two version of R2R are hereHEADmaster

1 files changed, 326 insertions, 0 deletions

diff --git a/.venv/lib/python3.12/site-packages/greenlet/platform/switch_x86_msvc.h b/.venv/lib/python3.12/site-packages/greenlet/platform/switch_x86_msvc.h
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+/*
+ * this is the internal transfer function.
+ *
+ * HISTORY
+ * 24-Nov-02  Christian Tismer  <tismer@tismer.com>
+ *      needed to add another magic constant to insure
+ *      that f in slp_eval_frame(PyFrameObject *f)
+ *      STACK_REFPLUS will probably be 1 in most cases.
+ *      gets included into the saved stack area.
+ * 26-Sep-02  Christian Tismer  <tismer@tismer.com>
+ *      again as a result of virtualized stack access,
+ *      the compiler used less registers. Needed to
+ *      explicit mention registers in order to get them saved.
+ *      Thanks to Jeff Senn for pointing this out and help.
+ * 17-Sep-02  Christian Tismer  <tismer@tismer.com>
+ *      after virtualizing stack save/restore, the
+ *      stack size shrunk a bit. Needed to introduce
+ *      an adjustment STACK_MAGIC per platform.
+ * 15-Sep-02  Gerd Woetzel       <gerd.woetzel@GMD.DE>
+ *      slightly changed framework for sparc
+ * 01-Mar-02  Christian Tismer  <tismer@tismer.com>
+ *      Initial final version after lots of iterations for i386.
+ */
+
+#define alloca _alloca
+
+#define STACK_REFPLUS 1
+
+#ifdef SLP_EVAL
+
+#define STACK_MAGIC 0
+
+/* Some magic to quell warnings and keep slp_switch() from crashing when built
+   with VC90. Disable global optimizations, and the warning: frame pointer
+   register 'ebp' modified by inline assembly code.
+
+   We used to just disable global optimizations ("g") but upstream stackless
+   Python, as well as stackman, turn off all optimizations.
+
+References:
+https://github.com/stackless-dev/stackman/blob/dbc72fe5207a2055e658c819fdeab9731dee78b9/stackman/platforms/switch_x86_msvc.h
+https://github.com/stackless-dev/stackless/blob/main-slp/Stackless/platf/switch_x86_msvc.h
+*/
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+
+#pragma optimize("", off) /* so that autos are stored on the stack */
+#pragma warning(disable:4731)
+#pragma warning(disable:4733) /* disable warning about modifying FS[0] */
+
+/**
+ * Most modern compilers and environments handle C++ exceptions without any
+ * special help from us. MSVC on 32-bit windows is an exception. There, C++
+ * exceptions are dealt with using Windows' Structured Exception Handling
+ * (SEH).
+ *
+ * SEH is implemented as a singly linked list of <function*, prev*> nodes. The
+ * head of this list is stored in the Thread Information Block, which itself
+ * is pointed to from the FS register. It's the first field in the structure,
+ * or offset 0, so we can access it using assembly FS:[0], or the compiler
+ * intrinsics and field offset information from the headers (as we do below).
+ * Somewhat unusually, the tail of the list doesn't have prev == NULL, it has
+ * prev == 0xFFFFFFFF.
+ *
+ * SEH was designed for C, and traditionally uses the MSVC compiler
+ * intrinsincs __try{}/__except{}. It is also utilized for C++ exceptions by
+ * MSVC; there, every throw of a C++ exception raises a SEH error with the
+ * ExceptionCode 0xE06D7363; the SEH handler list is then traversed to
+ * deal with the exception.
+ *
+ * If the SEH list is corrupt, then when a C++ exception is thrown the program
+ * will abruptly exit with exit code 1. This does not use std::terminate(), so
+ * std::set_terminate() is useless to debug this.
+ *
+ * The SEH list is closely tied to the call stack; entering a function that
+ * uses __try{} or most C++ functions will push a new handler onto the front
+ * of the list. Returning from the function will remove the handler. Saving
+ * and restoring the head node of the SEH list (FS:[0]) per-greenlet is NOT
+ * ENOUGH to make SEH or exceptions work.
+ *
+ * Stack switching breaks SEH because the call stack no longer necessarily
+ * matches the SEH list. For example, given greenlet A that switches to
+ * greenlet B, at the moment of entering greenlet B, we will have any SEH
+ * handlers from greenlet A on the SEH list; greenlet B can then add its own
+ * handlers to the SEH list. When greenlet B switches back to greenlet A,
+ * greenlet B's handlers would still be on the SEH stack, but when switch()
+ * returns control to greenlet A, we have replaced the contents of the stack
+ * in memory, so all the address that greenlet B added to the SEH list are now
+ * invalid: part of the call stack has been unwound, but the SEH list was out
+ * of sync with the call stack. The net effect is that exception handling
+ * stops working.
+ *
+ * Thus, when switching greenlets, we need to be sure that the SEH list
+ * matches the effective call stack, "cutting out" any handlers that were
+ * pushed by the greenlet that switched out and which are no longer valid.
