RISC-V: Add assembly support for TLSDESC.

gas/
    * tc-riscv.c (percent_op_*): Add support for %tlsdesc_hi,
    %tlsdesc_load_lo, %tlsdesc_add_lo and %tlsdesc_call. percent_op_rtype
    renamed to percent_op_relax_only as this matcher is extended to handle
    jalr as well which is not R-type.
    (riscv_ip): Apply the percent_op_relax_only rename and update comment.
    (md_apply_fix): Add TLSDESC_* to relaxable list. Add TLSDESC_HI20 to
    TLS relocation check list.
    * testsuite/gas/riscv/tlsdesc.*: New test cases for TLSDESC relocation
    generation.
opcodes/
    * riscv-opc.c (riscv_opcodes): Add a new syntax for jalr with
    %tlsdesc_call annotations.

3 files changed, 73 insertions, 5 deletions

diff --git a/gas/config/tc-riscv.c b/gas/config/tc-riscv.c
index cbead95..0966b7b 100644
--- a/gas/config/tc-riscv.c
+++ b/gas/config/tc-riscv.c
@@ -2202,6 +2202,7 @@ static const struct percent_op_match percent_op_utype[] =
   {"tprel_hi", BFD_RELOC_RISCV_TPREL_HI20},
   {"pcrel_hi", BFD_RELOC_RISCV_PCREL_HI20},
   {"got_pcrel_hi", BFD_RELOC_RISCV_GOT_HI20},
+  {"tlsdesc_hi", BFD_RELOC_RISCV_TLSDESC_HI20},
   {"tls_ie_pcrel_hi", BFD_RELOC_RISCV_TLS_GOT_HI20},
   {"tls_gd_pcrel_hi", BFD_RELOC_RISCV_TLS_GD_HI20},
   {"hi", BFD_RELOC_RISCV_HI20},
@@ -2213,6 +2214,8 @@ static const struct percent_op_match percent_op_itype[] =
   {"lo", BFD_RELOC_RISCV_LO12_I},
   {"tprel_lo", BFD_RELOC_RISCV_TPREL_LO12_I},
   {"pcrel_lo", BFD_RELOC_RISCV_PCREL_LO12_I},
+  {"tlsdesc_load_lo", BFD_RELOC_RISCV_TLSDESC_LOAD_LO12},
+  {"tlsdesc_add_lo", BFD_RELOC_RISCV_TLSDESC_ADD_LO12},
   {0, 0}
 };
 
@@ -2224,8 +2227,9 @@ static const struct percent_op_match percent_op_stype[] =
   {0, 0}
 };
 
-static const struct percent_op_match percent_op_rtype[] =
+static const struct percent_op_match percent_op_relax_only[] =
 {
+  {"tlsdesc_call", BFD_RELOC_RISCV_TLSDESC_CALL},
   {"tprel_add", BFD_RELOC_RISCV_TPREL_ADD},
   {0, 0}
 };
@@ -3386,10 +3390,10 @@ riscv_ip (char *str, struct riscv_cl_insn *ip, expressionS *imm_expr,
 	      *imm_reloc = BFD_RELOC_RISCV_LO12_I;
 	      goto load_store;
 	    case '1':
-	      /* This is used for TLS, where the fourth operand is
-		 %tprel_add, to get a relocation applied to an add
-		 instruction, for relaxation to use.  */
-	      p = percent_op_rtype;
+	      /* This is used for TLS relocations that acts as relaxation
+		 markers and do not change the instruction encoding,
+		 i.e. %tprel_add and %tlsdesc_call.  */
+	      p = percent_op_relax_only;
 	      goto alu_op;
 	    case '0': /* AMO displacement, which must be zero.  */
 	    load_store:
@@ -4252,6 +4256,7 @@ md_apply_fix (fixS *fixP, valueT *valP, segT seg ATTRIBUTE_UNUSED)
     case BFD_RELOC_RISCV_TPREL_LO12_I:
     case BFD_RELOC_RISCV_TPREL_LO12_S:
     case BFD_RELOC_RISCV_TPREL_ADD:
+    case BFD_RELOC_RISCV_TLSDESC_HI20:
       relaxable = true;
       /* Fall through.  */
 
