Re: [[RESEND & PING]PATCH V3 1/1] Add backend support for C-SKY

Re: [[RESEND & PING]PATCH V3 1/1] Add backend support for C-SKY

[Mao Han]

Hi Mark,
I can't find the origin mail thread in my mailbox, as my mutt can only 
keep the newest 5000 mails. So I just reply in a new thread.

> > I've generated binaries/core with an upstream toolchain, however the
> > divzero testcase doesn't cause any coredump, so I used a zeroptr
> > testcase instead.
> > https://github.com/c-sky/test-result/blob/master/elfutils/zeroptr
> > https://github.com/c-sky/test-result/raw/master/elfutils/core.zeroptr
>
> The zeroptr binary does seem to be a real EM_CSKY one now.
> But the core.zeroptr still seems to be a core file for EM_RCE (or
> EM_MCORE).
>
> I assume the kernel generated the core file and it doesn't yet produce
> real EM_CSKY ELF core files?
>
> If you have any other way to generate a core file (maybe gdb/gcore can
> do it?) that would be really helpful.

The ELF_ARCH was defined as 39 inside linux kernel(before 4.20), so
the the core file generated was EM_RCE.
I'v regenerated the core file with ELF_ARCH defined as 252:
https://github.com/c-sky/test-result/blob/master/elfutils/zeroptr
https://github.com/c-sky/test-result/raw/master/elfutils/core.zeroptr
We have extended our core dump reg set last year, linux kernel have
upstreamed this change, but the gdb does not. I'v only got an old
released toolchain(EM_RCE) and the upstream toolchain(out of date
reg set) in my enviroment, so I can't generate/verify EM_CSKY core
file with any toolchain I have.

> > 5. run-reverse-sections-self.sh
> > elfcopy --reverse-offs dose not work properly on C-SKY object file,
> > seems not related to arch specific code.
> > size.o before copy:
> > https://github.com/c-sky/test-result/blob/master/elfutils/size.o
> > size.o.rev after copy:
> > https://github.com/c-sky/test-result/blob/master/elfutils/size.o.rev
>
> This might be because these files are also EM_RCE instead of EM_CSKY.
> But most likely it was because there was a bug in the testcase.
> Make sure you have commit d08c68 tests: elfcopy --reverse-offs should
> only swap sections next to each other.
>
> It looks like in the original the .csky.attributes and .shstrtab are
> not really next to each other (they have consecutive section numbers,
> but the file offsets are far apart). And that could have fooled the
> original test case.
>
> Please make sure you have the above commit/fix in your tree and see if
> it passes then.

This case can pass with the newest elfutils. I believe it is fixed
with commit d08c68.

> OK.
>
> > +RELOC_TYPE (PCRELIMM8BY4,      REL)
> > +RELOC_TYPE (PCRELIMM11BY2,     REL)
>
> Do we want these two? They seem to be v1 only.
>
> > +RELOC_TYPE (PCREL32,           REL|DYN)
>
> This is probably wanted, but the CPU ABI document has it listed as ??.
>
> > +RELOC_TYPE (PCRELJSR_IMM11BY2, REL)
>
> Also v1 only?
>
> > +RELOC_TYPE (GOTOFF,            REL)
> > +RELOC_TYPE (GOTPC,             REL)
> > +RELOC_TYPE (GOT32,             REL)
> > +RELOC_TYPE (PLT32,             REL)
> > +RELOC_TYPE (ADDRGOT,           REL)
> > +RELOC_TYPE (ADDRPLT,           REL)
>
> v1 only?
>
>
> R_CKCORE_GOTOFF_IMM18 is missing, but it is also missing in elf.h.
>
> > +RELOC_TYPE (GOT_IMM18BY4,      REL)
> > +RELOC_TYPE (PLT_IMM18BY4,      REL)
>
> We can list the v1 variants also, their numbers don't overlap.
> Just checking it is done deliberately. If they can never occur in v2
> ELF binaries I would leave them out.

The content of the ABI manual is quite old, binutils souce code seems
much reliable to refer to. binutils/bfd/elf32-csky.c says,
only three relocations are abiv1 exclusive:
R_CKCORE_PCREL_JSR_IMM11BY2
R_CKCORE_PCREL_IMM8BY4
R_CKCORE_PCREL_IMM11BY2

The following relocations can occur in v2 ELF binaries.
R_CKCORE_PCREL32
R_CKCORE_GOTOFF
R_CKCORE_GOTPC
R_CKCORE_GOT32
R_CKCORE_PLT32
R_CKCORE_ADDRGOT
R_CKCORE_ADDRPLT

R_CKCORE_GOTOFF_IMM18 seems unused at present.

> On Thu, 2019-07-11 at 11:19 +0800, Mao Han wrote:
> > On Thu, Jul 11, 2019 at 12:11:17AM +0200, Mark Wielaard wrote:
> > > As far as I can see this is like a SHT_GNU_ATTRIBUTES or
> > > SHT_ARM_ATTRIBUTES section. If so, you will also want something
> > > like:
> > >
> > > diff --git a/src/readelf.c b/src/readelf.c
> > > index cda7c93..8017dc4 100644
> > > --- a/src/readelf.c
> > > +++ b/src/readelf.c
> > > @@ -3571,7 +3571,9 @@ print_attributes (Ebl *ebl, const GElf_Ehdr
> > > *ehdr)
> > >
> > >        if (shdr == NULL || (shdr->sh_type != SHT_GNU_ATTRIBUTES
> > >                            && (shdr->sh_type != SHT_ARM_ATTRIBUTES
> > > -                              || ehdr->e_machine != EM_ARM)))
> > > +                              || ehdr->e_machine != EM_ARM)
> > > +                          && (shdr->sh_type != SHT_CSKY_ATTRIBUTES
> > > +                              || ehdr->e_machine != EM_CSKY)))
> > >         continue;
> > >
> > >        printf (gettext ("\
> > >
> > > And then hook check_object_attribute to display any CSKY specific
> > > attribute names/values.
> >
> > Ok, I'll add check for C-SKY here.
>
> BTW. I couldn't find what generates the SHT_CSKY_ATTRIBUTES or what the
> defined attribute constants are. Are they documented somewhere?

