hw-breakpoints: Separate constraint space for data and instruction breakpoints

There are two outstanding fashions for archs to implement hardware
breakpoints.

The first is to separate breakpoint address pattern definition
space between data and instruction breakpoints. We then have
typically distinct instruction address breakpoint registers
and data address breakpoint registers, delivered with
separate control registers for data and instruction breakpoints
as well. This is the case of PowerPc and ARM for example.

The second consists in having merged breakpoint address space
definition between data and instruction breakpoint. Address
registers can host either instruction or data address and
the access mode for the breakpoint is defined in a control
register. This is the case of x86 and Super H.

This patch adds a new CONFIG_HAVE_MIXED_BREAKPOINTS_REGS config
that archs can select if they belong to the second case. Those
will have their slot allocation merged for instructions and
data breakpoints.

The others will have a separate slot tracking between data and
instruction breakpoints.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Paul Mundt <lethal@linux-sh.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Cc: K. Prasad <prasad@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>

1 files changed, 11 insertions, 0 deletions

diff --git a/arch/Kconfig b/arch/Kconfig
index f06010fb4838..acda512da2e2 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -137,6 +137,17 @@ config HAVE_HW_BREAKPOINT
         bool
         depends on PERF_EVENTS
 
+config HAVE_MIXED_BREAKPOINTS_REGS
+        bool
+        depends on HAVE_HW_BREAKPOINT
+        help
+          Depending on the arch implementation of hardware breakpoints,
+          some of them have separate registers for data and instruction
+          breakpoints addresses, others have mixed registers to store
+          them but define the access type in a control register.
+          Select this option if your arch implements breakpoints under the
+          latter fashion.
+
 config HAVE_USER_RETURN_NOTIFIER
         bool