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From: Nelson Chu <nelson.chu@sifive.com>
To: binutils@sourceware.org, gdb-patches@sourceware.org, jimw@sifive.com,
 andrew.burgess@embecosm.com, kito.cheng@sifive.com, palmer@dabbelt.com,
 andrew@sifive.com
Subject: [PATCH v2 2/3] RISC-V: PR27916, Support mapping symbols.
Date: Fri,  9 Jul 2021 00:28:24 -0700
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Similar to ARM/AARCH64, we add mapping symbols in the symbol table,
to mark the start addresses of data and instructions.  The $d means
data, the $x means instruction, and the $a means code alignment.
Then the disassembler uses these symbols to decide whether we should
dump data or instruction.

For example,
$ cat tmp.s
  .text
  .option norelax
  .option norvc
  .fill 2, 4, 0x1001    # $d for 8 bytes fill data.
  .byte 1               # $d1
  .word 0               # $d4
  .align 3              # $a1 for align.byte, $a for align.nop.
  nop                   # $x
  .fill 5, 2, 0x2002    # $d for 10 bytes fill data.
  nop                   # $x
  .data
  .word 0x1             # No need to add mapping symbols.
  .word 0x2

$ riscv64-unknown-elf-as tmp.s -o tmp.o
$ riscv64-unknown-elf-objdump -D tmp.o

Disassembly of section .text:

0000000000000000 <.text>:
   0:   00001001                .word   0x00001001
   4:   00001001                .word   0x00001001
   8:   01                      .byte   0x01
   9:   00000000                .word   0x00000000
   d:   00                      align.byte
   e:   0001                    align.nop
  10:   00000013                nop
  14:   10001000                .word   0x20022002
  18:   10001000                .word   0x20022002
  1c:   1000                    .short  0x2002
  1e:   00000013                nop
  22:   0001                    align.nop
  24:   00000013                align.nop

Disassembly of section .data:

0000000000000000 <.data>:
   0:   00000001                .word   0x00000001
   4:   00000002                .word   0x00000002

Disassembly of section .riscv.attributes:

0000000000000000 <.riscv.attributes>:
   0:   00002d41                .word   0x00002d41
... skip ...

There are too many issues we can discuss from the above example,
so I just pick some of them that I think are important to mention.

* The documentation for -D says that on ARM platforms -D should
  disassemble instructions.  Therefore, they dump data by searching
  mapping symbols only when the DISASSEMBLE_DATA is set.  That causes
  the mapping symbols are useless for -D.  I am not sure if any riscv
  document had mentioned this, so I prefer to keep them useful, but
  only for text sections.  Otherwise, dump other sections as datas.

* If the data are written by cons_worker, then we add mapping symbols
  with the data size, to show more detials.  For example,

  .text
  .byte 1
  .word 0

  The $d1 is added for .byte, and $d4 is added for .word, so that
  we can show the code that is closer to the user's original code,
  rather than the data with 5 bytes size.

* Add the align.<insn> prefix if the instructions are used for
  alignment and marked with $a/$a1.  One of the benefits is that,
  we can distinguish c.nop and align.nop, when the rvc is disabled.
  The c.nop is illegal, but the align.nop is legal.

  Besides, we may dump .align.unimp at the end of sections when relax
  is enabled, this is expected.  Since the tail section alignments are
  not handled in the riscv_frag_align_code, and it cannot be filled with
  nops in the riscv_handle_align either.

The elf/linux toolchain regressions all passed.  Besides, I also
disable the mapping symbols internally, but use the new objudmp, the
regressions passed, too.  Therefore, the new objudmp should dump
the objects corretly, even if they don't have any mapping symbols.

ChangeLog:

bfd/

	pr 27916
	* cpu-riscv.c (riscv_elf_is_mapping_symbols): Define mapping symbols.
	* cpu-riscv.h: extern riscv_elf_is_mapping_symbols.
	* elfnn-riscv.c (riscv_maybe_function_sym): Do not choose mapping
	symbols as a function name.
	(riscv_elf_is_target_special_symbol): Add mapping symbols.

binutils/

	pr 27916
	* readelf (get_symbol_for_build_attribute): Filter data mapping
	symbols with size.
	* testsuite/binutils-all/readelf.s: Updated.
	* testsuite/binutils-all/readelf.s-64: Likewise.
	* testsuite/binutils-all/readelf.s-64-unused: Likewise.
	* testsuite/binutils-all/readelf.ss: Likewise.
	* testsuite/binutils-all/readelf.ss-64: Likewise.
	* testsuite/binutils-all/readelf.ss-64-unused: Likewise.

gas/

	pr 27916
	config/tc-riscv.c (make_mapping_symbol): Create a new mapping symbol.
	(riscv_mapping_state): Decide whether to create mapping symbol for
	frag_now.  Only add the mapping symbols to text sections.
	(riscv_add_odd_padding_symbol): Add the odd bytes of paddings for
	riscv_handle_align.
	(riscv_check_mapping_symbols): Remove any excess mapping symbols.
	(md_assemble): Marked as MAP_INSN.
	(riscv_frag_align_code): Marked as MAP_ALIGN.
	(riscv_init_frag): Add mapping symbols for frag, it usually called
	by frag_var.  Marked as MAP_DATA for rs_align and rs_fill, and
	marked as alignment MAP_ALIGN for rs_align_code.
	(s_riscv_insn): Marked as MAP_INSN.
	(riscv_adjust_symtab): Call riscv_check_mapping_symbols.
	* config/tc-riscv.h (md_cons_align): Defined to riscv_mapping_state
	with MAP_DATA_CONS[0|1|2|3].
	(TC_SEGMENT_INFO_TYPE): Record mapping state for each segment.
	(TC_FRAG_TYPE): Record the first and last mapping symbols for the
	fragments.  The first mapping symbol must be placed at the start
	of the fragment.
	(TC_FRAG_INIT): Defined to riscv_init_frag.
	* testsuite/gas/riscv/mapping-01.s: New testcase.
	* testsuite/gas/riscv/mapping-01a.d: Likewise.
	* testsuite/gas/riscv/mapping-01b.d: Likewise.
	* testsuite/gas/riscv/mapping-02.s: Likewise.
	* testsuite/gas/riscv/mapping-02a.d: Likewise.
	* testsuite/gas/riscv/mapping-02b.d: Likewise.
	* testsuite/gas/riscv/mapping-03.s: Likewise.
	* testsuite/gas/riscv/mapping-03a.d: Likewise.
	* testsuite/gas/riscv/mapping-03b.d: Likewise.
	* testsuite/gas/riscv/mapping-04.s: Likewise.
	* testsuite/gas/riscv/mapping-04a.d: Likewise.
	* testsuite/gas/riscv/mapping-04b.d: Likewise.
	* testsuite/gas/riscv/mapping-norelax-04a.d: Likewise.
	* testsuite/gas/riscv/mapping-norelax-04b.d: Likewise.
	* testsuite/gas/riscv/no-relax-align.d: Updated.
	* testsuite/gas/riscv/no-relax-align-2.d: Likewise.

include/

	pr 27916
	* opcode/riscv.h (enum riscv_seg_mstate): Added.