These attributes including cpu name and some other ISA related descriptions.
Some thing like:
CSKY_ARCH_NAME: "ck810"
CSKY_CPU_NAME:  "ck810f"
CSKY_ISA_FLAG:  0x12345678
CSKY_ISA_EXT_FLAG:  5
They are not documented yet.
I'v ask the person who is responsible for these to update the ABI
documents, but I think it will take a quite long time for them to
do that. They are quite busy at present.

Thanks,
Mao Han

Re: [[RESEND & PING]PATCH V3 1/1] Add backend support for C-SKY

[Mark Wielaard]

On Mon, 2019-07-15 at 16:55 +0800, Mao Han wrote:
> I can't find the origin mail thread in my mailbox, as my mutt can
> only keep the newest 5000 mails. So I just reply in a new thread.

Sorry about taking so long to go over these patches.
Thanks for answering the questions. I do have the older emails and I do
see I did ask some of these earlier and you already had answered them.

Most of my confusion seems to come back to this RCE/MCORE vs CSKY
thing.

> The ELF_ARCH was defined as 39 inside linux kernel(before 4.20), so
> the the core file generated was EM_RCE.
> I'v regenerated the core file with ELF_ARCH defined as 252:
> https://github.com/c-sky/test-result/blob/master/elfutils/zeroptr
> https://github.com/c-sky/test-result/raw/master/elfutils/core.zeroptr
> We have extended our core dump reg set last year, linux kernel have
> upstreamed this change, but the gdb does not. I'v only got an old
> released toolchain(EM_RCE) and the upstream toolchain(out of date
> reg set) in my enviroment, so I can't generate/verify EM_CSKY core
> file with any toolchain I have.

So the zeroptr binary looks correct now.
But the core.zeroptr is probably generated by an older linux kernel and
still is EM_RCE. This confusion is a bit confusing since I makes it
really hard to check the details (register numbering, etc.) are really
correct. I can tweak the code a bit to accept EM_RCE as EM_CSKY but
then the PRSTATUS core note doesn't look correct. I am not sure that is
because the register set as dumped by the kernel is bogus or because
the prstatus_regs definition in csky_corenote.c is incorrect.

> > > 5. run-reverse-sections-self.sh
> > > elfcopy --reverse-offs dose not work properly on C-SKY object
> > > file,
> > > [...]
> This case can pass with the newest elfutils. I believe it is fixed
> with commit d08c68.

Cool.

> > We can list the v1 variants also, their numbers don't overlap.
> > Just checking it is done deliberately. If they can never occur in
> > v2
> > ELF binaries I would leave them out.
> 
> The content of the ABI manual is quite old, binutils souce code seems
> much reliable to refer to. binutils/bfd/elf32-csky.c says,
> only three relocations are abiv1 exclusive:
> R_CKCORE_PCREL_JSR_IMM11BY2
> R_CKCORE_PCREL_IMM8BY4
> R_CKCORE_PCREL_IMM11BY2
> 
> The following relocations can occur in v2 ELF binaries.
> R_CKCORE_PCREL32
> R_CKCORE_GOTOFF
> R_CKCORE_GOTPC
> R_CKCORE_GOT32
> R_CKCORE_PLT32
> R_CKCORE_ADDRGOT
> R_CKCORE_ADDRPLT
> 
> R_CKCORE_GOTOFF_IMM18 seems unused at present.

OK. It is fine as is then. Just wanted to make sure it was as intended.

> > On Thu, 2019-07-11 at 11:19 +0800, Mao Han wrote:
> > > On Thu, Jul 11, 2019 at 12:11:17AM +0200, Mark Wielaard wrote:
> > > > As far as I can see this is like a SHT_GNU_ATTRIBUTES or
> > > > SHT_ARM_ATTRIBUTES section. If so, you will also want something
> > > > like:
> > > > 
> > > > diff --git a/src/readelf.c b/src/readelf.c
> > > > index cda7c93..8017dc4 100644
> > > > --- a/src/readelf.c
> > > > +++ b/src/readelf.c
> > > > @@ -3571,7 +3571,9 @@ print_attributes (Ebl *ebl, const
> > > > GElf_Ehdr
> > > > *ehdr)
> > > > 
> > > >        if (shdr == NULL || (shdr->sh_type != SHT_GNU_ATTRIBUTES
> > > >                            && (shdr->sh_type !=
> > > > SHT_ARM_ATTRIBUTES
> > > > -                              || ehdr->e_machine != EM_ARM)))
> > > > +                              || ehdr->e_machine != EM_ARM)
> > > > +                          && (shdr->sh_type !=
> > > > SHT_CSKY_ATTRIBUTES
> > > > +                              || ehdr->e_machine != EM_CSKY)))
> > > >         continue;
> > > > 
> > > >        printf (gettext ("\
> > > > 
> > > > And then hook check_object_attribute to display any CSKY
> > > > specific
> > > > attribute names/values.
> > > 
> > > Ok, I'll add check for C-SKY here.
> > 
> > BTW. I couldn't find what generates the SHT_CSKY_ATTRIBUTES or what
> > the
> > defined attribute constants are. Are they documented somewhere?
> 
> These attributes including cpu name and some other ISA related
> descriptions.
> Some thing like:
> CSKY_ARCH_NAME: "ck810"
> CSKY_CPU_NAME:  "ck810f"
> CSKY_ISA_FLAG:  0x12345678
> CSKY_ISA_EXT_FLAG:  5
> They are not documented yet.
> I'v ask the person who is responsible for these to update the ABI
> documents, but I think it will take a quite long time for them to
> do that. They are quite busy at present.

OK. If you can add that tweak to src/readelf.c and add an
check_object_attribute hook that handles the above attributes that
would be good.

Ideally you also add a testcase for tests/readelf-A.sh
Some of those tests cheat and create the attributes by hand.
But it would be nice if you could generate a small .o file with the
latest toolchain to be used as testcase in some other tests.

Look for example at tests/run-addrcfi.sh. Which has this somewhat
"standard" test object file:

# = bar.c =
#
# static int b1 = 1;
# int b2 = 1;
#
# static int
# foo (int a)
# {
#   return a + b2;
# }
#
# int bar (int b)
# {
#   return b - foo (b - b1);
# }
#
# = foo.c =
#
# extern int bar (int b);
# extern int b2;
#
# int
# main (int argc, char ** argv)
# {
#   return bar (argc + b2);
# }
#
# gcc -g -O2 -m32 -c foo.c
# gcc -g -O2 -m32 -c bar.c
# gcc -g -O2 m32 -o testfileppc32 foo.o bar.o

If you could generate a 'testfilecsky' that could then be used
as test for tests/run-addrcfi.sh to check register mapping and CFI
rules.

