Module Name: src
Committed By: thorpej
Date: Wed Nov 24 15:05:16 UTC 2021
Modified Files:
src/lib/libc/arch/vax: genassym.cf
src/lib/libc/arch/vax/sys: __sigtramp3.S
Log Message:
Decorate the VAX signal trampoline with the appropriate .cfi
directives to allow exception unwind / backtrace across a signal
handler.
N.B. This is currently disabled, as these .cfi directives cause
linker warnings about incompatible TEXTREL relocations in .eh_frame.
To generate a diff of this commit:
cvs rdiff -u -r1.5 -r1.6 src/lib/libc/arch/vax/genassym.cf
cvs rdiff -u -r1.2 -r1.3 src/lib/libc/arch/vax/sys/__sigtramp3.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/vax/genassym.cf
diff -u src/lib/libc/arch/vax/genassym.cf:1.5 src/lib/libc/arch/vax/genassym.cf:1.6
--- src/lib/libc/arch/vax/genassym.cf:1.5 Tue Jan 25 02:38:15 2011
+++ src/lib/libc/arch/vax/genassym.cf Wed Nov 24 15:05:15 2021
@@ -1,4 +1,4 @@
-# $NetBSD: genassym.cf,v 1.5 2011/01/25 02:38:15 matt Exp $
+# $NetBSD: genassym.cf,v 1.6 2021/11/24 15:05:15 thorpej Exp $
#
# Copyright (c) 2001 The NetBSD Foundation, Inc.
@@ -43,18 +43,25 @@ define _UC_SIGMASK _UC_SIGMASK
define _UC_STACK _UC_STACK
define _UC_CPU _UC_CPU
-define _REG_R0 4*_REG_R0
-define _REG_R1 4*_REG_R1
-define _REG_R2 4*_REG_R2
-define _REG_R4 4*_REG_R4
-define _REG_R6 4*_REG_R6
-define _REG_R8 4*_REG_R8
-define _REG_R10 4*_REG_R10
-define _REG_AP 4*_REG_AP
-define _REG_SP 4*_REG_SP
-define _REG_FP 4*_REG_FP
-define _REG_PC 4*_REG_PC
-define _REG_PSL 4*_REG_PSL
+define _REG_R0 _REG_R0
+define _REG_R1 _REG_R1
+define _REG_R2 _REG_R2
+define _REG_R3 _REG_R3
+define _REG_R4 _REG_R4
+define _REG_R5 _REG_R5
+define _REG_R6 _REG_R6
+define _REG_R7 _REG_R7
+define _REG_R8 _REG_R8
+define _REG_R9 _REG_R9
+define _REG_R10 _REG_R10
+define _REG_R11 _REG_R11
+define _REG_AP _REG_AP
+define _REG_FP _REG_FP
+define _REG_SP _REG_SP
+define _REG_PC _REG_PC
+define _REG_PSL _REG_PSL
+
+define SIZEOF_SIGINFO sizeof(siginfo_t)
define SS_SP offsetof(stack_t, ss_sp)
define SS_SIZE offsetof(stack_t, ss_size)
Index: src/lib/libc/arch/vax/sys/__sigtramp3.S
diff -u src/lib/libc/arch/vax/sys/__sigtramp3.S:1.2 src/lib/libc/arch/vax/sys/__sigtramp3.S:1.3
--- src/lib/libc/arch/vax/sys/__sigtramp3.S:1.2 Tue Jan 25 02:38:15 2011
+++ src/lib/libc/arch/vax/sys/__sigtramp3.S Wed Nov 24 15:05:16 2021
@@ -1,4 +1,4 @@
-/* $NetBSD: __sigtramp3.S,v 1.2 2011/01/25 02:38:15 matt Exp $ */
+/* $NetBSD: __sigtramp3.S,v 1.3 2021/11/24 15:05:16 thorpej Exp $ */
/*
* Copyright (c) 2003 Matt Thomas <[email protected]>
@@ -27,23 +27,70 @@
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
+#include "SYS.h"
+#include "assym.h"
+
+#ifdef SYSLIBC_SCCS
+RCSID("$NetBSD: __sigtramp3.S,v 1.3 2021/11/24 15:05:16 thorpej Exp $")
+#endif
+
/*
* Signal trampoline; registers when called:
* pc, psl - obvious
- * sp, ap - points to argument list
- * 4(ap) -- signo
- * 8(ap) -- pointer to siginfo
- * 12(ap) -- pointer to ucontext
+ * sp, ap - points to a CALLG argument list
* fp - address of signal handler
+ *
+ * Stack is set up like so:
+ * ucontext structure
+ * siginfo structure
+ * vvvv CALLG argument list vvvv
+ * 12(ap) -- pointer to ucontext
+ * 8(ap) -- pointer to siginfo
+ * 4(ap) -- signal number
+ * sp -> 0(ap) -- argument count
+ * ^^^^ CALLG argument list ^^^^
+ *
+ * N.B. all of the DWARF register numbers match our _REG_* constants.
+ * Also notice that while the %ap is adjusted inside the trampoline,
+ * the %sp is not adjusted, and so the CFA base does not change.
*/
-#include "SYS.h"
+#define CFI_OFFSET(r) .cfi_offset r, r * 4
-#ifdef SYSLIBC_SCCS
-RCSID("$NetBSD: __sigtramp3.S,v 1.2 2011/01/25 02:38:15 matt Exp $")
+ .text
+#if 0
+ .cfi_startproc simple
+ .cfi_signal_frame
+ .cfi_def_cfa _REG_SP, 16 + SIZEOF_SIGINFO + UC_GREGS
+ CFI_OFFSET(_REG_R0)
+ CFI_OFFSET(_REG_R1)
+ CFI_OFFSET(_REG_R2)
+ CFI_OFFSET(_REG_R3)
+ CFI_OFFSET(_REG_R4)
+ CFI_OFFSET(_REG_R5)
+ CFI_OFFSET(_REG_R6)
+ CFI_OFFSET(_REG_R7)
+ CFI_OFFSET(_REG_R8)
+ CFI_OFFSET(_REG_R9)
+ CFI_OFFSET(_REG_R10)
+ CFI_OFFSET(_REG_R11)
+ CFI_OFFSET(_REG_AP)
+ CFI_OFFSET(_REG_FP)
+ CFI_OFFSET(_REG_SP)
+ CFI_OFFSET(_REG_PC)
+ CFI_OFFSET(_REG_PSL)
#endif
- .text
+/*
+ * The unwind entry includes one instruction slot prior to the trampoline
+ * because the unwinder will look up to (return PC - 1) 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.
+ */
+
+#if 0
+ nop
+#endif
_ALIGN_TEXT
.globl _C_LABEL(__sigtramp_siginfo_3)
@@ -53,3 +100,6 @@ _C_LABEL(__sigtramp_siginfo_3):
addl2 $8,%ap # arg is pointer to ucontext
SYSTRAP(setcontext) # exit from here
halt # illegal insn
+#if 0
+ .cfi_endproc
+#endif
