common: cmd_boot: Add stack canary test command.

This change will add stack canary test command in
u-boot command list.

The stack canary test command format like as :
canary <string>. The string must be 10 bytes long.

e.g
" #canary Helloworldhelloworld".

After this command we can see the below print.
Stack Canary test start.
stack-protector: U-boot stack is corrupted.
Resetting CPU ...

If stack-protection not enabled and stack overflow
occure then we will get the following print.

prefetch abort
pc : [<4a006f72>]          lr : [<4a90faf0>]
reloc pc : [<4a006f72>]    lr : [<4a90faf0>]
sp : 4a77f948  ip : 20f14495     fp : 4a90fab4
r10: 00000002  r9 : 4a77fea0     r8 : 00000000
r7 : 4a983d20  r6 : 6f6f6f6f     r5 : 6f6f6f6f  r4 : 6f6f6f6f
r3 : 00000000  r2 : 4a77f946     r1 : 4a78233b  r0 : 00000000
Flags: nZCv  IRQs off  FIQs off  Mode SVC_32
Resetting CPU ...

Change-Id: If36d1da3ecc1d0038cd1a6bad6ab3d265b47dac8
Signed-off-by: Md Sadre Alam <mdalam@codeaurora.org>

board/qca/arm/common/cmd_bootqca.c

@@ -82,6 +82,7 @@ typedef struct {
 void __stack_chk_fail(void)
 {
 	printf("stack-protector: U-boot stack is corrupted.\n");
+	bad_mode ();
 }
 /*
  * Set the root device and bootargs for mounting root filesystem.

common/cmd_boot.c

@@ -44,6 +44,25 @@ static int do_go(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 	printf ("## Application terminated, rc = 0x%lX\n", rc);
 	return rcode;
 }
+static int do_canary(cmd_tbl_t *cmdtp, int flag, int argc,
+		char * const argv[])
+{
+	char Buffer[10] = {'\0'};
+	printf("Stack Canary test start.\n");
+
+	if (argc < 2 || argc > 2)
+		return CMD_RET_USAGE;
+
+	strlcpy(Buffer, argv[1], strlen(argv[1]));
+
+	return 0;
+}
+
+U_BOOT_CMD(
+	canary, 2, 0, do_canary,
+	"test stack canary",
+	"\n canary HelloworldHelloWorld \n"
+);
 
 /* -------------------------------------------------------------------- */