[PATCH] Support N32(32-bit ABI on 64-bit ISA) in riscv

Guo Ren guoren@kernel.org
Sat Nov 16 08:58:40 GMT 2024
This patch works fine with the rv64ilp32 Linux kernel self building.

Tested-by: Guo Ren <guoren@kernel.org>

On Sat, Nov 16, 2024 at 12:16 PM Liao Shihua <shihua@iscas.ac.cn> wrote:
>
> RISC-V N32 ABI means using 32-bit ABI on 64-bit ISA, the discussion in
> https://github.com/riscv-non-isa/riscv-elf-psabi-doc/pull/381 .
> At this moment, N32 is supported batemental toolchain.
> Three OpenSource  RTOS using this feature and have been merged in upstream.
> You can see them in
> EasyXem (AUTOSAR CP R19-11): https://atomgit.com/easyxmen/XMen/tree/rv64ilp32-dev
> Nuttx: https://github.com/apache/nuttx
> RT-Thread:https://github.com/RT-Thread/rt-thread/pull/9194
>
> This patch add a new bfd_mach bfd_mach_riscv64n32 and a new e_flags N32.
> bfd_mach_riscv64n32 has the same bits in a word/address and ARCH_SIZE with rv32,
> but use rv64's PRSTATUS. N32 use the 6th bit of e_flags layout.
> In addition, this patch replace xlen with abi_xlen in riscv_target_format().
>
> bfd/ChangeLog:
>
>         * archures.c: Add bfd_mach_riscv64n32.
>         * bfd-in2.h (bfd_mach_riscv64n32): Ditto.
>         * cpu-riscv.c: Ditto.
>         * elfnn-riscv.c (ABI_N32_P):Add ABI_N32_P
>         (perform_relocation):Ditto.
>         (riscv_merge_arch_attr_info):Remove elf check when using N32.
>         (_bfd_riscv_elf_merge_private_bfd_data):Ditto.
>         (_bfd_riscv_relax_section):Ditto.
>         (riscv_elf_object_p):Using bfd_mach_riscv64n32 with N32.
>
> binutils/ChangeLog:
>
>         * readelf.c (decode_RISCV_machine_flags):Add N32 Flag.
>
> gas/ChangeLog:
>
>         * config/tc-riscv.c (riscv_set_n32):Set N32 flag.
>         (riscv_set_abi_by_arch):Removed check.
>         (riscv_target_format):Ditto
>         (md_begin):Ditto
>         (s_riscv_attribute):Ditto
>         * testsuite/gas/riscv/mabi-fail-rv64iq-ilp32.d: Removed.
>         * testsuite/gas/riscv/mabi-fail-rv64iq-ilp32.l: Removed.
>
> include/ChangeLog:
>
>         * elf/riscv.h (EF_RISCV_N32):Add N32 Flag.
>
> opcodes/ChangeLog:
>
>         * riscv-dis.c (print_insn_args):
>         (riscv_disassemble_insn):
>
> ---
>  bfd/archures.c                                |  1 +
>  bfd/bfd-in2.h                                 |  1 +
>  bfd/cpu-riscv.c                               |  2 ++
>  bfd/elfnn-riscv.c                             | 32 +++++++++++++------
>  binutils/readelf.c                            |  3 ++
>  gas/config/tc-riscv.c                         | 23 ++++++++++---
>  .../gas/riscv/mabi-fail-rv64iq-ilp32.d        |  3 --
>  .../gas/riscv/mabi-fail-rv64iq-ilp32.l        |  2 --
>  include/elf/riscv.h                           |  3 ++
>  opcodes/riscv-dis.c                           |  6 ++--
