gdbserver/s390: Add fast tracepoint support.

Fast tracepoints will only work on 6-byte intructions, and assume at least
a z900 CPU.  s390 also has 4-byte jump instructions, which also work on
pre-z900, but their range is limitted to +-64kiB, which is not very useful
(and wouldn't work at all with current jump pad allocation).

There's a little problem with s390_relocate_instruction function: it
converts BRAS/BRASL instructions to LARL of the return address + JG
to the target address.  On 31-bit, this sets the high bit of the target
register to 0, while BRAS/BRASL would set it to 1.  While this is not
a problem when the result is only used to address memory, it could
possibly break something that expects to compare such addresses for
equality without first masking the bit off.  In particular, I'm not sure
whether leaving the return address high bit unset is ABI-compliant
(could confuse some unwinder?).  If that's a problem, it could be fixed
by handling it in the jump pad (since at that point we can just modify
the GPRs in the save area without having to worry about preserving
CCs and only having that one GPR to work with - I'm not sure if it's
even possible to set the high bit with such constraints).

gdb/gdbserver/ChangeLog:

	PR 18377
	* Makefile.in: Add s390 IPA files.
	* configure.srv: Build IPA for s390.
	* linux-s390-ipa.c: New file.
	* linux-s390-low.c: New includes - inttypes.h and linux-s390-tdesc.h.
	(init_registers_s390_linux32): Move declaration to linux-s390-tdesc.h.
	(tdesc_s390_linux32): Likewise.
	(init_registers_s390_linux32v1): Likewise.
	(tdesc_s390_linux32v1): Likewise.
	(init_registers_s390_linux32v2): Likewise.
	(tdesc_s390_linux32v2): Likewise.
	(init_registers_s390_linux64): Likewise.
	(tdesc_s390_linux64): Likewise.
	(init_registers_s390_linux64v1): Likewise.
	(tdesc_s390_linux64v1): Likewise.
	(init_registers_s390_linux64v2): Likewise.
	(tdesc_s390_linux64v2): Likewise.
	(init_registers_s390_te_linux64): Likewise.
	(tdesc_s390_te_linux64): Likewise.
	(init_registers_s390_vx_linux64): Likewise.
	(tdesc_s390_vx_linux64): Likewise.
	(init_registers_s390_tevx_linux64): Likewise.
	(tdesc_s390_tevx_linux64): Likewise.
	(init_registers_s390x_linux64): Likewise.
	(tdesc_s390x_linux64): Likewise.
	(init_registers_s390x_linux64v1): Likewise.
	(tdesc_s390x_linux64v1): Likewise.
	(init_registers_s390x_linux64v2): Likewise.
	(tdesc_s390x_linux64v2): Likewise.
	(init_registers_s390x_te_linux64): Likewise.
	(tdesc_s390x_te_linux64): Likewise.
	(init_registers_s390x_vx_linux64): Likewise.
	(tdesc_s390x_vx_linux64): Likewise.
	(init_registers_s390x_tevx_linux64): Likewise.
	(tdesc_s390x_tevx_linux64): Likewise.
	(have_hwcap_s390_vx): New static variable.
	(s390_arch_setup): Fill have_hwcap_s390_vx.
	(s390_get_thread_area): New function.
	(s390_ft_entry_gpr_esa): New const.
	(s390_ft_entry_gpr_zarch): New const.
	(s390_ft_entry_misc): New const.
	(s390_ft_entry_fr): New const.
	(s390_ft_entry_vr): New const.
	(s390_ft_main_31): New const.
	(s390_ft_main_64): New const.
	(s390_ft_exit_fr): New const.
	(s390_ft_exit_vr): New const.
	(s390_ft_exit_misc): New const.
	(s390_ft_exit_gpr_esa): New const.
	(s390_ft_exit_gpr_zarch): New const.
	(append_insns): New function.
	(s390_relocate_instruction): New function.
	(s390_install_fast_tracepoint_jump_pad): New function.
	(s390_get_min_fast_tracepoint_insn_len): New function.
	(s390_get_ipa_tdesc_idx): New function.
	(struct linux_target_ops): Wire in the above functions.
	(initialize_low_arch) [!__s390x__]: Don't initialize s390x tdescs.
	* linux-s390-tdesc.h: New file.

