PowerPC remove 512 bytes region limit if 2nd DAWR is avaliable.

Power 10 introduces the 2nd DAWR (second watchpoint) and also removed
a restriction that limit the watch region to 512 bytes.

2020-11-08  Rogerio A. Cardoso  <rcardoso@linux.ibm.com>

/gdb

	* ppc-linux-nat.c: (PPC_DEBUG_FEATURE_DATA_BP_ARCH_31): New define.
	(region_ok_for_hw_watchpoint): Check if 2nd DAWR is avaliable before
	set region.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index a1814a0fda9dd309b2d649661483974cc0ffe70f..39637aa92a59103269361e5a7032ad4e0da4f379 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2020-12-01  Rogerio A. Cardoso  <rcardoso@linux.ibm.com>
+       * ppc-linux-nat.c: (PPC_DEBUG_FEATURE_DATA_BP_ARCH_31): New define.
+       (region_ok_for_hw_watchpoint): Check if 2nd DAWR is avaliable before
+       set region.
+
 2020-11-30  Tom de Vries  <tdevries@suse.de>
 
        PR symtab/26905

diff --git a/gdb/ppc-linux-nat.c b/gdb/ppc-linux-nat.c
index 095ed577a09cf71e7d112e3d7bc7274bb194a820..a4d216b4aaae3b3089aa3b263de46285221e5433 100644 (file)
--- a/gdb/ppc-linux-nat.c
+++ b/gdb/ppc-linux-nat.c
@@ -138,6 +138,11 @@ struct ppc_hw_breakpoint
 #define PPC_DEBUG_FEATURE_DATA_BP_DAWR 0x10
 #endif /* PPC_DEBUG_FEATURE_DATA_BP_DAWR */
 
+/* Feature defined on Linux kernel v5.1: Second watchpoint support.  */
+#ifndef PPC_DEBUG_FEATURE_DATA_BP_ARCH_31
+#define PPC_DEBUG_FEATURE_DATA_BP_ARCH_31 0x20
+#endif /* PPC_DEBUG_FEATURE_DATA_BP_ARCH_31 */
+
 /* The version of the PowerPC HWDEBUG kernel interface that we will use, if
    available.  */
 #define PPC_DEBUG_CURRENT_VERSION 1
@@ -2108,9 +2113,10 @@ ppc_linux_nat_target::region_ok_for_hw_watchpoint (CORE_ADDR addr, int len)
      watchpoints.  */
   if (m_dreg_interface.hwdebug_p ())
     {
-      int region_size;
       const struct ppc_debug_info &hwdebug_info = (m_dreg_interface
                                                   .hwdebug_info ());
+      int region_size = hwdebug_info.data_bp_alignment;
+      int region_align = region_size;
 
       /* Embedded DAC-based processors, like the PowerPC 440 have ranged
         watchpoints and can watch any access within an arbitrary memory
@@ -2122,15 +2128,19 @@ ppc_linux_nat_target::region_ok_for_hw_watchpoint (CORE_ADDR addr, int len)
        return 2;
       /* Check if the processor provides DAWR interface.  */
       if (hwdebug_info.features & PPC_DEBUG_FEATURE_DATA_BP_DAWR)
-       /* DAWR interface allows to watch up to 512 byte wide ranges which
-          can't cross a 512 byte boundary.  */
-       region_size = 512;
-      else
-       region_size = hwdebug_info.data_bp_alignment;
+       {
+         /* DAWR interface allows to watch up to 512 byte wide ranges.  */
+         region_size = 512;
+         /* DAWR interface allows to watch up to 512 byte wide ranges which
+            can't cross a 512 byte bondary on machines that doesn't have a
+            second DAWR (P9 or less).  */
+         if (!(hwdebug_info.features & PPC_DEBUG_FEATURE_DATA_BP_ARCH_31))
+           region_align = 512;
+       }
       /* Server processors provide one hardware watchpoint and addr+len should
         fall in the watchable region provided by the ptrace interface.  */
-      if (region_size
-         && (addr + len > (addr & ~(region_size - 1)) + region_size))
+      if (region_align
+         && (addr + len > (addr & ~(region_align - 1)) + region_size))
        return 0;
     }
   /* addr+len must fall in the 8 byte watchable region for DABR-based