bnx2x: validate FW trace prior to its printing

Signed-off-by: Dmitry Kravkov <dmitry@broadcom.com>
Signed-off-by: Yuval Mintz <yuvalmin@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnx2x/bnx2x_hsi.h

@@ -1129,6 +1129,8 @@ struct shm_dev_info {				/* size */
 
 #define FW_ACK_NUM_OF_POLL  (FW_ACK_TIME_OUT_MS/FW_ACK_POLL_TIME_MS)
 
+#define MFW_TRACE_SIGNATURE     0x54524342
+
 /****************************************************************************
  * Driver <-> FW Mailbox                                                    *
  ****************************************************************************/

drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c

@@ -719,7 +719,17 @@ void bnx2x_fw_dump_lvl(struct bnx2x *bp, const char *lvl)
 		trace_shmem_base = bp->common.shmem_base;
 	else
 		trace_shmem_base = SHMEM2_RD(bp, other_shmem_base_addr);
-	addr = trace_shmem_base - 0x0800 + 4;
+	addr = trace_shmem_base - 0x800;
+
+	/* validate TRCB signature */
+	mark = REG_RD(bp, addr);
+	if (mark != MFW_TRACE_SIGNATURE) {
+		BNX2X_ERR("Trace buffer signature is missing.");
+		return ;
+	}
+
+	/* read cyclic buffer pointer */
+	addr += 4;
 	mark = REG_RD(bp, addr);
 	mark = (CHIP_IS_E1x(bp) ? MCP_REG_MCPR_SCRATCH : MCP_A_REG_MCPR_SCRATCH)
 			+ ((mark + 0x3) & ~0x3) - 0x08000000;