[Qemu-devel] [PULL 21/26] translate-all: fix watchpoints if retranslation not possible

[Alexander Graf <agraf@suse.de>]

From: Aurelien Jarno <aurelien@aurel32.net>

The tb_check_watchpoint function currently assumes that all memory
access is done either directly through the TCG code or through an
helper which knows its return address. This is obviously wrong as the
helpers use cpu_ldxx/stxx_data functions to access the memory.

Instead of aborting in that case, don't try to retranslate the code, but
assume that the CPU state (and especially the program counter) has been
saved before calling the helper. Then invalidate the TB based on this
address.

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Alexander Graf <agraf@suse.de>
---
 translate-all.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/translate-all.c b/translate-all.c
index e2e7422..b6b0e1c 100644
--- a/translate-all.c
+++ b/translate-all.c
@@ -1431,12 +1431,22 @@ void tb_check_watchpoint(CPUState *cpu)
     TranslationBlock *tb;
 
     tb = tb_find_pc(cpu->mem_io_pc);
-    if (!tb) {
-        cpu_abort(cpu, "check_watchpoint: could not find TB for pc=%p",
-                  (void *)cpu->mem_io_pc);
+    if (tb) {
+        /* We can use retranslation to find the PC.  */
+        cpu_restore_state_from_tb(cpu, tb, cpu->mem_io_pc);
+        tb_phys_invalidate(tb, -1);
+    } else {
+        /* The exception probably happened in a helper.  The CPU state should
+           have been saved before calling it. Fetch the PC from there.  */
+        CPUArchState *env = cpu->env_ptr;
+        target_ulong pc, cs_base;
+        tb_page_addr_t addr;
+        int flags;
+
+        cpu_get_tb_cpu_state(env, &pc, &cs_base, &flags);
+        addr = get_page_addr_code(env, pc);
+        tb_invalidate_phys_range(addr, addr + 1);
     }
-    cpu_restore_state_from_tb(cpu, tb, cpu->mem_io_pc);
-    tb_phys_invalidate(tb, -1);
 }
 
 #ifndef CONFIG_USER_ONLY
-- 
1.7.12.4