>  10 files changed, 53 insertions(+), 23 deletions(-)
>  delete mode 100644 gas/testsuite/gas/riscv/mabi-fail-rv64iq-ilp32.d
>  delete mode 100644 gas/testsuite/gas/riscv/mabi-fail-rv64iq-ilp32.l
>
> diff --git a/bfd/archures.c b/bfd/archures.c
> index c4decc59e4a..063659631fa 100644
> --- a/bfd/archures.c
> +++ b/bfd/archures.c
> @@ -448,6 +448,7 @@ DESCRIPTION
>  .  bfd_arch_riscv,
>  .#define bfd_mach_riscv32      132
>  .#define bfd_mach_riscv64      164
> +.#define bfd_mach_riscv64n32   16432
>  .  bfd_arch_rl78,
>  .#define bfd_mach_rl78         0x75
>  .  bfd_arch_rx,               {* Renesas RX.  *}
> diff --git a/bfd/bfd-in2.h b/bfd/bfd-in2.h
> index 3b047d922f3..0ee6bbc2a73 100644
> --- a/bfd/bfd-in2.h
> +++ b/bfd/bfd-in2.h
> @@ -1714,6 +1714,7 @@ enum bfd_architecture
>    bfd_arch_riscv,
>  #define bfd_mach_riscv32       132
>  #define bfd_mach_riscv64       164
> +#define bfd_mach_riscv64n32    16432
>    bfd_arch_rl78,
>  #define bfd_mach_rl78          0x75
>    bfd_arch_rx,        /* Renesas RX.  */
> diff --git a/bfd/cpu-riscv.c b/bfd/cpu-riscv.c
> index 58cbdd846be..1df99dc6e2d 100644
> --- a/bfd/cpu-riscv.c
> +++ b/bfd/cpu-riscv.c
> @@ -86,6 +86,7 @@ riscv_scan (const struct bfd_arch_info *info, const char *string)
>  enum
>  {
>    I_riscv64,
> +  I_riscv64n32,
>    I_riscv32
>  };
>
> @@ -96,6 +97,7 @@ enum
>  static const bfd_arch_info_type arch_info_struct[] =
>  {
>    N (64, bfd_mach_riscv64, "riscv:rv64", false, NN (I_riscv64)),
> +  N (32, bfd_mach_riscv64n32, "riscv:rv64", false, NN (I_riscv64n32)),
>    N (32, bfd_mach_riscv32, "riscv:rv32", false, NULL)
>  };
>
> diff --git a/bfd/elfnn-riscv.c b/bfd/elfnn-riscv.c
> index c8bf45f4293..b05f4fde433 100644
> --- a/bfd/elfnn-riscv.c
> +++ b/bfd/elfnn-riscv.c
> @@ -138,6 +138,11 @@
>
>  #define RISCV_ELF_WORD_BYTES (1 << RISCV_ELF_LOG_WORD_BYTES)
>
> +#define ABI_N32_P(abfd) \
> +  ((elf_elfheader (abfd)->e_flags & EF_RISCV_N32) != 0)
> +
> +static bool ABI_N32 = false;
> +
>  /* The name of the dynamic interpreter.  This is put in the .interp
>     section.  */
>
> @@ -1823,7 +1828,8 @@ perform_relocation (const reloc_howto_type *howto,
>
>      case R_RISCV_CALL:
>      case R_RISCV_CALL_PLT:
> -      if (ARCH_SIZE > 32 && !VALID_UTYPE_IMM (RISCV_CONST_HIGH_PART (value)))
> +      if ((ARCH_SIZE > 32 || ABI_N32_P (input_bfd))
> +         && !VALID_UTYPE_IMM (RISCV_CONST_HIGH_PART (value)))
>         return bfd_reloc_overflow;
>        value = ENCODE_UTYPE_IMM (RISCV_CONST_HIGH_PART (value))
>               | (ENCODE_ITYPE_IMM (value) << 32);
> @@ -3927,7 +3933,7 @@ riscv_merge_arch_attr_info (bfd *ibfd, char *in_arch, char *out_arch)
>      return NULL;
>
>    /* Checking XLEN.  */
> -  if (xlen_out != xlen_in)
> +  if (xlen_out != xlen_in && !ABI_N32_P (ibfd))
>      {
>        _bfd_error_handler
