AArch64: Add pointer authentication feature

Pointer Authentication is a new feature in AArch64 v8.3-a. When enabled in
the compiler, function return addresses will be mangled by the kernel.

Add register description xml and wire up to aarch64_linux_read_description.
This description includes the two pauth user registers.

Nothing yet uses the feature - that is added in later patches.

gdb/ChangeLog:

	* aarch64-linux-nat.c
	(aarch64_linux_nat_target::read_description): Add pauth param.
	* aarch64-linux-tdep.c
	(aarch64_linux_core_read_description): Likewise.
	* aarch64-tdep.c (struct target_desc): Add in pauth.
	(aarch64_read_description): Add pauth param.
	(aarch64_gdbarch_init): Likewise.
	* aarch64-tdep.h (aarch64_read_description): Likewise.
	* arch/aarch64.c (aarch64_create_target_description): Likewise.
	* arch/aarch64.h (aarch64_create_target_description): Likewise.
	* features/Makefile: Add new files.
	* features/aarch64-pauth.c: New file.
	* features/aarch64-pauth.xml: New file.

gdb/doc/ChangeLog:

	* gdb.texinfo: Describe pauth feature.

gdb/gdbserver/ChangeLog:

	* linux-aarch64-ipa.c (get_ipa_tdesc): Add pauth param.
	(initialize_low_tracepoint): Likewise.
	* linux-aarch64-low.c (aarch64_arch_setup): Likewise.
	* linux-aarch64-tdesc-selftest.c (aarch64_tdesc_test): Likewise.
	* linux-aarch64-tdesc.c (struct target_desc): Likewise.
	(aarch64_linux_read_description): Likewise.
	* linux-aarch64-tdesc.h (aarch64_linux_read_description): Likewise.

6 files changed, 24 insertions, 12 deletions

diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index 9879481..9fdbe1d 100644
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,3 +1,14 @@
+2019-03-22  Alan Hayward  <alan.hayward@arm.com>
+	    Jiong Wang  <jiong.wang@arm.com>
+
+	* linux-aarch64-ipa.c (get_ipa_tdesc): Add pauth param.
+	(initialize_low_tracepoint): Likewise.
+	* linux-aarch64-low.c (aarch64_arch_setup): Likewise.
+	* linux-aarch64-tdesc-selftest.c (aarch64_tdesc_test): Likewise.
+	* linux-aarch64-tdesc.c (struct target_desc): Likewise.
+	(aarch64_linux_read_description): Likewise.
+	* linux-aarch64-tdesc.h (aarch64_linux_read_description): Likewise.
+
 2019-03-12  John Baldwin  <jhb@FreeBSD.org>
 
 	* linux-x86-tdesc.c (i386_linux_read_description): Update call to
diff --git a/gdb/gdbserver/linux-aarch64-ipa.c b/gdb/gdbserver/linux-aarch64-ipa.c
index 94db53f..3804b1e 100644
--- a/gdb/gdbserver/linux-aarch64-ipa.c
+++ b/gdb/gdbserver/linux-aarch64-ipa.c
@@ -147,12 +147,12 @@ get_raw_reg (const unsigned char *raw_regs, int regnum)
 
 /* Return target_desc to use for IPA, given the tdesc index passed by
    gdbserver.  Index is ignored, since we have only one tdesc
-   at the moment.  SVE not yet supported.  */
+   at the moment.  SVE and pauth not yet supported.  */
 
 const struct target_desc *
 get_ipa_tdesc (int idx)
 {
-  return aarch64_linux_read_description (0);
+  return aarch64_linux_read_description (0, false);
 }
 
