Re: [v2][PATCH 3/3] powerpc/kgdb: restore current_thread_info properly

For powerpc BooKE and e200, singlestep is handled on the critical/dbg
exception stack. This causes current_thread_info() to fail for kgdb
internal, so previously We work around this issue by copying
the thread_info from the kernel stack before calling kgdb_handle_exception,
and copying it back afterwards.

But actually we don't do this properly. We should backup current_thread_info
then restore that when exit.

Signed-off-by: Tiejun Chen <redacted>
---
v2: fix a typo in patch head description.

 arch/powerpc/kernel/kgdb.c |   11 +++++++++--
 1 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/kgdb.c b/arch/powerpc/kernel/kgdb.c
index 05adb69..c470a40 100644
--- a/arch/powerpc/kernel/kgdb.c
+++ b/arch/powerpc/kernel/kgdb.c

@@ -25,6 +25,7 @@
 #include <asm/processor.h>
 #include <asm/machdep.h>
 #include <asm/debug.h>
+#include <linux/slab.h>
 
 /*
  * This table contains the mapping between PowerPC hardware trap types, and

@@ -153,6 +154,8 @@ static int kgdb_handle_breakpoint(struct pt_regs *regs)
 static int kgdb_singlestep(struct pt_regs *regs)
 {
 	struct thread_info *thread_info, *exception_thread_info;
+	struct thread_info *backup_current_thread_info = \
+		(struct thread_info *)kmalloc(sizeof(struct thread_info), GFP_KERNEL);