backends: Hook abi_cfi for arm.

New arm_abi_cfi that defines initial CFA, rules for callee-saved regs,
including VFP ones and return register.

Note the DWARF abi extension for ARM says that "registers intentionally
unused" should also be initialized as if by DW_CFA_same_value.  The
example given is "an integer-only function might be included in one
executable file for targets with VFP and another for targets without".
We don't currently do this yet. See the DWARF and calling convention
documents:

DWARF for the ARM Architecture ABI r2.09
http://infocenter.arm.com/help/topic/com.arm.doc.ihi0040b/IHI0040B_aadwarf.pdf

Procedure Call Standard for the ARM Architecture ABI r2.09
http://infocenter.arm.com/help/topic/com.arm.doc.ihi0042e/IHI0042E_aapcs.pdf

Also adds addrcfi arm testcase.

Signed-off-by: Mark Wielaard <[email protected]>

1 files changed, 87 insertions, 0 deletions

diff --git a/backends/arm_cfi.c b/backends/arm_cfi.c
new file mode 100644
index 00000000..e0cc44bf
--- /dev/null
+++ b/backends/arm_cfi.c
@@ -0,0 +1,87 @@
+/* arm ABI-specified defaults for DWARF CFI.
+   Copyright (C) 2013 Red Hat, Inc.
+   This file is part of elfutils.
+
+   This file is free software; you can redistribute it and/or modify
+   it under the terms of either
+
+     * the GNU Lesser General Public License as published by the Free
+       Software Foundation; either version 3 of the License, or (at
+       your option) any later version
+
+   or
+
+     * the GNU General Public License as published by the Free
+       Software Foundation; either version 2 of the License, or (at
+       your option) any later version
+
+   or both in parallel, as here.
+
+   elfutils is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received copies of the GNU General Public License and
+   the GNU Lesser General Public License along with this program.  If
+   not, see <http://www.gnu.org/licenses/>.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <dwarf.h>
+
+#define BACKEND arm_
+#include "libebl_CPU.h"
+
+
+/* ABI-specified state of DWARF CFI based on:
+
+   "DWARF for the ARM Architecture ABI r2.09"
+http://infocenter.arm.com/help/topic/com.arm.doc.ihi0040b/IHI0040B_aadwarf.pdf
+
+   "Procedure Call Standard for the ARM Architecture ABI r2.09"
+http://infocenter.arm.com/help/topic/com.arm.doc.ihi0042e/IHI0042E_aapcs.pdf
+*/
+
+int
+arm_abi_cfi (Ebl *ebl __attribute__ ((unused)), Dwarf_CIE *abi_info)
+{
+  static const uint8_t abi_cfi[] =
+    {
+      /* The initial Canonical Frame Address is the value of the
+         Stack Pointer (r13) as setup in the previous frame. */
+      DW_CFA_def_cfa, ULEB128_7 (13), ULEB128_7 (0),
+
+#define SV(n) DW_CFA_same_value, ULEB128_7 (n)
+      /* Callee-saved regs r4-r8, r10, r11.  */
+      SV (4), SV (5), SV (6), SV (7), SV (8), SV (10), SV (11),
+
+      /* The link register contains the return address setup by caller.  */
+      SV (14),
+      DW_CFA_register, ULEB128_7 (15), ULEB128_7 (14), /* pc = lr */
+#undef SV
+
+      /* VFP S16-S31/D8-D15/Q4-Q7 are callee saved.
+         And uleb128 encoded with two bytes.  */
+#define ULEB128_8_2(x) ((x & 0x7f) | 0x80), 0x02
+#define SV(n) DW_CFA_same_value, ULEB128_8_2 (n)
+      SV (264), SV (265), SV (266), SV (267),
+      SV (268), SV (269), SV (270), SV (271),
+
+      /* XXX Note: registers intentionally unused by the program,
+	 for example as a consequence of the procedure call standard
+	 should be initialized as if by DW_CFA_same_value.  */
+    };
+#undef ULEB128_8_2
+#undef SV
+
+  abi_info->initial_instructions = abi_cfi;
+  abi_info->initial_instructions_end = &abi_cfi[sizeof abi_cfi];
+  abi_info->data_alignment_factor = 4;
+
+  abi_info->return_address_register = 15; /* pc.  */
+
+  return 0;
+}