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[PATCH v3 4/5] gdbserver: xtensa: add call0 support


Correctly handle a0- registers on requests from remote gdb. This fixes

  'Register 1 is not available'

and subsequent assertion in the remote gdb connecting to the gdbserver:

  'findvar.c:291: internal-error: value_of_register_lazy:
    Assertion `frame_id_p(get_frame_id (frame))' failed.'

The register structure is the same for windowed and call0 ABIs because
currently linux kernel internally requires windowed registers, so they
are always present.

gdb/gdbserver/
2017-01-18  Max Filippov  <jcmvbkbc@gmail.com>

	* linux-xtensa-low.c (xtensa_fill_gregset): Call collect_register
	for all registers in a0_regnum..a0_regnum + C0_NREGS range.
	(xtensa_store_gregset): Call supply_register for all registers in
	a0_regnum..a0_regnum + C0_NREGS range.
---
Changes v2->v3:
- make parts specific to call0 ABI conditional to fix gdbserver in
  windowed ABI.
- drop C0_NREGS from the commit message.

Changes v1->v2:
- add missing spaces to type casts;
- add parentheses to new conditions;
- move directory name up in the commit message.

 gdb/gdbserver/linux-xtensa-low.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/gdb/gdbserver/linux-xtensa-low.c b/gdb/gdbserver/linux-xtensa-low.c
index 98c0bf2..80b5d33 100644
--- a/gdb/gdbserver/linux-xtensa-low.c
+++ b/gdb/gdbserver/linux-xtensa-low.c
@@ -59,6 +59,20 @@ xtensa_fill_gregset (struct regcache *regcache, void *buf)
       ptr += register_size (tdesc, i);
     }
 
+  if (XSHAL_ABI == XTHAL_ABI_CALL0)
+    {
+      int a0_regnum = find_regno (tdesc, "a0");
+      ptr = (char *) &rset[R_A0 + 4 * rset[R_WB]];
+
+      for (i = a0_regnum; i < a0_regnum + C0_NREGS; i++)
+	{
+	  if ((4 * rset[R_WB] + i - a0_regnum) == XCHAL_NUM_AREGS)
+	    ptr = (char *) &rset[R_A0];
+	  collect_register (regcache, i, ptr);
+	  ptr += register_size (tdesc, i);
+	}
+    }
+
   /* Loop registers, if hardware has it.  */
 
 #if XCHAL_HAVE_LOOPS
@@ -94,6 +108,20 @@ xtensa_store_gregset (struct regcache *regcache, const void *buf)
       ptr += register_size (tdesc, i);
     }
 
+  if (XSHAL_ABI == XTHAL_ABI_CALL0)
+    {
+      int a0_regnum = find_regno (tdesc, "a0");
+      ptr = (char *) &rset[R_A0 + (4 * rset[R_WB]) % XCHAL_NUM_AREGS];
+
+      for (i = a0_regnum; i < a0_regnum + C0_NREGS; i++)
+	{
+	  if ((4 * rset[R_WB] + i - a0_regnum) == XCHAL_NUM_AREGS)
+	    ptr = (char *) &rset[R_A0];
+	  supply_register (regcache, i, ptr);
+	  ptr += register_size (tdesc, i);
+	}
+    }
+
   /* Loop registers, if hardware has it.  */
 
 #if XCHAL_HAVE_LOOPS
-- 
2.1.4


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