From b7fe5463cf0dd6d7701d0be5ae129a9d4ecd28bc Mon Sep 17 00:00:00 2001
From: John Baldwin <jhb@FreeBSD.org>
Date: Tue, 3 May 2022 16:05:10 -0700
Subject: [PATCH] Fetch the NT_ARM_TLS register set for native FreeBSD/Aarch64
 processes.

This permits resolving TLS variables.
---
 gdb/aarch64-fbsd-nat.c | 54 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)

diff --git a/gdb/aarch64-fbsd-nat.c b/gdb/aarch64-fbsd-nat.c
index 99e2bf35276..910bf5bb190 100644
--- a/gdb/aarch64-fbsd-nat.c
+++ b/gdb/aarch64-fbsd-nat.c
@@ -24,12 +24,15 @@
 #include "target.h"
 #include "nat/aarch64-hw-point.h"
 
+#include "elf/common.h"
+
 #include <sys/param.h>
 #include <sys/ptrace.h>
 #include <machine/armreg.h>
 #include <machine/reg.h>
 
 #include "fbsd-nat.h"
+#include "aarch64-tdep.h"
 #include "aarch64-fbsd-tdep.h"
 #include "aarch64-nat.h"
 #include "inf-ptrace.h"
@@ -50,6 +53,8 @@ struct aarch64_fbsd_nat_target final : public fbsd_nat_target
   void fetch_registers (struct regcache *, int) override;
   void store_registers (struct regcache *, int) override;
 
+  const struct target_desc *read_description () override;
+
 #ifdef HAVE_DBREG
   /* Hardware breakpoints and watchpoints.  */
   bool stopped_by_watchpoint () override;
@@ -84,6 +89,26 @@ aarch64_fbsd_nat_target::fetch_registers (struct regcache *regcache,
 				  &aarch64_fbsd_gregset);
   fetch_register_set<struct fpreg> (regcache, regnum, PT_GETFPREGS,
 				    &aarch64_fbsd_fpregset);
+
+  gdbarch *gdbarch = regcache->arch ();
+  aarch64_gdbarch_tdep *tdep = (aarch64_gdbarch_tdep *) gdbarch_tdep (gdbarch);
+  if (tdep->has_tls ())
+    {
+      const struct regcache_map_entry aarch64_fbsd_tls_regmap[] =
+	{
+	  { 1, tdep->tls_regnum, 8 },
+	  { 0 }
+	};
+
+      const struct regset aarch64_fbsd_tls_regset =
+	{
+	  aarch64_fbsd_tls_regmap,
+	  regcache_supply_regset, regcache_collect_regset
+	};
+
+      fetch_regset<uint64_t> (regcache, regnum, NT_ARM_TLS,
+			      &aarch64_fbsd_tls_regset);
+    }
 }
 
 /* Store register REGNUM back into the inferior.  If REGNUM is -1, do
@@ -97,6 +122,35 @@ aarch64_fbsd_nat_target::store_registers (struct regcache *regcache,
 				  &aarch64_fbsd_gregset);
   store_register_set<struct fpreg> (regcache, regnum, PT_GETFPREGS,
 				    PT_SETFPREGS, &aarch64_fbsd_fpregset);
+
+  gdbarch *gdbarch = regcache->arch ();
+  aarch64_gdbarch_tdep *tdep = (aarch64_gdbarch_tdep *) gdbarch_tdep (gdbarch);
+  if (tdep->has_tls ())
+    {
+      const struct regcache_map_entry aarch64_fbsd_tls_regmap[] =
+	{
+	  { 1, tdep->tls_regnum, 8 },
+	  { 0 }
+	};
+
+      const struct regset aarch64_fbsd_tls_regset =
+	{
+	  aarch64_fbsd_tls_regmap,
+	  regcache_supply_regset, regcache_collect_regset
+	};
+
+      store_regset<uint64_t> (regcache, regnum, NT_ARM_TLS,
+			      &aarch64_fbsd_tls_regset);
+    }
+}
+
+/* Implement the target read_description method.  */
+
+const struct target_desc *
+aarch64_fbsd_nat_target::read_description ()
+{
+  bool tls = have_regset (inferior_ptid, NT_ARM_TLS) != 0;
+  return aarch64_read_description (0, false, false, tls);
 }
 
 #ifdef HAVE_DBREG
-- 
2.30.2