diff mbox series

[bpf,v1] tools/libbpf: avoid counting local symbols in ABI check

Message ID 20200905214831.1565465-1-Tony.Ambardar@gmail.com
State New
Headers show
Series [bpf,v1] tools/libbpf: avoid counting local symbols in ABI check | expand

Commit Message

Tony Ambardar Sept. 5, 2020, 9:48 p.m. UTC 
Encountered the following failure building libbpf from kernel 5.8.5 sources
with GCC 8.4.0 and binutils 2.34: (long paths shortened)

  Warning: Num of global symbols in sharedobjs/libbpf-in.o (234) does NOT
  match with num of versioned symbols in libbpf.so (236). Please make sure
  all LIBBPF_API symbols are versioned in libbpf.map.
  --- libbpf_global_syms.tmp    2020-09-02 07:30:58.920084380 +0000
  +++ libbpf_versioned_syms.tmp 2020-09-02 07:30:58.924084388 +0000
  @@ -1,3 +1,5 @@
  +_fini
  +_init
   bpf_btf_get_fd_by_id
   bpf_btf_get_next_id
   bpf_create_map
  make[4]: *** [Makefile:210: check_abi] Error 1

Investigation shows _fini and _init are actually local symbols counted
amongst global ones:

  $ readelf --dyn-syms --wide libbpf.so|head -10

  Symbol table '.dynsym' contains 343 entries:
     Num:    Value  Size Type    Bind   Vis      Ndx Name
       0: 00000000     0 NOTYPE  LOCAL  DEFAULT  UND
       1: 00004098     0 SECTION LOCAL  DEFAULT   11
       2: 00004098     8 FUNC    LOCAL  DEFAULT   11 _init@@LIBBPF_0.0.1
       3: 00023040     8 FUNC    LOCAL  DEFAULT   14 _fini@@LIBBPF_0.0.1
       4: 00000000     0 OBJECT  GLOBAL DEFAULT  ABS LIBBPF_0.0.4
       5: 00000000     0 OBJECT  GLOBAL DEFAULT  ABS LIBBPF_0.0.1
       6: 0000ffa4     8 FUNC    GLOBAL DEFAULT   12 bpf_object__find_map_by_offset@@LIBBPF_0.0.1

A previous commit filtered global symbols in sharedobjs/libbpf-in.o. Do the
same with the libbpf.so DSO for consistent comparison.

Fixes: 306b267cb3c4 ("libbpf: Verify versioned symbols")

Signed-off-by: Tony Ambardar <Tony.Ambardar@gmail.com>
---
 tools/lib/bpf/Makefile | 2 ++
 1 file changed, 2 insertions(+)

Comments

Andrii Nakryiko Sept. 8, 2020, 7:53 p.m. UTC | #1 
On Sat, Sep 5, 2020 at 2:49 PM Tony Ambardar <tony.ambardar@gmail.com> wrote:
>
> Encountered the following failure building libbpf from kernel 5.8.5 sources
> with GCC 8.4.0 and binutils 2.34: (long paths shortened)
>
>   Warning: Num of global symbols in sharedobjs/libbpf-in.o (234) does NOT
>   match with num of versioned symbols in libbpf.so (236). Please make sure
>   all LIBBPF_API symbols are versioned in libbpf.map.
>   --- libbpf_global_syms.tmp    2020-09-02 07:30:58.920084380 +0000
>   +++ libbpf_versioned_syms.tmp 2020-09-02 07:30:58.924084388 +0000
>   @@ -1,3 +1,5 @@
>   +_fini
>   +_init
>    bpf_btf_get_fd_by_id
>    bpf_btf_get_next_id
>    bpf_create_map
>   make[4]: *** [Makefile:210: check_abi] Error 1
>
> Investigation shows _fini and _init are actually local symbols counted
> amongst global ones:
>
>   $ readelf --dyn-syms --wide libbpf.so|head -10
>
>   Symbol table '.dynsym' contains 343 entries:
>      Num:    Value  Size Type    Bind   Vis      Ndx Name
>        0: 00000000     0 NOTYPE  LOCAL  DEFAULT  UND
>        1: 00004098     0 SECTION LOCAL  DEFAULT   11
>        2: 00004098     8 FUNC    LOCAL  DEFAULT   11 _init@@LIBBPF_0.0.1
>        3: 00023040     8 FUNC    LOCAL  DEFAULT   14 _fini@@LIBBPF_0.0.1
>        4: 00000000     0 OBJECT  GLOBAL DEFAULT  ABS LIBBPF_0.0.4
>        5: 00000000     0 OBJECT  GLOBAL DEFAULT  ABS LIBBPF_0.0.1
>        6: 0000ffa4     8 FUNC    GLOBAL DEFAULT   12 bpf_object__find_map_by_offset@@LIBBPF_0.0.1
>
> A previous commit filtered global symbols in sharedobjs/libbpf-in.o. Do the
> same with the libbpf.so DSO for consistent comparison.
>
> Fixes: 306b267cb3c4 ("libbpf: Verify versioned symbols")
>
> Signed-off-by: Tony Ambardar <Tony.Ambardar@gmail.com>
> ---

LGTM, thanks!