If you are able to generate a core file with a current kernel that does
properly set the EM value and register PR_STATUS then it would also be
nice to have a testfile-csky-core for use in tests/run-readelf-mixed-
corenote.sh and tests/run-allregs.sh.

And to test to debug relocation resolving you might want to generate a
small kernel module for tests/run-strip-reloc.sh (there are
instructions in the test how to generate such a module).

If it is possible to generate such testcase binaries then it should
also be easier to test the csky backend on other arches.

Thanks,

Mark

Re: [[RESEND & PING]PATCH V3 1/1] Add backend support for C-SKY

[Mark Wielaard]

On Thu, 2019-07-11 at 11:19 +0800, Mao Han wrote:
> On Thu, Jul 11, 2019 at 12:11:17AM +0200, Mark Wielaard wrote:
> > As far as I can see this is like a SHT_GNU_ATTRIBUTES or
> > SHT_ARM_ATTRIBUTES section. If so, you will also want something
> > like:
> > 
> > diff --git a/src/readelf.c b/src/readelf.c
> > index cda7c93..8017dc4 100644
> > --- a/src/readelf.c
> > +++ b/src/readelf.c
> > @@ -3571,7 +3571,9 @@ print_attributes (Ebl *ebl, const GElf_Ehdr
> > *ehdr)
> >  
> >        if (shdr == NULL || (shdr->sh_type != SHT_GNU_ATTRIBUTES
> >                            && (shdr->sh_type != SHT_ARM_ATTRIBUTES
> > -                              || ehdr->e_machine != EM_ARM)))
> > +                              || ehdr->e_machine != EM_ARM)
> > +                          && (shdr->sh_type != SHT_CSKY_ATTRIBUTES
> > +                              || ehdr->e_machine != EM_CSKY)))
> >         continue;
> >  
> >        printf (gettext ("\
> > 
> > And then hook check_object_attribute to display any CSKY specific
> > attribute names/values.
> 
> Ok, I'll add check for C-SKY here.

BTW. I couldn't find what generates the SHT_CSKY_ATTRIBUTES or what the
defined attribute constants are. Are they documented somewhere?

Thanks,

Mark

Re: [[RESEND & PING]PATCH V3 1/1] Add backend support for C-SKY

[Mark Wielaard]

On Mon, 2019-06-03 at 16:16 +0800, Mao Han wrote:
> diff --git a/backends/csky_reloc.def b/backends/csky_reloc.def
> new file mode 100644
> index 0000000..1108f0c
> --- /dev/null
> +++ b/backends/csky_reloc.def
> @@ -0,0 +1,86 @@
> +/* List the relocation types for csky.  -*- C -*-
> +   Copyright (C) 2019 Hangzhou C-SKY Microsystems co.,ltd.
> +   This file is part of elfutils.
> +
> +   This file is free software; you can redistribute it and/or modify
> +   it under the terms of either
> +
> +     * the GNU Lesser General Public License as published by the Free
> +       Software Foundation; either version 3 of the License, or (at
> +       your option) any later version
> +
> +   or
> +
> +     * the GNU General Public License as published by the Free
> +       Software Foundation; either version 2 of the License, or (at
> +       your option) any later version
> +
> +   or both in parallel, as here.
> +
> +   elfutils is distributed in the hope that it will be useful, but
> +   WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   General Public License for more details.
> +
> +   You should have received copies of the GNU General Public License and
> +   the GNU Lesser General Public License along with this program.  If
> +   not, see <http://www.gnu.org/licenses/>.  */
> +
> +/*         NAME,               REL|EXEC|DYN    */
> +
> +
> +RELOC_TYPE (NONE,              REL|EXEC|DYN)
> +RELOC_TYPE (ADDR32,            REL|EXEC|DYN)

OK.

> +RELOC_TYPE (PCRELIMM8BY4,      REL)
> +RELOC_TYPE (PCRELIMM11BY2,     REL)

Do we want these two? They seem to be v1 only.

> +RELOC_TYPE (PCREL32,           REL|DYN)

This is probably wanted, but the CPU ABI document has it listed as ??.

> +RELOC_TYPE (PCRELJSR_IMM11BY2, REL)

Also v1 only?

> +RELOC_TYPE (RELATIVE,          EXEC|DYN)
> +RELOC_TYPE (COPY,              EXEC|DYN)
> +RELOC_TYPE (GLOB_DAT,          EXEC|DYN)
> +RELOC_TYPE (JUMP_SLOT,         EXEC|DYN)

OK.

> +RELOC_TYPE (GOTOFF,            REL)
> +RELOC_TYPE (GOTPC,             REL)
> +RELOC_TYPE (GOT32,             REL)
> +RELOC_TYPE (PLT32,             REL)
> +RELOC_TYPE (ADDRGOT,           REL)
> +RELOC_TYPE (ADDRPLT,           REL)

v1 only?

> +RELOC_TYPE (PCREL_IMM26BY2,    REL)
> +RELOC_TYPE (PCREL_IMM16BY2,    REL)
> +RELOC_TYPE (PCREL_IMM16BY4,    REL)
> +RELOC_TYPE (PCREL_IMM10BY2,    REL)
> +RELOC_TYPE (PCREL_IMM10BY4,    REL)
> +RELOC_TYPE (ADDR_HI16,         REL|DYN)
> +RELOC_TYPE (ADDR_LO16,         REL|DYN)
> +RELOC_TYPE (GOTPC_HI16,                REL)
> +RELOC_TYPE (GOTPC_LO16,                REL)
> +RELOC_TYPE (GOTOFF_HI16,       REL)
> +RELOC_TYPE (GOTOFF_LO16,       REL)
> +RELOC_TYPE (GOT12,             REL)
> +RELOC_TYPE (GOT_HI16,          REL)
> +RELOC_TYPE (GOT_LO16,          REL)
> +RELOC_TYPE (PLT12,             REL)
> +RELOC_TYPE (PLT_HI16,          REL)
> +RELOC_TYPE (PLT_LO16,          REL)
> +RELOC_TYPE (ADDRGOT_HI16,      REL)
> +RELOC_TYPE (ADDRGOT_LO16,      REL)
> +RELOC_TYPE (ADDRPLT_HI16,      REL)
> +RELOC_TYPE (ADDRPLT_LO16,      REL)
> +RELOC_TYPE (PCREL_JSR_IMM26BY2,        REL|DYN)
> +RELOC_TYPE (TOFFSET_LO16,      REL)
> +RELOC_TYPE (DOFFSET_LO16,      REL)
> +RELOC_TYPE (PCREL_IMM18BY2,    REL)
> +RELOC_TYPE (DOFFSET_IMM18,     REL)
> +RELOC_TYPE (DOFFSET_IMM18BY2,  REL)
> +RELOC_TYPE (DOFFSET_IMM18BY4,  REL)

