[DYNAREC] Re-introduce a simple HotPage handling, to speedup heavily obfuscated program loading (backported from box64)

src/custommem.c

@@ -881,6 +881,26 @@ int isprotectedDB(uintptr_t addr, size_t size)
     return 1;
 }
 
+uintptr_t hotpage = 0;
+int hotpage_cnt = 0;
+#define HOTPAGE_MARK 64
+void SetHotPage(uintptr_t addr)
+{
+    hotpage = addr&~(box86_pagesize-1);
+    hotpage_cnt = HOTPAGE_MARK;
+}
+int isInHotPage(uintptr_t addr)
+{
+    if(!hotpage_cnt)
+        return 0;
+    --hotpage_cnt;
+    return (addr>=hotpage) && (addr<hotpage+box86_pagesize);
+}
+int checkInHotPage(uintptr_t addr)
+{
+    return hotpage_cnt && (addr>=hotpage) && (addr<hotpage+box86_pagesize);
+}
+
 #endif
 
 void updateProtection(uintptr_t addr, uintptr_t size, uint32_t prot)

src/dynarec/dynablock.c

@@ -262,6 +262,8 @@ static dynablock_t* internalDBGetBlock(x86emu_t* emu, uintptr_t addr, uintptr_t
 
 dynablock_t* DBGetBlock(x86emu_t* emu, uintptr_t addr, int create)
 {
+    if(isInHotPage(addr))
+        return NULL;
     dynablock_t *db = internalDBGetBlock(emu, addr, addr, create, 1);
     if(db && db->done && db->block && getNeedTest(addr)) {
         if(db->always_test)

src/dynarec/dynarec.c

@@ -20,6 +20,7 @@
 #include "dynablock.h"
 #include "dynablock_private.h"
 #include "bridge.h"
+#include "custommem.h"
 void x86test_check(x86emu_t* ref, uintptr_t ip);
 #endif
 
@@ -59,9 +60,13 @@ void* LinkNext(x86emu_t* emu, uintptr_t addr, void* x2)
         // no block, let link table as is...
         #ifdef HAVE_TRACE
         if(LOG_INFO<=box86_dynarec_log) {
-            dynablock_t* db = FindDynablockFromNativeAddress(x2);
-            elfheader_t* h = FindElfAddress(my_context, (uintptr_t)x2);
-            dynarec_log(LOG_INFO, "Warning, jumping to a no-block address %p from %p (db=%p, x64addr=%p(elf=%s))\n", (void*)addr, x2, db, db?(void*)getX86Address(db, (uintptr_t)x2-4):NULL, h?ElfName(h):"(none)");
+            if(checkInHotPage(addr)) {
+                dynarec_log(LOG_INFO, "Not trying to run a block from a Hotpage at %p\n", (void*)addr);
+            } else {
+                dynablock_t* db = FindDynablockFromNativeAddress(x2-4);
+                elfheader_t* h = FindElfAddress(my_context, (uintptr_t)x2-4);
+                dynarec_log(LOG_INFO, "Warning, jumping to a no-block address %p from %p (db=%p, x86addr=%p(elf=%s))\n", (void*)addr, x2-4, db, db?(void*)getX86Address(db, (uintptr_t)x2-4):NULL, h?ElfName(h):"(none)");
+            }
         }
         #endif
         //tableupdate(arm_epilog, addr, table);

src/include/custommem.h

@@ -76,6 +76,10 @@ void fini_custommem_helper(box86context_t* ctx);
 // ---- StrongMemoryModel
 void addLockAddress(uintptr_t addr);    // add an address to the list of "LOCK"able
 int isLockAddress(uintptr_t addr);  // return 1 is the address is used as a LOCK, 0 else
+
+void SetHotPage(uintptr_t addr);
+int isInHotPage(uintptr_t addr);
+int checkInHotPage(uintptr_t addr);
 #endif
 
 #endif //__CUSTOM_MEM__H_

src/libtools/signals.c

@@ -850,11 +850,22 @@ void my_box86signalhandler(int32_t sig, siginfo_t* info, void * ucntx)
     int db_searched = 0;
     if ((sig==SIGSEGV) && (addr) && (info->si_code == SEGV_ACCERR) && (prot&PROT_CUSTOM)) {
         lock_signal();
-        // access error, unprotect the block (and mark them dirty)
-        unprotectDB((uintptr_t)addr, 1, 1);    // unprotect 1 byte... But then, the whole page will be unprotected
         // check if SMC inside block
         db = FindDynablockFromNativeAddress(pc);
         db_searched = 1;
+        static uintptr_t repeated_page = 0;
+        dynarec_log(LOG_DEBUG, "SIGSEGV with Access error on %p for %p , db=%p(%p), prot=0x%hhx (old page=%p)\n", pc, addr, db, db?((void*)db->x86_addr):NULL, prot, (void*)repeated_page);
+        static int repeated_count = 0;
+        if(repeated_page == ((uintptr_t)addr&~(box86_pagesize-1))) {
+            ++repeated_count;   // Access eoor multiple time on same page, disable dynarec on this page a few time...
+            dynarec_log(LOG_DEBUG, "Detecting a Hotpage at %p (%d)\n", (void*)repeated_page, repeated_count);
+            SetHotPage(repeated_page);
+        } else {
+            repeated_page = (uintptr_t)addr&~(box86_pagesize-1);
+            repeated_count = 0;
+        }
+        // access error, unprotect the block (and mark them dirty)
+        unprotectDB((uintptr_t)addr, 1, 1);    // unprotect 1 byte... But then, the whole page will be unprotected
         int db_need_test = (db && !box86_dynarec_fastpage)?getNeedTest((uintptr_t)db->x86_addr):0;
         dynarec_log(LOG_INFO/*LOG_DEBUG*/, "SIGSEGV with Access error on %p for %p , db=%p(%p)\n", pc, addr, db, db?((void*)db->x86_addr):NULL);
         if(db && ((addr>=db->x86_addr && addr<(db->x86_addr+db->x86_size)) || db_need_test)) {