Blackfin arch: Add ability to expend the hardware trace buffer

Add ability to expend the hardware trace buffer via a configurable
software buffer - so you can have lots of history when a crash occurs.

The interesting way we do printk in the traps.c confusese the checking
script

Signed-off-by: Robin Getz <robin.getz@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>

1 files changed, 46 insertions, 7 deletions

diff --git a/arch/blackfin/kernel/traps.c b/arch/blackfin/kernel/traps.c
index 792a8416fe10..0ec02fe663e9 100644
--- a/arch/blackfin/kernel/traps.c
+++ b/arch/blackfin/kernel/traps.c
@@ -55,6 +55,7 @@ asmlinkage void trap_c(struct pt_regs *fp);
 
 int kstack_depth_to_print = 48;
 
+#ifdef CONFIG_DEBUG_BFIN_HWTRACE_ON
 static int printk_address(unsigned long address)
 {
         struct vm_list_struct *vml;
@@ -131,10 +132,14 @@ static int printk_address(unsigned long address)
         /* we were unable to find this address anywhere */
         return printk("[<0x%p>]", (void *)address);
 }
+#endif
 
 asmlinkage void trap_c(struct pt_regs *fp)
 {
-        int j, sig = 0;
+#ifdef CONFIG_DEBUG_BFIN_HWTRACE_ON
+        int j;
+#endif
+        int sig = 0;
         siginfo_t info;
         unsigned long trapnr = fp->seqstat & SEQSTAT_EXCAUSE;
 
@@ -429,24 +434,56 @@ asmlinkage void trap_c(struct pt_regs *fp)
 
 /* Typical exception handling routines  */
 
+#define EXPAND_LEN ((1 << CONFIG_DEBUG_BFIN_HWTRACE_EXPAND_LEN) * 256 - 1)
+
 void dump_bfin_trace_buffer(void)
 {
-        int tflags;
+#ifdef CONFIG_DEBUG_BFIN_HWTRACE_ON
+        int tflags, i = 0;
+#ifdef CONFIG_DEBUG_BFIN_HWTRACE_EXPAND
+        int j, index;
+#endif
+
         trace_buffer_save(tflags);
 
+        printk(KERN_EMERG "Hardware Trace:\n");
+
         if (likely(bfin_read_TBUFSTAT() & TBUFCNT)) {
-                int i;
-                printk(KERN_EMERG "Hardware Trace:\n");
-                for (i = 0; bfin_read_TBUFSTAT() & TBUFCNT; i++) {
-                        printk(KERN_EMERG "%2i Target : ", i);
+                for (; bfin_read_TBUFSTAT() & TBUFCNT; i++) {
+                        printk(KERN_EMERG "%4i Target : ", i);
                         printk_address((unsigned long)bfin_read_TBUF());
-                        printk("\n" KERN_EMERG "   Source : ");
+                        printk("\n" KERN_EMERG "     Source : ");
                         printk_address((unsigned long)bfin_read_TBUF());
                         printk("\n");
                 }
         }
 
+#ifdef CONFIG_DEBUG_BFIN_HWTRACE_EXPAND
+        if (trace_buff_offset)
+                index = trace_buff_offset/4 - 1;
+        else
+                index = EXPAND_LEN;
+
+        j = (1 << CONFIG_DEBUG_BFIN_HWTRACE_EXPAND_LEN) * 128;
+        while (j) {
+                printk(KERN_EMERG "%4i Target : ", i);
+                printk_address(software_trace_buff[index]);
+                index -= 1;
+                if (index < 0 )
+                        index = EXPAND_LEN;
+                printk("\n" KERN_EMERG "     Source : ");
+                printk_address(software_trace_buff[index]);
+                index -= 1;
+                if (index < 0)
+                        index = EXPAND_LEN;
+                printk("\n");
+                j--;
+                i++;
+        }
+#endif
+
         trace_buffer_restore(tflags);
+#endif
 }
 EXPORT_SYMBOL(dump_bfin_trace_buffer);
 
@@ -510,7 +547,9 @@ void show_stack(struct task_struct *task, unsigned long *stack)
 void dump_stack(void)
 {
         unsigned long stack;
+#ifdef CONFIG_DEBUG_BFIN_HWTRACE_ON
         int tflags;
+#endif
         trace_buffer_save(tflags);
         dump_bfin_trace_buffer();
         show_stack(current, &stack);