R_CKCORE_GOTOFF_IMM18 is missing, but it is also missing in elf.h.

> +RELOC_TYPE (GOT_IMM18BY4,      REL)
> +RELOC_TYPE (PLT_IMM18BY4,      REL)

R_CKCORE_PCREL_IMM7BY4 missing?

> +RELOC_TYPE (PCREL_IMM7BY4,     REL)
> +RELOC_TYPE (TLS_LE32,          REL)
> +RELOC_TYPE (TLS_IE32,          REL)
> +RELOC_TYPE (TLS_GD32,          REL)
> +RELOC_TYPE (TLS_LDM32,         REL)
> +RELOC_TYPE (TLS_LDO32,         REL)
> +RELOC_TYPE (TLS_DTPMOD32,      EXEC|DYN)
> +RELOC_TYPE (TLS_DTPOFF32,      EXEC|DYN)
> +RELOC_TYPE (TLS_TPOFF32,       EXEC|DYN)

The TLS variants aren't yet listed in the CPU ABI doc, but are in
elf.h, so I assume they are OK.

We can list the v1 variants also, their numbers don't overlap.
Just checking it is done deliberately. If they can never occur in v2
ELF binaries I would leave them out.

Cheers,

Mark

Re: [[RESEND & PING]PATCH V3 1/1] Add backend support for C-SKY

[Mao Han]

Hi, Mark

On Thu, Jul 11, 2019 at 12:11:17AM +0200, Mark Wielaard wrote:
> As far as I can see this is like a SHT_GNU_ATTRIBUTES or
> SHT_ARM_ATTRIBUTES section. If so, you will also want something like:
> 
> diff --git a/src/readelf.c b/src/readelf.c
> index cda7c93..8017dc4 100644
> --- a/src/readelf.c
> +++ b/src/readelf.c
> @@ -3571,7 +3571,9 @@ print_attributes (Ebl *ebl, const GElf_Ehdr
> *ehdr)
>  
>        if (shdr == NULL || (shdr->sh_type != SHT_GNU_ATTRIBUTES
>                            && (shdr->sh_type != SHT_ARM_ATTRIBUTES
> -                              || ehdr->e_machine != EM_ARM)))
> +                              || ehdr->e_machine != EM_ARM)
> +                          && (shdr->sh_type != SHT_CSKY_ATTRIBUTES
> +                              || ehdr->e_machine != EM_CSKY)))
>         continue;
>  
>        printf (gettext ("\
> 
> And then hook check_object_attribute to display any CSKY specific
> attribute names/values.

Ok, I'll add check for C-SKY here.

Thanks,
Mao Han

Re: [[RESEND & PING]PATCH V3 1/1] Add backend support for C-SKY

[Mark Wielaard]

Hi Mao Han,

On Mon, 2019-06-03 at 16:16 +0800, Mao Han wrote:
> +const char *
> +csky_section_type_name (int type,
> +                      char *buf __attribute__ ((unused)),
> +                      size_t len __attribute__ ((unused)))
> +{
> +  if (type == SHT_CSKY_ATTRIBUTES)
> +    return "CSKY_ATTRIBUTES";
> +
> +  return NULL;
> +}

As far as I can see this is like a SHT_GNU_ATTRIBUTES or
SHT_ARM_ATTRIBUTES section. If so, you will also want something like:

diff --git a/src/readelf.c b/src/readelf.c
index cda7c93..8017dc4 100644
--- a/src/readelf.c
+++ b/src/readelf.c
@@ -3571,7 +3571,9 @@ print_attributes (Ebl *ebl, const GElf_Ehdr
*ehdr)
 
       if (shdr == NULL || (shdr->sh_type != SHT_GNU_ATTRIBUTES
                           && (shdr->sh_type != SHT_ARM_ATTRIBUTES
-                              || ehdr->e_machine != EM_ARM)))
+                              || ehdr->e_machine != EM_ARM)
+                          && (shdr->sh_type != SHT_CSKY_ATTRIBUTES
+                              || ehdr->e_machine != EM_CSKY)))
        continue;
 
       printf (gettext ("\

And then hook check_object_attribute to display any CSKY specific
attribute names/values.

Cheers,

Mark

[[RESEND & PING]PATCH V3 1/1] Add backend support for C-SKY

[Mao Han]

C-SKY V2 ABI manual:
https://github.com/c-sky/csky-doc/blob/master/C-SKY_V2_CPU_Applications_Binary_Interface_Standards_Manual.pdf
C-SKY architecture user guide:
https://github.com/c-sky/csky-doc/blob/master/CSKY%20Architecture%20user_guide.pdf

