| Age | Commit message (Collapse) | Author |
|---|
|
This patch fixes an integer overflow warning raised by GCC in
xdp_prognum1 of progs/test_xdp_vlan.c:
GCC-BPF [test_maps] test_xdp_vlan.bpf.o
progs/test_xdp_vlan.c: In function 'xdp_prognum1':
progs/test_xdp_vlan.c:163:25: error: integer overflow in expression
'(short int)(((__builtin_constant_p((int)vlan_hdr->h_vlan_TCI)) != 0
? (int)(short unsigned int)((short int)((int)vlan_hdr->h_vlan_TCI
<< 8 >> 8) << 8 | (short int)((int)vlan_hdr->h_vlan_TCI << 0 >> 8
<< 0)) & 61440 : (int)__builtin_bswap16(vlan_hdr->h_vlan_TCI)
& 61440) << 8 >> 8) << 8' of type 'short int' results in '0' [-Werror=overflow]
163 | bpf_htons((bpf_ntohs(vlan_hdr->h_vlan_TCI) & 0xf000)
| ^~~~~~~~~
The problem lies with the expansion of the bpf_htons macro and the
expression passed into it. The bpf_htons macro (and similarly the
bpf_ntohs macro) expand to a ternary operation using either
__builtin_bswap16 or ___bpf_swab16 to swap the bytes, depending on
whether the expression is constant.
For an expression, with 'value' as a u16, like:
bpf_htons (value & 0xf000)
The entire (value & 0xf000) is 'x' in the expansion of ___bpf_swab16
and we get as one part of the expanded swab16:
((__u16)(value & 0xf000) << 8 >> 8 << 8
This will always evaluate to 0, which is intentional since this
subexpression deals with the byte guaranteed to be 0 by the mask.
However, GCC warns because the precise reason this always evaluates to 0
is an overflow. Specifically, the plain 0xf000 in the expression is a
signed 32-bit integer, which causes 'value' to also be promoted to a
signed 32-bit integer, and the combination of the 8-bit left shift and
down-cast back to __u16 results in a signed overflow (really a 'warning:
overflow in conversion from int to __u16' which is propegated up through
the rest of the expression leading to the ultimate overflow warning
above), which is a valid warning despite being the intended result of
this code.
Clang does not warn on this case, likely because it performs constant
folding later in the compilation process relative to GCC. It seems that
by the time clang does constant folding for this expression, the side of
the ternary with this overflow has already been discarded.
Fortunately, this warning is easily silenced by simply making the 0xf000
mask explicitly unsigned. This has no impact on the result.
Signed-off-by: David Faust <david.faust@oracle.com>
Cc: jose.marchesi@oracle.com
Cc: cupertino.miranda@oracle.com
Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240508193512.152759-1-david.faust@oracle.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
Once we enable -Wall for BPF sources, compiler will complain about lots
of unused variables, variables that are set but never read, etc.
Fix all these issues first before enabling -Wall in Makefile.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230309054015.4068562-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
Run spell checker on files in selftest/bpf and fixed typos.
Signed-off-by: Taichi Nishimura <awkrail01@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/bpf/20230216085537.519062-1-awkrail01@gmail.com
|
|
Add the missing space after 'dest' variable assignment.
This change will resolve the following checkpatch.pl
script error:
ERROR: spaces required around that '+=' (ctx:VxW)
Signed-off-by: Roberto Valenzuela <valenzuelarober@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20230113180257.39769-1-valenzuelarober@gmail.com
|
|
Fix all selftests to include libbpf header files with the bpf/ prefix, to
be consistent with external users of the library. Also ensure that all
includes of exported libbpf header files (those that are exported on 'make
install' of the library) use bracketed includes instead of quoted.
To not break the build, keep the old include path until everything has been
changed to the new one; a subsequent patch will remove that.
Fixes: 6910d7d3867a ("selftests/bpf: Ensure bpf_helper_defs.h are taken from selftests dir")
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/157952560568.1683545.9649335788846513446.stgit@toke.dk
|
|
At the moment, all kernel bpf objects are listed under BPF_OBJ_FILES.
Listing them manually sometimes causing patch conflict when people are
adding new testcases simultaneously.
It is better to centre all the related source files under a subdir
"progs", then auto-generate the object file list.
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
