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// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#include "textflag.h"
// panicmem is the entrypoint for SIGSEGV as intercepted via a
// mach thread port as EXC_BAD_ACCESS. As the segfault may have happened
// in C code, we first need to load_g then call panicmem.
// R1 - LR at moment of fault
// R2 - PC at moment of fault
TEXT ·panicmem(SB),NOSPLIT,$-4
// If in external C code, we need to load the g register.
BL runtime·load_g(SB)
CMP $0, g
BNE ongothread
// On a foreign thread. We call badsignal, which will, if all
// goes according to plan, not return.
SUB $4, R13
MOVW $11, R1
MOVW $11, R2
MOVM.DB.W [R1,R2], (R13)
// TODO: badsignal should not return, but it does. Issue #10139.
//BL runtime·badsignal(SB)
MOVW $139, R1
MOVW R1, 4(R13)
B runtime·exit(SB)
// Trigger a SIGSEGV panic.
// The goal is to arrange the stack so it looks like the runtime
// function sigpanic was called from the PC that faulted. It has
// to be sigpanic, as the stack unwinding code in traceback.go
// looks explicitly for it.
// To do this we call into runtime·setsigsegv, which sets the
// appropriate state inside the g object. We give it the faulting
// PC on the stack, then put it in the LR before calling sigpanic.
MOVM.DB.W [R1,R2], (R13)
BL runtime·setsigsegv(SB)
MOVM.IA.W (R13), [R1,R2]
SUB $4, R13
MOVW R1, 0(R13)
MOVW R2, R14
B runtime·sigpanic(SB)