>         (_("error: %pB: ISA string of input (%s) doesn't match "
> @@ -3947,7 +3953,7 @@ riscv_merge_arch_attr_info (bfd *ibfd, char *in_arch, char *out_arch)
>    if (!riscv_merge_multi_letter_ext (&in, &out))
>      return NULL;
>
> -  if (xlen_in != xlen_out)
> +  if (xlen_in != xlen_out && !ABI_N32_P (ibfd))
>      {
>        _bfd_error_handler
>         (_("error: %pB: XLEN of input (%u) doesn't match "
> @@ -3955,7 +3961,7 @@ riscv_merge_arch_attr_info (bfd *ibfd, char *in_arch, char *out_arch)
>        return NULL;
>      }
>
> -  if (xlen_in != ARCH_SIZE)
> +  if (xlen_in != ARCH_SIZE && !ABI_N32_P (ibfd))
>      {
>        _bfd_error_handler
>         (_("error: %pB: unsupported XLEN (%u), you might be "
> @@ -3963,7 +3969,7 @@ riscv_merge_arch_attr_info (bfd *ibfd, char *in_arch, char *out_arch)
>        return NULL;
>      }
>
> -  merged_arch_str = riscv_arch_str (ARCH_SIZE, &merged_subsets);
> +  merged_arch_str = riscv_arch_str (xlen_in, &merged_subsets);
>
>    /* Release the subset lists.  */
>    riscv_release_subset_list (&in_subsets);
> @@ -4233,6 +4239,9 @@ _bfd_riscv_elf_merge_private_bfd_data (bfd *ibfd, struct bfd_link_info *info)
>
>    /* Allow linking TSO and non-TSO, and keep the TSO flag.  */
>    elf_elfheader (obfd)->e_flags |= new_flags & EF_RISCV_TSO;
> +
> +  /* Allow linking N32 and non-N32, and keep the N32 flag.  */
> +  elf_elfheader (obfd)->e_flags |= new_flags & EF_RISCV_N32;
>
>    return true;
>
> @@ -5400,7 +5409,7 @@ _bfd_riscv_relax_section (bfd *abfd, asection *sec,
>    return ret;
>  }
>
> -#if ARCH_SIZE == 32
> +#if ARCH_SIZE == 32 && !ABI_N32
>  # define PRSTATUS_SIZE                 204
>  # define PRSTATUS_OFFSET_PR_CURSIG     12
>  # define PRSTATUS_OFFSET_PR_PID                24
> @@ -5570,10 +5579,13 @@ riscv_elf_grok_psinfo (bfd *abfd, Elf_Internal_Note *note)
>  static bool
>  riscv_elf_object_p (bfd *abfd)
>  {
> -  /* There are only two mach types in RISCV currently.  */
> -  if (strcmp (abfd->xvec->name, "elf32-littleriscv") == 0
> -      || strcmp (abfd->xvec->name, "elf32-bigriscv") == 0)
> -    bfd_default_set_arch_mach (abfd, bfd_arch_riscv, bfd_mach_riscv32);
> +  ABI_N32 = ABI_N32_P (abfd);
> +  /* There are only three mach types in RISCV currently.  */
> +  if (ABI_N32)
> +    bfd_default_set_arch_mach (abfd, bfd_arch_riscv, bfd_mach_riscv64n32);
> +  else if (strcmp (abfd->xvec->name, "elf32-littleriscv") == 0
> +    || strcmp (abfd->xvec->name, "elf32-bigriscv") == 0)
> +       bfd_default_set_arch_mach (abfd, bfd_arch_riscv, bfd_mach_riscv32);
>    else
>      bfd_default_set_arch_mach (abfd, bfd_arch_riscv, bfd_mach_riscv64);
>
> diff --git a/binutils/readelf.c b/binutils/readelf.c
> index 73163e0ee21..58248d84135 100644
> --- a/binutils/readelf.c
> +++ b/binutils/readelf.c
> @@ -4532,6 +4532,9 @@ decode_RISCV_machine_flags (char *out, unsigned e_flags)
