Module Name: src
Committed By: thorpej
Date: Thu Nov 18 04:33:20 UTC 2021
Modified Files:
src/lib/libc/arch/mips: genassym.cf
src/lib/libc/arch/mips/sys: __sigtramp2.S
Log Message:
Decorate the MIPS 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 -r1.4 -r1.5 src/lib/libc/arch/mips/genassym.cf
cvs rdiff -u -r1.3 -r1.4 src/lib/libc/arch/mips/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/mips/genassym.cf
diff -u src/lib/libc/arch/mips/genassym.cf:1.4 src/lib/libc/arch/mips/genassym.cf:1.5
--- src/lib/libc/arch/mips/genassym.cf:1.4 Thu Oct 15 05:27:53 2020
+++ src/lib/libc/arch/mips/genassym.cf Thu Nov 18 04:33:20 2021
@@ -1,4 +1,4 @@
-# $NetBSD: genassym.cf,v 1.4 2020/10/15 05:27:53 skrll Exp $
+# $NetBSD: genassym.cf,v 1.5 2021/11/18 04:33:20 thorpej Exp $
#
# Copyright (c) 2001 The NetBSD Foundation, Inc.
@@ -40,9 +40,46 @@ define _UC_GREGS_V0 offsetof(ucontext_t,
define _UC_GREGS_GP offsetof(ucontext_t, uc_mcontext.__gregs[_REG_GP])
define _UC_GREGS_SP offsetof(ucontext_t, uc_mcontext.__gregs[_REG_SP])
define _UC_GREGS_EPC offsetof(ucontext_t, uc_mcontext.__gregs[_REG_EPC])
+define _UC_GREGS offsetof(ucontext_t, uc_mcontext.__gregs[0])
define _UC_LINK offsetof(ucontext_t, uc_link)
define UCONTEXT_SIZE sizeof(ucontext_t)
+define _REG_R0 _REG_R0
+define _REG_AT _REG_AT
+define _REG_V0 _REG_V0
+define _REG_V1 _REG_V1
+define _REG_A0 _REG_A0
+define _REG_A1 _REG_A1
+define _REG_A2 _REG_A2
+define _REG_A3 _REG_A3
+define _REG_T0 _REG_T0
+define _REG_T1 _REG_T1
+define _REG_T2 _REG_T2
+define _REG_T3 _REG_T3
+define _REG_T4 _REG_T4
+define _REG_T5 _REG_T5
+define _REG_T6 _REG_T6
+define _REG_T7 _REG_T7
+define _REG_S0 _REG_S0
+define _REG_S1 _REG_S1
+define _REG_S2 _REG_S2
+define _REG_S3 _REG_S3
+define _REG_S4 _REG_S4
+define _REG_S5 _REG_S5
+define _REG_S6 _REG_S6
+define _REG_S7 _REG_S7
+define _REG_T8 _REG_T8
+define _REG_T9 _REG_T9
+define _REG_K0 _REG_K0
+define _REG_K1 _REG_K1
+define _REG_GP _REG_GP
+define _REG_SP _REG_SP
+define _REG_S8 _REG_S8
+define _REG_RA _REG_RA
+define _REG_EPC _REG_EPC
+define _REG_MDLO _REG_MDLO
+define _REG_MDHI _REG_MDHI
+
define _SC_REGS offsetof(struct sigcontext, sc_regs[0])
define _SC_REGS_V0 offsetof(struct sigcontext, sc_regs[_R_V0])
define _SC_REGS_S0 offsetof(struct sigcontext, sc_regs[_R_S0])
Index: src/lib/libc/arch/mips/sys/__sigtramp2.S
diff -u src/lib/libc/arch/mips/sys/__sigtramp2.S:1.3 src/lib/libc/arch/mips/sys/__sigtramp2.S:1.4
--- src/lib/libc/arch/mips/sys/__sigtramp2.S:1.3 Mon Dec 14 01:07:42 2009
+++ src/lib/libc/arch/mips/sys/__sigtramp2.S Thu Nov 18 04:33:20 2021
@@ -1,4 +1,4 @@
-/* $NetBSD: __sigtramp2.S,v 1.3 2009/12/14 01:07:42 matt Exp $ */
+/* $NetBSD: __sigtramp2.S,v 1.4 2021/11/18 04:33:20 thorpej Exp $ */
/*-
* Copyright (c) 2002 The NetBSD Foundation, Inc.
