kgdbts: Use HW breakpoints with CONFIG_DEBUG_RODATA

Whenever CONFIG_DEBUG_RODATA is set in the kernel config many kernel
text sections become read-only, and the use of software breakpoints in
the kgdb tests will cause the kernel to fail to complete the start up.

Until such time that there is an official API for modifying read-only
text sections hardware breakpoints must be used to run the do_fork or
sys_open tests or the tests get skipped.

Also fix the duplicated include reported by:
Huang Weiyi <weiyi.huang@gmail.com>

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>

1 files changed, 24 insertions, 4 deletions

diff --git a/drivers/misc/kgdbts.c b/drivers/misc/kgdbts.c
index 2763ae086531..e4ff50b95a5e 100644
--- a/drivers/misc/kgdbts.c
+++ b/drivers/misc/kgdbts.c
@@ -102,7 +102,6 @@
 #include <linux/nmi.h>
 #include <linux/delay.h>
 #include <linux/kthread.h>
-#include <linux/delay.h>
 
 #define v1printk(a...) do { \
         if (verbose) \
@@ -130,6 +129,8 @@ static int repeat_test;
 static int test_complete;
 static int send_ack;
 static int final_ack;
+static int force_hwbrks;
+static int hwbreaks_ok;
 static int hw_break_val;
 static int hw_break_val2;
 #if defined(CONFIG_ARM) || defined(CONFIG_MIPS) || defined(CONFIG_SPARC)
@@ -233,12 +234,12 @@ static void break_helper(char *bp_type, char *arg, unsigned long vaddr)
 
 static void sw_break(char *arg)
 {
-        break_helper("Z0", arg, 0);
+        break_helper(force_hwbrks ? "Z1" : "Z0", arg, 0);
 }
 
 static void sw_rem_break(char *arg)
 {
-        break_helper("z0", arg, 0);
+        break_helper(force_hwbrks ? "z1" : "z0", arg, 0);
 }
 
 static void hw_break(char *arg)
@@ -780,6 +781,8 @@ static void run_breakpoint_test(int is_hw_breakpoint)
                 return;
 
         eprintk("kgdbts: ERROR %s test failed\n", ts.name);
+        if (is_hw_breakpoint)
+                hwbreaks_ok = 0;
 }
 
 static void run_hw_break_test(int is_write_test)
@@ -797,9 +800,11 @@ static void run_hw_break_test(int is_write_test)
         kgdb_breakpoint();
         hw_break_val_access();
         if (is_write_test) {
-                if (test_complete == 2)
+                if (test_complete == 2) {
                         eprintk("kgdbts: ERROR %s broke on access\n",
                                 ts.name);
+                        hwbreaks_ok = 0;
+                }
                 hw_break_val_write();
         }
         kgdb_breakpoint();
@@ -808,6 +813,7 @@ static void run_hw_break_test(int is_write_test)
                 return;
 
         eprintk("kgdbts: ERROR %s test failed\n", ts.name);
+        hwbreaks_ok = 0;
 }
 
 static void run_nmi_sleep_test(int nmi_sleep)
@@ -911,6 +917,7 @@ static void kgdbts_run_tests(void)
 
         /* All HW break point tests */
         if (arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT) {
+                hwbreaks_ok = 1;
                 v1printk("kgdbts:RUN hw breakpoint test\n");
                 run_breakpoint_test(1);
                 v1printk("kgdbts:RUN hw write breakpoint test\n");
@@ -924,6 +931,19 @@ static void kgdbts_run_tests(void)
                 run_nmi_sleep_test(nmi_sleep);
         }
 
+#ifdef CONFIG_DEBUG_RODATA
+        /* Until there is an api to write to read-only text segments, use
+         * HW breakpoints for the remainder of any tests, else print a
+         * failure message if hw breakpoints do not work.
+         */
+        if (!(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT && hwbreaks_ok)) {
+                eprintk("kgdbts: HW breakpoints do not work,"
+                        "skipping remaining tests\n");
+                return;
+        }
+        force_hwbrks = 1;
+#endif /* CONFIG_DEBUG_RODATA */
+
         /* If the do_fork test is run it will be the last test that is
          * executed because a kernel thread will be spawned at the very
          * end to unregister the debug hooks.