opcodes/

	pr 27916
	* riscv-dis.c (last_map_symbol, last_stop_offset, last_section,
	last_map_state): Added to dump sections with mapping symbols.
	(riscv_get_map_state): Get the mapping state from the symbol.
	(riscv_search_mapping_symbol): Check the sorted symbol table, and
	then find the suitable mapping symbol.
	(riscv_data_length): Decide which data size we should print.
	(riscv_disassemble_data): Dump the data contents.
	(riscv_disassemble_insn): Dump align.<insn> for MAP_ALIGN.
	(print_insn_riscv): Handle the mapping symbols.
	(riscv_symbol_is_valid): Marked mapping symbols as invalid.
---
 bfd/cpu-riscv.c                               |  10 +
 bfd/cpu-riscv.h                               |   3 +
 bfd/elfnn-riscv.c                             |  25 +-
 binutils/readelf.c                            |   8 +-
 binutils/testsuite/binutils-all/readelf.s-64  |   5 +-
 .../binutils-all/readelf.s-64-unused          |   5 +-
 binutils/testsuite/binutils-all/readelf.ss    |   2 +
 binutils/testsuite/binutils-all/readelf.ss-64 |   7 +-
 .../binutils-all/readelf.ss-64-unused         |   7 +-
 .../testsuite/binutils-all/readelf.ss-unused  |   2 +
 gas/config/tc-riscv.c                         | 223 ++++++++++++-
 gas/config/tc-riscv.h                         |  32 ++
 gas/testsuite/gas/riscv/mapping-01.s          |  18 +
 gas/testsuite/gas/riscv/mapping-01a.d         |  17 +
 gas/testsuite/gas/riscv/mapping-01b.d         |  21 ++
 gas/testsuite/gas/riscv/mapping-02.s          |  13 +
 gas/testsuite/gas/riscv/mapping-02a.d         |  15 +
 gas/testsuite/gas/riscv/mapping-02b.d         |  16 +
 gas/testsuite/gas/riscv/mapping-03.s          |  10 +
 gas/testsuite/gas/riscv/mapping-03a.d         |  16 +
 gas/testsuite/gas/riscv/mapping-03b.d         |  16 +
 gas/testsuite/gas/riscv/mapping-04.s          |  11 +
 gas/testsuite/gas/riscv/mapping-04a.d         |  21 ++
 gas/testsuite/gas/riscv/mapping-04b.d         |  24 ++
 gas/testsuite/gas/riscv/mapping-norelax-04a.d |  23 ++
 gas/testsuite/gas/riscv/mapping-norelax-04b.d |  25 ++
 gas/testsuite/gas/riscv/no-relax-align-2.d    |  19 +-
 gas/testsuite/gas/riscv/no-relax-align.d      |   4 +-
 include/opcode/riscv.h                        |  13 +
 opcodes/riscv-dis.c                           | 313 +++++++++++++++++-
 30 files changed, 885 insertions(+), 39 deletions(-)
 create mode 100644 gas/testsuite/gas/riscv/mapping-01.s
 create mode 100644 gas/testsuite/gas/riscv/mapping-01a.d
 create mode 100644 gas/testsuite/gas/riscv/mapping-01b.d
 create mode 100644 gas/testsuite/gas/riscv/mapping-02.s
 create mode 100644 gas/testsuite/gas/riscv/mapping-02a.d
 create mode 100644 gas/testsuite/gas/riscv/mapping-02b.d
 create mode 100644 gas/testsuite/gas/riscv/mapping-03.s
 create mode 100644 gas/testsuite/gas/riscv/mapping-03a.d
 create mode 100644 gas/testsuite/gas/riscv/mapping-03b.d
 create mode 100644 gas/testsuite/gas/riscv/mapping-04.s
 create mode 100644 gas/testsuite/gas/riscv/mapping-04a.d
 create mode 100644 gas/testsuite/gas/riscv/mapping-04b.d
 create mode 100644 gas/testsuite/gas/riscv/mapping-norelax-04a.d
 create mode 100644 gas/testsuite/gas/riscv/mapping-norelax-04b.d

diff --git a/bfd/cpu-riscv.c b/bfd/cpu-riscv.c
index 025e94afd34..dae76e7fdcc 100644
--- a/bfd/cpu-riscv.c
+++ b/bfd/cpu-riscv.c
@@ -140,3 +140,13 @@ riscv_get_priv_spec_class_from_numbers (unsigned int major,
   RISCV_GET_PRIV_SPEC_CLASS (buf, class_t);
   *class = class_t;
 }
+
+/* Define mapping symbols for riscv.  */
+
+bool
+riscv_elf_is_mapping_symbols (const char *name)
+{
+  return (!strncmp (name, "$d", 2)
+	  || !strncmp (name, "$x", 2)
+	  || !strncmp (name, "$a", 2));
+}
diff --git a/bfd/cpu-riscv.h b/bfd/cpu-riscv.h
index cafaca23be0..ed5ee7e60d5 100644
--- a/bfd/cpu-riscv.h
+++ b/bfd/cpu-riscv.h
@@ -79,3 +79,6 @@ riscv_get_priv_spec_class_from_numbers (unsigned int,
 					unsigned int,
 					unsigned int,
 					enum riscv_spec_class *);
+
+extern bool
+riscv_elf_is_mapping_symbols (const char *);
diff --git a/bfd/elfnn-riscv.c b/bfd/elfnn-riscv.c
index 85a99f3d610..a10384cd4d3 100644
--- a/bfd/elfnn-riscv.c
+++ b/bfd/elfnn-riscv.c
@@ -5150,14 +5150,32 @@ riscv_elf_obj_attrs_arg_type (int tag)
   return (tag & 1) != 0 ? ATTR_TYPE_FLAG_STR_VAL : ATTR_TYPE_FLAG_INT_VAL;
 }
 
-/* PR27584, Omit local and empty symbols since they usually generated
-   for pcrel relocations.  */
+/* Do not choose mapping symbols as a function name.  */
+
+static bfd_size_type
+riscv_maybe_function_sym (const asymbol *sym,
+			  asection *sec,
+			  bfd_vma *code_off)
+{
+  if (sym->flags & BSF_LOCAL
+      && riscv_elf_is_mapping_symbols (sym->name))
+    return 0;
+
+  return _bfd_elf_maybe_function_sym (sym, sec, code_off);
+}
+
+/* Treat the following cases as target special symbols, they are
+   usually omitted.  */
 
 static bool
 riscv_elf_is_target_special_symbol (bfd *abfd, asymbol *sym)
 {
+  /* PR27584, local and empty symbols.  Since they are usually
+     generated for pcrel relocations.  */
   return (!strcmp (sym->name, "")
-	  || _bfd_elf_is_local_label_name (abfd, sym->name));
+	  || _bfd_elf_is_local_label_name (abfd, sym->name)
+	  /* PR27916, mapping symbols.  */
+	  || riscv_elf_is_mapping_symbols (sym->name));
 }
 
 static int
@@ -5245,6 +5263,7 @@ riscv_elf_modify_segment_map (bfd *abfd,
 #define elf_backend_grok_psinfo			riscv_elf_grok_psinfo
 #define elf_backend_object_p			riscv_elf_object_p
 #define elf_backend_write_core_note		riscv_write_core_note
+#define elf_backend_maybe_function_sym		riscv_maybe_function_sym
 #define elf_info_to_howto_rel			NULL
 #define elf_info_to_howto			riscv_info_to_howto_rela
 #define bfd_elfNN_bfd_relax_section		_bfd_riscv_relax_section
diff --git a/binutils/readelf.c b/binutils/readelf.c
index 24ff069edf4..7560e0f6a51 100644
--- a/binutils/readelf.c
+++ b/binutils/readelf.c
@@ -20283,10 +20283,14 @@ get_symbol_for_build_attribute (Filedata *filedata,
 	  continue;
 
 	/* The AArch64 and ARM architectures define mapping symbols
-	   (eg $d, $x, $t) which we want to ignore.  */
+	   (eg $d, $x, $t) which we want to ignore.  Besides, riscv
+	   may defines data mapping symbols with size (eg $d1, $d2,
+	   $d4, $d8), which we also want to ignore.  */
 	if (ba_cache.strtab[sym->st_name] == '$'
 	    && ba_cache.strtab[sym->st_name + 1] != 0
-	    && ba_cache.strtab[sym->st_name + 2] == 0)
+	    && (ba_cache.strtab[sym->st_name + 2] == 0
+		|| (ba_cache.strtab[sym->st_name + 2] != 0
+		    && ba_cache.strtab[sym->st_name + 3] == 0)))
 	  continue;
 