 /* Allocate buffer for the jump pads.  The branch instruction has a reach
@@ -204,6 +204,6 @@ alloc_jump_pad_buffer (size_t size)
 void
 initialize_low_tracepoint (void)
 {
-  /* SVE not yet supported.  */
-  aarch64_linux_read_description (0);
+  /* SVE and pauth not yet supported.  */
+  aarch64_linux_read_description (0, false);
 }
diff --git a/gdb/gdbserver/linux-aarch64-low.c b/gdb/gdbserver/linux-aarch64-low.c
index 0b2946e..db329da 100644
--- a/gdb/gdbserver/linux-aarch64-low.c
+++ b/gdb/gdbserver/linux-aarch64-low.c
@@ -501,7 +501,8 @@ aarch64_arch_setup (void)
   if (is_elf64)
     {
       uint64_t vq = aarch64_sve_get_vq (tid);
-      current_process ()->tdesc = aarch64_linux_read_description (vq);
+      /* pauth not yet supported.  */
+      current_process ()->tdesc = aarch64_linux_read_description (vq, false);
     }
   else
     current_process ()->tdesc = tdesc_arm_with_neon;
diff --git a/gdb/gdbserver/linux-aarch64-tdesc-selftest.c b/gdb/gdbserver/linux-aarch64-tdesc-selftest.c
index 1b2453a..bf24a27 100644
--- a/gdb/gdbserver/linux-aarch64-tdesc-selftest.c
+++ b/gdb/gdbserver/linux-aarch64-tdesc-selftest.c
@@ -29,7 +29,7 @@ namespace tdesc {
 static void
 aarch64_tdesc_test ()
 {
-  const target_desc *tdesc = aarch64_linux_read_description (0);
+  const target_desc *tdesc = aarch64_linux_read_description (0, false);
   SELF_CHECK (*tdesc == *tdesc_aarch64);
 }
 }
diff --git a/gdb/gdbserver/linux-aarch64-tdesc.c b/gdb/gdbserver/linux-aarch64-tdesc.c
index 6ab473e..6f9b4f1 100644
--- a/gdb/gdbserver/linux-aarch64-tdesc.c
+++ b/gdb/gdbserver/linux-aarch64-tdesc.c
@@ -24,22 +24,22 @@
 #include <inttypes.h>
 
 /* All possible aarch64 target descriptors.  */
-struct target_desc *tdesc_aarch64_list[AARCH64_MAX_SVE_VQ + 1];
+struct target_desc *tdesc_aarch64_list[AARCH64_MAX_SVE_VQ + 1][2/*pauth*/];
 
 /* Create the aarch64 target description.  */
 
 const target_desc *
-aarch64_linux_read_description (uint64_t vq)
+aarch64_linux_read_description (uint64_t vq, bool pauth_p)
 {
   if (vq > AARCH64_MAX_SVE_VQ)
     error (_("VQ is %" PRIu64 ", maximum supported value is %d"), vq,
 	   AARCH64_MAX_SVE_VQ);
 
-  struct target_desc *tdesc = tdesc_aarch64_list[vq];
+  struct target_desc *tdesc = tdesc_aarch64_list[vq][pauth_p];
 
   if (tdesc == NULL)
     {
-      tdesc = aarch64_create_target_description (vq);
+      tdesc = aarch64_create_target_description (vq, pauth_p);
 
       static const char *expedite_regs_aarch64[] = { "x29", "sp", "pc", NULL };
       static const char *expedite_regs_aarch64_sve[] = { "x29", "sp", "pc",
@@ -50,7 +50,7 @@ aarch64_linux_read_description (uint64_t vq)
       else
 	init_target_desc (tdesc, expedite_regs_aarch64_sve);
 
-      tdesc_aarch64_list[vq] = tdesc;
+      tdesc_aarch64_list[vq][pauth_p] = tdesc;
     }
 
   return tdesc;
diff --git a/gdb/gdbserver/linux-aarch64-tdesc.h b/gdb/gdbserver/linux-aarch64-tdesc.h
index 7ce8150..06b3ec9 100644
--- a/gdb/gdbserver/linux-aarch64-tdesc.h
+++ b/gdb/gdbserver/linux-aarch64-tdesc.h
@@ -20,7 +20,7 @@
 #ifndef GDBSERVER_LINUX_AARCH64_TDESC_H
 #define GDBSERVER_LINUX_AARCH64_TDESC_H
 
-const target_desc * aarch64_linux_read_description (uint64_t vq);
+const target_desc * aarch64_linux_read_description (uint64_t vq, bool pauth_p);
 
 #if GDB_SELF_TEST
 void initialize_low_tdesc ();