From b2e32aeb37f28c260b5566163ab5ecde1244cce1 Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <icculus@icculus.org>
Date: Sun, 16 Oct 2016 12:24:38 -0400
Subject: [PATCH] Separate TIB from OS/2 stack.

---
 lx_loader.c       | 23 ++++++++++-------------
 lx_loader.h       |  4 +++-
 native/doscalls.c | 15 +++++++++------
 3 files changed, 22 insertions(+), 20 deletions(-)

diff --git a/lx_loader.c b/lx_loader.c
index debfc73..a334d55 100644
--- a/lx_loader.c
+++ b/lx_loader.c
@@ -20,6 +20,7 @@
 
 static LxLoaderState _GLoaderState;
 static LxLoaderState *GLoaderState = &_GLoaderState;
+static uint8 GMainTibSpace[LXTIBSIZE];
 
 // !!! FIXME: move this into an lx_common.c file.
 static int sanityCheckLxModule(uint8 **_exe, uint32 *_exelen)
@@ -280,22 +281,18 @@ static void *generateMissingTrampoline(const char *_module, const char *_entry)
 //  the EMX runtime) touch the register directly, so we have to deal with it.
 // You must call this once for each thread that will go into LX land, from
 //  that thread, as soon as possible after starting.
-static uint16 initOs2Tib(void *_topOfStack, const size_t stacklen, const uint32 tid)
+static uint16 initOs2Tib(uint8 *tibspace, void *_topOfStack, const size_t stacklen, const uint32 tid)
 {
     uint8 *topOfStack = (uint8 *) _topOfStack;
-    const size_t tiblen = (sizeof (LxTIB) + sizeof (LxTIB2));
-    assert(stacklen > tiblen);
 
-    // set aside the first 40 bytes of the thread's stack for
-    //  the Thread Information Block structs (24 for TIB and 16 for TIB2).
-    LxTIB *tib = (LxTIB *) (topOfStack - tiblen);
+    LxTIB *tib = (LxTIB *) tibspace;
     LxTIB2 *tib2 = (LxTIB2 *) (tib + 1);
-    memset(tib, '\0', tiblen);
+    memset(tib, '\0', LXTIBSIZE);
 
     FIXME("This is probably 50% wrong");
     tib->tib_pexchain = NULL;
-    tib->tib_pstack = (void *) topOfStack;
-    tib->tib_pstacklimit = topOfStack - stacklen;
+    tib->tib_pstack = topOfStack - stacklen;
+    tib->tib_pstacklimit = (void *) topOfStack;
     tib->tib_ptib2 = tib2;
     tib->tib_version = 20;  // !!! FIXME
     tib->tib_ordinal = 79;  // !!! FIXME
@@ -310,7 +307,7 @@ static uint16 initOs2Tib(void *_topOfStack, const size_t stacklen, const uint32
     struct user_desc entry;
     entry.entry_number = -1;
     entry.base_addr = (unsigned int) ((size_t)tib);
-    entry.limit = tiblen;
+    entry.limit = LXTIBSIZE;
     entry.seg_32bit = 1;
     entry.contents = MODIFY_LDT_CONTENTS_DATA;
     entry.read_exec_only = 0;
@@ -537,7 +534,7 @@ static void freeLxModule(LxModule *lxmod)
 
     if (lxmod->initialized) {
         if (!lxmod->nativelib) {
-            runLxLibraryTerm(lxmod);
+            runLxLibraryTerm(lxmod);  // !!! FIXME: check term flag and eip.
         } else {
             LxNativeModuleDeinitEntryPoint fn = (LxNativeModuleDeinitEntryPoint) dlsym(lxmod->nativelib, "lxNativeModuleDeinit");
             if (fn)
@@ -958,7 +955,7 @@ static LxModule *loadLxModule(const char *fname, uint8 *exe, uint32 exelen, int
     if (!isDLL) {
         // This needs to be set up now, so it's available to any library
         //  init code that runs in LX land.
-        initOs2Tib((void *) ((size_t) retval->esp), retval->mmaps[retval->lx.esp_object - 1].size, 0);
+        initOs2Tib(GMainTibSpace, (void *) ((size_t) retval->esp), retval->mmaps[retval->lx.esp_object - 1].size, 0);
     } // if
 
     // Set up our exports...
@@ -1100,7 +1097,7 @@ static LxModule *loadLxModule(const char *fname, uint8 *exe, uint32 exelen, int
         if (retval->eip) {
             assert(GLoaderState->main_module != NULL);
             assert(GLoaderState->main_module != retval);
-            runLxLibraryInit(retval);
+            runLxLibraryInit(retval);  // !!! FIXME: check term flag and eip.
         } // if
 
         retval->initialized = 1;
diff --git a/lx_loader.h b/lx_loader.h
index 4b8fab5..84ffafb 100644
--- a/lx_loader.h
+++ b/lx_loader.h
@@ -185,12 +185,14 @@ typedef struct LxTIB
 } LxTIB;
 #pragma pack(pop)
 
+#define LXTIBSIZE (sizeof (LxTIB) + sizeof (LxTIB2))
+
 typedef struct LxLoaderState
 {
     LxModule *loaded_modules;
     LxModule *main_module;
     int subprocess;
-    uint16 (*initOs2Tib)(void *_topOfStack, const size_t stacklen, const uint32 tid);
+    uint16 (*initOs2Tib)(uint8 *tibspace, void *_topOfStack, const size_t stacklen, const uint32 tid);
     void (*deinitOs2Tib)(const uint16 selector);
 } LxLoaderState;
 
diff --git a/native/doscalls.c b/native/doscalls.c
index 3e5d711..a95da27 100644
--- a/native/doscalls.c
+++ b/native/doscalls.c
@@ -1371,13 +1371,10 @@ APIRET DosQueryFileInfo(HFILE hf, ULONG ulInfoLevel, PVOID pInfo, ULONG cbInfoBu
 } // DosQueryFileInfo
 
 
-static void *os2ThreadEntry(void *_arg)
+static void os2ThreadEntry2(uint8 *tibspace, Thread *thread)
 {
-    Thread *thread = (Thread *) _arg;
-
-    // put our thread's TIB structs on the stack and call that the top of the stack.
-    uint8 tibdata[sizeof (TIB) + sizeof (TIB2)];
-    const uint16 selector = GLoaderState->initOs2Tib(tibdata + sizeof (tibdata), thread->stacklen, (TID) thread);
+    void *esp = NULL;  // close enough.
+    const uint16 selector = GLoaderState->initOs2Tib(tibspace, &esp, thread->stacklen, (TID) thread);
     thread->fn(thread->fnarg);
     GLoaderState->deinitOs2Tib(selector);
 
@@ -1386,7 +1383,13 @@ static void *os2ThreadEntry(void *_arg)
     thread->next = GDeadThreads;
     GDeadThreads = thread;
     ungrabLock(&GMutexDosCalls);
+} // os2ThreadEntry2
 
+static void *os2ThreadEntry(void *arg)
+{
+    // put our thread's TIB structs on the stack and call that the top of the stack.
+    uint8 tibspace[LXTIBSIZE];
+    os2ThreadEntry2(tibspace, (Thread *) arg);
     return NULL;  // OS/2 threads don't return a value here.
 } // os2ThreadEntry