>    if (e_flags & EF_RISCV_TSO)
>      out = stpcpy (out, ", TSO");
>
> +  if (e_flags & EF_RISCV_N32)
> +    out = stpcpy (out, ", N32");
> +
>    switch (e_flags & EF_RISCV_FLOAT_ABI)
>      {
>      case EF_RISCV_FLOAT_ABI_SOFT:
> diff --git a/gas/config/tc-riscv.c b/gas/config/tc-riscv.c
> index e19142dca19..dde9c52ccc1 100644
> --- a/gas/config/tc-riscv.c
> +++ b/gas/config/tc-riscv.c
> @@ -306,6 +306,13 @@ riscv_set_tso (void)
>    elf_flags |= EF_RISCV_TSO;
>  }
>
> +/* Turn on the n32 flag for elf_flags once we have enabled n32 model.  */
> +static void
> +riscv_set_n32 (void)
> +{
> +  elf_flags |= EF_RISCV_N32;
> +}
> +
>  /* The linked list hanging off of .subsets_list records all enabled extensions,
>     which are parsed from the architecture string.  The architecture string can
>     be set by the -march option, the elf architecture attributes, and the
> @@ -409,7 +416,7 @@ riscv_set_abi_by_arch (void)
>        gas_assert (abi_xlen != 0 && xlen != 0 && float_abi != FLOAT_ABI_DEFAULT);
>        if (abi_xlen > xlen)
>         as_bad ("can't have %d-bit ABI on %d-bit ISA", abi_xlen, xlen);
> -      else if (abi_xlen < xlen)
> +      else if (abi_xlen < xlen && (abi_xlen != 32 && xlen != 64))
>         as_bad ("%d-bit ABI not yet supported on %d-bit ISA", abi_xlen, xlen);
>
>        if (riscv_subset_supports (&riscv_rps_as, "e") && !rve_abi)
> @@ -435,6 +442,10 @@ riscv_set_abi_by_arch (void)
>
>    if (rve_abi)
>      elf_flags |= EF_RISCV_RVE;
> +
> +  if (abi_xlen == 32 && xlen == 64)
> +    riscv_set_n32 ();
> +
>  }
>
>  /* Handle of the OPCODE hash table.  */
> @@ -734,9 +745,9 @@ const char *
>  riscv_target_format (void)
>  {
>    if (target_big_endian)
> -    return xlen == 64 ? "elf64-bigriscv" : "elf32-bigriscv";
> +    return abi_xlen == 64 ? "elf64-bigriscv" : "elf32-bigriscv";
>    else
> -    return xlen == 64 ? "elf64-littleriscv" : "elf32-littleriscv";
> +    return abi_xlen == 64 ? "elf64-littleriscv" : "elf32-littleriscv";
>  }
>
>  /* Return the length of instruction INSN.  */
> @@ -1876,7 +1887,8 @@ riscv_record_pcrel_fixup (htab_t p, const asection *sec, bfd_vma address,
>  void
>  md_begin (void)
>  {
> -  unsigned long mach = xlen == 64 ? bfd_mach_riscv64 : bfd_mach_riscv32;
> +  unsigned long mach = xlen == 64 ?
> +      (abi_xlen == 32 ? bfd_mach_riscv64n32 : bfd_mach_riscv64) : bfd_mach_riscv32;
>
>    if (! bfd_set_arch_mach (stdoutput, bfd_arch_riscv, mach))
>      as_warn (_("could not set architecture and machine"));
> @@ -5674,7 +5686,8 @@ s_riscv_attribute (int ignored ATTRIBUTE_UNUSED)
>        if (old_xlen != xlen)
>         {
>           /* We must re-init bfd again if xlen is changed.  */
> -         unsigned long mach = xlen == 64 ? bfd_mach_riscv64 : bfd_mach_riscv32;
> +         unsigned long mach = xlen == 64 ?
