There is no particular reason why you can't have a watchpoint in TCG
that covers a large chunk of the address space. We could be clever
about it but these cases are pretty rare and we can assume the user
will expect a little performance degradation.
NB: In my testing gdb will silently squash a watchpoint like:
watch (char[0x7fffffffff]) *0x0
to a 4 byte watchpoint. Practically it will limit the maximum size
based on max-value-size. However given enough of a tweak the sky is
the limit.
Reported-by: Alexander Bulekov <alx...@bu.edu>
Signed-off-by: Alex Bennée <alex.ben...@linaro.org>
---
v2
- use cleaner in_page = -(addr | TARGET_PAGE_MASK) logic per rth
---
exec.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/exec.c b/exec.c
index 5162f0d12f9..65a4376df37 100644
--- a/exec.c
+++ b/exec.c
@@ -1036,6 +1036,7 @@ int cpu_watchpoint_insert(CPUState *cpu, vaddr addr,
vaddr len,
int flags, CPUWatchpoint **watchpoint)
{
CPUWatchpoint *wp;
+ vaddr in_page;
/* forbid ranges which are empty or run off the end of the address space */
if (len == 0 || (addr + len - 1) < addr) {
@@ -1056,7 +1057,12 @@ int cpu_watchpoint_insert(CPUState *cpu, vaddr addr,
vaddr len,
QTAILQ_INSERT_TAIL(&cpu->watchpoints, wp, entry);
}
- tlb_flush_page(cpu, addr);
+ in_page = -(addr | TARGET_PAGE_MASK);
+ if (len <= in_page) {
+ tlb_flush_page(cpu, addr);
+ } else {
+ tlb_flush(cpu);
+ }
if (watchpoint)
*watchpoint = wp;
--
2.20.1
