Module Name: src
Committed By: thorpej
Date: Sun Nov 21 23:58:09 UTC 2021
Modified Files:
src/lib/libc/arch/m68k: genassym.cf
src/lib/libc/arch/m68k/sys: __sigtramp2.S
Log Message:
Decorate the m68k signal trampoline with the appropriate .cfi
directives to allow exception unwind / backtrace across a signal
handler.
To generate a diff of this commit:
cvs rdiff -u -r1.1 -r1.2 src/lib/libc/arch/m68k/genassym.cf
cvs rdiff -u -r1.4 -r1.5 src/lib/libc/arch/m68k/sys/__sigtramp2.S
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/lib/libc/arch/m68k/genassym.cf
diff -u src/lib/libc/arch/m68k/genassym.cf:1.1 src/lib/libc/arch/m68k/genassym.cf:1.2
--- src/lib/libc/arch/m68k/genassym.cf:1.1 Wed Jul 17 01:41:17 2013
+++ src/lib/libc/arch/m68k/genassym.cf Sun Nov 21 23:58:09 2021
@@ -1,4 +1,4 @@
-# $NetBSD: genassym.cf,v 1.1 2013/07/17 01:41:17 matt Exp $
+# $NetBSD: genassym.cf,v 1.2 2021/11/21 23:58:09 thorpej Exp $
#
# Copyright (c) 2013 The NetBSD Foundation, Inc.
@@ -36,11 +36,32 @@ include <signal.h>
define UC_LINK offsetof(ucontext_t, uc_link)
define UC_SIGMASK offsetof(ucontext_t, uc_sigmask)
+define UC_GREGS offsetof(ucontext_t, uc_mcontext.__gregs[0])
define UC_MCONTEXT_D0 offsetof(ucontext_t, uc_mcontext.__gregs[_REG_D0])
define UC_MCONTEXT_SP offsetof(ucontext_t, uc_mcontext.__gregs[_REG_A7])
define UC_MCONTEXT_PC offsetof(ucontext_t, uc_mcontext.__gregs[_REG_PC])
define UC_SIZE sizeof(ucontext_t)
+define _REG_D0 _REG_D0
+define _REG_D1 _REG_D1
+define _REG_D2 _REG_D2
+define _REG_D3 _REG_D3
+define _REG_D4 _REG_D4
+define _REG_D5 _REG_D5
+define _REG_D6 _REG_D6
+define _REG_D7 _REG_D7
+define _REG_A0 _REG_A0
+define _REG_A1 _REG_A1
+define _REG_A2 _REG_A2
+define _REG_A3 _REG_A3
+define _REG_A4 _REG_A4
+define _REG_A5 _REG_A5
+define _REG_A6 _REG_A6
+define _REG_A7 _REG_A7
+define _REG_PC _REG_PC
+
+define SIZEOF_SIGINFO sizeof(siginfo_t)
+
define SC_ONSTACK offsetof(struct sigcontext, sc_onstack)
define SC___MASK13 offsetof(struct sigcontext, __sc_mask13)
define SC_SP offsetof(struct sigcontext, sc_sp)
Index: src/lib/libc/arch/m68k/sys/__sigtramp2.S
diff -u src/lib/libc/arch/m68k/sys/__sigtramp2.S:1.4 src/lib/libc/arch/m68k/sys/__sigtramp2.S:1.5
--- src/lib/libc/arch/m68k/sys/__sigtramp2.S:1.4 Tue Jul 16 22:19:16 2013
+++ src/lib/libc/arch/m68k/sys/__sigtramp2.S Sun Nov 21 23:58:09 2021
@@ -1,4 +1,4 @@
-/* $NetBSD: __sigtramp2.S,v 1.4 2013/07/16 22:19:16 matt Exp $ */
+/* $NetBSD: __sigtramp2.S,v 1.5 2021/11/21 23:58:09 thorpej Exp $ */
/*-
* Copyright (c) 2003 The NetBSD Foundation, Inc.
@@ -27,6 +27,7 @@
*/
#include "SYS.h"
+#include "assym.h"
/*
* The m68k signal trampoline is invoked only to return from
@@ -39,7 +40,57 @@
* pointer to ucontext structure [8]
* pointer to siginfo structure [4]
* sp-> signal number [0]
+ *
+ * The DWARF register numbers are 0-7 (dX), 8-15 (aX), 16-23 (fpX),
+ * which maps nicely to _REG_D[0-7] and _REG_A[0-7]. For m68k, there
+ * is a DWARF pseudo-register for the return address, and additionally
+ * another DWARF pseudo-register for signal handler return addresses.
+ * We will specify both return address pseudo-registers (without
+ * explicitly specifying .cfi_return_column) to keep the compiler
+ * run-time happy with whichever one it decides to use.
+ */
+
+#define DWARF_RETURN_REG 24
+#if defined(__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__)
+#define DWARF_SIGRETURN_REG __LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__
+#else
+#define DWARF_SIGRETURN_REG 25
+#endif
+
+#define CFI_OFFSET_DWARF_REG(d, r) .cfi_offset d, r * 4
+#define CFI_OFFSET(r) CFI_OFFSET_DWARF_REG(r, r)
+
+ .text
+ .cfi_startproc simple
+ .cfi_signal_frame
+ .cfi_def_cfa _REG_A7, 12 + SIZEOF_SIGINFO + UC_GREGS
+ CFI_OFFSET(_REG_D0)
+ CFI_OFFSET(_REG_D1)
+ CFI_OFFSET(_REG_D2)
+ CFI_OFFSET(_REG_D3)
+ CFI_OFFSET(_REG_D4)
+ CFI_OFFSET(_REG_D5)
+ CFI_OFFSET(_REG_D6)
+ CFI_OFFSET(_REG_D7)
+ CFI_OFFSET(_REG_A0)
+ CFI_OFFSET(_REG_A1)
+ CFI_OFFSET(_REG_A2)
+ CFI_OFFSET(_REG_A3)
+ CFI_OFFSET(_REG_A4)
+ CFI_OFFSET(_REG_A5)
+ CFI_OFFSET(_REG_A6)
+ CFI_OFFSET(_REG_A7)
+ CFI_OFFSET_DWARF_REG(DWARF_RETURN_REG, _REG_PC)
+ CFI_OFFSET_DWARF_REG(DWARF_SIGRETURN_REG, _REG_PC)
+
+/*
+ * The unwind entry includes one instruction slot prior to the trampoline
+ * because the unwinder will look up to (return PC - 1 insn) while unwinding.
+ * Normally this would be the jump / branch, but since there isn't one in
+ * this case, we place an explicit nop there instead.
*/
+ nop
+
ENTRY_NOPROFILE(__sigtramp_siginfo_2)
movl 8(%sp),%a0 /* get pointer to ucontext */
movl %a0,4(%sp) /* put it in the argument slot */
@@ -47,4 +98,5 @@ ENTRY_NOPROFILE(__sigtramp_siginfo_2)
SYSTRAP(setcontext)
movl %d0,4(%sp) /* error code */
SYSTRAP(exit) /* exit */
+ .cfi_endproc
END(__sigtramp_siginfo_2)
