arc: Add support for Linux coredump files

With the implemenations in this patch, ARC gdb can handle
coredump related matters.  The binutils counter part of
this patch has already been pushed [1].

v2 [2]:
- arc_linux_collect_gregset: Use "reg <= ARC_LAST_REGNUM" instead of
  "reg < ARC_LAST_REGNUM" for the condition check of the for-loop.
- arc-linux-tdep.c: Use "ARC_LAST_REGNUM < ARRAY_SIZE (...)" instead of
  "ARC_LAST_REGNUM <= ARRAY_SIZE (...)" for the "asserts".
- Use "buf + arc_linux_core_reg_offsets[ARC_ERET_REGNUM]" instead of
  "buf + REG_OFF (6)".
- Fix a few typos/indentation.

v3 [3]:
- Use gdb_assert_not_reached(text) instead of gdb_assert (!text).
- Remove unnecessary braces in the for loop.

[1] arc: Add support for ARC HS extra registers in core files
https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=2745674244d6aecddcf636475034bdb9c0a6b4a0

[2] First remarks
https://sourceware.org/pipermail/gdb-patches/2020-September/171912.html

[3] Second remarks
https://sourceware.org/pipermail/gdb-patches/2020-October/172302.html

gdb/ChangeLog:

	* arc-linux-tdep.h: New file.
	* arc-linux-tdep.c (arc_linux_core_reg_offsets,
	arc_linux_supply_gregset, arc_linux_supply_v2_regset,
	arc_linux_collect_gregset, arc_linux_collect_v2_regset,
	arc_linux_gregset, arc_linux_v2_regset,
	arc_linux_iterate_over_regset_sections,
	arc_linux_core_read_description): Implement.
	(arc_linux_init_osabi): Set iterate_over_regset_sections.
	* arc-tdep.h (ARC_OFFSET_NO_REGISTER): Declare.
        (arc_gdbarch_features_create): Add.
	* arc-tdep.c (arc_gdbarch_features_create): Not static anymore.

1 files changed, 11 insertions, 1 deletions

diff --git a/gdb/arc-tdep.h b/gdb/arc-tdep.h
index 6331d29..09fcbea 100644
--- a/gdb/arc-tdep.h
+++ b/gdb/arc-tdep.h
@@ -85,7 +85,9 @@ enum arc_regnum
     ARC_LP_END_REGNUM,
     /* Branch target address.  */
     ARC_BTA_REGNUM,
-    ARC_LAST_AUX_REGNUM = ARC_BTA_REGNUM,
+    /* Exception return address.  */
+    ARC_ERET_REGNUM,
+    ARC_LAST_AUX_REGNUM = ARC_ERET_REGNUM,
     ARC_LAST_REGNUM = ARC_LAST_AUX_REGNUM,
 
     /* Additional ABI constants.  */
@@ -105,6 +107,9 @@ enum arc_regnum
 /* STATUS32 register: current instruction is a delay slot.  */
 #define ARC_STATUS32_DE_MASK (1 << 6)
 
+/* Special value for register offset arrays.  */
+#define ARC_OFFSET_NO_REGISTER (-1)
+
 #define arc_print(fmt, args...) fprintf_unfiltered (gdb_stdlog, fmt, ##args)
 
 extern int arc_debug;
@@ -182,4 +187,9 @@ CORE_ADDR arc_insn_get_branch_target (const struct arc_instruction &insn);
 
 CORE_ADDR arc_insn_get_linear_next_pc (const struct arc_instruction &insn);
 
+/* Create an arc_arch_features instance from the provided data.  */
+
+arc_arch_features arc_arch_features_create (const bfd *abfd,
+					    const unsigned long mach);
+
 #endif /* ARC_TDEP_H */