1 files changed, 102 insertions, 0 deletions

diff --git a/gdb/gdbserver/linux-s390-tdesc.h b/gdb/gdbserver/linux-s390-tdesc.h
new file mode 100644
index 00000000000..501cc8811f7
--- /dev/null
+++ b/gdb/gdbserver/linux-s390-tdesc.h
@@ -0,0 +1,102 @@
+/* Low level support for s390, shared between gdbserver and IPA.
+
+   Copyright (C) 2016 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* Note: since IPA obviously knows what ABI it's running on (s390 vs s390x),
+   it's sufficient to pass only the register set here.  This, together with
+   the ABI known at IPA compile time, maps to a tdesc.  */
+
+enum s390_linux_tdesc {
+  S390_TDESC_32,
+  S390_TDESC_32V1,
+  S390_TDESC_32V2,
+  S390_TDESC_64,
+  S390_TDESC_64V1,
+  S390_TDESC_64V2,
+  S390_TDESC_TE,
+  S390_TDESC_VX,
+  S390_TDESC_TEVX,
+};
+
+#ifdef __s390x__
+
+/* Defined in auto-generated file s390x-linux64.c.  */
+void init_registers_s390x_linux64 (void);
+extern const struct target_desc *tdesc_s390x_linux64;
+
+/* Defined in auto-generated file s390x-linux64v1.c.  */
+void init_registers_s390x_linux64v1 (void);
+extern const struct target_desc *tdesc_s390x_linux64v1;
+
+/* Defined in auto-generated file s390x-linux64v2.c.  */
+void init_registers_s390x_linux64v2 (void);
+extern const struct target_desc *tdesc_s390x_linux64v2;
+
+/* Defined in auto-generated file s390x-te-linux64.c.  */
+void init_registers_s390x_te_linux64 (void);
+extern const struct target_desc *tdesc_s390x_te_linux64;
+
+/* Defined in auto-generated file s390x-vx-linux64.c.  */
+void init_registers_s390x_vx_linux64 (void);
+extern const struct target_desc *tdesc_s390x_vx_linux64;
+
+/* Defined in auto-generated file s390x-tevx-linux64.c.  */
+void init_registers_s390x_tevx_linux64 (void);
+extern const struct target_desc *tdesc_s390x_tevx_linux64;
+
+#endif
+
+#if !defined __s390x__ || !defined IN_PROCESS_AGENT
+
+/* Defined in auto-generated file s390-linux32.c.  */
+void init_registers_s390_linux32 (void);
+extern const struct target_desc *tdesc_s390_linux32;
+
+/* Defined in auto-generated file s390-linux32v1.c.  */
+void init_registers_s390_linux32v1 (void);
+extern const struct target_desc *tdesc_s390_linux32v1;
+
+/* Defined in auto-generated file s390-linux32v2.c.  */
+void init_registers_s390_linux32v2 (void);
+extern const struct target_desc *tdesc_s390_linux32v2;
+
+/* Defined in auto-generated file s390-linux64.c.  */
+void init_registers_s390_linux64 (void);
+extern const struct target_desc *tdesc_s390_linux64;
+
+/* Defined in auto-generated file s390-linux64v1.c.  */
+void init_registers_s390_linux64v1 (void);
+extern const struct target_desc *tdesc_s390_linux64v1;
+
+/* Defined in auto-generated file s390-linux64v2.c.  */
+void init_registers_s390_linux64v2 (void);
+extern const struct target_desc *tdesc_s390_linux64v2;
+
+/* Defined in auto-generated file s390-te-linux64.c.  */
+void init_registers_s390_te_linux64 (void);
+extern const struct target_desc *tdesc_s390_te_linux64;
+
+/* Defined in auto-generated file s390-vx-linux64.c.  */
+void init_registers_s390_vx_linux64 (void);
+extern const struct target_desc *tdesc_s390_vx_linux64;
+
+/* Defined in auto-generated file s390-tevx-linux64.c.  */
+void init_registers_s390_tevx_linux64 (void);
+extern const struct target_desc *tdesc_s390_tevx_linux64;
+
+#endif