[ros-diffs] [sir_richard] 49520: [NTOS]: Context switch in C instead of ASM. Can be made more portable, but it's a good start. Unless Timo rewrites it.

Author: sir_richard
Date: Mon Nov  8 02:15:53 2010
New Revision: 49520

URL: http://svn.reactos.org/svn/reactos?rev=49520&view=rev
Log:
[NTOS]: Context switch in C instead of ASM. Can be made more portable, but it's a good
start. Unless Timo rewrites it.

Modified:
    trunk/reactos/ntoskrnl/ke/i386/ctxswitch.S
    trunk/reactos/ntoskrnl/ke/i386/thrdini.c

Modified: trunk/reactos/ntoskrnl/ke/i386/ctxswitch.S
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/ntoskrnl/ke/i386/ctxswitch…
==============================================================================
--- trunk/reactos/ntoskrnl/ke/i386/ctxswitch.S [iso-8859-1] (original)
+++ trunk/reactos/ntoskrnl/ke/i386/ctxswitch.S [iso-8859-1] Mon Nov  8 02:15:53 2010
@@ -40,284 +40,16 @@
 .globl @KiSwapContextInternal@0
 .func @KiSwapContextInternal@0, @KiSwapContextInternal@0
 @KiSwapContextInternal@0:
-
-    /* Save the IRQL */
-    push ecx
-
-#ifdef CONFIG_SMP
-GetSwapLock:
-    /* Acquire the swap lock */
-    cmp byte ptr [esi+KTHREAD_SWAP_BUSY], 0
-    jz NotBusy
-    pause
-    jmp GetSwapLock
-NotBusy:
-#endif
-    /* Increase context switches (use ES for lazy load) */
-    inc dword ptr es:[ebx+KPCR_CONTEXT_SWITCHES]
-
-    /* Save the Exception list */
-    push [ebx+KPCR_EXCEPTION_LIST]
-
-    /* Check for WMI */
-    cmp dword ptr [ebx+KPCR_PERF_GLOBAL_GROUP_MASK], 0
-    jnz WmiTrace
-
-AfterTrace:
-#ifdef CONFIG_SMP
-#if DBG
-    /* Assert that we're on the right CPU */
-    mov cl, [esi+KTHREAD_NEXT_PROCESSOR]
-    cmp cl, [ebx+KPCR_PROCESSOR_NUMBER]
-    jnz WrongCpu
-#endif
-#endif
-
-    /* Get CR0 and save it */
-    mov ebp, cr0
-    mov edx, ebp
-
-#ifdef CONFIG_SMP
-    /* Check NPX State */
-    cmp byte ptr [edi+KTHREAD_NPX_STATE], NPX_STATE_LOADED
-    jz NpxLoaded
-SetStack:
-#endif
-
-    /* Set new stack */
-    mov [edi+KTHREAD_KERNEL_STACK], esp
-
-    /* Checking NPX, disable interrupts now */
-    mov eax, [esi+KTHREAD_INITIAL_STACK]
-    cli
-
-    /* Get the NPX State */
-    movzx ecx, byte ptr [esi+KTHREAD_NPX_STATE]
-
-    /* Clear the other bits, merge in CR0, merge in FPU CR0 bits and compare */
-    and edx, ~(CR0_MP + CR0_EM + CR0_TS)
-    or ecx, edx
-    or ecx, [eax - (NPX_FRAME_LENGTH - FN_CR0_NPX_STATE)]
-    cmp ebp, ecx
-    jnz NewCr0
-
-StackOk:
-    /* Enable interrupts and set the current stack */
-    sti
-    mov esp, [esi+KTHREAD_KERNEL_STACK]
-
-    /* Check if address space switch is needed */
-    mov ebp, [esi+KTHREAD_APCSTATE_PROCESS]
-    mov eax, [edi+KTHREAD_APCSTATE_PROCESS]
-    cmp ebp, eax
-    jz SameProcess
-
-#ifdef CONFIG_SMP
-    /* Get the active processors and XOR with the process' */
-    mov ecx, [ebx+KPCR_SET_MEMBER_COPY]
-    lock xor [ebp+KPROCESS_ACTIVE_PROCESSORS], ecx
-    lock xor [eax+KPROCESS_ACTIVE_PROCESSORS], ecx
-
-    /* Assert change went ok */
-#if DBG
-    test [ebp+KPROCESS_ACTIVE_PROCESSORS], ecx
-    jz WrongActiveCpu
-    test [eax+KPROCESS_ACTIVE_PROCESSORS], ecx
-    jnz WrongActiveCpu
-#endif
-#endif
-
-    /* Check if we need an LDT */
-    mov ecx, [ebp+KPROCESS_LDT_DESCRIPTOR0]
-    or ecx, [eax+KPROCESS_LDT_DESCRIPTOR0]
-    jnz LdtReload
-
-UpdateCr3:
-    /* Switch address space */
-    mov eax, [ebp+KPROCESS_DIRECTORY_TABLE_BASE]
-    mov cr3, eax
-
-SameProcess:
-
-#ifdef CONFIG_SMP
-    /* Release swap lock */
-    and byte ptr [edi+KTHREAD_SWAP_BUSY], 0
-#endif
-
-    /* Clear gs */
-    xor eax, eax
-    mov gs, ax
-
-    /* Set the TEB */
-    mov eax, [esi+KTHREAD_TEB]
-    mov [ebx+KPCR_TEB], eax
-    mov ecx, [ebx+KPCR_GDT]
-    mov [ecx+0x3A], ax