 	if (is_open_attr)
diff --git a/binutils/testsuite/binutils-all/readelf.s-64 b/binutils/testsuite/binutils-all/readelf.s-64
index 4c957f7a938..0b1bafee537 100644
--- a/binutils/testsuite/binutils-all/readelf.s-64
+++ b/binutils/testsuite/binutils-all/readelf.s-64
@@ -19,8 +19,9 @@ Section Headers:
  +\[ .\] .symtab +SYMTAB +0000000000000000 +0+.*
 # aarch64-elf targets have one more data symbol.
 # x86 targets may have .note.gnu.property.
-# riscv targets have .riscv.attributes.
- +0+.* +0000000000000018 +(6|7) +(3|4) +8
+# riscv targets have five more symbols, one is .riscv.attributes,
+# others are mapping data symbols.
+ +0+.* +0000000000000018 +(6|7) +(3|4|8) +8
  +\[ .\] .strtab +STRTAB +0000000000000000 +0+.*
  +0+.* +0000000000000000 .* +0 +0 +1
  +\[ .\] .shstrtab +STRTAB +0000000000000000 +[0-9a-f]+
diff --git a/binutils/testsuite/binutils-all/readelf.s-64-unused b/binutils/testsuite/binutils-all/readelf.s-64-unused
index 771439411a0..542bbb70064 100644
--- a/binutils/testsuite/binutils-all/readelf.s-64-unused
+++ b/binutils/testsuite/binutils-all/readelf.s-64-unused
@@ -19,8 +19,9 @@ Section Headers:
  +\[ .\] .symtab +SYMTAB +0000000000000000 +0+.*
 # aarch64-elf targets have one more data symbol.
 # x86 targets may have .note.gnu.property.
-# riscv targets have .riscv.attributes.
- +0+.* +0000000000000018 +(6|7) +(6|7) +8
+# riscv targets have five more symbols, one is .riscv.attributes,
+# others are mapping data symbols.
+ +0+.* +0000000000000018 +(6|7) +(6|7|11) +8
  +\[ .\] .strtab +STRTAB +0000000000000000 +0+.*
  +0+.* +0000000000000000 .* +0 +0 +1
  +\[ .\] .shstrtab +STRTAB +0000000000000000 +[0-9a-f]+
diff --git a/binutils/testsuite/binutils-all/readelf.ss b/binutils/testsuite/binutils-all/readelf.ss
index b81c016e9e7..5d96649c2a0 100644
--- a/binutils/testsuite/binutils-all/readelf.ss
+++ b/binutils/testsuite/binutils-all/readelf.ss
@@ -5,8 +5,10 @@ Symbol table '.symtab' contains .* entries:
  +1: 00000000 +0 +NOTYPE +LOCAL +DEFAULT +1 static_text_symbol
 # ARM targets add the $d mapping symbol here...
 # NDS32 targets add the $d2 mapping symbol here...
+# riscv targets add the $d4 mapping symbols here...
 #...
  +.: 00000000 +0 +NOTYPE +LOCAL +DEFAULT +[34] static_data_symbol
+# ... or here ...
 # v850 targets include extra SECTION symbols here for the .call_table_data
 # and .call_table_text sections.
 # riscv targets add .riscv.attribute symbol here...
diff --git a/binutils/testsuite/binutils-all/readelf.ss-64 b/binutils/testsuite/binutils-all/readelf.ss-64
index c6ffb0fc523..105f1b88361 100644
--- a/binutils/testsuite/binutils-all/readelf.ss-64
+++ b/binutils/testsuite/binutils-all/readelf.ss-64
@@ -4,13 +4,14 @@ Symbol table '.symtab' contains .* entries:
  +0: 0000000000000000 +0 +NOTYPE +LOCAL +DEFAULT +UND 
  +1: 0000000000000000 +0 +NOTYPE +LOCAL +DEFAULT +1 static_text_symbol
 # aarch64-elf targets add the $d mapping symbol here...
+# riscv targets add the $d4 mapping symbols here...
 #...
  +.: 0000000000000000 +0 +NOTYPE +LOCAL +DEFAULT +3 static_data_symbol
 # ... or here ...
 # riscv targets add .riscv.attribute symbol here...
 #...
-.* +.: 0000000000000000 +0 +NOTYPE +GLOBAL +DEFAULT +1 text_symbol
- +.: 0000000000000000 +0 +NOTYPE +GLOBAL +DEFAULT +UND external_symbol
- +.: 0000000000000000 +0 +NOTYPE +GLOBAL +DEFAULT +3 data_symbol
+.* +[0-9]+: 0000000000000000 +0 +NOTYPE +GLOBAL +DEFAULT +1 text_symbol
+ +[0-9]+: 0000000000000000 +0 +NOTYPE +GLOBAL +DEFAULT +UND external_symbol
+ +[0-9]+: 0000000000000000 +0 +NOTYPE +GLOBAL +DEFAULT +3 data_symbol
  +[0-9]+: 0000000000000004 +4 +(COMMON|OBJECT) +GLOBAL +DEFAULT +COM common_symbol
 #pass
diff --git a/binutils/testsuite/binutils-all/readelf.ss-64-unused b/binutils/testsuite/binutils-all/readelf.ss-64-unused
index cf515aa60d0..50fca025b31 100644
--- a/binutils/testsuite/binutils-all/readelf.ss-64-unused
+++ b/binutils/testsuite/binutils-all/readelf.ss-64-unused
@@ -7,13 +7,14 @@ Symbol table '.symtab' contains .* entries:
  +3: 0000000000000000 +0 +SECTION +LOCAL +DEFAULT +4.*
  +4: 0000000000000000 +0 +NOTYPE +LOCAL +DEFAULT +1 static_text_symbol
 # aarch64-elf targets add the $d mapping symbol here...
+# riscv targets add the $d4 mapping symbols here...
 #...
  +.: 0000000000000000 +0 +NOTYPE +LOCAL +DEFAULT +3 static_data_symbol
 # ... or here ...
 # riscv targets add .riscv.attribute symbol here...
 #...
-.* +.: 0000000000000000 +0 +NOTYPE +GLOBAL +DEFAULT +1 text_symbol
- +.: 0000000000000000 +0 +NOTYPE +GLOBAL +DEFAULT +UND external_symbol
- +.: 0000000000000000 +0 +NOTYPE +GLOBAL +DEFAULT +3 data_symbol
+.* +[0-9]+: 0000000000000000 +0 +NOTYPE +GLOBAL +DEFAULT +1 text_symbol
+ +[0-9]+: 0000000000000000 +0 +NOTYPE +GLOBAL +DEFAULT +UND external_symbol
+ +[0-9]+: 0000000000000000 +0 +NOTYPE +GLOBAL +DEFAULT +3 data_symbol
  +[0-9]+: 0000000000000004 +4 +(COMMON|OBJECT) +GLOBAL +DEFAULT +COM common_symbol
 #pass
diff --git a/binutils/testsuite/binutils-all/readelf.ss-unused b/binutils/testsuite/binutils-all/readelf.ss-unused
index 3107af930eb..944ab45cc46 100644
--- a/binutils/testsuite/binutils-all/readelf.ss-unused
+++ b/binutils/testsuite/binutils-all/readelf.ss-unused
@@ -8,8 +8,10 @@ Symbol table '.symtab' contains .* entries:
  +4: 00000000 +0 +NOTYPE +LOCAL +DEFAULT +1 static_text_symbol
 # ARM targets add the $d mapping symbol here...
 # NDS32 targets add the $d2 mapping symbol here...
+# riscv targets add the $d4 mapping symbols here...
 #...
  +.: 00000000 +0 +NOTYPE +LOCAL +DEFAULT +[34] static_data_symbol
+# ... or here ...
 # v850 targets include extra SECTION symbols here for the .call_table_data
 # and .call_table_text sections.
 #...
diff --git a/gas/config/tc-riscv.c b/gas/config/tc-riscv.c
index df37579c843..55c49471825 100644
--- a/gas/config/tc-riscv.c
+++ b/gas/config/tc-riscv.c
@@ -561,6 +561,179 @@ static bool explicit_priv_attr = false;
 
 static char *expr_end;
 
