[PATCH] opcodes/csky: return the default disassembler when there is no bfd

[PATCH] opcodes/csky: return the default disassembler when there is no bfd

[Andrew Burgess]

The disassembler function should return a valid disassembler function
even when there is no BFD present.  This is implied (I believe) by the
comment in dis-asm.h which says the BFD may be NULL.  Further, it
makes sense when considering that the disassembler is used in GDB, and
GDB may connect to a target and perform debugging even without a BFD
being supplied.

This commit makes the csky_get_disassembler function return the
default disassembler configuration when no bfd is supplied, this is
the same default configuration as is used when a BFD is supplied, but
the BFD has no attributes section.

Before the change configuring GDB with --enable-targets=all and
running the tests gdb.base/all-architectures-2.exp results in many
errors, but after this change there are no failures.

opcodes/ChangeLog:

	* csky-dis.c (csky_get_disassembler): Don't return NULL when there
	is no BFD.
---
 opcodes/ChangeLog  |  5 +++++
 opcodes/csky-dis.c | 32 +++++++++++++++++---------------
 2 files changed, 22 insertions(+), 15 deletions(-)

diff --git a/opcodes/csky-dis.c b/opcodes/csky-dis.c
index ba0f4605f54..a28160b984e 100644
--- a/opcodes/csky-dis.c
+++ b/opcodes/csky-dis.c
@@ -239,23 +239,25 @@ csky_get_disassembler (bfd *abfd)
   obj_attribute *attr;
   const char *sec_name = NULL;
   if (!abfd)
-    return NULL;
-
-  mach_flag = elf_elfheader (abfd)->e_flags;
-
-  sec_name = get_elf_backend_data (abfd)->obj_attrs_section;
-  /* Skip any input that hasn't attribute section.
-     This enables to link object files without attribute section with
-     any others.  */
-  if (bfd_get_section_by_name (abfd, sec_name) != NULL)
+    dis_info.isa = CSKY_DEFAULT_ISA;
+  else
     {
-      attr = elf_known_obj_attributes_proc (abfd);
-      dis_info.isa = attr[Tag_CSKY_ISA_EXT_FLAGS].i;
-      dis_info.isa <<= 32;
-      dis_info.isa |= attr[Tag_CSKY_ISA_FLAGS].i;
+      mach_flag = elf_elfheader (abfd)->e_flags;
+
+      sec_name = get_elf_backend_data (abfd)->obj_attrs_section;
+      /* Skip any input that hasn't attribute section.
+         This enables to link object files without attribute section with
+         any others.  */
+      if (bfd_get_section_by_name (abfd, sec_name) != NULL)
+        {
+          attr = elf_known_obj_attributes_proc (abfd);
+          dis_info.isa = attr[Tag_CSKY_ISA_EXT_FLAGS].i;
+          dis_info.isa <<= 32;
+          dis_info.isa |= attr[Tag_CSKY_ISA_FLAGS].i;
+        }
+      else
+        dis_info.isa = CSKY_DEFAULT_ISA;
     }
-  else
-    dis_info.isa = CSKY_DEFAULT_ISA;
 
    return print_insn_csky;
 }
-- 
2.25.4

Re: [PATCH] opcodes/csky: return the default disassembler when there is no bfd

[Lifang Xia]

Hi Andrew,

Thanks al lot for that.

Best Regards
Lifang Xia

On 2020/9/16 17:12, Andrew Burgess wrote:
> The disassembler function should return a valid disassembler function
> even when there is no BFD present.  This is implied (I believe) by the
> comment in dis-asm.h which says the BFD may be NULL.  Further, it
> makes sense when considering that the disassembler is used in GDB, and
> GDB may connect to a target and perform debugging even without a BFD
> being supplied.
>
> This commit makes the csky_get_disassembler function return the
> default disassembler configuration when no bfd is supplied, this is
> the same default configuration as is used when a BFD is supplied, but
> the BFD has no attributes section.
>
> Before the change configuring GDB with --enable-targets=all and
> running the tests gdb.base/all-architectures-2.exp results in many
> errors, but after this change there are no failures.
>
> opcodes/ChangeLog:
>
> 	* csky-dis.c (csky_get_disassembler): Don't return NULL when there
> 	is no BFD.
> ---
>   opcodes/ChangeLog  |  5 +++++
>   opcodes/csky-dis.c | 32 +++++++++++++++++---------------
>   2 files changed, 22 insertions(+), 15 deletions(-)
>
> diff --git a/opcodes/csky-dis.c b/opcodes/csky-dis.c
> index ba0f4605f54..a28160b984e 100644
> --- a/opcodes/csky-dis.c
> +++ b/opcodes/csky-dis.c
> @@ -239,23 +239,25 @@ csky_get_disassembler (bfd *abfd)
>     obj_attribute *attr;
>     const char *sec_name = NULL;
>     if (!abfd)
> -    return NULL;
> -
> -  mach_flag = elf_elfheader (abfd)->e_flags;
> -
> -  sec_name = get_elf_backend_data (abfd)->obj_attrs_section;
> -  /* Skip any input that hasn't attribute section.
> -     This enables to link object files without attribute section with
> -     any others.  */
> -  if (bfd_get_section_by_name (abfd, sec_name) != NULL)
> +    dis_info.isa = CSKY_DEFAULT_ISA;
> +  else
>       {
> -      attr = elf_known_obj_attributes_proc (abfd);
> -      dis_info.isa = attr[Tag_CSKY_ISA_EXT_FLAGS].i;
> -      dis_info.isa <<= 32;
> -      dis_info.isa |= attr[Tag_CSKY_ISA_FLAGS].i;
> +      mach_flag = elf_elfheader (abfd)->e_flags;
> +
> +      sec_name = get_elf_backend_data (abfd)->obj_attrs_section;
> +      /* Skip any input that hasn't attribute section.
> +         This enables to link object files without attribute section with
> +         any others.  */
> +      if (bfd_get_section_by_name (abfd, sec_name) != NULL)
> +        {
> +          attr = elf_known_obj_attributes_proc (abfd);
> +          dis_info.isa = attr[Tag_CSKY_ISA_EXT_FLAGS].i;
> +          dis_info.isa <<= 32;
> +          dis_info.isa |= attr[Tag_CSKY_ISA_FLAGS].i;
> +        }
> +      else
> +        dis_info.isa = CSKY_DEFAULT_ISA;
>       }
> -  else
> -    dis_info.isa = CSKY_DEFAULT_ISA;
>   
>      return print_insn_csky;
>   }