This is the mail archive of the
gdb-patches@sourceware.org
mailing list for the GDB project.
Re: [PATCH] Enable hw watchpoint with longer ranges using DAWR on Power
- From: Edjunior Barbosa Machado <emachado at linux dot vnet dot ibm dot com>
- To: gdb-patches at sourceware dot org
- Cc: Edjunior Barbosa Machado <emachado at linux dot vnet dot ibm dot com>, Ulrich dot Weigand at de dot ibm dot com, eliz at gnu dot org, lgustavo at codesourcery dot com
- Date: Tue, 2 Jul 2013 18:02:18 -0300
- Subject: Re: [PATCH] Enable hw watchpoint with longer ranges using DAWR on Power
On 07/02/2013 05:03 PM, Eli Zaretskii wrote:
> Is only one watchpoint of this kind possible at any given time? If
> more than one such watchpoint can be used at the same time, I don't
> see why we should expose the 512-byte limitation to users. Just use
> more than one such watchpoint to cover the range of addresses
> requested by the user command.
Yes, currently there is only one hw watchpoint available on Power servers. The
new feature just allows to watch longer ranges using this hw watchpoint, up to
512 bytes, instead of previous 8 bytes limit.
I'm resending the patch fixing the comment as Luis suggested. And I also hope
we can get the 'booke' renaming upstream soon :)
Thanks for the feedback.
--
Edjunior
gdb/ChangeLog
2013-07-02 Edjunior Barbosa Machado <emachado@linux.vnet.ibm.com>
* ppc-linux-nat.c (PPC_DEBUG_FEATURE_DATA_BP_DAWR): New define.
(ppc_linux_region_ok_for_hw_watchpoint): Add checking to use the new
DAWR interface for longer ranges hardware watchpoint (up to 512 bytes).
---
gdb/ppc-linux-nat.c | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)
diff --git a/gdb/ppc-linux-nat.c b/gdb/ppc-linux-nat.c
index 65d4f4a..ce437dd 100644
--- a/gdb/ppc-linux-nat.c
+++ b/gdb/ppc-linux-nat.c
@@ -177,7 +177,11 @@ struct ppc_hw_breakpoint
(1<<((n)+PPC_BREAKPOINT_CONDITION_BE_SHIFT))
#endif /* PPC_PTRACE_GETHWDBGINFO */
-
+/* Feature defined on Linux kernel v3.9: DAWR interface, that enables wider
+ watchpoint (up to 512 bytes). */
+#ifndef PPC_DEBUG_FEATURE_DATA_BP_DAWR
+#define PPC_DEBUG_FEATURE_DATA_BP_DAWR 0x10
+#endif /* PPC_DEBUG_FEATURE_DATA_BP_DAWR */
/* Similarly for the general-purpose (gp0 -- gp31)
and floating-point registers (fp0 -- fp31). */
@@ -1502,6 +1506,7 @@ ppc_linux_region_ok_for_hw_watchpoint (CORE_ADDR addr, int len)
to determine the hardcoded watchable region for watchpoints. */
if (have_ptrace_booke_interface ())
{
+ int region_size;
/* Embedded DAC-based processors, like the PowerPC 440 have ranged
watchpoints and can watch any access within an arbitrary memory
region. This is useful to watch arrays and structs, for instance. It
@@ -1510,11 +1515,17 @@ ppc_linux_region_ok_for_hw_watchpoint (CORE_ADDR addr, int len)
&& booke_debug_info.features & PPC_DEBUG_FEATURE_DATA_BP_RANGE
&& ppc_linux_get_hwcap () & PPC_FEATURE_BOOKE)
return 2;
+ /* Check if the processor provides DAWR interface. */
+ if (booke_debug_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 = booke_debug_info.data_bp_alignment;
/* Server processors provide one hardware watchpoint and addr+len should
fall in the watchable region provided by the ptrace interface. */
- if (booke_debug_info.data_bp_alignment
- && (addr + len > (addr & ~(booke_debug_info.data_bp_alignment - 1))
- + booke_debug_info.data_bp_alignment))
+ if (region_size
+ && (addr + len > (addr & ~(region_size - 1)) + region_size))
return 0;
}
/* addr+len must fall in the 8 byte watchable region for DABR-based
--
1.8.2.1