+/* Create a new mapping symbol for the transition to STATE.  */
+
+static void
+make_mapping_symbol (enum riscv_seg_mstate state,
+		     valueT value,
+		     fragS *frag)
+{
+  const char *name;
+  switch (state)
+    {
+    case MAP_DATA:
+      name = "$d";
+      break;
+    case MAP_DATA_CONS0:
+      name = "$d1";
+      break;
+    case MAP_DATA_CONS1:
+      name = "$d2";
+      break;
+    case MAP_DATA_CONS2:
+      name = "$d4";
+      break;
+    case MAP_DATA_CONS3:
+      name = "$d8";
+      break;
+    case MAP_INSN:
+      name = "$x";
+      break;
+    case MAP_ALIGN:
+      name = "$a";
+      break;
+    case MAP_ALIGN_ODD:
+      name = "$a1";
+      break;
+    default:
+      abort ();
+    }
+
+  symbolS *symbol = symbol_new (name, now_seg, frag, value);
+  symbol_get_bfdsym (symbol)->flags |= (BSF_NO_FLAGS | BSF_LOCAL);
+
+  /* If .fill or other data filling directive generates zero sized data,
+     or we are adding odd alignemnts, then the mapping symbol for the
+     following code will have the same value.  */
+  if (value == 0)
+    {
+       if (frag->tc_frag_data.first_map_symbol != NULL)
+	{
+	  know (S_GET_VALUE (frag->tc_frag_data.first_map_symbol)
+		== S_GET_VALUE (symbol));
+	  /* Remove the old one.  */
+	  symbol_remove (frag->tc_frag_data.first_map_symbol,
+			 &symbol_rootP, &symbol_lastP);
+	}
+      frag->tc_frag_data.first_map_symbol = symbol;
+    }
+  if (frag->tc_frag_data.last_map_symbol != NULL)
+    {
+      /* The mapping symbols should be added in offset order.  */
+      know (S_GET_VALUE (frag->tc_frag_data.last_map_symbol)
+			 <= S_GET_VALUE (symbol));
+      /* Remove the old one.  */
+      if (S_GET_VALUE (frag->tc_frag_data.last_map_symbol)
+	  == S_GET_VALUE (symbol))
+	symbol_remove (frag->tc_frag_data.last_map_symbol,
+		       &symbol_rootP, &symbol_lastP);
+    }
+  frag->tc_frag_data.last_map_symbol = symbol;
+}
+
+/* Set the mapping state for frag_now.  */
+
+void
+riscv_mapping_state (enum riscv_seg_mstate to_state,
+		     int max_chars)
+{
+  enum riscv_seg_mstate from_state =
+	seg_info (now_seg)->tc_segment_info_data.map_state;
+
+  if (!SEG_NORMAL (now_seg)
+      /* For now I only add the mapping symbols to text sections.
+	 Therefore, the dis-assembler only show the actual contents
+	 distribution for text.  Other sections will be shown as
+	 data without the details.  */
+      || !subseg_text_p (now_seg))
+    return;
+
+  /* Keep inserting the MAP_DATA_CONS in text.  Otherwise, the mapping
+     symbol should be emitted.  */
+  if (from_state == to_state
+      && from_state != MAP_DATA_CONS0
+      && from_state != MAP_DATA_CONS1
+      && from_state != MAP_DATA_CONS2
+      && from_state != MAP_DATA_CONS3)
+    return;
+
+  valueT value = (valueT) (frag_now_fix () - max_chars);
+  seg_info (now_seg)->tc_segment_info_data.map_state = to_state;
+  make_mapping_symbol (to_state, value, frag_now);
+}
+
+/* Add the odd bytes of paddings for riscv_handle_align.  */
+
+static void
+riscv_add_odd_padding_symbol (fragS *frag)
+{
+  /* If there was already a mapping symbol, it should be
+     removed in the make_mapping_symbol.  */
+  make_mapping_symbol (MAP_ALIGN_ODD, frag->fr_fix, frag);
+  make_mapping_symbol (MAP_ALIGN, frag->fr_fix + 1, frag);
+}
+
+/* Remove any excess mapping symbols generated for alignment frags in
+   SEC.  We may have created a mapping symbol before a zero byte
+   alignment; remove it if there's a mapping symbol after the
+   alignment.  */
+
+static void
+riscv_check_mapping_symbols (bfd *abfd ATTRIBUTE_UNUSED,
+			     asection *sec,
+			     void *dummy ATTRIBUTE_UNUSED)
+{
+  segment_info_type *seginfo = seg_info (sec);
+  fragS *fragp;
+
+  if (seginfo == NULL || seginfo->frchainP == NULL)
+    return;
+
+  for (fragp = seginfo->frchainP->frch_root;
+       fragp != NULL;
+       fragp = fragp->fr_next)
+    {
+      symbolS *last = fragp->tc_frag_data.last_map_symbol;
+      fragS *next = fragp->fr_next;
+
+      if (last == NULL || next == NULL)
+	continue;
+
+      /* Check the last mapping symbol if it is at the boundary of
+	 fragmnet.  */
+      if (S_GET_VALUE (last) < next->fr_address)
+	continue;
+      know (S_GET_VALUE (last) == next->fr_address);
+
+      do
+	{
+	  if (next->tc_frag_data.first_map_symbol != NULL)
+	    {
+	      /* The last mapping symbol overlaps with another one
+		 which at the start of the next frag.  */
+	      symbol_remove (last, &symbol_rootP, &symbol_lastP);
+	      break;
+	    }
+
+	  if (next->fr_next == NULL)
+	    {
+	      /* The last mapping symbol is at the end of the section.  */
+	      know (next->fr_fix == 0 && next->fr_var == 0);
+	      symbol_remove (last, &symbol_rootP, &symbol_lastP);
+	      break;
+	    }
+
+	  /* Since we may have empty frags without any mapping symbols,
+	     keep looking until the non-empty frag.  */
+	  if (next->fr_address != next->fr_next->fr_address)
+	    break;
+
+	  next = next->fr_next;
+	}
+      while (next != NULL);
+    }
+}
+
 /* The default target format to use.  */
 
 const char *
@@ -2767,6 +2940,8 @@ md_assemble (char *str)
        return;
     }
 
+  riscv_mapping_state (MAP_INSN, 0);
+
   const char *error = riscv_ip (str, &insn, &imm_expr, &imm_reloc, op_hash);
 
   if (error)
@@ -3422,6 +3597,8 @@ riscv_frag_align_code (int n)
   fix_new_exp (frag_now, nops - frag_now->fr_literal, 0,
 	       &ex, false, BFD_RELOC_RISCV_ALIGN);
 
+  riscv_mapping_state (MAP_ALIGN, worst_case_bytes);
+
   return true;
 }
 
@@ -3441,6 +3618,7 @@ riscv_handle_align (fragS *fragP)
 	  /* We have 4 byte uncompressed nops.  */
 	  bfd_signed_vma size = 4;
 	  bfd_signed_vma excess = bytes % size;
+	  bfd_boolean odd_padding = (excess % 2 == 1);
 	  char *p = fragP->fr_literal + fragP->fr_fix;
 
 	  if (bytes <= 0)
@@ -3449,12 +3627,20 @@ riscv_handle_align (fragS *fragP)
 	  /* Insert zeros or compressed nops to get 4 byte alignment.  */
 	  if (excess)
 	    {
+	      if (odd_padding)
+		riscv_add_odd_padding_symbol (fragP);
 	      riscv_make_nops (p, excess);
 	      fragP->fr_fix += excess;
 	      p += excess;
 	    }
 
-	  /* Insert variable number of 4 byte uncompressed nops.  */
+	  /* The frag will be changed to `rs_fill` later.  The function
+	     `write_contents` will try to fill the remaining spaces
+	     according to the patterns we give.  In this case, we give
+	     a 4 byte uncompressed nop as the pattern, and set the size
+	     of the pattern into `fr_var`.  The nop will be output to the
+	     file `fr_offset` times.  However, `fr_offset` could be zero
+	     if we don't need to pad the boundary finally.  */
 	  riscv_make_nops (p, size);
 	  fragP->fr_var = size;
 	}
@@ -3465,6 +3651,30 @@ riscv_handle_align (fragS *fragP)
     }
 }
 
+/* This usually called from frag_var.  */
+
+void
+riscv_init_frag (fragS * fragP, int max_chars)
+{
+  /* Do not add mapping symbol to debug sections.  */
+  if (bfd_section_flags (now_seg) & SEC_DEBUGGING)
+    return;
+
+  switch (fragP->fr_type)
+    {
+    case rs_fill:
+    case rs_align:
+    case rs_align_test:
+      riscv_mapping_state (MAP_DATA, max_chars);
+      break;
+    case rs_align_code:
+      riscv_mapping_state (MAP_ALIGN, max_chars);
+      break;
+    default:
+      break;
+    }
+}
+
 int
 md_estimate_size_before_relax (fragS *fragp, asection *segtype)
 {
@@ -3721,6 +3931,8 @@ s_riscv_insn (int x ATTRIBUTE_UNUSED)
   save_c = *input_line_pointer;
   *input_line_pointer = '\0';
 