@@ -33,7 +33,7 @@
#include "assym.h"
#if defined(SYSLIBC_SCCS) && !defined(lint)
- RCSID("$NetBSD: __sigtramp2.S,v 1.3 2009/12/14 01:07:42 matt Exp $")
+ RCSID("$NetBSD: __sigtramp2.S,v 1.4 2021/11/18 04:33:20 thorpej Exp $")
#endif /* SYSLIBC_SCCS and not lint */
@@ -43,12 +43,80 @@
*
* On entry, stack looks like:
*
- * sp -> siginfo_t structure
- * sp + SIGINFO_SIZE -> ucontext_t structure
+ * ucontext structure sp + sizeof(siginfo_t)
+ * sp-> siginfo structure
+ *
+ * The DWARF register numbers for the general purpose registers are the
+ * same as the architected register numbers. For MIPS, there is a DWARF
+ * psuedo-register for signal handler return addresses, as well as for the
+ * MDLO and MDHI registers.
*/
+
+#define DWARF_MDHI_REG 64
+#define DWARF_MDLO_REG 65
+
+#if defined(__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__)
+#define DWARF_SIGRETURN_REG __LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__
+#else
+#define DWARF_SIGRETURN_REG 66
+#endif
+
+#define CFI_OFFSET_DWARF_REG(d, r) .cfi_offset d, r * SZREG
+#define CFI_OFFSET(r) CFI_OFFSET_DWARF_REG(r, r)
+
+ .text
+ .cfi_startproc
+ .cfi_signal_frame
+ .cfi_def_cfa _REG_SP, SIGINFO_SIZE + _UC_GREGS
+ CFI_OFFSET(_REG_R0)
+ CFI_OFFSET(_REG_AT)
+ CFI_OFFSET(_REG_V0)
+ CFI_OFFSET(_REG_V1)
+ CFI_OFFSET(_REG_A0)
+ CFI_OFFSET(_REG_A1)
+ CFI_OFFSET(_REG_A2)
+ CFI_OFFSET(_REG_A3)
+ CFI_OFFSET(_REG_T0)
+ CFI_OFFSET(_REG_T1)
+ CFI_OFFSET(_REG_T2)
+ CFI_OFFSET(_REG_T3)
+ CFI_OFFSET(_REG_T4)
+ CFI_OFFSET(_REG_T5)
+ CFI_OFFSET(_REG_T6)
+ CFI_OFFSET(_REG_T7)
+ CFI_OFFSET(_REG_S0)
+ CFI_OFFSET(_REG_S1)
+ CFI_OFFSET(_REG_S2)
+ CFI_OFFSET(_REG_S3)
+ CFI_OFFSET(_REG_S4)
+ CFI_OFFSET(_REG_S5)
+ CFI_OFFSET(_REG_S6)
+ CFI_OFFSET(_REG_S7)
+ CFI_OFFSET(_REG_T8)
+ CFI_OFFSET(_REG_T9)
+ CFI_OFFSET(_REG_K0)
+ CFI_OFFSET(_REG_K1)
+ CFI_OFFSET(_REG_GP)
+ CFI_OFFSET(_REG_SP)
+ CFI_OFFSET(_REG_S8)
+ CFI_OFFSET(_REG_RA)
+ CFI_OFFSET_DWARF_REG(DWARF_MDHI_REG, _REG_MDHI)
+ CFI_OFFSET_DWARF_REG(DWARF_MDLO_REG, _REG_MDLO)
+ .cfi_return_column DWARF_SIGRETURN_REG
+ CFI_OFFSET_DWARF_REG(DWARF_SIGRETURN_REG, _REG_EPC)
+
+/*
+ * 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
+
LEAF_NOPROFILE(__sigtramp_siginfo_2)
PTR_ADDU a0, sp, SIGINFO_SIZE /* address of ucontext */
SYSTRAP(setcontext) /* and do setcontext */
move a0, v0 /* exit with errno */
SYSTRAP(exit) /* if sigreturn fails */
+ .cfi_endproc
END(__sigtramp_siginfo_2)