-    shr eax, 16
-    mov [ecx+0x3C], al
-    mov [ecx+0x3F], ah
-
-    /* Get stack pointer */
-    mov eax, [esi+KTHREAD_INITIAL_STACK]
-
-    /* Make space for the NPX Frame */
-    sub eax, NPX_FRAME_LENGTH
-
-    /* Check if this isn't V86 Mode, so we can bias the Esp0 */
-    test dword ptr [eax - KTRAP_FRAME_SIZE + KTRAP_FRAME_EFLAGS], EFLAGS_V86_MASK
-    jnz NoAdjust
-
-    /* Bias esp */
-    sub eax, KTRAP_FRAME_V86_GS - KTRAP_FRAME_SS
-
-NoAdjust:
-
-    /* Set new ESP0 */
-    mov ecx, [ebx+KPCR_TSS]
-    mov [ecx+KTSS_ESP0], eax
-
-    /* Set current IOPM offset in the TSS */
-    mov ax, [ebp+KPROCESS_IOPM_OFFSET]
-    mov [ecx+KTSS_IOMAPBASE], ax
-
-    /* Increase context switches */
-    inc dword ptr [esi+KTHREAD_CONTEXT_SWITCHES]
-
-    /* Restore exception list */
-    pop [ebx+KPCR_EXCEPTION_LIST]
-
-    /* Restore IRQL */
-    pop ecx
-
-    /* DPC shouldn't be active */
-    cmp byte ptr [ebx+KPCR_PRCB_DPC_ROUTINE_ACTIVE], 0
-    jnz BugCheckDpc
-
-    /* Check if kernel APCs are pending */
-    cmp byte ptr [esi+KTHREAD_PENDING_KERNEL_APC], 0
-    jnz CheckApc
-
-    /* No APCs, return */
-    xor eax, eax
-    ret
-
-CheckApc:
-
-    /* Check if they're disabled */
-    cmp word ptr [esi+KTHREAD_SPECIAL_APC_DISABLE], 0
-    jnz ApcReturn
-    test cl, cl
-    jz ApcReturn
-
-    /* Request APC Delivery */
-    mov cl, APC_LEVEL
-    call @HalRequestSoftwareInterrupt@4
-    or eax, esp
-
-ApcReturn:
-
-    /* Return with APC pending */
-    setz al
-    ret
-
-LdtReload:
-    /* Check if it's empty */
-    mov eax, [ebp+KPROCESS_LDT_DESCRIPTOR0]
-    test eax, eax
-    jz LoadLdt
-
-    /* Write the LDT Selector */
-    mov ecx, [ebx+KPCR_GDT]
-    mov [ecx+KGDT_LDT], eax
-    mov eax, [ebp+KPROCESS_LDT_DESCRIPTOR1]
-    mov [ecx+KGDT_LDT+4], eax
-
-    /* Write the INT21 handler */
-    mov ecx, [ebx+KPCR_IDT]
-    mov eax, [ebp+KPROCESS_INT21_DESCRIPTOR0]
-    mov [ecx+0x108], eax
-    mov eax, [ebp+KPROCESS_INT21_DESCRIPTOR1]
-    mov [ecx+0x10C], eax
-
-    /* Save LDT Selector */
-    mov eax, KGDT_LDT
-
-LoadLdt:
-    lldt ax
-    jmp UpdateCr3
-
-NewCr0:
-
-#if DBG
-    /* Assert NPX State */
-    test byte ptr [esi+KTHREAD_NPX_STATE], ~(NPX_STATE_NOT_LOADED)
-    jnz InvalidNpx
-    test dword ptr [eax - (NPX_FRAME_LENGTH - FN_CR0_NPX_STATE)], ~(CR0_PE + CR0_MP +
CR0_EM + CR0_TS)
-    jnz InvalidNpx
-#endif
-
-    /* Update CR0 */
-    mov cr0, ecx
-    jmp StackOk
-
-#ifdef CONFIG_SMP
-NpxLoaded:
-
-    /* Mask out FPU flags */
-    and edx, ~(CR0_MP + CR0_EM + CR0_TS)
-
-    /* Get the NPX Frame */
-    mov ecx, [edi+KTHREAD_INITIAL_STACK]
-    sub ecx, NPX_FRAME_LENGTH
-
-    /* Check if we have a new CR0 */
-    cmp ebp, edx
-    jz Cr0Equal
-
-    /* We do, update it */
-    mov cr0, edx
-    mov ebp, edx
-
-Cr0Equal:
-
-    /* Save the NPX State */
-    fxsave [ecx]
-    mov byte ptr [edi+KTHREAD_NPX_STATE], NPX_STATE_NOT_LOADED
-
-    /* Clear the NPX Thread */
-    mov dword ptr [ebx+KPCR_NPX_THREAD], 0
-
-    /* Jump back */
-    jmp SetStack
-#endif
-
-WmiTrace:
-
-    /* No WMI support yet */
-    int 3
-
-    /* Jump back */
-    jmp AfterTrace
-
-BugCheckDpc:
-
-    /* Bugcheck the machine, printing out the threads being switched */
-    mov eax, [edi+KTHREAD_INITIAL_STACK]
-    push 0
-    push eax
-    push esi
-    push edi
-    push ATTEMPTED_SWITCH_FROM_DPC
-    call _KeBugCheckEx@20
-
-#if DBG
-InvalidNpx:
-    int 3
-WrongActiveCpu:
-    int 3
-WrongCpu:
-    int 3
-#endif
+    /* Set APC Bypass Disable and old thread pointer */
+    mov edx, edi
+    or dl, cl
+
+    /* Build switch frame */
+    sub esp, 2 * 4
+    mov ecx, esp
+    call @KiSwapContextEntry@8
+    mov ecx, 0xB00BFACA
+    jmp $
 .endfunc
 