+  riscv_mapping_state (MAP_INSN, 0);
+
   const char *error = riscv_ip (str, &insn, &imm_expr,
 				&imm_reloc, insn_type_hash);
 
@@ -3811,6 +4023,15 @@ riscv_md_end (void)
   riscv_set_public_attributes ();
 }
 
+/* Adjust the symbol table.  */
+
+void
+riscv_adjust_symtab (void)
+{
+  bfd_map_over_sections (stdoutput, riscv_check_mapping_symbols, (char *) 0);
+  elf_adjust_symtab ();
+}
+
 /* Given a symbolic attribute NAME, return the proper integer value.
    Returns -1 if the attribute is not known.  */
 
diff --git a/gas/config/tc-riscv.h b/gas/config/tc-riscv.h
index 1de138458d8..1702b25bc51 100644
--- a/gas/config/tc-riscv.h
+++ b/gas/config/tc-riscv.h
@@ -128,4 +128,36 @@ extern void riscv_elf_final_processing (void);
 extern void riscv_md_end (void);
 extern int riscv_convert_symbolic_attribute (const char *);
 
+/* Set mapping symbol states.  */
+#define md_cons_align(nbytes)					\
+  switch (nbytes)						\
+    {								\
+    default: riscv_mapping_state (MAP_DATA, 0); break;		\
+    case 1:  riscv_mapping_state (MAP_DATA_CONS0, 0); break;	\
+    case 2:  riscv_mapping_state (MAP_DATA_CONS1, 0); break;	\
+    case 4:  riscv_mapping_state (MAP_DATA_CONS2, 0); break;	\
+    case 8:  riscv_mapping_state (MAP_DATA_CONS3, 0); break;	\
+    }
+void riscv_mapping_state (enum riscv_seg_mstate, int);
+
+/* Define target segment type.  */
+#define TC_SEGMENT_INFO_TYPE struct riscv_segment_info_type
+struct riscv_segment_info_type
+{
+  enum riscv_seg_mstate map_state;
+};
+
+/* Define target fragment type.  */
+#define TC_FRAG_TYPE struct riscv_frag_type
+struct riscv_frag_type
+{
+  symbolS *first_map_symbol, *last_map_symbol;
+};
+
+#define TC_FRAG_INIT(fragp, max_bytes) riscv_init_frag (fragp, max_bytes)
+extern void riscv_init_frag (struct frag *, int);
+
+#define obj_adjust_symtab() riscv_adjust_symtab ()
+extern void riscv_adjust_symtab (void);
+
 #endif /* TC_RISCV */
diff --git a/gas/testsuite/gas/riscv/mapping-01.s b/gas/testsuite/gas/riscv/mapping-01.s
new file mode 100644
index 00000000000..0a270454b1b
--- /dev/null
+++ b/gas/testsuite/gas/riscv/mapping-01.s
@@ -0,0 +1,18 @@
+	.option norvc
+	.text
+	.global	funcA
+funcA:
+	nop
+	j	funcB
+
+	.global	funcB
+funcB:
+	nop
+	bne	a0, a1, funcB
+
+	.data
+	.word 0x123456
+
+	.section	.foo, "ax"
+foo:
+	nop
diff --git a/gas/testsuite/gas/riscv/mapping-01a.d b/gas/testsuite/gas/riscv/mapping-01a.d
new file mode 100644
index 00000000000..32e0027a13d
--- /dev/null
+++ b/gas/testsuite/gas/riscv/mapping-01a.d
@@ -0,0 +1,17 @@
+#as:
+#source: mapping-01.s
+#objdump: --syms --special-syms
+
+.*file format.*riscv.*
+
+SYMBOL TABLE:
+0+00 l    d  .text	0+00 .text
+0+00 l    d  .data	0+00 .data
+0+00 l    d  .bss	0+00 .bss
+0+00 l       .text	0+00 \$x
+0+00 l    d  .foo	0+00 .foo
+0+00 l       .foo	0+00 foo
+0+00 l       .foo	0+00 \$x
+0+00 l    d  .riscv.attributes	0+00 .riscv.attributes
+0+00 g       .text	0+00 funcA
+0+08 g       .text	0+00 funcB
diff --git a/gas/testsuite/gas/riscv/mapping-01b.d b/gas/testsuite/gas/riscv/mapping-01b.d
new file mode 100644
index 00000000000..723bd5951cb
--- /dev/null
+++ b/gas/testsuite/gas/riscv/mapping-01b.d
@@ -0,0 +1,21 @@
+#as:
+#source: mapping-01.s
+#objdump: -d
+
+.*:[ 	]+file format .*
+
+
+Disassembly of section .text:
+
+0+000 <funcA>:
+[ 	]+0:[ 	]+00000013[ 	]+nop
+[ 	]+4:[ 	]+0040006f[ 	]+j[ 	]+8 <funcB>
+
+0+008 <funcB>:
+[ 	]+8:[ 	]+00000013[ 	]+nop
+[ 	]+c:[ 	]+feb51ee3[ 	]+bne[ 	]+a0,a1,8 <funcB>
+
+Disassembly of section .foo:
+
+0+000 <foo>:
+[ 	]+0:[ 	]+00000013[ 	]+nop
diff --git a/gas/testsuite/gas/riscv/mapping-02.s b/gas/testsuite/gas/riscv/mapping-02.s
new file mode 100644
index 00000000000..d3de6dedac8
--- /dev/null
+++ b/gas/testsuite/gas/riscv/mapping-02.s
@@ -0,0 +1,13 @@
+	.option norvc
+	.text
+	.global main
+	.type   main, %function
+main:
+	nop
+foo:
+	nop
+	nop
+	.size   main, .-main
+	.ident  ""
+
+	nop
diff --git a/gas/testsuite/gas/riscv/mapping-02a.d b/gas/testsuite/gas/riscv/mapping-02a.d
new file mode 100644
index 00000000000..d0cb460e08e
--- /dev/null
+++ b/gas/testsuite/gas/riscv/mapping-02a.d
@@ -0,0 +1,15 @@
+#as:
+#source: mapping-02.s
+#objdump: --syms --special-syms
+
+.*file format.*riscv.*
+
+SYMBOL TABLE:
+0+00 l    d  .text	0+00 .text
+0+00 l    d  .data	0+00 .data
+0+00 l    d  .bss	0+00 .bss
+0+00 l       .text	0+00 \$x
+0+04 l       .text	0+00 foo
+0+00 l    d  .comment	0+00 .comment
+0+00 l    d  .riscv.attributes	0+00 .riscv.attributes
+0+00 g     F .text	0+0c main
diff --git a/gas/testsuite/gas/riscv/mapping-02b.d b/gas/testsuite/gas/riscv/mapping-02b.d
new file mode 100644
index 00000000000..3e875600a9c
--- /dev/null
+++ b/gas/testsuite/gas/riscv/mapping-02b.d
@@ -0,0 +1,16 @@
+#as:
+#source: mapping-02.s
+#objdump: -d
+
+.*:[ 	]+file format .*
+
+
+Disassembly of section .text:
+
+0+000 <main>:
+[ 	]+0:[ 	]+00000013[ 	]+nop
+
+0+004 <foo>:
+[ 	]+4:[ 	]+00000013[ 	]+nop
+[ 	]+8:[ 	]+00000013[ 	]+nop
+[ 	]+c:[ 	]+00000013[ 	]+nop
diff --git a/gas/testsuite/gas/riscv/mapping-03.s b/gas/testsuite/gas/riscv/mapping-03.s
new file mode 100644
index 00000000000..49964f20288
--- /dev/null
+++ b/gas/testsuite/gas/riscv/mapping-03.s
@@ -0,0 +1,10 @@
+	.option norvc
