mirror of
https://github.com/danbulant/Cosmos
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69 lines
2.2 KiB
Text
69 lines
2.2 KiB
Text
// We need to make sure Int3 can never run more than one instance at a time.
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// 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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// Two Int3 calls currently can never happen at the same time normally, but IRQs can happen while the DebugStub is
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// running. We also need to make sure IRQs are allowed to run during DebugStub as DebugStub can wait for
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// a long time on commands.
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// So we need to disable interrupts immediately and set a flag, then reenable interrupts if they were enabled
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// when we disabled them. Later this can be replaced by some kind of critical section / lock around this code.
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// 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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// -http://www.codemaestro.com/reviews/8
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// -http://en.wikipedia.org/wiki/Spinlock - Uses a register which is a problem for us
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// -http://wiki.osdev.org/Spinlock
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// -Looks good and also allows testing intead of waiting
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// -Wont require us to disable / enable IRQs
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//This method also handles INT1
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namespace DebugStub
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Interrupt TracerEntry {
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// This code is temporarily disabled as IRQs are not enabled right now.
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// LockOrExit
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// First, disable interrupts, so debugging is much more stable
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! cli
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+All
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// Save current ESP so we can look at the results of PushAll later
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.PushAllPtr = ESP
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.CallerEBP = EBP
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// Get current ESP and add 32. This will skip over the PushAll and point
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// us at the call data from Int3.
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EBP = ESP
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EBP + 32
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// Caller EIP
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EAX = EBP[0]
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// 12 bytes for EFLAGS, CS, EIP
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EBP + 12
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.CallerESP = EBP
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// EIP is pointer to op after our call. Int3 is 1 byte so we subtract 1.
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// Note - when we used call it was 5 (size of our call + address)
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// so we get the EIP as IL2CPU records it. Its also useful for when we
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// wil be changing ops that call this stub.
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//Check whether this call is result of (i.e. after) INT1. If so, don't subtract 1!
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EBX = EAX
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! MOV EAX, DR6
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EAX & $4000
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if EAX != $4000 {
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EBX--
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}
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EAX = EBX
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// Store it for later use.
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.CallerEIP = EAX
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Executing()
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-All
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// restore interupts
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! sti
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// Temp disabled, see comment on LockOrExit above
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// Unlock
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}
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