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>
diff --git a/arch/blackfin/mach-common/entry.S b/arch/blackfin/mach-common/entry.S
index 207e697..ab278a7 100644
--- a/arch/blackfin/mach-common/entry.S
+++ b/arch/blackfin/mach-common/entry.S
@@ -731,6 +731,75 @@
rts;
ENDPROC(_init_exception_buff)
+/* We handle this 100% in exception space - to reduce overhead
+ * Only potiential problem is if the software buffer gets swapped out of the
+ * CPLB table - then double fault. - so we don't let this happen in other places
+ */
+#ifdef CONFIG_DEBUG_BFIN_HWTRACE_EXPAND
+ENTRY(_ex_trace_buff_full)
+ [--sp] = P3;
+ [--sp] = P2;
+ [--sp] = LC0;
+ [--sp] = LT0;
+ [--sp] = LB0;
+ P5.L = _trace_buff_offset;
+ P5.H = _trace_buff_offset;
+ P3 = [P5]; /* trace_buff_offset */
+ P5.L = lo(TBUFSTAT);
+ P5.H = hi(TBUFSTAT);
+ R7 = [P5];
+ R7 <<= 1; /* double, since we need to read twice */
+ LC0 = R7;
+ R7 <<= 2; /* need to shift over again,
+ * to get the number of bytes */
+ P5.L = lo(TBUF);
+ P5.H = hi(TBUF);
+ R6 = ((1 << CONFIG_DEBUG_BFIN_HWTRACE_EXPAND_LEN)*1024) - 1;
+
+ P2 = R7;
+ P3 = P3 + P2;
+ R7 = P3;
+ R7 = R7 & R6;
+ P3 = R7;
+ P2.L = _trace_buff_offset;
+ P2.H = _trace_buff_offset;
+ [P2] = P3;
+
+ P2.L = _software_trace_buff;
+ P2.H = _software_trace_buff;
+
+ LSETUP (.Lstart, .Lend) LC0;
+.Lstart:
+ R7 = [P5]; /* read TBUF */
+ P4 = P3 + P2;
+ [P4] = R7;
+ P3 += -4;
+ R7 = P3;
+ R7 = R7 & R6;
+.Lend:
+ P3 = R7;
+
+ LB0 = [sp++];
+ LT0 = [sp++];
+ LC0 = [sp++];
+ P2 = [sp++];
+ P3 = [sp++];
+ jump _return_from_exception;
+
+#if CONFIG_DEBUG_BFIN_HWTRACE_EXPAND_LEN == 4
+.data
+#else
+.section .l1.data.B
+#endif
+ENTRY(_trace_buff_offset)
+ .long 0;
+ALIGN
+ENTRY(_software_trace_buff)
+ .rept ((1 << CONFIG_DEBUG_BFIN_HWTRACE_EXPAND_LEN)*256);
+ .long 0
+ .endr
+#endif
+
/*
* Put these in the kernel data section - that should always be covered by
* a CPLB. This is needed to ensure we don't get double fault conditions
@@ -764,7 +833,11 @@
.long _ex_trap_c /* 0x0E - User Defined */
.long _ex_trap_c /* 0x0F - User Defined */
.long _ex_single_step /* 0x10 - HW Single step */
+#ifdef CONFIG_DEBUG_BFIN_HWTRACE_EXPAND
+ .long _ex_trace_buff_full /* 0x11 - Trace Buffer Full */
+#else
.long _ex_trap_c /* 0x11 - Trace Buffer Full */
+#endif
.long _ex_trap_c /* 0x12 - Reserved */
.long _ex_trap_c /* 0x13 - Reserved */
.long _ex_trap_c /* 0x14 - Reserved */