Decorate the m68k signal trampoline with the appropriate .cfi
directives to allow exception unwind / backtrace across a signal handler.
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parent
a2dfa8a4c3
commit
93b0ea009f
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@ -1,4 +1,4 @@
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# $NetBSD: genassym.cf,v 1.1 2013/07/17 01:41:17 matt Exp $
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# $NetBSD: genassym.cf,v 1.2 2021/11/21 23:58:09 thorpej Exp $
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#
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# Copyright (c) 2013 The NetBSD Foundation, Inc.
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@ -36,11 +36,32 @@ include <signal.h>
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define UC_LINK offsetof(ucontext_t, uc_link)
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define UC_SIGMASK offsetof(ucontext_t, uc_sigmask)
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define UC_GREGS offsetof(ucontext_t, uc_mcontext.__gregs[0])
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define UC_MCONTEXT_D0 offsetof(ucontext_t, uc_mcontext.__gregs[_REG_D0])
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define UC_MCONTEXT_SP offsetof(ucontext_t, uc_mcontext.__gregs[_REG_A7])
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define UC_MCONTEXT_PC offsetof(ucontext_t, uc_mcontext.__gregs[_REG_PC])
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define UC_SIZE sizeof(ucontext_t)
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define _REG_D0 _REG_D0
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define _REG_D1 _REG_D1
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define _REG_D2 _REG_D2
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define _REG_D3 _REG_D3
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define _REG_D4 _REG_D4
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define _REG_D5 _REG_D5
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define _REG_D6 _REG_D6
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define _REG_D7 _REG_D7
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define _REG_A0 _REG_A0
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define _REG_A1 _REG_A1
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define _REG_A2 _REG_A2
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define _REG_A3 _REG_A3
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define _REG_A4 _REG_A4
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define _REG_A5 _REG_A5
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define _REG_A6 _REG_A6
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define _REG_A7 _REG_A7
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define _REG_PC _REG_PC
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define SIZEOF_SIGINFO sizeof(siginfo_t)
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define SC_ONSTACK offsetof(struct sigcontext, sc_onstack)
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define SC___MASK13 offsetof(struct sigcontext, __sc_mask13)
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define SC_SP offsetof(struct sigcontext, sc_sp)
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@ -1,4 +1,4 @@
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/* $NetBSD: __sigtramp2.S,v 1.4 2013/07/16 22:19:16 matt Exp $ */
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/* $NetBSD: __sigtramp2.S,v 1.5 2021/11/21 23:58:09 thorpej Exp $ */
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/*-
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* Copyright (c) 2003 The NetBSD Foundation, Inc.
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@ -27,6 +27,7 @@
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*/
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#include "SYS.h"
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#include "assym.h"
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/*
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* The m68k signal trampoline is invoked only to return from
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@ -39,7 +40,57 @@
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* pointer to ucontext structure [8]
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* pointer to siginfo structure [4]
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* sp-> signal number [0]
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*
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* The DWARF register numbers are 0-7 (dX), 8-15 (aX), 16-23 (fpX),
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* which maps nicely to _REG_D[0-7] and _REG_A[0-7]. For m68k, there
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* is a DWARF pseudo-register for the return address, and additionally
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* another DWARF pseudo-register for signal handler return addresses.
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* We will specify both return address pseudo-registers (without
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* explicitly specifying .cfi_return_column) to keep the compiler
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* run-time happy with whichever one it decides to use.
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*/
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#define DWARF_RETURN_REG 24
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#if defined(__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__)
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#define DWARF_SIGRETURN_REG __LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__
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#else
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#define DWARF_SIGRETURN_REG 25
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#endif
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#define CFI_OFFSET_DWARF_REG(d, r) .cfi_offset d, r * 4
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#define CFI_OFFSET(r) CFI_OFFSET_DWARF_REG(r, r)
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.text
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.cfi_startproc simple
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.cfi_signal_frame
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.cfi_def_cfa _REG_A7, 12 + SIZEOF_SIGINFO + UC_GREGS
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CFI_OFFSET(_REG_D0)
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CFI_OFFSET(_REG_D1)
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CFI_OFFSET(_REG_D2)
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CFI_OFFSET(_REG_D3)
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CFI_OFFSET(_REG_D4)
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CFI_OFFSET(_REG_D5)
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CFI_OFFSET(_REG_D6)
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CFI_OFFSET(_REG_D7)
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CFI_OFFSET(_REG_A0)
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CFI_OFFSET(_REG_A1)
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CFI_OFFSET(_REG_A2)
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CFI_OFFSET(_REG_A3)
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CFI_OFFSET(_REG_A4)
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CFI_OFFSET(_REG_A5)
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CFI_OFFSET(_REG_A6)
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CFI_OFFSET(_REG_A7)
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CFI_OFFSET_DWARF_REG(DWARF_RETURN_REG, _REG_PC)
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CFI_OFFSET_DWARF_REG(DWARF_SIGRETURN_REG, _REG_PC)
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/*
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* The unwind entry includes one instruction slot prior to the trampoline
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* because the unwinder will look up to (return PC - 1 insn) while unwinding.
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* Normally this would be the jump / branch, but since there isn't one in
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* this case, we place an explicit nop there instead.
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*/
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nop
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ENTRY_NOPROFILE(__sigtramp_siginfo_2)
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movl 8(%sp),%a0 /* get pointer to ucontext */
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movl %a0,4(%sp) /* put it in the argument slot */
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@ -47,4 +98,5 @@ ENTRY_NOPROFILE(__sigtramp_siginfo_2)
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SYSTRAP(setcontext)
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movl %d0,4(%sp) /* error code */
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SYSTRAP(exit) /* exit */
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.cfi_endproc
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END(__sigtramp_siginfo_2)
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