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[src/trunk]: src/lib/libc/arch/powerpc Decorate the powerpc signal trampoline...
details: https://anonhg.NetBSD.org/src/rev/7aa4b27d7390
branches: trunk
changeset: 1026394:7aa4b27d7390
user: thorpej <thorpej%NetBSD.org@localhost>
date: Sun Nov 21 21:31:24 2021 +0000
description:
Decorate the powerpc signal trampoline with the appropriate .cfi
directives to allow exception unwind / backtrace across a signal
handler.
diffstat:
lib/libc/arch/powerpc/genassym.cf | 41 ++++++++++++++++-
lib/libc/arch/powerpc/sys/__sigtramp2.S | 82 ++++++++++++++++++++++++++++++++-
2 files changed, 120 insertions(+), 3 deletions(-)
diffs (168 lines):
diff -r 2da680d11bb3 -r 7aa4b27d7390 lib/libc/arch/powerpc/genassym.cf
--- a/lib/libc/arch/powerpc/genassym.cf Sun Nov 21 21:15:17 2021 +0000
+++ b/lib/libc/arch/powerpc/genassym.cf Sun Nov 21 21:31:24 2021 +0000
@@ -1,4 +1,4 @@
-# $NetBSD: genassym.cf,v 1.5 2018/02/28 21:00:02 uwe Exp $
+# $NetBSD: genassym.cf,v 1.6 2021/11/21 21:31:24 thorpej Exp $
#
# Copyright (c) 2001 The NetBSD Foundation, Inc.
@@ -42,11 +42,50 @@
define CALLFRAME_R30 offsetof(struct callframe, cf_r30)
define CALLFRAME_R31 offsetof(struct callframe, cf_r31)
+define UC_GREGS offsetof(ucontext_t, uc_mcontext.__gregs[0])
define UC_GREGS_R1 offsetof(ucontext_t, uc_mcontext.__gregs[_REG_R1])
define UC_GREGS_R3 offsetof(ucontext_t, uc_mcontext.__gregs[_REG_R3])
define UC_GREGS_R30 offsetof(ucontext_t, uc_mcontext.__gregs[_REG_R30])
define UC_GREGS_PC offsetof(ucontext_t, uc_mcontext.__gregs[_REG_PC])
+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_R12 _REG_R12
+define _REG_R13 _REG_R13
+define _REG_R14 _REG_R14
+define _REG_R15 _REG_R15
+define _REG_R16 _REG_R16
+define _REG_R17 _REG_R17
+define _REG_R18 _REG_R18
+define _REG_R19 _REG_R19
+define _REG_R20 _REG_R20
+define _REG_R21 _REG_R21
+define _REG_R22 _REG_R22
+define _REG_R23 _REG_R23
+define _REG_R24 _REG_R24
+define _REG_R25 _REG_R25
+define _REG_R26 _REG_R26
+define _REG_R27 _REG_R27
+define _REG_R28 _REG_R28
+define _REG_R29 _REG_R29
+define _REG_R30 _REG_R30
+define _REG_R31 _REG_R31
+define _REG_CR _REG_CR
+define _REG_LR _REG_LR
+define _REG_PC _REG_PC
+define _REG_CTR _REG_CTR
+define _REG_XER _REG_XER
+
define SIG_BLOCK SIG_BLOCK
define SIG_SETMASK SIG_SETMASK
diff -r 2da680d11bb3 -r 7aa4b27d7390 lib/libc/arch/powerpc/sys/__sigtramp2.S
--- a/lib/libc/arch/powerpc/sys/__sigtramp2.S Sun Nov 21 21:15:17 2021 +0000
+++ b/lib/libc/arch/powerpc/sys/__sigtramp2.S Sun Nov 21 21:31:24 2021 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: __sigtramp2.S,v 1.3 2011/01/15 07:31:12 matt Exp $ */
+/* $NetBSD: __sigtramp2.S,v 1.4 2021/11/21 21:31:24 thorpej Exp $ */
/*-
* Copyright (c) 2002 The NetBSD Foundation, Inc.
@@ -30,9 +30,10 @@
*/
#include "SYS.h"
+#include "assym.h"
#if defined(LIBC_SCCS) && !defined(lint)
-__RCSID("$NetBSD: __sigtramp2.S,v 1.3 2011/01/15 07:31:12 matt Exp $")
+__RCSID("$NetBSD: __sigtramp2.S,v 1.4 2021/11/21 21:31:24 thorpej Exp $")
#endif /* LIBC_SCCS && !lint */
/*
@@ -45,9 +46,86 @@
* srr0 address of handler
* lr address of this trampoline
*
+ * We use r30 as the CFA base register since it's been conveniently set up
+ * for us that way. The DWARF register numbers used in the .eh_frame are:
+ *
+ * 0 - 31 GPRs
+ * 32 - 63 FPRs
+ * 65 LR
+ * 66 CTR
+ * 68-75 CRs
+ * 76 XER
+ * 77 - 108 AltiVec regs
+ * 99 signal trampoline return address
+ * 109 VRSAVE
+ * 110 VCSR
+ *
+ * N.B. Only one CR slot is used (CR2) in the SVR4 ABI.
*/
+
+#define DWARF_LR_REG 65
+#define DWARF_CTR_REG 66
+#define DWARF_CR2_REG 70
+#define DWARF_XER_REG 76
+#define DWARF_SIGRETURN_REG 99
+
+#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_R30, 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_R12)
+ CFI_OFFSET(_REG_R13)
+ CFI_OFFSET(_REG_R14)
+ CFI_OFFSET(_REG_R15)
+ CFI_OFFSET(_REG_R16)
+ CFI_OFFSET(_REG_R17)
+ CFI_OFFSET(_REG_R18)
+ CFI_OFFSET(_REG_R19)
+ CFI_OFFSET(_REG_R20)
+ CFI_OFFSET(_REG_R21)
+ CFI_OFFSET(_REG_R22)
+ CFI_OFFSET(_REG_R23)
+ CFI_OFFSET(_REG_R24)
+ CFI_OFFSET(_REG_R25)
+ CFI_OFFSET(_REG_R26)
+ CFI_OFFSET(_REG_R27)
+ CFI_OFFSET(_REG_R28)
+ CFI_OFFSET(_REG_R29)
+ CFI_OFFSET(_REG_R30)
+ CFI_OFFSET(_REG_R31)
+ CFI_OFFSET_DWARF_REG(DWARF_CR2_REG, _REG_CR)
+ CFI_OFFSET_DWARF_REG(DWARF_LR_REG, _REG_LR)
+ CFI_OFFSET_DWARF_REG(DWARF_CTR_REG, _REG_CTR)
+ CFI_OFFSET_DWARF_REG(DWARF_XER_REG, _REG_XER)
+ .cfi_return_column DWARF_SIGRETURN_REG
+ 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)
mr %r3,%r30 /* restore ucontext pointer */
_DOSYSCALL(setcontext) /* restore machine state */
_DOSYSCALL(exit) /* or exit with errno if failed */
+ .cfi_endproc
END(__sigtramp_siginfo_2)
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