+	.text
+	.word 0
+	nop
+	.data
+	.word 0
+	.text
+	nop
+	.short 0
+	nop
diff --git a/gas/testsuite/gas/riscv/mapping-03a.d b/gas/testsuite/gas/riscv/mapping-03a.d
new file mode 100644
index 00000000000..8567820b941
--- /dev/null
+++ b/gas/testsuite/gas/riscv/mapping-03a.d
@@ -0,0 +1,16 @@
+#as:
+#source: mapping-03.s
+#objdump: --syms --special-syms
+
+.*file format.*riscv.*
+
+SYMBOL TABLE:
+0+00 l    d  .text	0+00 .text
+0+00 l    d  .data	0+00 .data
+0+00 l    d  .bss	0+00 .bss
+0+00 l       .text	0+00 \$d4
+0+04 l       .text	0+00 \$x
+0+0c l       .text	0+00 \$d2
+0+0e l       .text	0+00 \$x
+0+12 l       .text	0+00 \$a
+0+00 l    d  .riscv.attributes	0+00 .riscv.attributes
diff --git a/gas/testsuite/gas/riscv/mapping-03b.d b/gas/testsuite/gas/riscv/mapping-03b.d
new file mode 100644
index 00000000000..ed87fcf33d2
--- /dev/null
+++ b/gas/testsuite/gas/riscv/mapping-03b.d
@@ -0,0 +1,16 @@
+#as:
+#source: mapping-03.s
+#objdump: -d
+
+.*:[ 	]+file format .*
+
+
+Disassembly of section .text:
+
+0+000 <.text>:
+[ 	]+0:[ 	]+00000000[ 	]+.word[ 	]+0x00000000
+[ 	]+4:[ 	]+00000013[ 	]+nop
+[ 	]+8:[ 	]+00000013[ 	]+nop
+[ 	]+c:[ 	]+0000[ 	]+.short[ 	]+0x0000
+[ 	]+e:[ 	]+00000013[ 	]+nop
+#...
diff --git a/gas/testsuite/gas/riscv/mapping-04.s b/gas/testsuite/gas/riscv/mapping-04.s
new file mode 100644
index 00000000000..36bfac11050
--- /dev/null
+++ b/gas/testsuite/gas/riscv/mapping-04.s
@@ -0,0 +1,11 @@
+	.option norvc
+	.text
+	nop
+	.long	0
+	.align	4
+	.word	0x12345678
+	nop
+	.byte	1
+	.long	0
+	.align	4
+	.word	0x12345678
diff --git a/gas/testsuite/gas/riscv/mapping-04a.d b/gas/testsuite/gas/riscv/mapping-04a.d
new file mode 100644
index 00000000000..a3bb31a98b4
--- /dev/null
+++ b/gas/testsuite/gas/riscv/mapping-04a.d
@@ -0,0 +1,21 @@
+#as:
+#source: mapping-04.s
+#objdump: --syms --special-syms
+
+.*file format.*riscv.*
+
+SYMBOL TABLE:
+0+00 l    d  .text	0+00 .text
+0+00 l    d  .data	0+00 .data
+0+00 l    d  .bss	0+00 .bss
+0+00 l       .text	0+00 \$x
+0+04 l       .text	0+00 \$d4
+0+08 l       .text	0+00 \$a
+0+14 l       .text	0+00 \$d4
+0+18 l       .text	0+00 \$x
+0+1c l       .text	0+00 \$d1
+0+1d l       .text	0+00 \$d4
+0+21 l       .text	0+00 \$a
+0+2d l       .text	0+00 \$d4
+0+31 l       .text	0+00 \$a
+0+00 l    d  .riscv.attributes	0+00 .riscv.attributes
diff --git a/gas/testsuite/gas/riscv/mapping-04b.d b/gas/testsuite/gas/riscv/mapping-04b.d
new file mode 100644
index 00000000000..d27b98db2ae
--- /dev/null
+++ b/gas/testsuite/gas/riscv/mapping-04b.d
@@ -0,0 +1,24 @@
+#as:
+#source: mapping-04.s
+#objdump: -d
+
+.*:[ 	]+file format .*
+
+
+Disassembly of section .text:
+
+0+000 <.text>:
+[ 	]+0:[ 	]+00000013[ 	]+nop
+[ 	]+4:[ 	]+00000000[ 	]+.word[ 	]+0x00000000
+[ 	]+8:[ 	]+00000013[ 	]+align.nop
+[ 	]+c:[ 	]+00000013[ 	]+align.nop
+[ 	]+10:[ 	]+00000013[ 	]+align.nop
+[ 	]+14:[ 	]+12345678[ 	]+.word[ 	]+0x12345678
+[ 	]+18:[ 	]+00000013[ 	]+nop
+[ 	]+1c:[ 	]+01[ 	]+.byte[ 	]+0x01
+[ 	]+1d:[ 	]+00000000[ 	]+.word[ 	]+0x00000000
+[ 	]+21:[ 	]+00000013[ 	]+align.nop
+[ 	]+25:[ 	]+00000013[ 	]+align.nop
+[ 	]+29:[ 	]+00000013[ 	]+align.nop
+[ 	]+2d:[ 	]+12345678[ 	]+.word[ 	]+0x12345678
+#...
diff --git a/gas/testsuite/gas/riscv/mapping-norelax-04a.d b/gas/testsuite/gas/riscv/mapping-norelax-04a.d
new file mode 100644
index 00000000000..785b9d9f922
--- /dev/null
+++ b/gas/testsuite/gas/riscv/mapping-norelax-04a.d
@@ -0,0 +1,23 @@
+#as: -mno-relax
+#source: mapping-04.s
+#objdump: --syms --special-syms
+
+.*file format.*riscv.*
+
+SYMBOL TABLE:
+0+00 l    d  .text	0+00 .text
+0+00 l    d  .data	0+00 .data
+0+00 l    d  .bss	0+00 .bss
+0+00 l       .text	0+00 \$x
+0+04 l       .text	0+00 \$d4
+0+08 l       .text	0+00 \$a
+0+10 l       .text	0+00 \$d4
+0+14 l       .text	0+00 \$x
+0+18 l       .text	0+00 \$d1
+0+19 l       .text	0+00 \$d4
+0+20 l       .text	0+00 \$d4
+0+24 l       .text	0+00 \$a
+0+1d l       .text	0+00 \$a1
+0+1e l       .text	0+00 \$a
+# Maybe section symbol for .riscv.attributes
+#...
diff --git a/gas/testsuite/gas/riscv/mapping-norelax-04b.d b/gas/testsuite/gas/riscv/mapping-norelax-04b.d
new file mode 100644
index 00000000000..8765c6cd129
--- /dev/null
+++ b/gas/testsuite/gas/riscv/mapping-norelax-04b.d
@@ -0,0 +1,25 @@
+#as: -mno-relax
+#source: mapping-04.s
+#objdump: -d
+
+.*:[ 	]+file format .*
+
+
+Disassembly of section .text:
+
+0+000 <.text>:
+[ 	]+0:[ 	]+00000013[ 	]+nop
+[ 	]+4:[ 	]+00000000[ 	]+.word[ 	]+0x00000000
+[ 	]+8:[ 	]+00000013[ 	]+align.nop
+[ 	]+c:[ 	]+00000013[ 	]+align.nop
+[ 	]+10:[ 	]+12345678[ 	]+.word[ 	]+0x12345678
+[ 	]+14:[ 	]+00000013[ 	]+nop
+[ 	]+18:[ 	]+01[ 	]+.byte[ 	]+0x01
+[ 	]+19:[ 	]+00000000[ 	]+.word[ 	]+0x00000000
+[ 	]+1d:[ 	]+00[ 	]+align.byte
+[ 	]+1e:[ 	]+0001[ 	]+align.nop
+[ 	]+20:[ 	]+12345678[ 	]+.word[ 	]+0x12345678
+[ 	]+24:[ 	]+00000013[ 	]+align.nop
+[ 	]+28:[ 	]+00000013[ 	]+align.nop
+[ 	]+2c:[ 	]+00000013[ 	]+align.nop
+#...
diff --git a/gas/testsuite/gas/riscv/no-relax-align-2.d b/gas/testsuite/gas/riscv/no-relax-align-2.d
index 7407b495a8f..3c4323cc186 100644
--- a/gas/testsuite/gas/riscv/no-relax-align-2.d
+++ b/gas/testsuite/gas/riscv/no-relax-align-2.d
@@ -7,13 +7,14 @@
 Disassembly of section .text:
 
