[PATCH] Fix hardware watchpoints on PowerPC servers

Edjunior Barbosa Machado
2013-05-13T06:29:02Z

Hi,

initially developed only for bookE (embedded processors), the new ptrace
interface is now available for Power server processors too [1].

This patch fixes the insertion of hardware watchpoints on Power servers
using this new interface available on kernel 3.7 and newer (currently, the
region should be aligned to 8 bytes, which is also the max length). It reduces
the number of unexpected failures in gdb testsuite in 40 failures (ppc64
running kernel 3.8).

Thanks and regards,
--
Edjunior.

[1] http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/arch/powerpc/kernel/ptrace.c?id=6c7a2856ade6a58c20038024247d16a12a8d2323

gdb/ChangeLog
2013-05-12 Edjunior Machado <emachado@linux.vnet.ibm.com>

* ppc-linux-nat.c (ppc_linux_region_ok_for_hw_watchpoint): Check if the
region is ok for a hardware watchpoint using the new ptrace interface
on Power servers.

---
gdb/ppc-linux-nat.c | 19 +++++++++++--------
1 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/gdb/ppc-linux-nat.c b/gdb/ppc-linux-nat.c
index 280dcbe..1ff00a6 100644
--- a/gdb/ppc-linux-nat.c
+++ b/gdb/ppc-linux-nat.c
@@ -1503,16 +1503,19 @@ 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 ())
{
- /* DAC-based processors (i.e., embedded 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 takes two hardware watchpoints though. */
+ /* 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
+ takes two hardware watchpoints though. */
if (len > 1
- && booke_debug_info.features & PPC_DEBUG_FEATURE_DATA_BP_RANGE)
+ && booke_debug_info.features & PPC_DEBUG_FEATURE_DATA_BP_RANGE
+ && ppc_linux_get_hwcap () & PPC_FEATURE_BOOKE)
return 2;
- else if (booke_debug_info.data_bp_alignment
- && (addr + len > (addr & ~(booke_debug_info.data_bp_alignment - 1))
- + 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))
return 0;
}
/* addr+len must fall in the 8 byte watchable region for DABR-based
--
1.7.1