT_ILL && do_bpt(regs))
+                return;
 
         /* Re-enable interrupts, if they were previously enabled. */
         if (!(regs->flags & PT_FLAGS_DISABLE_IRQ))
@@ -230,7 +273,7 @@ void __kprobes do_trap(struct pt_regs *regs, int fault_num,
          * If it hits in kernel mode and we can't fix it up, just exit the
          * current process and hope for the best.
          */
-        if (!user_mode(regs)) {
+        if (is_kernel) {
                 const char *name;
                 char buf[100];
                 if (fixup_exception(regs))  /* ILL_TRANS or UNALIGN_DATA */