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SubjectRe: [PATCH bpf-next 1/5] bpf: Unify memory address casting operation style
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On 7/16/22 5:51 AM, Pu Lehui wrote:
> Memory addresses are conceptually unsigned, (unsigned long) casting
> makes more sense, so let's make a change for conceptual uniformity
> and there is no functional change.
>
> Signed-off-by: Pu Lehui <pulehui@huawei.com>

Only a few in bpf system, agree that we can do the change so in
the future we can recommend 'unsigned long' vs. 'long' casting
based on existing code base.

Acked-by: Yonghong Song <yhs@fb.com>

> ---
> kernel/bpf/core.c | 2 +-
> kernel/bpf/helpers.c | 6 +++---
> kernel/bpf/syscall.c | 2 +-
> kernel/bpf/verifier.c | 6 +++---
> 4 files changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
> index cfb8a50a9f12..e14b399dd408 100644
> --- a/kernel/bpf/core.c
> +++ b/kernel/bpf/core.c
> @@ -1954,7 +1954,7 @@ static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn)
> CONT; \
> LDX_PROBE_MEM_##SIZEOP: \
> bpf_probe_read_kernel(&DST, sizeof(SIZE), \
> - (const void *)(long) (SRC + insn->off)); \
> + (const void *)(unsigned long) (SRC + insn->off)); \
> DST = *((SIZE *)&DST); \
> CONT;
>
> diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
> index a1c84d256f83..92c01dd007a6 100644
> --- a/kernel/bpf/helpers.c
> +++ b/kernel/bpf/helpers.c
> @@ -903,7 +903,7 @@ int bpf_bprintf_prepare(char *fmt, u32 fmt_size, const u64 *raw_args,
> err = snprintf(tmp_buf,
> (tmp_buf_end - tmp_buf),
> "%pB",
> - (void *)(long)raw_args[num_spec]);
> + (void *)(unsigned long)raw_args[num_spec]);
> tmp_buf += (err + 1);
> }
>
> @@ -929,7 +929,7 @@ int bpf_bprintf_prepare(char *fmt, u32 fmt_size, const u64 *raw_args,
> goto out;
> }
>
> - unsafe_ptr = (char *)(long)raw_args[num_spec];
> + unsafe_ptr = (char *)(unsigned long)raw_args[num_spec];
> err = copy_from_kernel_nofault(cur_ip, unsafe_ptr,
> sizeof_cur_ip);
> if (err < 0)
> @@ -966,7 +966,7 @@ int bpf_bprintf_prepare(char *fmt, u32 fmt_size, const u64 *raw_args,
> goto out;
> }
>
> - unsafe_ptr = (char *)(long)raw_args[num_spec];
> + unsafe_ptr = (char *)(unsigned long)raw_args[num_spec];
> err = bpf_trace_copy_string(tmp_buf, unsafe_ptr,
> fmt_ptype,
> tmp_buf_end - tmp_buf);
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index 83c7136c5788..d1380473e620 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -5108,7 +5108,7 @@ BPF_CALL_3(bpf_sys_bpf, int, cmd, union bpf_attr *, attr, u32, attr_size)
> bpf_prog_put(prog);
> return -EBUSY;
> }
> - attr->test.retval = bpf_prog_run(prog, (void *) (long) attr->test.ctx_in);
> + attr->test.retval = bpf_prog_run(prog, (void *) (unsigned long) attr->test.ctx_in);
> __bpf_prog_exit_sleepable(prog, 0 /* bpf_prog_run does runtime stats */, &run_ctx);
> bpf_prog_put(prog);
> return 0;
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index c59c3df0fea6..d91f17598833 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -4445,7 +4445,7 @@ static int bpf_map_direct_read(struct bpf_map *map, int off, int size, u64 *val)
> err = map->ops->map_direct_value_addr(map, &addr, off);
> if (err)
> return err;
> - ptr = (void *)(long)addr + off;
> + ptr = (void *)(unsigned long)addr + off;
>
> switch (size) {
> case sizeof(u8):
> @@ -6113,7 +6113,7 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
> return err;
> }
>
> - str_ptr = (char *)(long)(map_addr);
> + str_ptr = (char *)(unsigned long)(map_addr);
> if (!strnchr(str_ptr + map_off, map->value_size - map_off, 0)) {
> verbose(env, "string is not zero-terminated\n");
> return -EINVAL;
> @@ -7099,7 +7099,7 @@ static int check_bpf_snprintf_call(struct bpf_verifier_env *env,
> verbose(env, "verifier bug\n");
> return -EFAULT;
> }
> - fmt = (char *)(long)fmt_addr + fmt_map_off;
> + fmt = (char *)(unsigned long)fmt_addr + fmt_map_off;
>
> /* We are also guaranteed that fmt+fmt_map_off is NULL terminated, we
> * can focus on validating the format specifiers.

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