[gdb] Fix warning in foreach_arch selftests

When running the selftests, I run into:
...
$ gdb -q -batch -ex "maint selftest"
  ...
Running selftest execute_cfa_program::aarch64:ilp32.
warning: A handler for the OS ABI "GNU/Linux" is not built into this
configuration of GDB.  Attempting to continue with the default aarch64:ilp32
settings.
...
and likewise for execute_cfa_program::i8086 and
execute_cfa_program::ia64-elf32.

The warning can easily be reproduced outside the selftests by doing:
...
$ gdb -q -batch -ex "set arch aarch64:ilp32"
...
and can be prevented by first doing "set osabi none".

Fix the warning by setting osabi to none while doing selftests that iterate
over all architectures.

This causes a regression in the print_one_insn selftests for the ARC
architecture.

The problem is pre-existing, and can be demonstrated (already without this
patch) using:
...
$ gdb -q -batch -ex "set osabi none" -ex "maint selftest print_one_insn::A6"
Running selftest print_one_insn::A6.
Self test failed: Cannot access memory at address 0x0
Ran 1 unit tests, 1 failed
$
...

For ARC, we use the generic case in print_one_insn_test, containing this code:
...
       int kind = gdbarch_breakpoint_kind_from_pc (gdbarch, &pc);
       ...
       insn = gdbarch_sw_breakpoint_from_kind (gdbarch, kind, &bplen);
...

The problem is that with osabi linux we trigger:
...
static int
arc_linux_breakpoint_kind_from_pc (struct gdbarch *gdbarch, CORE_ADDR *pcptr)
{
  return trap_size;
}
...
but with osabi none:
...
arc_breakpoint_kind_from_pc (struct gdbarch *gdbarch, CORE_ADDR *pcptr)
{
  size_t length_with_limm = gdb_insn_length (gdbarch, *pcptr);
...
which needs access to memory, and will consequently fail.

Fix this in print_one_insn_test, in the default case, by iterating over
supported osabi's to makes sure we trigger arc_linux_breakpoint_kind_from_pc
which will give us a usable instruction to disassemble.

Tested on x86_64-linux.

1 files changed, 43 insertions, 3 deletions

diff --git a/gdb/disasm-selftests.c b/gdb/disasm-selftests.c
index 928d26f..7daa013 100644
--- a/gdb/disasm-selftests.c
+++ b/gdb/disasm-selftests.c
@@ -101,12 +101,52 @@ print_one_insn_test (struct gdbarch *gdbarch)
       {
 	/* Test disassemble breakpoint instruction.  */
 	CORE_ADDR pc = 0;
-	int kind = gdbarch_breakpoint_kind_from_pc (gdbarch, &pc);
+	int kind;
 	int bplen;
 
-	insn = gdbarch_sw_breakpoint_from_kind (gdbarch, kind, &bplen);
-	len = bplen;
+	struct gdbarch_info info;
+	info.bfd_arch_info = gdbarch_bfd_arch_info (gdbarch);
+
+	enum gdb_osabi it;
+	bool found = false;
+	for (it = GDB_OSABI_UNKNOWN; it != GDB_OSABI_INVALID;
+	     it = static_cast<enum gdb_osabi>(static_cast<int>(it) + 1))
+	  {
+	    if (it == GDB_OSABI_UNKNOWN)
+	      continue;
+
+	    info.osabi = it;
+
+	    if (it != GDB_OSABI_NONE)
+	      {
+		if (!has_gdb_osabi_handler (info))
+		  /* Unsupported.  Skip to prevent warnings like:
+		     A handler for the OS ABI <x> is not built into this
+		     configuration of GDB.  Attempting to continue with the
+		     default <y> settings.  */
+		  continue;
+	      }
+
+	    gdbarch = gdbarch_find_by_info (info);
+	    SELF_CHECK (gdbarch != NULL);
+
+	    try
+	      {
+		kind = gdbarch_breakpoint_kind_from_pc (gdbarch, &pc);
+		insn = gdbarch_sw_breakpoint_from_kind (gdbarch, kind, &bplen);
+	      }
+	    catch (...)
+	      {
+		continue;
+	      }
+	    found = true;
+	    break;
+	  }
+
+	/* Assert that we have found an instruction to disassemble.  */
+	SELF_CHECK (found);
 
+	len = bplen;
 	break;
       }
     }