arm: Correctly handle watchpoints for BE32 CPUs
In BE32 mode, sub-word size watchpoints can fail to trigger because the
address of the access is adjusted in the opcode helpers before being
compared with the watchpoint registers. This patch reverses the address
adjustment before performing the comparison with the help of a new CPUClass
hook.
This version of the patch augments and tidies up comments a little.
Signed-off-by: Julian Brown <julian@codesourcery.com>
Message-id: caaf64ffc72f6ae183015337b7afdbd4b8989cb6.1484929304.git.julian@codesourcery.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
diff --git a/exec.c b/exec.c
index 8b9ed73..6fa337b 100644
--- a/exec.c
+++ b/exec.c
@@ -2115,6 +2115,7 @@
return;
}
vaddr = (cpu->mem_io_vaddr & TARGET_PAGE_MASK) + offset;
+ vaddr = cc->adjust_watchpoint_address(cpu, vaddr, len);
QTAILQ_FOREACH(wp, &cpu->watchpoints, entry) {
if (cpu_watchpoint_address_matches(wp, vaddr, len)
&& (wp->flags & flags)) {
diff --git a/include/qom/cpu.h b/include/qom/cpu.h
index ca4d0fb..45bcf21 100644
--- a/include/qom/cpu.h
+++ b/include/qom/cpu.h
@@ -132,6 +132,8 @@
* @cpu_exec_exit: Callback for cpu_exec cleanup.
* @cpu_exec_interrupt: Callback for processing interrupts in cpu_exec.
* @disas_set_info: Setup architecture specific components of disassembly info
+ * @adjust_watchpoint_address: Perform a target-specific adjustment to an
+ * address before attempting to match it against watchpoints.
*
* Represents a CPU family or model.
*/
@@ -195,6 +197,7 @@
bool (*cpu_exec_interrupt)(CPUState *cpu, int interrupt_request);
void (*disas_set_info)(CPUState *cpu, disassemble_info *info);
+ vaddr (*adjust_watchpoint_address)(CPUState *cpu, vaddr addr, int len);
} CPUClass;
#ifdef HOST_WORDS_BIGENDIAN
diff --git a/qom/cpu.c b/qom/cpu.c
index d57faf3..0e19b1a 100644
--- a/qom/cpu.c
+++ b/qom/cpu.c
@@ -391,6 +391,11 @@
return cpu->cpu_index;
}
+static vaddr cpu_adjust_watchpoint_address(CPUState *cpu, vaddr addr, int len)
+{
+ return addr;
+}
+
static void cpu_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
@@ -415,6 +420,7 @@
k->cpu_exec_enter = cpu_common_noop;
k->cpu_exec_exit = cpu_common_noop;
k->cpu_exec_interrupt = cpu_common_exec_interrupt;
+ k->adjust_watchpoint_address = cpu_adjust_watchpoint_address;
set_bit(DEVICE_CATEGORY_CPU, dc->categories);
dc->realize = cpu_common_realizefn;
dc->unrealize = cpu_common_unrealizefn;
diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index 81448ca..4ee250c 100644
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -1675,6 +1675,9 @@
cc->gdb_stop_before_watchpoint = true;
cc->debug_excp_handler = arm_debug_excp_handler;
cc->debug_check_watchpoint = arm_debug_check_watchpoint;
+#if !defined(CONFIG_USER_ONLY)
+ cc->adjust_watchpoint_address = arm_adjust_watchpoint_address;
+#endif
cc->disas_set_info = arm_disas_set_info;
}
diff --git a/target/arm/internals.h b/target/arm/internals.h
index 2e65bc1..f742a41 100644
--- a/target/arm/internals.h
+++ b/target/arm/internals.h
@@ -444,6 +444,11 @@
/* Callback function for checking if a watchpoint should trigger. */
bool arm_debug_check_watchpoint(CPUState *cs, CPUWatchpoint *wp);
+/* Adjust addresses (in BE32 mode) before testing against watchpoint
+ * addresses.
+ */
+vaddr arm_adjust_watchpoint_address(CPUState *cs, vaddr addr, int len);
+
/* Callback function for when a watchpoint or breakpoint triggers. */
void arm_debug_excp_handler(CPUState *cs);
diff --git a/target/arm/op_helper.c b/target/arm/op_helper.c
index ba796d8..fb366fd 100644
--- a/target/arm/op_helper.c
+++ b/target/arm/op_helper.c
@@ -1225,6 +1225,28 @@
return check_watchpoints(cpu);
}
+vaddr arm_adjust_watchpoint_address(CPUState *cs, vaddr addr, int len)
+{
+ ARMCPU *cpu = ARM_CPU(cs);
+ CPUARMState *env = &cpu->env;
+
+ /* In BE32 system mode, target memory is stored byteswapped (on a
+ * little-endian host system), and by the time we reach here (via an
+ * opcode helper) the addresses of subword accesses have been adjusted
+ * to account for that, which means that watchpoints will not match.
+ * Undo the adjustment here.
+ */
+ if (arm_sctlr_b(env)) {
+ if (len == 1) {
+ addr ^= 3;
+ } else if (len == 2) {
+ addr ^= 2;
+ }
+ }
+
+ return addr;
+}
+
void arm_debug_excp_handler(CPUState *cs)
{
/* Called by core code when a watchpoint or breakpoint fires;