 /*++
@@ -511,6 +243,20 @@
     jmp $
 .endfunc
 
+.globl @KiSwitchThreads@8
+.func @KiSwitchThreads@8, @KiSwitchThreads@8
+@KiSwitchThreads@8:
+
+    /* Load the new kernel stack and switch OS to new thread */
+    mov esp, [edx+KTHREAD_KERNEL_STACK]
+    mov edx, esp
+    call @KiSwapContextExit@8
+    
+    /* Now we're on the new thread. Return to the caller to restore registers */
+    add esp, 2 * 4
+    ret
+.endfunc
+
 .globl @Ki386BiosCallReturnAddress@4
 @Ki386BiosCallReturnAddress@4:
 

Modified: trunk/reactos/ntoskrnl/ke/i386/thrdini.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/ntoskrnl/ke/i386/thrdini.c…
==============================================================================
--- trunk/reactos/ntoskrnl/ke/i386/thrdini.c [iso-8859-1] (original)
+++ trunk/reactos/ntoskrnl/ke/i386/thrdini.c [iso-8859-1] Mon Nov  8 02:15:53 2010
@@ -41,6 +41,13 @@
     KSTART_FRAME StartFrame;
     FX_SAVE_AREA FxSaveArea;
 } KKINIT_FRAME, *PKKINIT_FRAME;
+
+VOID
+FASTCALL
+KiSwitchThreads(
+    IN PKTHREAD OldThread,
+    IN PKTHREAD NewThread
+);
 
