[RFC PATCH 4/5] gdb/aarch64: core file support for FPMR

[<Ezra.Sitorus@arm.com>]

From: Ezra Sitorus <ezra.sitorus@arm.com>

Add support for FPMR dumps/reads for core files.

Manually validated with Shrinkwrap (Arm FVP).
---
 gdb/aarch64-linux-tdep.c | 67 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 67 insertions(+)

diff --git a/gdb/aarch64-linux-tdep.c b/gdb/aarch64-linux-tdep.c
index b4911d36410..731f05bae5a 100644
--- a/gdb/aarch64-linux-tdep.c
+++ b/gdb/aarch64-linux-tdep.c
@@ -1519,6 +1519,56 @@ aarch64_linux_collect_zt_regset (const struct regset *regset,
 			    AARCH64_SME2_ZT0_SIZE);
 }
 
+/* Supply register REGNUM from BUF to REGCACHE, using the register map
+   in REGSET.  If REGNUM is -1, do this for all registers in REGSET.
+   If BUF is NULL, set the registers to "unavailable" status.  */
+
+static void
+aarch64_linux_supply_fpmr_regset (const struct regset *regset,
+				struct regcache *regcache,
+				int regnum, const void *buf, size_t size)
+{
+  /* Read the FPMR note from a core file into the register buffer.  */
+
+  /* Make sure the buffer contains at least the expected amount of data we are
+     supposed to get.  */
+  gdb_assert (size >= sizeof (uint64_t));
+
+  /* Handle an empty buffer.  */
+  if (buf == nullptr)
+    return regcache->supply_regset (regset, regnum, nullptr, size);
+
+  aarch64_gdbarch_tdep *tdep
+    = gdbarch_tdep<aarch64_gdbarch_tdep> (regcache->arch ());
+
+  /* Supply the ZT0 register contents.  */
+  regcache->raw_supply (tdep->fpmr_regnum, buf);
+}
+
+/* Collect register REGNUM from REGCACHE to BUF, using the register
+   map in REGSET.  If REGNUM is -1, do this for all registers in
+   REGSET.  */
+
+static void
+aarch64_linux_collect_fpmr_regset (const struct regset *regset,
+				 const struct regcache *regcache,
+				 int regnum, void *buf, size_t size)
+{
+  /* Read the FPMR contents from the register buffer into the core
+     file section.  */
+
+  /* Make sure the buffer can hold the data we need to return.  */
+  gdb_assert (size >= sizeof (uint64_t));
+  gdb_assert (buf != nullptr);
+
+  aarch64_gdbarch_tdep *tdep
+    = gdbarch_tdep<aarch64_gdbarch_tdep> (regcache->arch ());
+
+  /* Dump the register cache contents for the FPMR to the buffer.  */
+  regcache->collect_regset (regset, tdep->fpmr_regnum, buf,
+			    sizeof (uint64_t));
+}
+
 /* Implement the "iterate_over_regset_sections" gdbarch method.  */
 
 static void
@@ -1636,6 +1686,23 @@ aarch64_linux_iterate_over_regset_sections (struct gdbarch *gdbarch,
 	}
     }
 
+  if (tdep->has_fpmr ())
+    {
+      const struct regcache_map_entry fpmr_regmap[] =
+	{
+	  { 1, tdep->fpmr_regnum, sizeof (uint64_t) }
+	};
+
+	const struct regset aarch64_linux_fpmr_regset =
+	{
+	  fpmr_regmap, aarch64_linux_supply_fpmr_regset,
+	  aarch64_linux_collect_fpmr_regset
+	};
+
+	cb (".reg-aarch-fpmr", sizeof (uint64_t), sizeof (uint64_t),
+	    &aarch64_linux_fpmr_regset, "FPMR", cb_data);
+    }
+
   if (tdep->has_pauth ())
     {
       /* Create this on the fly in order to handle the variable location.  */
-- 
2.45.2