[Qemu-devel] [PATCH v6 2/3] softmmu: Add probe_write()

[Yongbok Kim]

Add probe_write() in order to support such functionality that probes
if a specified guest virtual address exists in TLB and is writable.
The function forces a tlb_fill() if the address does not exist or is
not writable, as a result an exception can occur.

Signed-off-by: Yongbok Kim <address@hidden>
---
 include/exec/exec-all.h |    2 ++
 softmmu_template.h      |   18 ++++++++++++++++++
 2 files changed, 20 insertions(+), 0 deletions(-)

diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h
index b58cd47..af51203 100644
--- a/include/exec/exec-all.h
+++ b/include/exec/exec-all.h
@@ -109,6 +109,8 @@ void tlb_set_page_with_attrs(CPUState *cpu, target_ulong 
vaddr,
                              hwaddr paddr, MemTxAttrs attrs,
                              int prot, int mmu_idx, target_ulong size);
 void tb_invalidate_phys_addr(AddressSpace *as, hwaddr addr);
+void probe_write(CPUArchState *env, target_ulong addr, int mmu_idx,
+                 uintptr_t retaddr);
 #else
 static inline void tlb_flush_page(CPUState *cpu, target_ulong addr)
 {
diff --git a/softmmu_template.h b/softmmu_template.h
index 9cb1659..1558b8b 100644
--- a/softmmu_template.h
+++ b/softmmu_template.h
@@ -548,6 +548,24 @@ glue(glue(helper_st, SUFFIX), MMUSUFFIX)(CPUArchState 
*env, target_ulong addr,
     helper_te_st_name(env, addr, val, oi, GETRA());
 }
 
+#if DATA_SIZE == 1
+/* Probe if the specified guest virtual address exists in TLB and is writable,
+   if not force a tlb_fill(). As a result an exception can occur. */
+void probe_write(CPUArchState *env, target_ulong addr, int mmu_idx,
+                 uintptr_t retaddr)
+{
+    int index = (addr >> TARGET_PAGE_BITS) & (CPU_TLB_SIZE - 1);
+    target_ulong tlb_addr = env->tlb_table[mmu_idx][index].addr_write;
+
+    if ((addr & TARGET_PAGE_MASK)
+        != (tlb_addr & (TARGET_PAGE_MASK | TLB_INVALID_MASK))) {
+        /* TLB entry is for a different page */
+        if (!VICTIM_TLB_HIT(addr_write)) {
+            tlb_fill(ENV_GET_CPU(env), addr, MMU_DATA_STORE, mmu_idx, retaddr);
+        }
+    }
+}
+#endif
 #endif /* !defined(SOFTMMU_CODE_ACCESS) */
 
 #undef READ_ACCESS_TYPE
-- 
1.7.5.4