accel/tcg: Add probe_access_flags

This new interface will allow targets to probe for a page
and then handle watchpoints themselves.  This will be most
useful for vector predicated memory operations, where one
page lookup can be used for many operations, and one test
can avoid many watchpoint checks.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200508154359.7494-6-richard.henderson@linaro.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 34 insertions, 9 deletions

diff --git a/accel/tcg/user-exec.c b/accel/tcg/user-exec.c
index 03538e2..987342c 100644
--- a/accel/tcg/user-exec.c
+++ b/accel/tcg/user-exec.c
@@ -190,13 +190,12 @@ static inline int handle_cpu_signal(uintptr_t pc, siginfo_t *info,
     g_assert_not_reached();
 }
 
-void *probe_access(CPUArchState *env, target_ulong addr, int size,
-                   MMUAccessType access_type, int mmu_idx, uintptr_t retaddr)
+static int probe_access_internal(CPUArchState *env, target_ulong addr,
+                                 int fault_size, MMUAccessType access_type,
+                                 bool nonfault, uintptr_t ra)
 {
     int flags;
 
-    g_assert(-(addr | TARGET_PAGE_MASK) >= size);
-
     switch (access_type) {
     case MMU_DATA_STORE:
         flags = PAGE_WRITE;
@@ -212,12 +211,38 @@ void *probe_access(CPUArchState *env, target_ulong addr, int size,
     }
 
     if (!guest_addr_valid(addr) || page_check_range(addr, 1, flags) < 0) {
-        CPUState *cpu = env_cpu(env);
-        CPUClass *cc = CPU_GET_CLASS(cpu);
-        cc->tlb_fill(cpu, addr, size, access_type, MMU_USER_IDX, false,
-                     retaddr);
-        g_assert_not_reached();
+        if (nonfault) {
+            return TLB_INVALID_MASK;
+        } else {
+            CPUState *cpu = env_cpu(env);
+            CPUClass *cc = CPU_GET_CLASS(cpu);
+            cc->tlb_fill(cpu, addr, fault_size, access_type,
+                         MMU_USER_IDX, false, ra);
+            g_assert_not_reached();
+        }
     }
+    return 0;
+}
+
+int probe_access_flags(CPUArchState *env, target_ulong addr,
+                       MMUAccessType access_type, int mmu_idx,
+                       bool nonfault, void **phost, uintptr_t ra)
+{
+    int flags;
+
+    flags = probe_access_internal(env, addr, 0, access_type, nonfault, ra);
+    *phost = flags ? NULL : g2h(addr);
+    return flags;
+}
+
+void *probe_access(CPUArchState *env, target_ulong addr, int size,
+                   MMUAccessType access_type, int mmu_idx, uintptr_t ra)
+{
+    int flags;
+
+    g_assert(-(addr | TARGET_PAGE_MASK) >= size);
+    flags = probe_access_internal(env, addr, size, access_type, false, ra);
+    g_assert(flags == 0);
 
     return size ? g2h(addr) : NULL;
 }