Signed-off-by: Mao Han <han_mao@c-sky.com>
---
 backends/ChangeLog       |  11 ++++++
 backends/Makefile.am     |   9 ++++-
 backends/csky_cfi.c      |  60 ++++++++++++++++++++++++++++
 backends/csky_corenote.c |  61 ++++++++++++++++++++++++++++
 backends/csky_init.c     |  65 ++++++++++++++++++++++++++++++
 backends/csky_initreg.c  |  87 ++++++++++++++++++++++++++++++++++++++++
 backends/csky_regs.c     | 101 +++++++++++++++++++++++++++++++++++++++++++++++
 backends/csky_reloc.def  |  86 ++++++++++++++++++++++++++++++++++++++++
 backends/csky_symbol.c   |  77 ++++++++++++++++++++++++++++++++++++
 libebl/ChangeLog         |   4 ++
 libebl/eblopenbackend.c  |   1 +
 src/ChangeLog            |   4 ++
 src/elflint.c            |   2 +-
 13 files changed, 565 insertions(+), 3 deletions(-)
 create mode 100644 backends/csky_cfi.c
 create mode 100644 backends/csky_corenote.c
 create mode 100644 backends/csky_init.c
 create mode 100644 backends/csky_initreg.c
 create mode 100644 backends/csky_regs.c
 create mode 100644 backends/csky_reloc.def
 create mode 100644 backends/csky_symbol.c

diff --git a/backends/ChangeLog b/backends/ChangeLog
index 6c2b47a..9271f9c 100644
--- a/backends/ChangeLog
+++ b/backends/ChangeLog
@@ -1,3 +1,14 @@
+2019-04-29 Mao Han <han_mao@c-sky.com>
+
+	* Makefile.am: Add C-SKY.
+	* csky_cfi.c: New file.
+	* csky_corenote.c: Likewise.
+	* csky_init.c: Likewise.
+	* csky_initreg.c: Likewise.
+	* csky_regs.c: Likewise.
+	* csky_reloc.def: Likewise.
+	* csky_symbol.c: Likewise.
+
 2019-04-14  Mark Wielaard  <mark@klomp.org>
 
 	* riscv_cfi.c: Fix BACKEND define.
diff --git a/backends/Makefile.am b/backends/Makefile.am
index 2126a2e..f221997 100644
--- a/backends/Makefile.am
+++ b/backends/Makefile.am
@@ -33,12 +33,13 @@ AM_CPPFLAGS += -I$(top_srcdir)/libebl -I$(top_srcdir)/libasm \
 
 
 modules = i386 sh x86_64 ia64 alpha arm aarch64 sparc ppc ppc64 s390 \
-	  tilegx m68k bpf riscv
+	  tilegx m68k bpf riscv csky
 libebl_pic = libebl_i386_pic.a libebl_sh_pic.a libebl_x86_64_pic.a    \
 	     libebl_ia64_pic.a libebl_alpha_pic.a libebl_arm_pic.a    \
 	     libebl_aarch64_pic.a libebl_sparc_pic.a libebl_ppc_pic.a \
 	     libebl_ppc64_pic.a libebl_s390_pic.a libebl_tilegx_pic.a \
-	     libebl_m68k_pic.a libebl_bpf_pic.a libebl_riscv_pic.a
+	     libebl_m68k_pic.a libebl_bpf_pic.a libebl_riscv_pic.a    \
+	     libebl_csky_pic.a
 noinst_LIBRARIES = $(libebl_pic)
 noinst_DATA = $(libebl_pic:_pic.a=.so)
 
@@ -136,6 +137,10 @@ riscv_SRCS = riscv_init.c riscv_symbol.c riscv_cfi.c riscv_regs.c \
 libebl_riscv_pic_a_SOURCES = $(riscv_SRCS)
 am_libebl_riscv_pic_a_OBJECTS = $(riscv_SRCS:.c=.os)
 
+csky_SRCS = csky_init.c csky_symbol.c csky_cfi.c csky_regs.c \
+	    csky_initreg.c csky_corenote.c
+libebl_csky_pic_a_SOURCES = $(csky_SRCS)
+am_libebl_csky_pic_a_OBJECTS = $(csky_SRCS:.c=.os)
 
