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// TITLE("Long Jump")//++//// Copyright (c) 1993 Microsoft Corporation// Copyright (c) 1993 Digital Equipment Corporation//// Module Name://// longjmp.s//// Abstract://// This module implements the Alpha specific routine to perform a long// jump operation. Three jump buffer types are supported: unsafe, safe// acc-style (virtual frame pointer, PC mapped SEH scope), and safe// GEM-style (real frame pointer, SEB-based SEH context).//// N.B. This routine conditionally provides UNSAFE handling of longjmp// which is NOT integrated with structured exception handling. The// determination is made based on whether an unitialized variable// has been set to a nonzero value.//// Author://// David N. Cutler (davec) 2-Apr-1993//// Environment://// Any mode.//// Revision History://// Thomas Van Baak (tvb) 22-Apr-1993//// Adapted for Alpha AXP.////--
#include "ksalpha.h"
//// Define jump buffer types.//// _JMPBUF_TYPE_ZERO was used for Beta2 which functions the same as// _JMPBUF_TYPE_ACC.//// _JMPBUF_TYPE_FAST is for jump buffers containing the set of// non-volatile integer and floating registers. This form// of setjmp/longjmp is not compatible with SEH.//// _JMPBUF_TYPE_ACC is for setjmp/longjmp compatible with SEH.// The Alpha acc compiler uses a virtual frame pointer.//// _JMPBUF_TYPE_GEM is for setjmp/longjmp compatible with SEH.// The Alpha GEM C compiler uses a real frame pointer, and// SEH scope is maintained with a SEB pointer.//
#define _JMPBUF_TYPE_ZERO 0
#define _JMPBUF_TYPE_FAST 1
#define _JMPBUF_TYPE_ACC 2
#define _JMPBUF_TYPE_GEM 3
SBTTL("Long Jump")//++//// int// longjmp (// IN jmp_buf JumpBuffer,// IN int ReturnValue// )//// Routine Description://// This function performs a long jump to the context specified by the// jump buffer.//// Arguments://// JumpBuffer (a0) - Supplies the address of a jump buffer that contains// jump information.//// ReturnValue (a1) - Supplies the value that is to be returned to the// caller of set jump.//// Return Value://// None.////--
LEAF_ENTRY(longjmp)
ldil t0, 1 // force nonzero value, if cmoveq a1, t0, a1 // given return value is zero
ldl t1, JbType(a0) // get setjmp context type flag subq t1, 1, t2 // if eq 1, fast, unsafe longjmp bne t2, 10f // otherwise, provide safe longjmp
//// Type 0x1: Provide unsafe handling of longjmp.//
mov a1, v0 // set return value
ldt f2, JbFltF2(a0) // restore floating registers f2 - f9 ldt f3, JbFltF3(a0) // ldt f4, JbFltF4(a0) // ldt f5, JbFltF5(a0) // ldt f6, JbFltF6(a0) // ldt f7, JbFltF7(a0) // ldt f8, JbFltF8(a0) // ldt f9, JbFltF9(a0) //
ldq s0, JbIntS0(a0) // restore integer registers s0 - s6/fp ldq s1, JbIntS1(a0) // ldq s2, JbIntS2(a0) // ldq s3, JbIntS3(a0) // ldq s4, JbIntS4(a0) // ldq s5, JbIntS5(a0) // ldq fp, JbIntS6(a0) //
ldq a1, JbFir(a0) // get setjmp return address ldq sp, JbIntSp(a0) // restore stack pointer jmp zero, (a1) // jump back to setjmp site
//// Type 0x0: Provide safe handling of longjmp (idw 404 style).// Type 0x2: Provide safe handling of longjmp (acc style).//
10: bic t1, 0x2, t2 // if 0 or 2, safe acc longjmp bne t2, longjmpRfp // if not, safe GEM longjmp
mov a1, a3 // set return value mov zero, a2 // set exception record addres ldl a1, JbPc(a0) // set target instruction address ldl a0, JbFp(a0) // set target virtual frame pointer br zero, RtlUnwind // finish in common code
.end longjmp SBTTL("Long Jump - GEM")
.struct 0LjRa: .space 8 // saved return address .space 8 // padding for 16-byte stack alignmentLjEr: .space ExceptionRecordLength // local exception recordLongjmpFrameLength:
//// Type 0x3: Provide safe handling of longjmp (GEM style).//
NESTED_ENTRY(longjmpRfp, LongjmpFrameLength, ra)
lda sp, -LongjmpFrameLength(sp) // allocate stack frame stq ra, LjRa(sp) // save return address
PROLOGUE_END
//// Set up the following local exception record://// ExceptionRecord.ExceptionCode = STATUS_UNWIND;
// ExceptionRecord.ExceptionFlags = EXCEPTION_UNWINDING;
// ExceptionRecord.ExceptionRecord = NULL;
// ExceptionRecord.ExceptionAddress = 0;
// ExceptionRecord.NumberParameters = 1;
// ExceptionRecord.ExceptionInformation[0] = Seb;
//
10: mov a1, a3 // set return value lda a2, LjEr(sp) // set exception record address
ldil t0, STATUS_UNWIND // get status code stl t0, ErExceptionCode(a2) // store in exception record ldil t1, EXCEPTION_UNWINDING // get exception flags stl t1, ErExceptionFlags(a2) // store in exception record stl zero, ErExceptionRecord(a2) // store in exception record stl zero, ErExceptionAddress(a2) // store in exception record ldil t2, 1 // get number of parameters stl t2, ErNumberParameters(a2) // store in exception record ldl t3, JbSeb(a0) // get SEB pointer stl t3, ErExceptionInformation(a2) // store in exception record ldl a1, JbPc(a0) // set target instruction address ldl a0, JbFp(a0) // set target real frame pointer
bsr ra, RtlUnwindRfp // finish in common code
.end longjmpRfp
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