@@ -4433,6 +4438,9 @@ md_apply_fix (fixS *fixP, valueT *valP, segT seg ATTRIBUTE_UNUSED)
 
     case BFD_RELOC_RISCV_CALL:
     case BFD_RELOC_RISCV_CALL_PLT:
+    case BFD_RELOC_RISCV_TLSDESC_LOAD_LO12:
+    case BFD_RELOC_RISCV_TLSDESC_ADD_LO12:
+    case BFD_RELOC_RISCV_TLSDESC_CALL:
       relaxable = true;
       break;
 
diff --git a/gas/testsuite/gas/riscv/tlsdesc.d b/gas/testsuite/gas/riscv/tlsdesc.d
new file mode 100644
index 0000000..5cd26ac
--- /dev/null
+++ b/gas/testsuite/gas/riscv/tlsdesc.d
@@ -0,0 +1,36 @@
+#source: tlsdesc.s
+#objdump: -dr
+
+.*:[ 	]+file format .*
+
+
+Disassembly of section .text:
+
+0+00 <_start>:
+[ 	]+0:[ 	]+00000517[ 	]+auipc[ 	]+a0,0x0
+[ 	]+0:[ 	]+R_RISCV_TLSDESC_HI20[ 	]+sg1
+[ 	]+0:[ 	]+R_RISCV_RELAX[ 	]+\*ABS\*
+[ 	]+4:[ 	]+00052283[ 	]+lw[ 	]+t0,0\(a0\) # 0( <.*>)?
+[ 	]+4:[ 	]+R_RISCV_TLSDESC_LOAD_LO12[ 	]+\.desc1
+[ 	]+4:[ 	]+R_RISCV_RELAX[ 	]+\*ABS\*
+[ 	]+8:[ 	]+00050513[ 	]+mv[ 	]+a0,a0
+[ 	]+8:[ 	]+R_RISCV_TLSDESC_ADD_LO12[ 	]+\.desc1
+[ 	]+8:[ 	]+R_RISCV_RELAX[ 	]+\*ABS\*
+[ 	]+c:[ 	]+000282e7[ 	]+jalr[ 	]+t0,t0
+[ 	]+c:[ 	]+R_RISCV_TLSDESC_CALL[ 	]+\.desc1
+[ 	]+c:[ 	]+R_RISCV_RELAX[ 	]+\*ABS\*
+
+0+10 <\.desc2>:
+[ 	]+10:[ 	]+00000517[ 	]+auipc[ 	]+a0,0x0
+[ 	]+10:[ 	]+R_RISCV_TLSDESC_HI20[ 	]+sl1
+[ 	]+10:[ 	]+R_RISCV_RELAX[ 	]+\*ABS\*
+[ 	]+14:[ 	]+00052283[ 	]+lw[ 	]+t0,0\(a0\) # 10( <.*>)?
+[ 	]+14:[ 	]+R_RISCV_TLSDESC_LOAD_LO12[ 	]+\.desc2
+[ 	]+14:[ 	]+R_RISCV_RELAX[ 	]+\*ABS\*
+[ 	]+18:[ 	]+00050513[ 	]+mv[ 	]+a0,a0
+[ 	]+18:[ 	]+R_RISCV_TLSDESC_ADD_LO12[ 	]+\.desc2
+[ 	]+18:[ 	]+R_RISCV_RELAX[ 	]+\*ABS\*
+[ 	]+1c:[ 	]+000282e7[ 	]+jalr[ 	]+t0,t0
+[ 	]+1c:[ 	]+R_RISCV_TLSDESC_CALL[ 	]+\.desc2
+[ 	]+1c:[ 	]+R_RISCV_RELAX[ 	]+\*ABS\*
+[ 	]+20:[ 	]+00008067[ 	]+ret
diff --git a/gas/testsuite/gas/riscv/tlsdesc.s b/gas/testsuite/gas/riscv/tlsdesc.s
new file mode 100644
index 0000000..15468d5
--- /dev/null
+++ b/gas/testsuite/gas/riscv/tlsdesc.s
@@ -0,0 +1,24 @@
+	.section	.tbss,"awT",@nobits
+	.global sg1
+sg1:
+	.zero	4
+sl1:
+	.zero	4
+
+	.text
+	.globl	_start
+	.type	_start,@function
+_start:
+.desc1:
+	auipc	a0, %tlsdesc_hi(sg1)
+	lw	t0, %tlsdesc_load_lo(.desc1)(a0)
+	addi	a0, a0, %tlsdesc_add_lo(.desc1)
+	jalr	t0, t0, %tlsdesc_call(.desc1)
+
+.desc2:
+	auipc	a0, %tlsdesc_hi(sl1)
+	lw	t0, %tlsdesc_load_lo(.desc2)(a0)
+	addi	a0, a0, %tlsdesc_add_lo(.desc2)
+	jalr	t0, t0, %tlsdesc_call(.desc2)
+
+	ret