 0+000 <.text>:
-[ 	]+0:[ 	]+0000[ 	]+unimp
-[ 	]+2:[ 	]+0001[ 	]+nop
-[ 	]+4:[ 	]+00000013[ 	]+nop
-[ 	]+8:[ 	]+00000013[ 	]+nop
-[ 	]+c:[ 	]+00000013[ 	]+nop
+[ 	]+0:[ 	]+00[ 	]+.byte[ 	]+0x00
+[ 	]+1:[ 	]+00[ 	]+align.byte
+[ 	]+2:[ 	]+0001[ 	]+align.nop
+[ 	]+4:[ 	]+00000013[ 	]+align.nop
+[ 	]+8:[ 	]+00000013[ 	]+align.nop
+[ 	]+c:[ 	]+00000013[ 	]+align.nop
 [ 	]+10:[ 	]+0001[ 	]+nop
-[ 	]+12:[ 	]+0001[ 	]+nop
-[ 	]+14:[ 	]+00000013[ 	]+nop
-[ 	]+18:[ 	]+00000013[ 	]+nop
-[ 	]+1c:[ 	]+00000013[ 	]+nop
+[ 	]+12:[ 	]+0001[ 	]+align.nop
+[ 	]+14:[ 	]+00000013[ 	]+align.nop
+[ 	]+18:[ 	]+00000013[ 	]+align.nop
+[ 	]+1c:[ 	]+00000013[ 	]+align.nop
diff --git a/gas/testsuite/gas/riscv/no-relax-align.d b/gas/testsuite/gas/riscv/no-relax-align.d
index ced07d3c830..960db2a58bc 100644
--- a/gas/testsuite/gas/riscv/no-relax-align.d
+++ b/gas/testsuite/gas/riscv/no-relax-align.d
@@ -9,5 +9,5 @@ Disassembly of section .text:
 0+000 <.text>:
 [ 	]+0:[ 	]+00000013[ 	]+nop
 [ 	]+4:[ 	]+00000013[ 	]+nop
-[ 	]+8:[ 	]+00000013[ 	]+nop
-[ 	]+c:[ 	]+00000013[ 	]+nop
+[ 	]+8:[ 	]+00000013[ 	]+align.nop
+[ 	]+c:[ 	]+00000013[ 	]+align.nop
diff --git a/include/opcode/riscv.h b/include/opcode/riscv.h
index fdf3df4f5c1..3cea9e93c96 100644
--- a/include/opcode/riscv.h
+++ b/include/opcode/riscv.h
@@ -425,6 +425,19 @@ enum
   M_NUM_MACROS
 };
 
+/* The mapping symbol states.  */
+enum riscv_seg_mstate
+{
+  MAP_NONE = 0,		/* Must be zero, for seginfo in new sections.  */
+  MAP_DATA,		/* The rs_fill and rs_align.  */
+  MAP_DATA_CONS0,	/* Added for cons_worker, with the data size.  */
+  MAP_DATA_CONS1,
+  MAP_DATA_CONS2,
+  MAP_DATA_CONS3,
+  MAP_INSN,		/* Instructions.  */
+  MAP_ALIGN,		/* The rs_align_code, added nops.  */
+  MAP_ALIGN_ODD,	/* The rs_align_code, added odd byte.  */
+};
 
 extern const char * const riscv_gpr_names_numeric[NGPR];
 extern const char * const riscv_gpr_names_abi[NGPR];
diff --git a/opcodes/riscv-dis.c b/opcodes/riscv-dis.c
index fe8dfb88d90..b41cad8f4aa 100644
--- a/opcodes/riscv-dis.c
+++ b/opcodes/riscv-dis.c
@@ -41,6 +41,12 @@ struct riscv_private_data
   bfd_vma hi_addr[OP_MASK_RD + 1];
 };
 
+/* Used for mapping symbols.  */
+static int last_map_symbol = -1;
+static bfd_vma last_stop_offset = 0;
+static asection *last_section = NULL;
+enum riscv_seg_mstate last_map_state;
+
 static const char * const *riscv_gpr_names;
 static const char * const *riscv_fpr_names;
 
@@ -507,6 +513,27 @@ riscv_disassemble_insn (bfd_vma memaddr, insn_t word, disassemble_info *info)
 	  if ((op->xlen_requirement != 0) && (op->xlen_requirement != xlen))
 	    continue;
 
+	  /* Add the "align." prefix if it is used for alignment.
+
+	     Consider the following case,
+	     .text
+	     .byte 0
+	     nop
+
+	     0000000000000000 <.text>:
+	     0:	00		.byte   0x00
+	     1:	00000013	nop
+	     5:	0000		align.unimp
+		...
+
+	     The tail section alignments are not handled in the
+	     riscv_frag_align_code, and since the relax is enable,
+	     it cannot be filled with nops in the riscv_handle_align
+	     either.  Therefore, we may get align.unimp at the end
+	     of the sections, I think this is expected.  */
+	  if (last_map_state == MAP_ALIGN)
+	    (*info->fprintf_func) (info->stream, "align.");
+
 	  /* It's a match.  */
 	  (*info->fprintf_func) (info->stream, "%s", op->name);
 	  print_insn_args (op->args, word, memaddr, info);
@@ -556,13 +583,238 @@ riscv_disassemble_insn (bfd_vma memaddr, insn_t word, disassemble_info *info)
   return insnlen;
 }
 