+ *
+ * The easiest way to do this is to capture the SEH list at the time the main
+ * greenlet for a thread is created, and, when initially starting a greenlet,
+ * start a new SEH list for it, which contains nothing but the handler
+ * established for the new greenlet itself, with the tail being the handlers
+ * for the main greenlet. If we then save and restore the SEH per-greenlet,
+ * they won't interfere with each others SEH lists. (No greenlet can unwind
+ * the call stack past the handlers established by the main greenlet).
+ *
+ * By observation, a new thread starts with three SEH handlers on the list. By
+ * the time we get around to creating the main greenlet, though, there can be
+ * many more, established by transient calls that lead to the creation of the
+ * main greenlet. Therefore, 3 is a magic constant telling us when to perform
+ * the initial slice.
+ *
+ * All of this can be debugged using a vectored exception handler, which
+ * operates independently of the SEH handler list, and is called first.
+ * Walking the SEH list at key points can also be helpful.
+ *
+ * References:
+ * https://en.wikipedia.org/wiki/Win32_Thread_Information_Block
+ * https://devblogs.microsoft.com/oldnewthing/20100730-00/?p=13273
+ * https://docs.microsoft.com/en-us/cpp/cpp/try-except-statement?view=msvc-160
+ * https://docs.microsoft.com/en-us/cpp/cpp/structured-exception-handling-c-cpp?view=msvc-160
+ * https://docs.microsoft.com/en-us/windows/win32/debug/structured-exception-handling
+ * https://docs.microsoft.com/en-us/windows/win32/debug/using-a-vectored-exception-handler
+ * https://bytepointer.com/resources/pietrek_crash_course_depths_of_win32_seh.htm
+ */
+#define GREENLET_NEEDS_EXCEPTION_STATE_SAVED
+
+
+typedef struct _GExceptionRegistration {
+    struct _GExceptionRegistration* prev;
+    void* handler_f;
+} GExceptionRegistration;
+
+static void
+slp_set_exception_state(const void *const seh_state)
+{
+    // Because the stack from from which we do this is ALSO a handler, and
+    // that one we want to keep, we need to relink the current SEH handler
+    // frame to point to this one, cutting out the middle men, as it were.
+    //
+    // Entering a try block doesn't change the SEH frame, but entering a
+    // function containing a try block does.
+    GExceptionRegistration* current_seh_state = (GExceptionRegistration*)__readfsdword(FIELD_OFFSET(NT_TIB, ExceptionList));
+    current_seh_state->prev = (GExceptionRegistration*)seh_state;
+}
+
+
+static GExceptionRegistration*
+x86_slp_get_third_oldest_handler()
+{
+    GExceptionRegistration* a = NULL; /* Closest to the top */
+    GExceptionRegistration* b = NULL; /* second */
+    GExceptionRegistration* c = NULL;
+    GExceptionRegistration* seh_state = (GExceptionRegistration*)__readfsdword(FIELD_OFFSET(NT_TIB, ExceptionList));
+    a = b = c = seh_state;
+
+    while (seh_state && seh_state != (GExceptionRegistration*)0xFFFFFFFF) {
+        if ((void*)seh_state->prev < (void*)100) {
+            fprintf(stderr, "\tERROR: Broken SEH chain.\n");
+            return NULL;
+        }
+        a = b;
+        b = c;
+        c = seh_state;
+
+        seh_state = seh_state->prev;
+    }
+    return a ? a : (b ? b : c);
+}
+
+
+static void*
+slp_get_exception_state()
+{
+    // XXX: There appear to be three SEH handlers on the stack already at the
+    // start of the thread. Is that a guarantee? Almost certainly not. Yet in
+    // all observed cases it has been three. This is consistent with
+    // faulthandler off or on, and optimizations off or on. It may not be
+    // consistent with other operating system versions, though: we only have
+    // CI on one or two versions (don't ask what there are).
+    // In theory we could capture the number of handlers on the chain when
+    // PyInit__greenlet is called: there are probably only the default
+    // handlers at that point (unless we're embedded and people have used
+    // __try/__except or a C++ handler)?
+    return x86_slp_get_third_oldest_handler();
+}
+
+static int
+slp_switch(void)
+{
+    /* MASM syntax is typically reversed from other assemblers.
