[PATCH] RISC-V: Add FP register core file support.

[Jim Wilson <jimw@sifive.com>]

This adds fp reg support similar to the existing general reg support.

This fixes one gdb testsuite failure
FAIL: gdb.base/gcore.exp: corefile restored system registers
which fails without the patch because fcsr was missing.  Otherwise, no
regressions with riscv64-linux native testsuite run.

	gdb/
	* riscv-linux-tdep.c (riscv_linux_fregmap): New.
	(riscv_linux_fregset): New.
	(riscv_linux_iterate_over_regset_sections): Call cb for .reg2 section.
---
 gdb/riscv-linux-tdep.c | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/gdb/riscv-linux-tdep.c b/gdb/riscv-linux-tdep.c
index e1f8e76567..91061c5b3e 100644
--- a/gdb/riscv-linux-tdep.c
+++ b/gdb/riscv-linux-tdep.c
@@ -37,6 +37,16 @@ static const struct regcache_map_entry riscv_linux_gregmap[] =
   { 0 }
 };
 
+/* Define the FP register mapping.  The kernel puts the 32 FP regs first, and
+   then FCSR.  */
+
+static const struct regcache_map_entry riscv_linux_fregmap[] =
+{
+  { 32, RISCV_FIRST_FP_REGNUM, 0 },
+  { 1, RISCV_CSR_FCSR_REGNUM, 0 },
+  { 0 }
+};
+
 /* Define the general register regset.  */
 
 static const struct regset riscv_linux_gregset =
@@ -44,6 +54,13 @@ static const struct regset riscv_linux_gregset =
   riscv_linux_gregmap, regcache_supply_regset, regcache_collect_regset
 };
 
+/* Define the FP register regset.  */
+
+static const struct regset riscv_linux_fregset =
+{
+  riscv_linux_fregmap, regcache_supply_regset, regcache_collect_regset
+};
+
 /* Define hook for core file support.  */
 
 static void
@@ -54,8 +71,10 @@ riscv_linux_iterate_over_regset_sections (struct gdbarch *gdbarch,
 {
   cb (".reg", (32 * riscv_isa_xlen (gdbarch)), (32 * riscv_isa_xlen (gdbarch)),
       &riscv_linux_gregset, NULL, cb_data);
-
-  /* TODO: Add FP register support.  */
+  /* The kernel is adding 8 bytes for FCSR.  */
+  cb (".reg2", (32 * riscv_isa_flen (gdbarch)) + 8,
+      (32 * riscv_isa_flen (gdbarch)) + 8,
+      &riscv_linux_fregset, NULL, cb_data);
 }
 
 /* Signal trampoline support.  */
-- 
2.17.1