Add an interface to find the ARM.exidx table for use by the ARM EHABI unwinder.

Makes exceptions work in C++ code work again om armv7.

ok guenther@

5 files changed, 88 insertions, 2 deletions

diff --git a/lib/libc/arch/arm/Makefile.inc b/lib/libc/arch/arm/Makefile.inc
index 3347bcd9a54..a20ce0c317e 100644
--- a/lib/libc/arch/arm/Makefile.inc
+++ b/lib/libc/arch/arm/Makefile.inc
@@ -1,4 +1,4 @@
-# $OpenBSD: Makefile.inc,v 1.6 2016/05/07 19:05:21 guenther Exp $
+# $OpenBSD: Makefile.inc,v 1.7 2016/09/17 20:13:48 kettenis Exp $
 # $NetBSD: Makefile.inc,v 1.5 2002/07/10 04:29:06 thorpej Exp $
 
 .include <bsd.own.mk>
@@ -9,3 +9,5 @@ CPPFLAGS += -DSOFTFLOAT
 
 SOFTFLOAT_BITS=32
 .include <arch/arm/softfloat/Makefile.inc>
+
+.include <arch/arm/dlfcn/Makefile.inc>
diff --git a/lib/libc/arch/arm/Symbols.list b/lib/libc/arch/arm/Symbols.list
index 26b3ee1a5b1..3401e5e20f5 100644
--- a/lib/libc/arch/arm/Symbols.list
+++ b/lib/libc/arch/arm/Symbols.list
@@ -85,3 +85,7 @@ shortShift64Left
 shortShift96Left
 sub64
 sub96
+
+/* dlfcn */
+dl_unwind_find_exidx
+__gnu_Unwind_Find_exidx
diff --git a/lib/libc/arch/arm/dlfcn/Makefile.inc b/lib/libc/arch/arm/dlfcn/Makefile.inc
new file mode 100644
index 00000000000..d0ada6a2360
--- /dev/null
+++ b/lib/libc/arch/arm/dlfcn/Makefile.inc
@@ -0,0 +1,5 @@
+# $OpenBSD: Makefile.inc,v 1.1 2016/09/17 20:13:48 kettenis Exp $
+
+SRCS += exidx.c
+
+.PATH: ${.CURDIR}/dlfcn
diff --git a/lib/libc/arch/arm/dlfcn/exidx.c b/lib/libc/arch/arm/dlfcn/exidx.c
new file mode 100644
index 00000000000..5f012edbc0a
--- /dev/null
+++ b/lib/libc/arch/arm/dlfcn/exidx.c
@@ -0,0 +1,75 @@
+/*	$OpenBSD: exidx.c,v 1.1 2016/09/17 20:13:48 kettenis Exp $ */
+/*
+ * Copyright (c) 2016 Mark Kettenis <kettenis@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/types.h>
+#include <link.h>
+
+void *dl_unwind_find_exidx(const void *pc, int *pcount) __attribute__((weak));
+
+struct exidx_data {
+	u_long pc;
+	void *exidx;
+	int *pcount;
+};
+
+struct exidx_entry {
+	uint32_t data[2];
+};
+
+static int
+find_exidx(struct dl_phdr_info *info, size_t size, void *p)
+{
+	struct exidx_data *data = p;
+	const Elf_Phdr *phdr;
+	void *exidx;
+	int count = 0;
+	int found = 0;
+	int i;
+
+	for (i = 0; i < info->dlpi_phnum; i++) {
+		phdr = &info->dlpi_phdr[i];
+		if (data->pc >= info->dlpi_addr + phdr->p_vaddr &&
+		    data->pc < info->dlpi_addr + phdr->p_vaddr + phdr->p_memsz)
+			found = 1;
+		if (phdr->p_type == PT_ARM_EXIDX) {
+			exidx = (void *)(info->dlpi_addr + phdr->p_vaddr);
+			count = phdr->p_memsz / sizeof(struct exidx_entry);
+		}
+	}
+
+	if (found && count > 0) {
+		data->exidx = exidx;
+		*data->pcount = count;
+		return 1;
+	}
+
+	return 0;
+}
+
+void *
+dl_unwind_find_exidx(const void *pc, int *pcount)
+{
+	struct exidx_data data;
+
+	data.pc = (u_long)pc;
+	data.pcount = pcount;
+	if (dl_iterate_phdr(find_exidx, &data))
+		return data.exidx;
+	return NULL;
+}
+
+__strong_alias(__gnu_Unwind_Find_exidx, dl_unwind_find_exidx);
diff --git a/lib/libc/shlib_version b/lib/libc/shlib_version
index 08c19ac1165..4821cfc2bd0 100644
--- a/lib/libc/shlib_version
+++ b/lib/libc/shlib_version
@@ -1,4 +1,4 @@
 major=89
-minor=1
+minor=2
 # note: If changes were made to include/thread_private.h or if system
 # calls were added/changed then librthread/shlib_version also be updated.