[Crash-utility] [PATCH] Fix for "bpf -m|-M" options on Linux 5.3 and later

[Dave Anderson]

Hi Kazu,

Thanks for catching this -- queued for crash-7.2.9:

  https://github.com/crash-utility/crash/commit/af71d71f35372df7308788a6d49b539b75ea19b5

Dave


----- Original Message -----
> Fix for the "bpf -m|-M" options on Linux 5.3 and later kernels that
> contain commit 3539b96e041c06e4317082816d90ec09160aeb11, titled
> "bpf: group memory related fields in struct bpf_map_memory".
> Without the patch, the options prints "(unknown)" for MEMLOCK and UID.
> 
> Signed-off-by: Kazuhito Hagio <k-hagio-ab at nec.com>
> ---
>  bpf.c     | 22 ++++++++++++++++++++--
>  defs.h    |  3 +++
>  symbols.c |  6 ++++++
>  3 files changed, 29 insertions(+), 2 deletions(-)
> 
> diff --git a/bpf.c b/bpf.c
> index 056e286..39ced88 100644
> --- a/bpf.c
> +++ b/bpf.c
> @@ -202,6 +202,13 @@ bpf_init(struct bpf_info *bpf)
>  		MEMBER_OFFSET_INIT(bpf_map_user, "bpf_map", "user");
>  		MEMBER_OFFSET_INIT(user_struct_uid, "user_struct", "uid");
>  
> +		/* Linux 5.3 */
> +		MEMBER_OFFSET_INIT(bpf_map_memory, "bpf_map", "memory");
> +		if (VALID_MEMBER(bpf_map_memory)) {
> +			MEMBER_OFFSET_INIT(bpf_map_memory_pages, "bpf_map_memory", "pages");
> +			MEMBER_OFFSET_INIT(bpf_map_memory_user, "bpf_map_memory", "user");
> +		}
> +
>  		if (!bpf_type_size_init()) {
>  			bpf->status = FALSE;
>  			command_not_supported();
> @@ -576,7 +583,11 @@ do_map_only:
>  				fprintf(fp, "(unknown)");
>  
>  			fprintf(fp, "  MEMLOCK: ");
> -			if (VALID_MEMBER(bpf_map_pages)) {
> +			if (VALID_MEMBER(bpf_map_memory) && VALID_MEMBER(bpf_map_memory_pages)) {
> +				map_pages = UINT(bpf->bpf_map_buf + OFFSET(bpf_map_memory)
> +						+ OFFSET(bpf_map_memory_pages));
> +				fprintf(fp, "%d\n", map_pages * PAGESIZE());
> +			} else if (VALID_MEMBER(bpf_map_pages)) {
>  				map_pages = UINT(bpf->bpf_map_buf + OFFSET(bpf_map_pages));
>  				fprintf(fp, "%d\n", map_pages * PAGESIZE());
>  			} else
> @@ -594,8 +605,15 @@ do_map_only:
>  				fprintf(fp, "(unknown)\n");
>  
>  			fprintf(fp, "  UID: ");
> -			if (VALID_MEMBER(bpf_map_user) && VALID_MEMBER(user_struct_uid)) {
> +			if (VALID_MEMBER(bpf_map_memory) && VALID_MEMBER(bpf_map_memory_user))
> +				user = ULONG(bpf->bpf_map_buf + OFFSET(bpf_map_memory)
> +						+ OFFSET(bpf_map_memory_user));
> +			else if (VALID_MEMBER(bpf_map_user))
>  				user = ULONG(bpf->bpf_map_buf + OFFSET(bpf_map_user));
> +			else
> +				user = 0;
> +
> +			if (user && VALID_MEMBER(user_struct_uid)) {
>  				if (readmem(user + OFFSET(user_struct_uid), KVADDR, &uid, sizeof(uint),
>  				    "user_struct.uid", QUIET|RETURN_ON_ERROR))
>  					fprintf(fp, "%d\n", uid);
> diff --git a/defs.h b/defs.h
> index ac24a5d..fbd19b0 100644
> --- a/defs.h
> +++ b/defs.h
> @@ -2075,6 +2075,9 @@ struct offset_table {                    /* stash of
> commonly-used offsets */
>  	long device_private_knode_class;
>  	long timerqueue_head_rb_root;
>  	long rb_root_cached_rb_leftmost;
> +	long bpf_map_memory;
> +	long bpf_map_memory_pages;
> +	long bpf_map_memory_user;
>  };
>  
>  struct size_table {         /* stash of commonly-used sizes */
> diff --git a/symbols.c b/symbols.c
> index f04e8b5..f1f659b 100644
> --- a/symbols.c
> +++ b/symbols.c
> @@ -10479,6 +10479,12 @@ dump_offset_table(char *spec, ulong makestruct)
>  		OFFSET(bpf_map_name));
>  	fprintf(fp, "                  bpf_map_user: %ld\n",
>  		OFFSET(bpf_map_user));
> +	fprintf(fp, "                bpf_map_memory: %ld\n",
> +		OFFSET(bpf_map_memory));
> +	fprintf(fp, "          bpf_map_memory_pages: %ld\n",
> +		OFFSET(bpf_map_memory_pages));
> +	fprintf(fp, "           bpf_map_memory_user: %ld\n",
> +		OFFSET(bpf_map_memory_user));
>  
>  	fprintf(fp, "     bpf_prog_aux_used_map_cnt: %ld\n",
>  		OFFSET(bpf_prog_aux_used_map_cnt));
> --
> 2.24.1
> 
>