+/* Return true if we find the suitable mapping symbol,
+   and also update the STATE.  Otherwise, return false.  */
+
+static bool
+riscv_get_map_state (int n,
+		     enum riscv_seg_mstate *state,
+		     struct disassemble_info *info)
+{
+  const char *name;
+
+  /* If the symbol is in a different section, ignore it.  */
+  if (info->section != NULL
+      && info->section != info->symtab[n]->section)
+    return false;
+
+  name = bfd_asymbol_name(info->symtab[n]);
+  if (strcmp (name, "$x") == 0)
+    *state = MAP_INSN;
+  else if (strcmp (name, "$d") == 0)
+    *state = MAP_DATA;
+  else if (strcmp (name, "$d1") == 0)
+    *state = MAP_DATA_CONS0;
+  else if (strcmp (name, "$d2") == 0)
+    *state = MAP_DATA_CONS1;
+  else if (strcmp (name, "$d4") == 0)
+    *state = MAP_DATA_CONS2;
+  else if (strcmp (name, "$d8") == 0)
+    *state = MAP_DATA_CONS3;
+  else if (strcmp (name, "$a") == 0)
+    *state = MAP_ALIGN;
+  else if (strcmp (name, "$a1") == 0)
+    *state = MAP_ALIGN_ODD;
+  else
+    return false;
+
+  return true;
+}
+
+/* Check the sorted symbol table (sorted by the symbol value), find the
+   suitable mapping symbols.  */
+
+static enum riscv_seg_mstate
+riscv_search_mapping_symbol (bfd_vma memaddr,
+			     struct disassemble_info *info)
+{
+  enum riscv_seg_mstate mstate;
+  bool from_last_map_symbol;
+  bool found = false;
+  int symbol = -1;
+  int n;
+
+  /* Decide whether to print the data or instruction by default, in case
+     we can not find the corresponding mapping symbols.  */
+  mstate = MAP_DATA;
+  if ((info->section
+       && info->section->flags & SEC_CODE)
+      || !info->section)
+    mstate = MAP_INSN;
+
+  if (info->symtab_size == 0
+      || bfd_asymbol_flavour (*info->symtab) != bfd_target_elf_flavour)
+    return mstate;
+
+  /* Reset the last_map_symbol if we start to dump a new section.  */
+  if (memaddr <= 0)
+    last_map_symbol = -1;
+
+  /* If the last stop offset is different from the current one, then
+     don't use the last_map_symbol to search.  We usually reset the
+     info->stop_offset when handling a new section.  */
+  from_last_map_symbol = (last_map_symbol >= 0
+			  && info->stop_offset == last_stop_offset);
+
+  /* Start scanning at the start of the function, or wherever
+     we finished last time.  */
+  n = info->symtab_pos + 1;
+  if (from_last_map_symbol && n >= last_map_symbol)
+    n = last_map_symbol;
+
+  /* Find the suitable mapping symbol to dump.  */
+  for (; n < info->symtab_size; n++)
+    {
+      bfd_vma addr = bfd_asymbol_value (info->symtab[n]);
+      /* We have searched all possible symbols in the range.  */
+      if (addr > memaddr)
+	break;
+      if (riscv_get_map_state (n, &mstate, info))
+	{
+	  symbol = n;
+	  found = true;
+	  /* Do not stop searching, in case there are some mapping
+	     symbols have the same value, but have different names.
+	     Use the last one.  */
+	}
+    }
+
+  /* We can not find the suitable mapping symbol above.  Therefore, we
+     look forwards and try to find it again, but don't go pass the start
+     of the section.  Otherwise a data section without mapping symbols
+     can pick up a text mapping symbol of a preceeding section.  */
+  if (!found)
+    {
+      n = info->symtab_pos;
+      if (from_last_map_symbol && n >= last_map_symbol)
+	n = last_map_symbol;
+
+      for (; n >= 0; n--)
+	{
+	  bfd_vma addr = bfd_asymbol_value (info->symtab[n]);
+	  /* We have searched all possible symbols in the range.  */
+	  if (addr < (info->section ? info->section->vma : 0))
+	    break;
+	  /* Stop searching once we find the closed mapping symbol.  */
+	  if (riscv_get_map_state (n, &mstate, info))
+	    {
+	      symbol = n;
+	      found = true;
+	      break;
+	    }
+	}
+    }
+
+  /* Save the information for next use.  */
+  last_map_symbol = symbol;
+  last_stop_offset = info->stop_offset;
+  last_section = info->section;
+
+  return mstate;
+}
+
+/* Decide which data size we should print.  */
+
+static bfd_vma
+riscv_data_length (bfd_vma memaddr,
+		   enum riscv_seg_mstate mstate,
+		   disassemble_info *info)
+{
+  bfd_vma length;
+  bool found = false;
+
+  switch (mstate)
+    {
+    case MAP_DATA:	 length = 0; break;
+    case MAP_DATA_CONS0: length = 1; break;
+    case MAP_DATA_CONS1: length = 2; break;
+    case MAP_DATA_CONS2: length = 4; break;
+    case MAP_DATA_CONS3: length = 8; break;
+    default: abort ();
+    }
+  if (length > 0)
+    return length;
+
+  length = 4;
+  if (info->symtab_size != 0
+      && bfd_asymbol_flavour (*info->symtab) == bfd_target_elf_flavour
+      && last_map_symbol >= 0)
+    {
+      int n;
+      enum riscv_seg_mstate m = MAP_NONE;
+      for (n = last_map_symbol + 1; n < info->symtab_size; n++)
+	{
+	  bfd_vma addr = bfd_asymbol_value (info->symtab[n]);
+	  if (addr > memaddr
+	      && riscv_get_map_state (n, &m, info))
+	    {
+	      if (addr - memaddr < length)
+		length = addr - memaddr;
+	      found = true;
+	      break;
+	    }
+	}
+    }
+  if (!found)
+    {
+      /* Do not set the length which exceeds the section size.  */
+      bfd_vma offset = info->section->vma + info->section->size;
+      offset -= memaddr;
+      length = (offset < length) ? offset : length;
+    }
+  length = length == 3 ? 2 : length;
+  return length;
+}
+
+/* Dump the data contents.  */
+
+static int
+riscv_disassemble_data (bfd_vma memaddr ATTRIBUTE_UNUSED,
+			insn_t data,
+			disassemble_info *info)
+{
+  info->display_endian = info->endian;
+
+  switch (info->bytes_per_chunk)
+    {
+    case 1:
+      info->bytes_per_line = 6;
+      if (last_map_state == MAP_ALIGN_ODD)
+	(*info->fprintf_func) (info->stream, "align.byte");
+      else
+	(*info->fprintf_func) (info->stream, ".byte\t0x%02llx",
+			       (unsigned long long) data);
+      break;
+    case 2:
+      info->bytes_per_line = 8;
+      (*info->fprintf_func) (info->stream, ".short\t0x%04llx",
+			     (unsigned long long) data);
+      break;
+    case 4:
+      info->bytes_per_line = 8;
+      (*info->fprintf_func) (info->stream, ".word\t0x%08llx",
+			     (unsigned long long) data);
+      break;
+    case 8:
+      info->bytes_per_line = 8;
+      (*info->fprintf_func) (info->stream, ".dword\t0x%016llx",
+			     (unsigned long long) data);
+      break;
+    default:
+      abort ();
+    }
+  return info->bytes_per_chunk;
+}
+
 int
 print_insn_riscv (bfd_vma memaddr, struct disassemble_info *info)
 {
-  bfd_byte packet[2];
+  bfd_byte packet[8];
   insn_t insn = 0;
-  bfd_vma n;
+  bfd_vma dump_size;
   int status;
+  enum riscv_seg_mstate mstate;
+  int (*riscv_disassembler) (bfd_vma, insn_t, struct disassemble_info *);
 
   if (info->disassembler_options != NULL)
     {
@@ -573,23 +825,59 @@ print_insn_riscv (bfd_vma memaddr, struct disassemble_info *info)
   else if (riscv_gpr_names == NULL)
     set_default_riscv_dis_options ();
 
-  /* Instructions are a sequence of 2-byte packets in little-endian order.  */
-  for (n = 0; n < sizeof (insn) && n < riscv_insn_length (insn); n += 2)
+  mstate = riscv_search_mapping_symbol (memaddr, info);
+  /* Save the last mapping state.  */
+  last_map_state = mstate;
+
+  /* Set the size to dump.  */
+  if (mstate == MAP_DATA
+      || mstate == MAP_DATA_CONS0
+      || mstate == MAP_DATA_CONS1
+      || mstate == MAP_DATA_CONS2
+      || mstate == MAP_DATA_CONS3)
     {
-      status = (*info->read_memory_func) (memaddr + n, packet, 2, info);
+      /* The documentation for -D says that on Arm platforms -D should
+	 disassemble instructions.  Therefore, they dump data by searching
+	 mapping symbols only when the DISASSEMBLE_DATA is set.  That causes
+	 the mapping symbols are useless for -D.  I am not sure if any riscv
+	 document had mentioned this, so I prefer to keep them useful, but
+	 only for text sections.  If we decide not only to support mapping
+	 symbols for text sections, then the riscv_mapping_state in the
+	 gas/config/tc-riscv.c should be updated.  */
+      dump_size = riscv_data_length (memaddr, mstate, info);
+      info->bytes_per_chunk = dump_size;
+      riscv_disassembler = riscv_disassemble_data;
+    }
+  else if (mstate == MAP_ALIGN_ODD)
+    {
+      dump_size = 1;
+      info->bytes_per_chunk = dump_size;
+      riscv_disassembler = riscv_disassemble_data;
+    }
+  else
+    {
+      /* Get the first 2-bytes to check the lenghth of instruction.  */
+      status = (*info->read_memory_func) (memaddr, packet, 2, info);
       if (status != 0)
 	{
-	  /* Don't fail just because we fell off the end.  */
-	  if (n > 0)
-	    break;
 	  (*info->memory_error_func) (status, memaddr, info);
-	  return status;
+	  return 1;
 	}
+      insn = (insn_t) bfd_getl16 (packet);
+      dump_size = riscv_insn_length (insn);
+      riscv_disassembler = riscv_disassemble_insn;
+    }
 
-      insn |= ((insn_t) bfd_getl16 (packet)) << (8 * n);
+  /* Fetch the instruction to dump.  */
+  status = (*info->read_memory_func) (memaddr, packet, dump_size, info);
+  if (status != 0)
+    {
+      (*info->memory_error_func) (status, memaddr, info);
+      return 1;
     }
+  insn = (insn_t) bfd_get_bits (packet, dump_size * 8, false);
 
-  return riscv_disassemble_insn (memaddr, insn, info);
+  return (*riscv_disassembler) (memaddr, insn, info);
 }
 
 disassembler_ftype
@@ -631,7 +919,8 @@ riscv_symbol_is_valid (asymbol * sym,
 
   name = bfd_asymbol_name (sym);
 
-  return (strcmp (name, RISCV_FAKE_LABEL_NAME) != 0);
+  return (strcmp (name, RISCV_FAKE_LABEL_NAME) != 0
+	  && !riscv_elf_is_mapping_symbols (name));
 }
 
 void
-- 
2.30.2