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[PATCH v1 04/14] exec: flush the whole TLB if a watchpoint crosses a pag
From: |
Alex Bennée |
Subject: |
[PATCH v1 04/14] exec: flush the whole TLB if a watchpoint crosses a page boundary |
Date: |
Fri, 5 Jun 2020 16:49:19 +0100 |
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 <alxndr@bu.edu>
Signed-off-by: Alex Bennée <alex.bennee@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 3d4c94a9dc3..7cd45e94fce 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
- [PATCH v1 00/14] various fixes for next PR (testing, vhost, guest_base fixes), Alex Bennée, 2020/06/05
- [PATCH v1 04/14] exec: flush the whole TLB if a watchpoint crosses a page boundary,
Alex Bennée <=
- [PATCH v1 02/14] scripts/clean-includes: Mark 'qemu/qemu-plugin.h' as special header, Alex Bennée, 2020/06/05
- [PATCH v1 01/14] qemu-plugin.h: add missing include <stddef.h> to define size_t, Alex Bennée, 2020/06/05
- [PATCH v1 05/14] .travis.yml: allow failure for unreliable hosts, Alex Bennée, 2020/06/05
- [PATCH v1 03/14] tests/plugin: correctly honour io_count, Alex Bennée, 2020/06/05
- [PATCH v1 06/14] .shippable: temporaily disable some cross builds, Alex Bennée, 2020/06/05
- [PATCH v1 08/14] tests/docker: fix pre-requisite for debian-tricore-cross, Alex Bennée, 2020/06/05
- [PATCH v1 10/14] hw/virtio/vhost: re-factor vhost-section and allow DIRTY_MEMORY_CODE, Alex Bennée, 2020/06/05
- [PATCH v1 09/14] docker: update Ubuntu to 20.04, Alex Bennée, 2020/06/05
- [PATCH v1 12/14] linux-user: deal with address wrap for ARM_COMMPAGE on 32 bit, Alex Bennée, 2020/06/05