 libebl_%.so libebl_%.map: libebl_%_pic.a $(libelf) $(libdw) $(libeu)
 	@rm -f $(@:.so=.map)
diff --git a/backends/csky_cfi.c b/backends/csky_cfi.c
new file mode 100644
index 0000000..7277dbd
--- /dev/null
+++ b/backends/csky_cfi.c
@@ -0,0 +1,60 @@
+/* C-SKY ABI-specified defaults for DWARF CFI.
+   Copyright (C) 2019 Hangzhou C-SKY Microsystems co.,ltd.
+   This file is part of elfutils.
+
+   This file is free software; you can redistribute it and/or modify
+   it under the terms of either
+
+     * the GNU Lesser General Public License as published by the Free
+       Software Foundation; either version 3 of the License, or (at
+       your option) any later version
+
+   or
+
+     * the GNU General Public License as published by the Free
+       Software Foundation; either version 2 of the License, or (at
+       your option) any later version
+
+   or both in parallel, as here.
+
+   elfutils is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received copies of the GNU General Public License and
+   the GNU Lesser General Public License along with this program.  If
+   not, see <http://www.gnu.org/licenses/>.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <dwarf.h>
+
+#define BACKEND csky_
+#include "libebl_CPU.h"
+
+
+int
+csky_abi_cfi (Ebl *ebl __attribute__ ((unused)), Dwarf_CIE *abi_info)
+{
+  static const uint8_t abi_cfi[] =
+    {
+      DW_CFA_def_cfa, ULEB128_7 (14), ULEB128_7 (0),
+      DW_CFA_val_offset, ULEB128_7 (14), ULEB128_7 (0),
+
+#define SV(n) DW_CFA_same_value, ULEB128_7 (n)
+      SV(4), SV (5), SV (6), SV (7), SV (8), SV (9),
+      SV(10), SV (11), SV (15), SV (16), SV (17)
+#undef SV
+    };
+
+  abi_info->initial_instructions = abi_cfi;
+  abi_info->initial_instructions_end = &abi_cfi[sizeof abi_cfi];
+  abi_info->data_alignment_factor = -4;
+
+  abi_info->return_address_register = 15; /* lr.  */
+
+  return 0;
+}
diff --git a/backends/csky_corenote.c b/backends/csky_corenote.c
new file mode 100644
index 0000000..a1479bd
--- /dev/null
+++ b/backends/csky_corenote.c
@@ -0,0 +1,61 @@
+/* C-SKY specific core note handling.
+   Copyright (C) 2019 Hangzhou C-SKY Microsystems co.,ltd.
+   This file is part of elfutils.
+
+   This file is free software; you can redistribute it and/or modify
+   it under the terms of either
+
+     * the GNU Lesser General Public License as published by the Free
+       Software Foundation; either version 3 of the License, or (at
+       your option) any later version
+
+   or
+
+     * the GNU General Public License as published by the Free
+       Software Foundation; either version 2 of the License, or (at
+       your option) any later version
+
+   or both in parallel, as here.
+
+   elfutils is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received copies of the GNU General Public License and
+   the GNU Lesser General Public License along with this program.  If
+   not, see <http://www.gnu.org/licenses/>.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <elf.h>
+#include <inttypes.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <sys/time.h>
+
+#define BACKEND	csky_
+#include "libebl_CPU.h"
+
+#define ULONG			uint32_t
+#define PID_T			int32_t
+#define UID_T			uint32_t
+#define GID_T			uint32_t
+#define ALIGN_ULONG		4
+#define ALIGN_PID_T		4
+#define ALIGN_UID_T		4
+#define ALIGN_GID_T		4
+#define TYPE_ULONG		ELF_T_WORD
+#define TYPE_PID_T		ELF_T_SWORD
+#define TYPE_UID_T		ELF_T_WORD
+#define TYPE_GID_T		ELF_T_WORD
+
+static const Ebl_Register_Location prstatus_regs[] =
+  {
+    { .offset = 0, .regno = 0, .count = 36, .bits = 32 } /* r0..r31 */
+  };
+#define PRSTATUS_REGS_SIZE	(36 * 4)
+
+#include "linux-core-note.c"
diff --git a/backends/csky_init.c b/backends/csky_init.c
new file mode 100644
index 0000000..f0f93d4
--- /dev/null
+++ b/backends/csky_init.c
@@ -0,0 +1,65 @@
+/* Initialization of C-SKY specific backend library.
+   Copyright (C) 2019 Hangzhou C-SKY Microsystems co.,ltd.
+   This file is part of elfutils.
+
+   This file is free software; you can redistribute it and/or modify
+   it under the terms of either
+
+     * the GNU Lesser General Public License as published by the Free
+       Software Foundation; either version 3 of the License, or (at
+       your option) any later version
+
+   or
+
+     * the GNU General Public License as published by the Free
+       Software Foundation; either version 2 of the License, or (at
+       your option) any later version
+
+   or both in parallel, as here.
+
+   elfutils is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received copies of the GNU General Public License and
+   the GNU Lesser General Public License along with this program.  If
+   not, see <http://www.gnu.org/licenses/>.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#define BACKEND		csky_
+#define RELOC_PREFIX	R_CKCORE_
+#include "libebl_CPU.h"
+
+/* This defines the common reloc hooks based on csky_reloc.def.  */
+#include "common-reloc.c"
+
+const char *
+csky_init (Elf *elf __attribute__ ((unused)),
+	   GElf_Half machine __attribute__ ((unused)),
+	   Ebl *eh,
+	   size_t ehlen)
+{
+  /* Check whether the Elf_BH object has a sufficent size.  */
+  if (ehlen < sizeof (Ebl))
+    return NULL;
+
+  /* We handle it.  */
+  eh->name = "C-SKY";
+  csky_init_reloc (eh);
+  HOOK (eh, reloc_simple_type);
+  HOOK (eh, register_info);
+  HOOK (eh, abi_cfi);
+  HOOK (eh, core_note);
+  HOOK (eh, set_initial_registers_tid);
+  HOOK (eh, machine_flag_check);
+  HOOK (eh, section_type_name);
+
+  /* gcc/config/ #define DWARF_FRAME_REGISTERS.  */
+  eh->frame_nregs = 38;
+
+  return MODVERSION;
+}
diff --git a/backends/csky_initreg.c b/backends/csky_initreg.c
new file mode 100644
index 0000000..81a0da3
--- /dev/null
+++ b/backends/csky_initreg.c
@@ -0,0 +1,87 @@
+/* Fetch live process registers from TID. C-SKY version.
+   Copyright (C) 2019 Hangzhou C-SKY Microsystems co.,ltd.
+   This file is part of elfutils.
+
+   This file is free software; you can redistribute it and/or modify
+   it under the terms of either
+
+     * the GNU Lesser General Public License as published by the Free
+       Software Foundation; either version 3 of the License, or (at
+       your option) any later version
+
+   or
+
+     * the GNU General Public License as published by the Free
+       Software Foundation; either version 2 of the License, or (at
+       your option) any later version
+
+   or both in parallel, as here.
+
+   elfutils is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received copies of the GNU General Public License and
+   the GNU Lesser General Public License along with this program.  If
+   not, see <http://www.gnu.org/licenses/>.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include "system.h"
+#include <assert.h>
+#if defined __CSKY__ && defined __linux__
+# include <sys/uio.h>
+# include <sys/procfs.h>
+# include <sys/ptrace.h>
+#endif
+
+#define BACKEND csky_
+#include "libebl_CPU.h"
+
+bool
+csky_set_initial_registers_tid (pid_t tid __attribute__ ((unused)),
+			ebl_tid_registers_t *setfunc __attribute__ ((unused)),
+				void *arg __attribute__ ((unused)))
+{
+#if !defined __CSKY__ || !defined __linux__
+  return false;
+#else /* __CSKY__ */
+  struct pt_regs user_regs;
+  struct iovec iovec;
+  iovec.iov_base = &user_regs;
+  iovec.iov_len = sizeof (user_regs);
+  if (ptrace (PTRACE_GETREGSET, tid, NT_PRSTATUS, &iovec) != 0)
+    return false;
+
+  Dwarf_Word dwarf_regs[38];
+
+  /* lr.  */
+  dwarf_regs[15] = user_regs.lr;
+  /* sp.  */
+  dwarf_regs[14] = user_regs.usp;
+  /* r0 ~ r13.  */
+  dwarf_regs[0] = user_regs.a0;
+  dwarf_regs[1] = user_regs.a1;
+  dwarf_regs[2] = user_regs.a2;
+  dwarf_regs[3] = user_regs.a3;
+  for (int i = 4; i < 14; i++)
+    dwarf_regs[i] = user_regs.regs[i - 4];
