Re: [PATCH v4][makedumpfile 1/7] Reserve sections for makedumpfile and extenions

[Stephen Brennan <stephen.s.brennan@oracle.com>]

Tao Liu <ltao@redhat.com> writes:
> This patch makes preparation for btf/kallsyms support of
> makedumpfile and extensions. Any needed kernel symbols/types
> will be reserved within a special section, .init_ksyms for
> kallsyms symbols and .init_ktypes for kernel types. During
> makedumpfile kallsyms/btf initialization, those missing info
> will be resolved. A makedumpfile.ld script is introduced for the
> purpose.
>
> Suggested-by: Stephen Brennan <stephen.s.brennan@oracle.com>
> Signed-off-by: Tao Liu <ltao@redhat.com>

As I mentioned before, I don't think this patch is strictly necessary.
If we rename the sections to avoid the "." at the start of the names,
then the compiler should automatically provide the start and stop
symbols. But that said, there's nothing wrong with doing it this way,
and it is a bit more explicit, so I see the value in keeping it.

Reviewed-by: Stephen Brennan <stephen.s.brennan@oracle.com>

> ---
>  Makefile        |  2 +-
>  makedumpfile.ld | 15 +++++++++++++++
>  2 files changed, 16 insertions(+), 1 deletion(-)
>  create mode 100644 makedumpfile.ld
>
> diff --git a/Makefile b/Makefile
> index 05ab5f2..15a4ba0 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -113,7 +113,7 @@ $(OBJ_ARCH): $(SRC_ARCH)
>  	$(CC) $(CFLAGS_ARCH) -c -o ./$@ $(VPATH)$(@:.o=.c)
>  
>  makedumpfile: $(SRC_BASE) $(OBJ_PART) $(OBJ_ARCH)
> -	$(CC) $(CFLAGS) $(LDFLAGS) $(OBJ_PART) $(OBJ_ARCH) -rdynamic -o $@ $< $(LIBS)
> +	$(CC) $(CFLAGS) $(LDFLAGS) $(OBJ_PART) $(OBJ_ARCH) -rdynamic -Wl,-T,makedumpfile.ld -o $@ $< $(LIBS)
>  	@sed -e "s/@DATE@/$(DATE)/" \
>  	     -e "s/@VERSION@/$(VERSION)/" \
>  	     $(VPATH)makedumpfile.8.in > $(VPATH)makedumpfile.8
> diff --git a/makedumpfile.ld b/makedumpfile.ld
> new file mode 100644
> index 0000000..231a162
> --- /dev/null
> +++ b/makedumpfile.ld
> @@ -0,0 +1,15 @@
> +SECTIONS
> +{
> +	.init_ksyms ALIGN(8) : {
> +		__start_init_ksyms = .;
> +		KEEP(*(.init_ksyms*))
> +		__stop_init_ksyms = .;
> +	}
> +
> +	.init_ktypes ALIGN(8) : {
> +		__start_init_ktypes = .;
> +		KEEP(*(.init_ktypes*))
> +		__stop_init_ktypes = .;
> +	}
> +}
> +INSERT AFTER .data;
> \ No newline at end of file
> -- 
> 2.47.0