perf bpf-utils: Constify bpil_array_desc

[ Upstream commit 1654a0e ]

The array's contents is a compile time constant. Constify to make the
code more intention revealing and avoid unintended errors.

Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20250902181713.309797-3-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Stable-dep-of: 01be43f ("perf bpf-utils: Harden get_bpf_prog_info_linear")
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: captain5050

tools/perf/util/bpf-utils.c

@@ -20,7 +20,7 @@ struct bpil_array_desc {
 				 */
 };
 
-static struct bpil_array_desc bpil_array_desc[] = {
+static const struct bpil_array_desc bpil_array_desc[] = {
 	[PERF_BPIL_JITED_INSNS] = {
 		offsetof(struct bpf_prog_info, jited_prog_insns),
 		offsetof(struct bpf_prog_info, jited_prog_len),
@@ -129,12 +129,10 @@ get_bpf_prog_info_linear(int fd, __u64 arrays)
 
 	/* step 2: calculate total size of all arrays */
 	for (i = PERF_BPIL_FIRST_ARRAY; i < PERF_BPIL_LAST_ARRAY; ++i) {
+		const struct bpil_array_desc *desc = &bpil_array_desc[i];
 		bool include_array = (arrays & (1UL << i)) > 0;
-		struct bpil_array_desc *desc;
 		__u32 count, size;
 
-		desc = bpil_array_desc + i;
-
 		/* kernel is too old to support this field */
 		if (info_len < desc->array_offset + sizeof(__u32) ||
 		    info_len < desc->count_offset + sizeof(__u32) ||
@@ -163,13 +161,12 @@ get_bpf_prog_info_linear(int fd, __u64 arrays)
 	ptr = info_linear->data;
 
 	for (i = PERF_BPIL_FIRST_ARRAY; i < PERF_BPIL_LAST_ARRAY; ++i) {
-		struct bpil_array_desc *desc;
+		const struct bpil_array_desc *desc = &bpil_array_desc[i];
 		__u32 count, size;
 
 		if ((arrays & (1UL << i)) == 0)
 			continue;
 
-		desc  = bpil_array_desc + i;
 		count = bpf_prog_info_read_offset_u32(&info, desc->count_offset);
 		size  = bpf_prog_info_read_offset_u32(&info, desc->size_offset);
 		bpf_prog_info_set_offset_u32(&info_linear->info,
@@ -192,13 +189,12 @@ get_bpf_prog_info_linear(int fd, __u64 arrays)
 
 	/* step 6: verify the data */
 	for (i = PERF_BPIL_FIRST_ARRAY; i < PERF_BPIL_LAST_ARRAY; ++i) {
-		struct bpil_array_desc *desc;
+		const struct bpil_array_desc *desc = &bpil_array_desc[i];
 		__u32 v1, v2;
 
 		if ((arrays & (1UL << i)) == 0)
 			continue;
 
-		desc = bpil_array_desc + i;
 		v1 = bpf_prog_info_read_offset_u32(&info, desc->count_offset);
 		v2 = bpf_prog_info_read_offset_u32(&info_linear->info,
 						   desc->count_offset);
@@ -224,13 +220,12 @@ void bpil_addr_to_offs(struct perf_bpil *info_linear)
 	int i;
 
 	for (i = PERF_BPIL_FIRST_ARRAY; i < PERF_BPIL_LAST_ARRAY; ++i) {
-		struct bpil_array_desc *desc;
+		const struct bpil_array_desc *desc = &bpil_array_desc[i];
 		__u64 addr, offs;
 
 		if ((info_linear->arrays & (1UL << i)) == 0)
 			continue;
 
-		desc = bpil_array_desc + i;
 		addr = bpf_prog_info_read_offset_u64(&info_linear->info,
 						     desc->array_offset);
 		offs = addr - ptr_to_u64(info_linear->data);
@@ -244,13 +239,12 @@ void bpil_offs_to_addr(struct perf_bpil *info_linear)
 	int i;
 
 	for (i = PERF_BPIL_FIRST_ARRAY; i < PERF_BPIL_LAST_ARRAY; ++i) {
-		struct bpil_array_desc *desc;
+		const struct bpil_array_desc *desc = &bpil_array_desc[i];
 		__u64 addr, offs;
 
 		if ((info_linear->arrays & (1UL << i)) == 0)
 			continue;
 
-		desc = bpil_array_desc + i;
 		offs = bpf_prog_info_read_offset_u64(&info_linear->info,
 						     desc->array_offset);
 		addr = offs + ptr_to_u64(info_linear->data);