+  /* r ~ r13.  */
+  for (int i = 16; i < 31; i++)
+    dwarf_regs[i] = user_regs.exregs[i - 16];
+  /* tls.  */
+  dwarf_regs[31] = user_regs.tls;
+  /* hi.  */
+  dwarf_regs[36] = user_regs.rhi;
+  /* lo.  */
+  dwarf_regs[37] = user_regs.rlo;
+  /* pc.  */
+  dwarf_regs[32] = user_regs.pc;
+  setfunc (-1, 1, &dwarf_regs[32], arg);
+
+  return setfunc (0, 38, dwarf_regs, arg);
+#endif
+}
diff --git a/backends/csky_regs.c b/backends/csky_regs.c
new file mode 100644
index 0000000..7e41381
--- /dev/null
+++ b/backends/csky_regs.c
@@ -0,0 +1,101 @@
+/* Register names and numbers for C-SKY DWARF.
+   Copyright (C) 2019 Hangzhou C-SKY Microsystems co.,ltd.
+   This file is part of elfutils.
+
+   This file is free software; you can redistribute it and/or modify
+   it under the terms of either
+
+     * the GNU Lesser General Public License as published by the Free
+       Software Foundation; either version 3 of the License, or (at
+       your option) any later version
+
+   or
+
+     * the GNU General Public License as published by the Free
+       Software Foundation; either version 2 of the License, or (at
+       your option) any later version
+
+   or both in parallel, as here.
+
+   elfutils is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received copies of the GNU General Public License and
+   the GNU Lesser General Public License along with this program.  If
+   not, see <http://www.gnu.org/licenses/>.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <string.h>
+#include <dwarf.h>
+
+#define BACKEND csky_
+#include "libebl_CPU.h"
+
+ssize_t
+csky_register_info (Ebl *ebl  __attribute__ ((unused)),
+		    int regno, char *name, size_t namelen,
+		    const char **prefix, const char **setname,
+		    int *bits, int *type)
+{
+  if (name == NULL)
+    return 38;
+
+  *prefix = "";
+  *bits = 32;
+  *type = DW_ATE_signed;
+  *setname = "integer";
+
+  switch (regno)
+    {
+    case 0 ... 9:
+      name[0] = 'r';
+      name[1] = regno + '0';
+      namelen = 2;
+      break;
+
+    case 10 ... 13:
+    case 16 ... 30:
+      name[0] = 'r';
+      name[1] = regno / 10 + '0';
+      name[2] = regno % 10 + '0';
+      namelen = 2;
+      break;
+
+    case 14:
+      stpcpy (name, "sp");
+      namelen = 2;
+      break;
+
+    case 15:
+      stpcpy (name, "lr");
+      namelen = 2;
+      break;
+
+    case 31:
+      stpcpy (name, "tls");
+      namelen = 3;
+      break;
+
+    case 36:
+      stpcpy (name, "hi");
+      namelen = 2;
+      break;
+
+    case 37:
+      stpcpy (name, "lo");
+      namelen = 2;
+      break;
+
+    default:
+      *setname = NULL;
+      return 0;
+    }
+
+  name[namelen++] = '\0';
+  return namelen;
+}
diff --git a/backends/csky_reloc.def b/backends/csky_reloc.def
new file mode 100644
index 0000000..1108f0c
--- /dev/null
+++ b/backends/csky_reloc.def
@@ -0,0 +1,86 @@
+/* List the relocation types for csky.  -*- C -*-
+   Copyright (C) 2019 Hangzhou C-SKY Microsystems co.,ltd.
+   This file is part of elfutils.
+
+   This file is free software; you can redistribute it and/or modify
+   it under the terms of either
+
+     * the GNU Lesser General Public License as published by the Free
+       Software Foundation; either version 3 of the License, or (at
+       your option) any later version
+
+   or
+
+     * the GNU General Public License as published by the Free
+       Software Foundation; either version 2 of the License, or (at
+       your option) any later version
+
+   or both in parallel, as here.
+
+   elfutils is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received copies of the GNU General Public License and
+   the GNU Lesser General Public License along with this program.  If
+   not, see <http://www.gnu.org/licenses/>.  */
+
+/*	    NAME,		REL|EXEC|DYN	*/
+
+
+RELOC_TYPE (NONE,		REL|EXEC|DYN)
+RELOC_TYPE (ADDR32,		REL|EXEC|DYN)
+RELOC_TYPE (PCRELIMM8BY4,	REL)
+RELOC_TYPE (PCRELIMM11BY2,	REL)
+RELOC_TYPE (PCREL32,		REL|DYN)
+RELOC_TYPE (PCRELJSR_IMM11BY2,	REL)
+RELOC_TYPE (RELATIVE,		EXEC|DYN)
+RELOC_TYPE (COPY,		EXEC|DYN)
+RELOC_TYPE (GLOB_DAT,		EXEC|DYN)
+RELOC_TYPE (JUMP_SLOT,		EXEC|DYN)
+RELOC_TYPE (GOTOFF,		REL)
+RELOC_TYPE (GOTPC,		REL)
+RELOC_TYPE (GOT32,		REL)
+RELOC_TYPE (PLT32,		REL)
+RELOC_TYPE (ADDRGOT,		REL)
+RELOC_TYPE (ADDRPLT,		REL)
+RELOC_TYPE (PCREL_IMM26BY2,	REL)
+RELOC_TYPE (PCREL_IMM16BY2,	REL)
+RELOC_TYPE (PCREL_IMM16BY4,	REL)
+RELOC_TYPE (PCREL_IMM10BY2,	REL)
+RELOC_TYPE (PCREL_IMM10BY4,	REL)
+RELOC_TYPE (ADDR_HI16,		REL|DYN)
+RELOC_TYPE (ADDR_LO16,		REL|DYN)
+RELOC_TYPE (GOTPC_HI16,		REL)
+RELOC_TYPE (GOTPC_LO16,		REL)
+RELOC_TYPE (GOTOFF_HI16,	REL)
+RELOC_TYPE (GOTOFF_LO16,	REL)
+RELOC_TYPE (GOT12,		REL)
+RELOC_TYPE (GOT_HI16,		REL)
+RELOC_TYPE (GOT_LO16,		REL)
+RELOC_TYPE (PLT12,		REL)
+RELOC_TYPE (PLT_HI16,		REL)
+RELOC_TYPE (PLT_LO16,		REL)
+RELOC_TYPE (ADDRGOT_HI16,	REL)
+RELOC_TYPE (ADDRGOT_LO16,	REL)
+RELOC_TYPE (ADDRPLT_HI16,	REL)
+RELOC_TYPE (ADDRPLT_LO16,	REL)
+RELOC_TYPE (PCREL_JSR_IMM26BY2,	REL|DYN)
+RELOC_TYPE (TOFFSET_LO16,	REL)
+RELOC_TYPE (DOFFSET_LO16,	REL)
+RELOC_TYPE (PCREL_IMM18BY2,	REL)
+RELOC_TYPE (DOFFSET_IMM18,	REL)
+RELOC_TYPE (DOFFSET_IMM18BY2,	REL)
+RELOC_TYPE (DOFFSET_IMM18BY4,	REL)
+RELOC_TYPE (GOT_IMM18BY4,	REL)
+RELOC_TYPE (PLT_IMM18BY4,	REL)
+RELOC_TYPE (PCREL_IMM7BY4,	REL)
+RELOC_TYPE (TLS_LE32,		REL)
+RELOC_TYPE (TLS_IE32,		REL)
+RELOC_TYPE (TLS_GD32,		REL)
+RELOC_TYPE (TLS_LDM32,		REL)
+RELOC_TYPE (TLS_LDO32,		REL)
+RELOC_TYPE (TLS_DTPMOD32,	EXEC|DYN)
+RELOC_TYPE (TLS_DTPOFF32,	EXEC|DYN)
+RELOC_TYPE (TLS_TPOFF32,	EXEC|DYN)
diff --git a/backends/csky_symbol.c b/backends/csky_symbol.c
new file mode 100644
index 0000000..79b5bf9
--- /dev/null
+++ b/backends/csky_symbol.c
@@ -0,0 +1,77 @@
+/* C-SKY specific symbolic name handling.
+   Copyright (C) 2019 Hangzhou C-SKY Microsystems co.,ltd.
+   This file is part of elfutils.
+
+   This file is free software; you can redistribute it and/or modify
+   it under the terms of either
+
+     * the GNU Lesser General Public License as published by the Free
+       Software Foundation; either version 3 of the License, or (at
+       your option) any later version
+
+   or
+
+     * the GNU General Public License as published by the Free
+       Software Foundation; either version 2 of the License, or (at
+       your option) any later version
+
+   or both in parallel, as here.
+
+   elfutils is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received copies of the GNU General Public License and
+   the GNU Lesser General Public License along with this program.  If
+   not, see <http://www.gnu.org/licenses/>.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <assert.h>
+#include <elf.h>
+#include <stddef.h>
+#include <string.h>
+
+#define BACKEND csky_
+#include "libebl_CPU.h"
+
+/* Check for the simple reloc types.  */
+Elf_Type
+csky_reloc_simple_type (Ebl *ebl __attribute__ ((unused)), int type,
+			int *addsub __attribute__ ((unused)))
+{
+  switch (type)
+    {
+    case R_CKCORE_ADDR32:
+      return ELF_T_WORD;
+    default:
+      return ELF_T_NUM;
+    }
+}
+
+bool
+csky_machine_flag_check (GElf_Word flags)
+{
+  switch (flags & EF_CSKY_ABIMASK)
+    {
+    case EF_CSKY_ABIV2:
+      return true;
+    case EF_CSKY_ABIV1:
+    default:
+      return false;
+    }
+}
+
+const char *
+csky_section_type_name (int type,
+		       char *buf __attribute__ ((unused)),
+		       size_t len __attribute__ ((unused)))
+{
+  if (type == SHT_CSKY_ATTRIBUTES)
+    return "CSKY_ATTRIBUTES";
+
+  return NULL;
+}
diff --git a/libebl/ChangeLog b/libebl/ChangeLog
index e050bfc..aaec22a 100644
--- a/libebl/ChangeLog
+++ b/libebl/ChangeLog
@@ -1,3 +1,7 @@
+2019-04-29 Mao Han <han_mao@c-sky.com>
+
+	* eblopenbackend.c: Add C-SKY.
+
 2019-04-28  Mark Wielaard  <mark@klomp.org>
 
