[RFC PATCH -tip 07/16] kdb: Provide original instruction modified by sw breakpoint

[Masami Hiramatsu <masami.hiramatsu@gmail.com>]

Add kdb_get_saved_instr() for someone who needs to know
the original instruction in kernel text.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu@gmail.com>
---
 include/linux/kgdb.h      |    1 +
 kernel/debug/debug_core.c |   14 ++++++++++++++
 2 files changed, 15 insertions(+), 0 deletions(-)

diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h
index fa39183..e1eb57c 100644
--- a/include/linux/kgdb.h
+++ b/include/linux/kgdb.h
@@ -209,6 +209,7 @@ extern void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc);
 extern int kgdb_validate_break_address(unsigned long addr);
 extern int kgdb_arch_set_breakpoint(unsigned long addr, char *saved_instr);
 extern int kgdb_arch_remove_breakpoint(unsigned long addr, char *bundle);
+extern int kgdb_get_saved_instr(unsigned long addr, unsigned char *buf);
 
 /**
  *	kgdb_arch_late - Perform any architecture specific initalization.
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index 1dc53ba..8982ba0 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -349,6 +349,20 @@ int kgdb_isremovedbreak(unsigned long addr)
 	return 0;
 }
 
+int kgdb_get_saved_instr(unsigned long addr, unsigned char *buf)
+{
+	int i;
+	for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
+		if (kgdb_break[i].bpt_addr == addr &&
+		    kgdb_break[i].state == BP_ACTIVE) {
+			memcpy(buf, kgdb_break[i].saved_instr,
+				BREAK_INSTR_SIZE);
+			return 1;
+		}
+	}
+	return 0;
+}
+
 int dbg_remove_all_break(void)
 {
 	unsigned long addr;