> +      (abi_xlen == 32 ? bfd_mach_riscv64n32 : bfd_mach_riscv64) : bfd_mach_riscv32;
>           bfd_find_target (riscv_target_format (), stdoutput);
>
>           if (! bfd_set_arch_mach (stdoutput, bfd_arch_riscv, mach))
> diff --git a/gas/testsuite/gas/riscv/mabi-fail-rv64iq-ilp32.d b/gas/testsuite/gas/riscv/mabi-fail-rv64iq-ilp32.d
> deleted file mode 100644
> index e3155f48956..00000000000
> --- a/gas/testsuite/gas/riscv/mabi-fail-rv64iq-ilp32.d
> +++ /dev/null
> @@ -1,3 +0,0 @@
> -#as: -march-attr -mabi=ilp32
> -#source: mabi-attr-rv64iq.s
> -#error_output: mabi-fail-rv64iq-ilp32.l
> diff --git a/gas/testsuite/gas/riscv/mabi-fail-rv64iq-ilp32.l b/gas/testsuite/gas/riscv/mabi-fail-rv64iq-ilp32.l
> deleted file mode 100644
> index 8d45a07fd36..00000000000
> --- a/gas/testsuite/gas/riscv/mabi-fail-rv64iq-ilp32.l
> +++ /dev/null
> @@ -1,2 +0,0 @@
> -.*Assembler messages:
> -.*Error: 32-bit ABI not yet supported on 64-bit ISA
> diff --git a/include/elf/riscv.h b/include/elf/riscv.h
> index 24903c04d91..f88a1c0701a 100644
> --- a/include/elf/riscv.h
> +++ b/include/elf/riscv.h
> @@ -140,6 +140,9 @@ END_RELOC_NUMBERS (R_RISCV_max)
>  /* File uses the TSO model. */
>  #define EF_RISCV_TSO 0x0010
>
> +/* File uses the N32 model.  */
> +#define EF_RISCV_N32 0x0020
> +
>  /* Additional section types.  */
>  #define SHT_RISCV_ATTRIBUTES (SHT_LOPROC + 3) /* Section holds attributes.  */
>
> diff --git a/opcodes/riscv-dis.c b/opcodes/riscv-dis.c
> index 80018db837a..09fac0c3cbe 100644
> --- a/opcodes/riscv-dis.c
> +++ b/opcodes/riscv-dis.c
> @@ -349,7 +349,7 @@ print_insn_args (const char *oparg, insn_t l, bfd_vma pc, disassemble_info *info
>             case 'j':
>               if (((l & MASK_C_ADDI) == MATCH_C_ADDI) && rd != 0)
>                 maybe_print_address (pd, rd, EXTRACT_CITYPE_IMM (l), 0);
> -             if (info->mach == bfd_mach_riscv64
> +             if (info->mach == bfd_mach_riscv64 || info->mach == bfd_mach_riscv64n32
>                   && ((l & MASK_C_ADDIW) == MATCH_C_ADDIW) && rd != 0)
>                 maybe_print_address (pd, rd, EXTRACT_CITYPE_IMM (l), 1);
>               print (info->stream, dis_style_immediate, "%d",
> @@ -555,7 +555,7 @@ print_insn_args (const char *oparg, insn_t l, bfd_vma pc, disassemble_info *info
>           if (((l & MASK_ADDI) == MATCH_ADDI && rs1 != 0)
>               || (l & MASK_JALR) == MATCH_JALR)
>             maybe_print_address (pd, rs1, EXTRACT_ITYPE_IMM (l), 0);
> -         if (info->mach == bfd_mach_riscv64
> +         if (info->mach == bfd_mach_riscv64|| info->mach == bfd_mach_riscv64n32
>               && ((l & MASK_ADDIW) == MATCH_ADDIW) && rs1 != 0)
>             maybe_print_address (pd, rs1, EXTRACT_ITYPE_IMM (l), 1);
>           print (info->stream, dis_style_immediate, "%d",
> @@ -941,7 +941,7 @@ riscv_disassemble_insn (bfd_vma memaddr,
>    if (op != NULL)
>      {
>        /* If XLEN is not known, get its value from the ELF class.  */
> -      if (info->mach == bfd_mach_riscv64)
> +      if (info->mach == bfd_mach_riscv64 || info->mach == bfd_mach_riscv64n32)
>         xlen = 64;
>        else if (info->mach == bfd_mach_riscv32)
>         xlen = 32;
> --
> 2.34.1
>
>


-- 
Best Regards
 Guo Ren


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