 /* FUNCTIONS *****************************************************************/
 
@@ -311,4 +318,133 @@
     }
 }
 
+BOOLEAN
+FASTCALL
+KiSwapContextExit(IN PKTHREAD OldThread,
+                  IN PKSWITCHFRAME SwitchFrame)
+{
+    PKIPCR Pcr = (PKIPCR)KeGetPcr();
+    PKPROCESS OldProcess, NewProcess;
+    PKGDTENTRY GdtEntry;
+    PKTHREAD NewThread;
+    PKUINIT_FRAME InitFrame;
+    
+    /* We are on the new thread stack now */
+    NewThread = Pcr->PrcbData.CurrentThread;
+
+    /* Now we are the new thread. Check if it's in a new process */
+    OldProcess = OldThread->ApcState.Process;
+    NewProcess = NewThread->ApcState.Process;
+    if (OldProcess != NewProcess)
+    {
+        /* Check if there is a different LDT */
+        if (*(PULONGLONG)&OldProcess->LdtDescriptor !=
*(PULONGLONG)&NewProcess->LdtDescriptor)
+        {
+            DPRINT1("LDT switch not implemented\n");
+            ASSERT(FALSE);            
+        }
+
+        /* Switch address space and flush TLB */
+        __writecr3(NewProcess->DirectoryTableBase[0]);
+    }
+    
+    /* Clear GS */
+    Ke386SetGs(0);
+    
+    /* Set the TEB */
+    Pcr->NtTib.Self = (PVOID)NewThread->Teb;
+    GdtEntry = &Pcr->GDT[KGDT_R3_TEB / sizeof(KGDTENTRY)];
+    GdtEntry->BaseLow = (USHORT)((ULONG_PTR)NewThread->Teb & 0xFFFF);
+    GdtEntry->HighWord.Bytes.BaseMid = (UCHAR)((ULONG_PTR)NewThread->Teb >>
16);
+    GdtEntry->HighWord.Bytes.BaseHi = (UCHAR)((ULONG_PTR)NewThread->Teb >>
24);
+    
+    /* Set new TSS fields */
+    InitFrame = (PKUINIT_FRAME)NewThread->InitialStack - 1;
+    Pcr->TSS->Esp0 = (ULONG_PTR)&InitFrame->TrapFrame;
+    if (!(InitFrame->TrapFrame.EFlags & EFLAGS_V86_MASK))
+    {
+        Pcr->TSS->Esp0 -= (FIELD_OFFSET(KTRAP_FRAME, V86Gs) -
FIELD_OFFSET(KTRAP_FRAME, HardwareSegSs));
+    }
+    Pcr->TSS->IoMapBase = NewProcess->IopmOffset;
+    
+    /* Increase thread context switches */
+    NewThread->ContextSwitches++;
+
+    /* Load data from switch frame */
+    Pcr->NtTib.ExceptionList = SwitchFrame->ExceptionList;
+
+    /* DPCs shouldn't be active */
+    if (Pcr->PrcbData.DpcRoutineActive)
+    {
+        /* Crash the machine */
+        KeBugCheckEx(ATTEMPTED_SWITCH_FROM_DPC,
+                     (ULONG_PTR)OldThread,
+                     (ULONG_PTR)NewThread,
+                     (ULONG_PTR)OldThread->InitialStack,
+                     0);
+    }
+    
+    /* Kernel APCs may be pending */
+    if (NewThread->ApcState.KernelApcPending)
+    {
+        /* Are APCs enabled? */
+        if (!NewThread->SpecialApcDisable)
+        {
+            /* Request APC delivery */
+            if (!SwitchFrame->ApcBypassDisable)
HalRequestSoftwareInterrupt(APC_LEVEL);
+            return TRUE;
+        }
+    }
+    
+    /* Return */
+    return FALSE;
+}
+
+VOID
+FASTCALL
+KiSwapContextEntry(IN PKSWITCHFRAME SwitchFrame,
+                   IN ULONG_PTR OldThreadAndApcFlag)
+{
+    PKIPCR Pcr = (PKIPCR)KeGetPcr();
+    PKTHREAD OldThread, NewThread;
+    ULONG Cr0, NewCr0;
+
+    /* Switch threads, check for APC disable */
+    ASSERT(OldThreadAndApcFlag &~ 1);
+
+    /* Save APC bypass disable */
+    SwitchFrame->ApcBypassDisable = OldThreadAndApcFlag & 3;
+    SwitchFrame->ExceptionList = Pcr->NtTib.ExceptionList;
+
+    /* Increase context switch count and check if tracing is enabled */
+    Pcr->ContextSwitches++;
+    if (Pcr->PerfGlobalGroupMask)
+    {
+        /* We don't support this yet on x86 either */
+        DPRINT1("WMI Tracing not supported\n");
+        ASSERT(FALSE);
+    }
+
+    /* Get thread pointers */
+    OldThread = (PKTHREAD)(OldThreadAndApcFlag & ~3);
+    NewThread = Pcr->PrcbData.CurrentThread;
+    
+    /* Get the old thread and set its kernel stack */
+    OldThread->KernelStack = SwitchFrame;
+
+    /* ISRs can change FPU state, so disable interrupts while checking */
+    _disable();
+    
+    /* Get current and new CR0 and check if they've changed */
+    Cr0 = __readcr0();
+    NewCr0 = NewThread->NpxState |
+             (Cr0 & ~(CR0_MP | CR0_EM | CR0_TS)) |
+             ((PKUINIT_FRAME)NewThread->InitialStack - 1)->FxSaveArea.Cr0NpxState;
+    if (Cr0 != NewCr0)  __writecr0(NewCr0);
+
+    /* Now enable interrupts and do the switch */
+    _enable();
+    KiSwitchThreads(OldThread, NewThread);
+}
+
 /* EOF */