 	* eblsymbolbindingname.c (ebl_symbol_binding_name): Check ebl is
diff --git a/libebl/eblopenbackend.c b/libebl/eblopenbackend.c
index d54b720..e229dbd 100644
--- a/libebl/eblopenbackend.c
+++ b/libebl/eblopenbackend.c
@@ -135,6 +135,7 @@ static const struct
   { "bpf", "elf_bpf", "bpf", 3, EM_BPF, 0, 0 },
   { "riscv", "elf_riscv", "riscv", 5, EM_RISCV, ELFCLASS64, ELFDATA2LSB },
   { "riscv", "elf_riscv", "riscv", 5, EM_RISCV, ELFCLASS32, ELFDATA2LSB },
+  { "csky", "elf_csky", "csky", 4, EM_CSKY, ELFCLASS32, ELFDATA2LSB },
 };
 #define nmachines (sizeof (machines) / sizeof (machines[0]))
 
diff --git a/src/ChangeLog b/src/ChangeLog
index 580eea9..092067f 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,7 @@
+2019-04-29 Mao Han <han_mao@c-sky.com>
+
+	* elflint.c: Add C-SKY.
+
 2019-05-10  Mark Wielaard  <mark@klomp.org>
 
 	* readelf.c (struct attrcb_args): Rename die to dies.
diff --git a/src/elflint.c b/src/elflint.c
index 810c8bd..edb466d 100644
--- a/src/elflint.c
+++ b/src/elflint.c
@@ -330,7 +330,7 @@ static const int valid_e_machine[] =
     EM_CRIS, EM_JAVELIN, EM_FIREPATH, EM_ZSP, EM_MMIX, EM_HUANY, EM_PRISM,
     EM_AVR, EM_FR30, EM_D10V, EM_D30V, EM_V850, EM_M32R, EM_MN10300,
     EM_MN10200, EM_PJ, EM_OPENRISC, EM_ARC_A5, EM_XTENSA, EM_ALPHA,
-    EM_TILEGX, EM_TILEPRO, EM_AARCH64, EM_BPF, EM_RISCV
+    EM_TILEGX, EM_TILEPRO, EM_AARCH64, EM_BPF, EM_RISCV, EM_CSKY
   };
 #define nvalid_e_machine \
   (sizeof (valid_e_machine) / sizeof (valid_e_machine[0]))
-- 
2.7.4