mirror of
https://github.com/danbulant/Cosmos
synced 2026-05-20 12:58:39 +00:00
63 lines
4.2 KiB
C#
63 lines
4.2 KiB
C#
using System;
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using System.Linq;
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using Cosmos.Assembler;
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using Cosmos.Assembler.x86;
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namespace Cosmos.Debug.DebugStub {
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public class TracerEntry : Cosmos.Assembler.Code {
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public override void Assemble() {
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new Comment("We need to make sure Int3 can never run more than one instance at a time.");
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new Comment("We are not threaded yet, when we are we have to change stuff to thread vars and a lot of other stuff.");
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new Comment("Two Int3 calls currently can never happen at the same time normally, but IRQs can happen while the DebugStub is");
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new Comment("running. We also need to make sure IRQs are allowed to run during DebugStub as DebugStub can wait for");
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new Comment("a long time on commands.");
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new Comment("So we need to disable interrupts immediately and set a flag, then reenable interrupts if they were enabled");
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new Comment("when we disabled them. Later this can be replaced by some kind of critical section / lock around this code.");
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new Comment("Currently IRQs are disabled - we need to fix DS before we can reenable them and add support for critical sections / locks here.");
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new Comment("-http:#www.codemaestro.com/reviews/8");
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new Comment("-http:#en.wikipedia.org/wiki/Spinlock - Uses a register which is a problem for us");
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new Comment("-http:#wiki.osdev.org/Spinlock");
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new Comment("-Looks good and also allows testing intead of waiting");
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new Comment("-Wont require us to disable / enable IRQs");
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new Comment("Comment");
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new Label("DebugStub_TracerEntry");
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new Comment("This code is temporarily disabled as IRQs are not enabled right now.");
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new Comment("LockOrExit");
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new Comment("EBP is restored by PopAll, but SendFrame uses it. Could");
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new Comment("get it from the PushAll data, but this is easier.");
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new Mov { DestinationRef = Cosmos.Assembler.ElementReference.New("DebugStub_CallerEBP"), DestinationIsIndirect = true , SourceReg = RegistersEnum.EBP };
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new Comment("Could get ESP from PushAll but this is easier.");
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new Comment("Also allows us to use the stack before PushAll if we ever need it.");
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new Comment("We cant modify any registers since we havent done PushAll yet");
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new Comment("Maybe we could do a sub(4) on memory direct..");
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new Comment("But for now we remove from ESP which the Int3 produces,");
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new Comment("store ESP, then restore ESP so we don't cause stack corruption.");
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new Comment("12 bytes for EFLAGS, CS, EIP");
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new Add { DestinationReg = RegistersEnum.ESP, SourceValue = 12 };
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new Mov { DestinationRef = Cosmos.Assembler.ElementReference.New("DebugStub_CallerESP"), DestinationIsIndirect = true , SourceReg = RegistersEnum.ESP };
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new Sub { DestinationReg = RegistersEnum.ESP, SourceValue = 12 };
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new Pushad();
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new Comment("Save current ESP so we can look at the results of PushAll later");
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new Mov { DestinationRef = Cosmos.Assembler.ElementReference.New("DebugStub_PushAllPtr"), DestinationIsIndirect = true , SourceReg = RegistersEnum.ESP };
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new Comment("Get current ESP and add 32. This will skip over the PushAll and point");
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new Comment("us at the call data from Int3.");
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new Mov{ DestinationReg = RegistersEnum.EBP, SourceReg = RegistersEnum.ESP };
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new Add { DestinationReg = RegistersEnum.EBP, SourceValue = 32 };
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new Comment("Caller EIP");
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new Mov { DestinationReg = RegistersEnum.EAX, SourceReg = RegistersEnum.EBP, SourceIsIndirect = true, SourceDisplacement = 0};
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new Comment("EIP is pointer to op after our call. Int3 is 1 byte so we subtract 1.");
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new Comment("Note - when we used call it was 5 (size of our call + address)");
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new Comment("so we get the EIP as IL2CPU records it. Its also useful for when we");
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new Comment("wil be changing ops that call this stub.");
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new Dec { DestinationReg = RegistersEnum.EAX };
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new Comment("Store it for later use.");
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new Mov { DestinationRef = Cosmos.Assembler.ElementReference.New("DebugStub_CallerEIP"), DestinationIsIndirect = true , SourceReg = RegistersEnum.EAX };
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new Call { DestinationLabel = "DebugStub_Executing" };
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new Popad();
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new Comment("Temp disabled, see comment on LockOrExit above");
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new Comment("Unlock");
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new Label("DebugStub_TracerEntry_Exit");
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new IRET();
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}
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}
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}
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