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>

3 files changed, 97 insertions, 0 deletions

diff --git a/arch/mips/include/asm/break.h b/arch/mips/include/asm/break.h
index 44437ed765e8..9161e684cb4c 100644
--- a/arch/mips/include/asm/break.h
+++ b/arch/mips/include/asm/break.h
@@ -30,6 +30,8 @@
 #define BRK_BUG         512     /* Used by BUG() */
 #define BRK_KDB         513     /* Used in KDB_ENTER() */
 #define BRK_MEMU        514     /* Used by FPU emulator */
+#define BRK_KPROBE_BP   515     /* Kprobe break */
+#define BRK_KPROBE_SSTEPBP 516  /* Kprobe single step software implementation */
 #define BRK_MULOVF      1023    /* Multiply overflow */
 
 #endif /* __ASM_BREAK_H */
diff --git a/arch/mips/include/asm/kdebug.h b/arch/mips/include/asm/kdebug.h
index 5bf62aafc890..6a9af5fcb5d7 100644
--- a/arch/mips/include/asm/kdebug.h
+++ b/arch/mips/include/asm/kdebug.h
@@ -8,6 +8,9 @@ enum die_val {
         DIE_FP,
         DIE_TRAP,
         DIE_RI,
+        DIE_PAGE_FAULT,
+        DIE_BREAK,
+        DIE_SSTEPBP
 };
 
 #endif /* _ASM_MIPS_KDEBUG_H */
diff --git a/arch/mips/include/asm/kprobes.h b/arch/mips/include/asm/kprobes.h
new file mode 100644
index 000000000000..e6ea4d4d7205
--- /dev/null
+++ b/arch/mips/include/asm/kprobes.h
@@ -0,0 +1,92 @@
+/*
+ *  Kernel Probes (KProbes)
+ *  include/asm-mips/kprobes.h
+ *
+ *  Copyright 2006 Sony Corp.
+ *  Copyright 2010 Cavium Networks
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; version 2 of the License.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#ifndef _ASM_KPROBES_H
+#define _ASM_KPROBES_H
+
+#include <linux/ptrace.h>
+#include <linux/types.h>
+
+#include <asm/cacheflush.h>
+#include <asm/kdebug.h>
+#include <asm/inst.h>
+
+#define  __ARCH_WANT_KPROBES_INSN_SLOT
+
+struct kprobe;
+struct pt_regs;
+
+typedef union mips_instruction kprobe_opcode_t;
+
+#define MAX_INSN_SIZE 2
+
+#define flush_insn_slot(p)                                              \
+do {                                                                    \
+        flush_icache_range((unsigned long)p->addr,                      \
+                           (unsigned long)p->addr +                     \
+                           (MAX_INSN_SIZE * sizeof(kprobe_opcode_t)));  \
+} while (0)
+
+
+#define kretprobe_blacklist_size 0
+
+void arch_remove_kprobe(struct kprobe *p);
+
+/* Architecture specific copy of original instruction*/
+struct arch_specific_insn {
+        /* copy of the original instruction */
+        kprobe_opcode_t *insn;
+};
+
+struct prev_kprobe {
+        struct kprobe *kp;
+        unsigned long status;
+        unsigned long old_SR;
+        unsigned long saved_SR;
+        unsigned long saved_epc;
+};
+
+#define MAX_JPROBES_STACK_SIZE 128
+#define MAX_JPROBES_STACK_ADDR \
+        (((unsigned long)current_thread_info()) + THREAD_SIZE - 32 - sizeof(struct pt_regs))
+
+#define MIN_JPROBES_STACK_SIZE(ADDR)                                    \
+        ((((ADDR) + MAX_JPROBES_STACK_SIZE) > MAX_JPROBES_STACK_ADDR)   \
+                ? MAX_JPROBES_STACK_ADDR - (ADDR)                       \
+                : MAX_JPROBES_STACK_SIZE)
+
+
+/* per-cpu kprobe control block */
+struct kprobe_ctlblk {
+        unsigned long kprobe_status;
+        unsigned long kprobe_old_SR;
+        unsigned long kprobe_saved_SR;
+        unsigned long kprobe_saved_epc;
+        unsigned long jprobe_saved_sp;
+        struct pt_regs jprobe_saved_regs;
+        u8 jprobes_stack[MAX_JPROBES_STACK_SIZE];
+        struct prev_kprobe prev_kprobe;
+};
+
+extern int kprobe_exceptions_notify(struct notifier_block *self,
+                                    unsigned long val, void *data);
+
+#endif                          /* _ASM_KPROBES_H */