On Thu, Mar 14, 2024 at 3:32 AM Ben Dooks <ben.dooks@xxxxxxxxxxxxxxx> wrote: > > When building W=1, the following warningds get generated by lib/test_bpf.c > due to the BPF_LD_IMM64_RAW() truncating a 64bit to 32bit value without > a specific mask to do so. > > lib/test_bpf.c:6441:25: warning: cast truncates bits from constant value (ffffffff0000 becomes ffff0000) > lib/test_bpf.c:6442:25: warning: cast truncates bits from constant value (ffffffff0000 becomes ffff0000) > lib/test_bpf.c:6473:25: warning: cast truncates bits from constant value (123456789abcdef becomes 89abcdef) > lib/test_bpf.c:6489:25: warning: cast truncates bits from constant value (123456789abcdef becomes 89abcdef) > lib/test_bpf.c:6490:25: warning: cast truncates bits from constant value (123456780a0c0e0 becomes 80a0c0e0) > lib/test_bpf.c:6599:25: warning: cast truncates bits from constant value (123456789abcdef becomes 89abcdef) > lib/test_bpf.c:6637:25: warning: cast truncates bits from constant value (ffffffff0000 becomes ffff0000) > > (more warnings truncated) > > Signed-off-by: Ben Dooks <ben.dooks@xxxxxxxxxxxxxxx> > --- > include/linux/filter.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/linux/filter.h b/include/linux/filter.h > index c99bc3df2d28..c1ff6511f365 100644 > --- a/include/linux/filter.h > +++ b/include/linux/filter.h > @@ -238,7 +238,7 @@ static inline bool insn_is_zext(const struct bpf_insn *insn) > .dst_reg = DST, \ > .src_reg = SRC, \ > .off = 0, \ > - .imm = (__u32) (IMM) }), \ > + .imm = (__u32) ((IMM) & (__u64)0xffffffff) }), \ What compiler is this? I don't think it's a good idea to uglify this macro just to shut up a compiler. As Stan said there are plenty of other places where such _explicit_ u32 cast is used. We're not going to mess with all of them. pw-bot: cr