Acked-by: Andrii Nakryiko <andriin@fb.com>

>  tools/lib/bpf/Makefile | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
> index b78484e7a608..9ae8f4ef0aac 100644
> --- a/tools/lib/bpf/Makefile
> +++ b/tools/lib/bpf/Makefile
> @@ -152,6 +152,7 @@ GLOBAL_SYM_COUNT = $(shell readelf -s --wide $(BPF_IN_SHARED) | \
>                            awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}' | \
>                            sort -u | wc -l)
>  VERSIONED_SYM_COUNT = $(shell readelf --dyn-syms --wide $(OUTPUT)libbpf.so | \
> +                             awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}' | \
>                               grep -Eo '[^ ]+@LIBBPF_' | cut -d@ -f1 | sort -u | wc -l)
>
>  CMD_TARGETS = $(LIB_TARGET) $(PC_FILE)
> @@ -219,6 +220,7 @@ check_abi: $(OUTPUT)libbpf.so
>                     awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}'|  \
>                     sort -u > $(OUTPUT)libbpf_global_syms.tmp;           \
>                 readelf --dyn-syms --wide $(OUTPUT)libbpf.so |           \
> +                   awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}'|  \
>                     grep -Eo '[^ ]+@LIBBPF_' | cut -d@ -f1 |             \
>                     sort -u > $(OUTPUT)libbpf_versioned_syms.tmp;        \
>                 diff -u $(OUTPUT)libbpf_global_syms.tmp                  \
> --
> 2.25.1
>
Alexei Starovoitov Sept. 8, 2020, 11:27 p.m. UTC | #2 
On Tue, Sep 8, 2020 at 12:53 PM Andrii Nakryiko
<andrii.nakryiko@gmail.com> wrote:
>
> On Sat, Sep 5, 2020 at 2:49 PM Tony Ambardar <tony.ambardar@gmail.com> wrote:
> >
> > Encountered the following failure building libbpf from kernel 5.8.5 sources
> > with GCC 8.4.0 and binutils 2.34: (long paths shortened)
> >
> >   Warning: Num of global symbols in sharedobjs/libbpf-in.o (234) does NOT
> >   match with num of versioned symbols in libbpf.so (236). Please make sure
> >   all LIBBPF_API symbols are versioned in libbpf.map.
> >   --- libbpf_global_syms.tmp    2020-09-02 07:30:58.920084380 +0000
> >   +++ libbpf_versioned_syms.tmp 2020-09-02 07:30:58.924084388 +0000
> >   @@ -1,3 +1,5 @@
> >   +_fini
> >   +_init
> >    bpf_btf_get_fd_by_id
> >    bpf_btf_get_next_id
> >    bpf_create_map
> >   make[4]: *** [Makefile:210: check_abi] Error 1
> >
> > Investigation shows _fini and _init are actually local symbols counted
> > amongst global ones:
> >
> >   $ readelf --dyn-syms --wide libbpf.so|head -10
> >
> >   Symbol table '.dynsym' contains 343 entries:
> >      Num:    Value  Size Type    Bind   Vis      Ndx Name
> >        0: 00000000     0 NOTYPE  LOCAL  DEFAULT  UND
> >        1: 00004098     0 SECTION LOCAL  DEFAULT   11
> >        2: 00004098     8 FUNC    LOCAL  DEFAULT   11 _init@@LIBBPF_0.0.1
> >        3: 00023040     8 FUNC    LOCAL  DEFAULT   14 _fini@@LIBBPF_0.0.1
> >        4: 00000000     0 OBJECT  GLOBAL DEFAULT  ABS LIBBPF_0.0.4
> >        5: 00000000     0 OBJECT  GLOBAL DEFAULT  ABS LIBBPF_0.0.1
> >        6: 0000ffa4     8 FUNC    GLOBAL DEFAULT   12 bpf_object__find_map_by_offset@@LIBBPF_0.0.1
> >
> > A previous commit filtered global symbols in sharedobjs/libbpf-in.o. Do the
> > same with the libbpf.so DSO for consistent comparison.
> >
> > Fixes: 306b267cb3c4 ("libbpf: Verify versioned symbols")
> >
> > Signed-off-by: Tony Ambardar <Tony.Ambardar@gmail.com>

Applied. Thanks
diff mbox series

Patch

diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
index b78484e7a608..9ae8f4ef0aac 100644
--- a/tools/lib/bpf/Makefile
+++ b/tools/lib/bpf/Makefile
@@ -152,6 +152,7 @@  GLOBAL_SYM_COUNT = $(shell readelf -s --wide $(BPF_IN_SHARED) | \
 			   awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}' | \
 			   sort -u | wc -l)
 VERSIONED_SYM_COUNT = $(shell readelf --dyn-syms --wide $(OUTPUT)libbpf.so | \
+			      awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}' | \
 			      grep -Eo '[^ ]+@LIBBPF_' | cut -d@ -f1 | sort -u | wc -l)
 
 CMD_TARGETS = $(LIB_TARGET) $(PC_FILE)
@@ -219,6 +220,7 @@  check_abi: $(OUTPUT)libbpf.so
 		    awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}'|  \
 		    sort -u > $(OUTPUT)libbpf_global_syms.tmp;		 \
 		readelf --dyn-syms --wide $(OUTPUT)libbpf.so |		 \
+		    awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}'|  \
 		    grep -Eo '[^ ]+@LIBBPF_' | cut -d@ -f1 |		 \
 		    sort -u > $(OUTPUT)libbpf_versioned_syms.tmp; 	 \
 		diff -u $(OUTPUT)libbpf_global_syms.tmp			 \