[PATCH][kgdb][v3] Make mem access function weak in kgdb.c and kgdb.h

[sonic zhang <sonic.adi@gmail.com>]

L1 instruction memory and MMR memory on blackfin can not be accessed by
common functions probe_kernel_read() and probe_kernel_write().
Blackfin asks for 2/4 byte align access to MMR memory and DMA access to
L1 instruction memory. These functions need to be reimplemented in
architecture specific kgdb.c. Update documentation and prototypes as
well.

Signed-off-by: Sonic Zhang <sonic.adi@gmail.com>
---
 include/linux/kgdb.h |   42 ++++++++++++++++++++++++++++++++++++++++--
 kernel/kgdb.c        |    6 +++---
 2 files changed, 43 insertions(+), 5 deletions(-)

diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h
index 8fdd3cb..cb8a3d6 100644
--- a/include/linux/kgdb.h
+++ b/include/linux/kgdb.h
@@ -267,8 +267,46 @@ extern int kgdb_register_io_module(struct kgdb_io
*local_kgdb_io_ops);
 extern void kgdb_unregister_io_module(struct kgdb_io
*local_kgdb_io_ops);
 
 extern int kgdb_hex2long(char **ptr, unsigned long *long_val);
-extern int kgdb_mem2hex(char *mem, char *buf, int count);
-extern int kgdb_hex2mem(char *buf, char *mem, int count);
+
+/**
+ *      kgdb_mem2hex - (optional arch override) translate bin to hex
chars
+ *      @mem: source buffer
+ *      @buf: target buffer
+ *      @count: number of bytes in mem
+ *
+ *      Architectures which do not support probe_kernel_(read|write),
+ *      can make an alternate implementation of this function.
+ *      This function safely reads memory into hex
+ *      characters for use with the kgdb protocol.
+ */
+extern int __weak kgdb_mem2hex(char *mem, char *buf, int count);
+
+/**
+ *      kgdb_hex2mem - (optional arch override) translate hex chars to
bin
+ *      @buf: source buffer
+ *      @mem: target buffer
+ *      @count: number of bytes in mem
+ *
+ *      Architectures which do not support probe_kernel_(read|write),
+ *      can make an alternate implementation of this function.
+ *      This function safely writes hex characters into memory
+ *      for use with the kgdb protocol.
+ */
+extern int __weak kgdb_hex2mem(char *buf, char *mem, int count);
+
+/**
+ *      kgdb_ebin2mem - (optional arch override) Copy the binary array
+ *     pointed to by buf into mem.
+ *      @buf: source buffer
+ *      @mem: target buffer
+ *      @count: number of bytes in mem
+ *
+ *      Architectures which do not support probe_kernel_(read|write),
+ *      can make an alternate implementation of this function.
+ *      This function safely copies binary array into memory
+ *      for use with the kgdb protocol.
+ */
+extern int __weak kgdb_ebin2mem(char *buf, char *mem, int count);
 
 extern int kgdb_isremovedbreak(unsigned long addr);
 
diff --git a/kernel/kgdb.c b/kernel/kgdb.c
index c803730..aae578e 100644
--- a/kernel/kgdb.c
+++ b/kernel/kgdb.c
@@ -364,7 +364,7 @@ static void put_packet(char *buffer)
  * Convert the memory pointed to by mem into hex, placing result in
buf.
  * Return a pointer to the last char put in buf (null). May return an
error.
  */
-int kgdb_mem2hex(char *mem, char *buf, int count)
+int __weak kgdb_mem2hex(char *mem, char *buf, int count)
 {
        char *tmp;
        int err;
@@ -394,7 +394,7 @@ int kgdb_mem2hex(char *mem, char *buf, int count)
  * 0x7d escaped with 0x7d.  Return a pointer to the character after
  * the last byte written.
  */
-static int kgdb_ebin2mem(char *buf, char *mem, int count)
+int __weak kgdb_ebin2mem(char *buf, char *mem, int count)
 {
        int err = 0;
        char c;
@@ -419,7 +419,7 @@ static int kgdb_ebin2mem(char *buf, char *mem, int
count)
  * Return a pointer to the character AFTER the last byte written.
  * May return an error.
  */
-int kgdb_hex2mem(char *buf, char *mem, int count)
+int __weak kgdb_hex2mem(char *buf, char *mem, int count)
 {
        char *tmp_raw;
        char *tmp_hex;
-- 
1.6.0