Re: [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@xxxxxxxxxx>

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@xxxxxx>

---
  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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