+       It is usually <instruction> <destination> <source>
+     */
+    int *stackref, stsizediff;
+    /* store the structured exception state for this stack */
+    DWORD seh_state = __readfsdword(FIELD_OFFSET(NT_TIB, ExceptionList));
+    __asm mov stackref, esp;
+    /* modify EBX, ESI and EDI in order to get them preserved */
+    __asm mov ebx, ebx;
+    __asm xchg esi, edi;
+    {
+        SLP_SAVE_STATE(stackref, stsizediff);
+        __asm {
+            mov     eax, stsizediff
+            add     esp, eax
+            add     ebp, eax
+        }
+        SLP_RESTORE_STATE();
+    }
+    __writefsdword(FIELD_OFFSET(NT_TIB, ExceptionList), seh_state);
+    return 0;
+}
+
+/* re-enable ebp warning and global optimizations. */
+#pragma optimize("", on)
+#pragma warning(default:4731)
+#pragma warning(default:4733) /* disable warning about modifying FS[0] */
+
+
+#endif
+
+/*
+ * further self-processing support
+ */
+
+/* we have IsBadReadPtr available, so we can peek at objects */
+#define STACKLESS_SPY
+
+#ifdef GREENLET_DEBUG
+
+#define CANNOT_READ_MEM(p, bytes) IsBadReadPtr(p, bytes)
+
+static int IS_ON_STACK(void*p)
+{
+    int stackref;
+    int stackbase = ((int)&stackref) & 0xfffff000;
+    return (int)p >= stackbase && (int)p < stackbase + 0x00100000;
+}
+
+static void
+x86_slp_show_seh_chain()
+{
+    GExceptionRegistration* seh_state = (GExceptionRegistration*)__readfsdword(FIELD_OFFSET(NT_TIB, ExceptionList));
+    fprintf(stderr, "====== SEH Chain ======\n");
+    while (seh_state && seh_state != (GExceptionRegistration*)0xFFFFFFFF) {
+        fprintf(stderr, "\tSEH_chain addr: %p handler: %p prev: %p\n",
+                seh_state,
+                seh_state->handler_f, seh_state->prev);
+        if ((void*)seh_state->prev < (void*)100) {
+            fprintf(stderr, "\tERROR: Broken chain.\n");
+            break;
+        }
+        seh_state = seh_state->prev;
+    }
+    fprintf(stderr, "====== End SEH Chain ======\n");
+    fflush(NULL);
+    return;
+}
+
+//addVectoredExceptionHandler constants:
+//CALL_FIRST means call this exception handler first;
+//CALL_LAST means call this exception handler last
+#define CALL_FIRST 1
+#define CALL_LAST 0
+
+LONG WINAPI
+GreenletVectorHandler(PEXCEPTION_POINTERS ExceptionInfo)
+{
+    // We get one of these for every C++ exception, with code
+    // E06D7363
+    // This is a special value that means "C++ exception from MSVC"
+    // https://devblogs.microsoft.com/oldnewthing/20100730-00/?p=13273
+    //
+    // Install in the module init function with:
+    // AddVectoredExceptionHandler(CALL_FIRST, GreenletVectorHandler);
+    PEXCEPTION_RECORD ExceptionRecord = ExceptionInfo->ExceptionRecord;
+
+    fprintf(stderr,
+            "GOT VECTORED EXCEPTION:\n"
+            "\tExceptionCode   : %p\n"
+            "\tExceptionFlags  : %p\n"
+            "\tExceptionAddr   : %p\n"
+            "\tNumberparams    : %ld\n",
+            ExceptionRecord->ExceptionCode,
+            ExceptionRecord->ExceptionFlags,
+            ExceptionRecord->ExceptionAddress,
+            ExceptionRecord->NumberParameters
+            );
+    if (ExceptionRecord->ExceptionFlags & 1) {
+        fprintf(stderr,  "\t\tEH_NONCONTINUABLE\n" );
+    }
+    if (ExceptionRecord->ExceptionFlags & 2) {
+        fprintf(stderr,  "\t\tEH_UNWINDING\n" );
+    }
+    if (ExceptionRecord->ExceptionFlags & 4) {
+        fprintf(stderr, "\t\tEH_EXIT_UNWIND\n" );
+    }
+    if (ExceptionRecord->ExceptionFlags & 8) {
+        fprintf(stderr,  "\t\tEH_STACK_INVALID\n" );
+    }
+    if (ExceptionRecord->ExceptionFlags & 0x10) {
+        fprintf(stderr,  "\t\tEH_NESTED_CALL\n" );
+    }
+    if (ExceptionRecord->ExceptionFlags & 0x20) {
+        fprintf(stderr,  "\t\tEH_TARGET_UNWIND\n" );
+    }
+    if (ExceptionRecord->ExceptionFlags & 0x40) {
+        fprintf(stderr,  "\t\tEH_COLLIDED_UNWIND\n" );
+    }
+    fprintf(stderr, "\n");
+    fflush(NULL);
+    for(DWORD i = 0; i < ExceptionRecord->NumberParameters; i++) {
+        fprintf(stderr, "\t\t\tParam %ld: %lX\n", i, ExceptionRecord->ExceptionInformation[i]);
+    }
+
+    if (ExceptionRecord->NumberParameters == 3) {
+        fprintf(stderr, "\tAbout to traverse SEH chain\n");
+        // C++ Exception records have 3 params.
+        x86_slp_show_seh_chain();
+    }
+
+    return EXCEPTION_CONTINUE_SEARCH;
+}
+
+
+
+
+#endif