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__sigtramp2.S revision 1.7 
      1 /* $NetBSD: __sigtramp2.S,v 1.7 2021/11/23 02:49:56 thorpej Exp $ */
      2 
      3 /*-
      4  * Copyright (c) 2014 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Matt Thomas of 3am Software Foundry.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include "SYS.h"
     33 #include "assym.h"
     34 
     35 /*
     36  * The ARM64 signal trampoline is invoked only to return from
     37  * the signal; the kernel calls the signal handler directly.
     38  *
     39  * On entry, the stack looks like:
     40  *
     41  *		ucontext structure
     42  *	sp->	siginfo structure
     43  * and x28 points to the ucontext
     44  *
     45  * A DWARF pseudo-register is used for the return address from the
     46  * signal trampoline.
     47  */
     48 
     49 #if defined(__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__)
     50 #define	DWARF_SIGRETURN_REG		__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__
     51 #else
     52 #define	DWARF_SIGRETURN_REG		96
     53 #endif
     54 
     55 #define	CFI_OFFSET_DWARF_REG(d, r)	.cfi_offset d, r * 8
     56 #define	CFI_OFFSET(r)			CFI_OFFSET_DWARF_REG(r, r)
     57 
     58 	.text
     59 	.cfi_startproc simple
     60 	.cfi_signal_frame
     61 	.cfi_def_cfa _REG_X28, _UC_GREGS
     62 	CFI_OFFSET(_REG_X0)
     63 	CFI_OFFSET(_REG_X1)
     64 	CFI_OFFSET(_REG_X2)
     65 	CFI_OFFSET(_REG_X3)
     66 	CFI_OFFSET(_REG_X4)
     67 	CFI_OFFSET(_REG_X5)
     68 	CFI_OFFSET(_REG_X6)
     69 	CFI_OFFSET(_REG_X7)
     70 	CFI_OFFSET(_REG_X8)
     71 	CFI_OFFSET(_REG_X9)
     72 	CFI_OFFSET(_REG_X10)
     73 	CFI_OFFSET(_REG_X11)
     74 	CFI_OFFSET(_REG_X12)
     75 	CFI_OFFSET(_REG_X13)
     76 	CFI_OFFSET(_REG_X14)
     77 	CFI_OFFSET(_REG_X15)
     78 	CFI_OFFSET(_REG_X16)
     79 	CFI_OFFSET(_REG_X17)
     80 	CFI_OFFSET(_REG_X18)
     81 	CFI_OFFSET(_REG_X19)
     82 	CFI_OFFSET(_REG_X20)
     83 	CFI_OFFSET(_REG_X21)
     84 	CFI_OFFSET(_REG_X22)
     85 	CFI_OFFSET(_REG_X23)
     86 	CFI_OFFSET(_REG_X24)
     87 	CFI_OFFSET(_REG_X25)
     88 	CFI_OFFSET(_REG_X26)
     89 	CFI_OFFSET(_REG_X27)
     90 	CFI_OFFSET(_REG_X28)
     91 	CFI_OFFSET(_REG_X29)
     92 	CFI_OFFSET(_REG_X30)	/* a.k.a. _REG_LR */
     93 	CFI_OFFSET(_REG_X31)	/* a.k.a. _REG_SP */
     94 	.cfi_return_column DWARF_SIGRETURN_REG
     95 	CFI_OFFSET_DWARF_REG(DWARF_SIGRETURN_REG, _REG_PC)
     96 
     97 /*
     98  * The unwind entry includes the one instruction prior to the trampoline
     99  * because the unwinder will look up (return PC - 1) while unwinding.
    100  * Normally this would be the jump / branch, but since there isn't one in
    101  * this case, we place an explicit nop there instead.
    102  */
    103 	nop
    104 
    105 ENTRY_NP(__sigtramp_siginfo_2)
    106 	mov	x0, x28				/* set the arg         */
    107 	SYSTRAP(setcontext)			/* and call setcontext */
    108 
    109 	/* If that failed, exit with the error code. */
    110 	SYSTRAP(exit)
    111 	.cfi_endproc
    112 END(__sigtramp_siginfo_2)
    113