[PATCH RFC 1/1] tcg: Always pass the full write size to notdirty_write()

[Ilya Leoshkevich <iii@linux.ibm.com>]

One of notdirty_write()'s responsibilities is detecting self-modifying
code. Some functions pass the full size of a write to it, some pass 1.
When a write to a code section begins before a TB start, but then
overlaps the TB, the paths that pass 1 don't flush a TB and don't
return to the translator loop.

This may be masked, one example being HELPER(vstl). There,
probe_write_access() ultimately calls notdirty_write() with a size of
1 and misses self-modifying code. However, cpu_stq_be_data_ra()
ultimately calls mmu_watch_or_dirty(), which in turn calls
notdirty_write() with the full size.

It's still worth improving this, because there may still be
user-visible adverse effects in other helpers.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 accel/tcg/cputlb.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c
index d68fa6867ce..aa3cffbc11a 100644
--- a/accel/tcg/cputlb.c
+++ b/accel/tcg/cputlb.c
@@ -1582,7 +1582,7 @@ int probe_access_full(CPUArchState *env, vaddr addr, int size,
 
     /* Handle clean RAM pages.  */
     if (unlikely(flags & TLB_NOTDIRTY)) {
-        notdirty_write(env_cpu(env), addr, 1, *pfull, retaddr);
+        notdirty_write(env_cpu(env), addr, size, *pfull, retaddr);
         flags &= ~TLB_NOTDIRTY;
     }
 
@@ -1605,7 +1605,7 @@ int probe_access_full_mmu(CPUArchState *env, vaddr addr, int size,
 
     /* Handle clean RAM pages.  */
     if (unlikely(flags & TLB_NOTDIRTY)) {
-        notdirty_write(env_cpu(env), addr, 1, *pfull, 0);
+        notdirty_write(env_cpu(env), addr, size, *pfull, 0);
         flags &= ~TLB_NOTDIRTY;
     }
 
@@ -1626,7 +1626,7 @@ int probe_access_flags(CPUArchState *env, vaddr addr, int size,
 
     /* Handle clean RAM pages. */
     if (unlikely(flags & TLB_NOTDIRTY)) {
-        notdirty_write(env_cpu(env), addr, 1, full, retaddr);
+        notdirty_write(env_cpu(env), addr, size, full, retaddr);
         flags &= ~TLB_NOTDIRTY;
     }
 
@@ -1661,7 +1661,7 @@ void *probe_access(CPUArchState *env, vaddr addr, int size,
 
         /* Handle clean RAM pages.  */
         if (flags & TLB_NOTDIRTY) {
-            notdirty_write(env_cpu(env), addr, 1, full, retaddr);
+            notdirty_write(env_cpu(env), addr, size, full, retaddr);
         }
     }
 
-- 
2.41.0