ARM kprobes: core code

This is a full implementation of Kprobes including Jprobes and
Kretprobes support.

This ARM implementation does not follow the usual kprobes double-
exception model. The traditional model is where the initial kprobes
breakpoint calls kprobe_handler(), which returns from exception to
execute the instruction in its original context, then immediately
re-enters after a second breakpoint (or single-stepping exception)
into post_kprobe_handler(), each time the probe is hit..  The ARM
implementation only executes one kprobes exception per hit, so no
post_kprobe_handler() phase. All side-effects from the kprobe'd
instruction are resolved before returning from the initial exception.
As a result, all instructions are _always_ effectively boosted
regardless of the type of instruction, and even regardless of whether
or not there is a post-handler for the probe.

Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com>
Signed-off-by: Quentin Barnes <qbarnes@gmail.com>
Signed-off-by: Nicolas Pitre <nico@marvell.com>

1 files changed, 29 insertions, 0 deletions

diff --git a/include/asm-arm/kprobes.h b/include/asm-arm/kprobes.h
index 951322328793..273f37413ee6 100644
--- a/include/asm-arm/kprobes.h
+++ b/include/asm-arm/kprobes.h
@@ -18,6 +18,16 @@
 
 #include <linux/types.h>
 #include <linux/ptrace.h>
+#include <linux/percpu.h>
+
+#define ARCH_SUPPORTS_KRETPROBES
+#define __ARCH_WANT_KPROBES_INSN_SLOT
+#define MAX_INSN_SIZE                   2
+#define MAX_STACK_SIZE                  64      /* 32 would probably be OK */
+
+#define regs_return_value(regs)         ((regs)->ARM_r0)
+#define flush_insn_slot(p)              do { } while (0)
+#define kretprobe_blacklist_size        0
 
 typedef u32 kprobe_opcode_t;
 
@@ -30,6 +40,25 @@ struct arch_specific_insn {
         kprobe_insn_handler_t   *insn_handler;
 };
 
+struct prev_kprobe {
+        struct kprobe *kp;
+        unsigned int status;
+};
+
+/* per-cpu kprobe control block */
+struct kprobe_ctlblk {
+        unsigned int kprobe_status;
+        struct prev_kprobe prev_kprobe;
+        struct pt_regs jprobe_saved_regs;
+        char jprobes_stack[MAX_STACK_SIZE];
+};
+
+void arch_remove_kprobe(struct kprobe *);
+
+int kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr);
+int kprobe_exceptions_notify(struct notifier_block *self,
+                             unsigned long val, void *data);
+
 enum kprobe_insn {
         INSN_REJECTED,
         INSN_GOOD,