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108 lines
3.0 KiB
108 lines
3.0 KiB
// TITLE("LdrInitializeThunk")
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//++
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//
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// Copyright (c) 1989 Microsoft Corporation
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//
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// Module Name:
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//
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// ldrthunk.s
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//
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// Abstract:
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//
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// This module implements the thunk for the LdrpInitialize APC routine.
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//
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// Author:
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//
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// Chuck Bauman 20-Mar-1993
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//
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// Environment:
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//
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// Any mode.
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//
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// Revision History:
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//
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// Port NT product1 source to PowerPC 12-Aug-1993
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// Changed to nested function and added conversion of function
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// descriptor. Peter Johnston ([email protected]) 18-Aug-1994
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//
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//--
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#include "ksppc.h"
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//++
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//
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// VOID
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// LdrInitializeThunk(
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// IN PVOID NormalContext,
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// IN PVOID SystemArgument1,
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// IN PVOID SystemArgument2
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// )
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//
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// Routine Description:
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//
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// This routine is called via APC and is the first code executed in
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// user mode for every user mode thread.
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//
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// On entry to this routine, the current stack frame is immediately
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// preceeded by a context record containing the initial state of the
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// new thread.
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//
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// This function computes a pointer to the context record on the stack
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// and calls LdrpInitialize with that pointer as its parameter.
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//
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// On return from LdrpInitialize, we convert the function descriptor
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// whose address is in the Context record Iar field from a pointer to
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// a function descriptor to the actual TOC and entry point values for
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// the thread.
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//
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// Arguments:
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//
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// NormalContext (r.3) - User Mode APC context parameter (ignored).
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//
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// SystemArgument1 (r.4) - User Mode APC system argument 1 (ignored).
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//
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// SystemArgument2 (r.5) - User Mode APC system argument 2 (ignored).
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//
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// Return Value:
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//
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// None.
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//
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//--
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.extern ..LdrpInitialize
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.struct 0
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.space STK_MIN_FRAME
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LitLr: .space 4
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.align 3
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LitFr1: .space STK_MIN_FRAME
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LitCx: .space ContextFrameLength
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.align 3
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LitFrameLen:
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SPECIAL_ENTRY(LdrInitializeThunk)
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mflr r.0
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stwu r.sp, -LitFr1(r.sp) // buy stack frame
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addi r.3, r.sp, LitCx // compute context record addr
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stw r.0, LitLr(r.sp) // save return address
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PROLOGUE_END(LdrInitializeThunk)
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bl ..LdrpInitialize // Jump to LdrpInitialize
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lwz r.11, LitCx + CxGpr2(r.sp) // TOC set
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cmpwi r.11, 0 // jif true context passed
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// (e.g: fork)
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lwz r.11, LitCx + CxIar(r.sp) // read fn descr from Cr Iar
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lwz r.0, LitLr(r.sp) // get return address
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bne truectx
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lwz r.12, 4(r.11) // get toc
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lwz r.11, 0(r.11) // get fn entry
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stw r.12, LitCx + CxGpr2(r.sp) // set initial toc
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stw r.11, LitCx + CxIar(r.sp) // set entry point
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truectx:
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mtlr r.0 // restore return address
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addi r.sp, r.sp, LitFr1 // free out stack frame
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SPECIAL_EXIT(LdrInitializeThunk)
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