[PATCH bpf-next] bpf: Fix a compilation failure with clang lto build

[PATCH bpf-next] bpf: Fix a compilation failure with clang lto build

[Yonghong Song]

When building the kernel with clang lto (CONFIG_LTO_CLANG_FULL=y), the
following compilation error will appear:

  $ make LLVM=1 LLVM_IAS=1 -j
  ...
  ld.lld: error: ld-temp.o <inline asm>:26889:1: symbol 'cgroup_storage_map_btf_ids' is already defined
  cgroup_storage_map_btf_ids:;
  ^
  make[1]: *** [/.../bpf-next/scripts/Makefile.vmlinux_o:61: vmlinux.o] Error 1

In local_storage.c, we have
  BTF_ID_LIST_SINGLE(cgroup_storage_map_btf_ids, struct, bpf_local_storage_map)
Commit c4bcfb38a95e ("bpf: Implement cgroup storage available to
non-cgroup-attached bpf progs") added the above identical BTF_ID_LIST_SINGLE
definition in bpf_cgrp_storage.c. With duplicated definitions, llvm linker
complains with lto build.

Also, extracting btf_id of 'struct bpf_local_storage_map' is defined four times
for sk, inode, task and cgrp local storages. Let us define a single global one
with a different name than cgroup_storage_map_btf_ids, which also fixed
the lto compilation error.

Fixes: c4bcfb38a95e ("bpf: Implement cgroup storage available to non-cgroup-attached bpf progs")
Signed-off-by: Yonghong Song <yhs@fb.com>
---
 include/linux/btf_ids.h        | 1 +
 kernel/bpf/bpf_cgrp_storage.c  | 3 +--
 kernel/bpf/bpf_inode_storage.c | 4 +---
 kernel/bpf/bpf_task_storage.c  | 4 ++--
 net/core/bpf_sk_storage.c      | 3 +--
 5 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/include/linux/btf_ids.h b/include/linux/btf_ids.h
index 93397711a68c..3a4f7cd882ca 100644
--- a/include/linux/btf_ids.h
+++ b/include/linux/btf_ids.h
@@ -266,5 +266,6 @@ MAX_BTF_TRACING_TYPE,
 
 extern u32 btf_tracing_ids[];
 extern u32 bpf_cgroup_btf_id[];
+extern u32 bpf_local_storage_map_btf_id[];
 
 #endif
diff --git a/kernel/bpf/bpf_cgrp_storage.c b/kernel/bpf/bpf_cgrp_storage.c
index 309403800f82..6cdf6d9ed91d 100644
--- a/kernel/bpf/bpf_cgrp_storage.c
+++ b/kernel/bpf/bpf_cgrp_storage.c
@@ -211,7 +211,6 @@ BPF_CALL_2(bpf_cgrp_storage_delete, struct bpf_map *, map, struct cgroup *, cgro
 	return ret;
 }
 
-BTF_ID_LIST_SINGLE(cgroup_storage_map_btf_ids, struct, bpf_local_storage_map)
 const struct bpf_map_ops cgrp_storage_map_ops = {
 	.map_meta_equal = bpf_map_meta_equal,
 	.map_alloc_check = bpf_local_storage_map_alloc_check,
@@ -222,7 +221,7 @@ const struct bpf_map_ops cgrp_storage_map_ops = {
 	.map_update_elem = bpf_cgrp_storage_update_elem,
 	.map_delete_elem = bpf_cgrp_storage_delete_elem,
 	.map_check_btf = bpf_local_storage_map_check_btf,
-	.map_btf_id = &cgroup_storage_map_btf_ids[0],
+	.map_btf_id = &bpf_local_storage_map_btf_id[0],
 	.map_owner_storage_ptr = cgroup_storage_ptr,
 };
 
diff --git a/kernel/bpf/bpf_inode_storage.c b/kernel/bpf/bpf_inode_storage.c
index 6a1d4d22816a..05f4c66c9089 100644
--- a/kernel/bpf/bpf_inode_storage.c
+++ b/kernel/bpf/bpf_inode_storage.c
@@ -213,8 +213,6 @@ static void inode_storage_map_free(struct bpf_map *map)
 	bpf_local_storage_map_free(map, &inode_cache, NULL);
 }
 
-BTF_ID_LIST_SINGLE(inode_storage_map_btf_ids, struct,
-		   bpf_local_storage_map)
 const struct bpf_map_ops inode_storage_map_ops = {
 	.map_meta_equal = bpf_map_meta_equal,
 	.map_alloc_check = bpf_local_storage_map_alloc_check,
@@ -225,7 +223,7 @@ const struct bpf_map_ops inode_storage_map_ops = {
 	.map_update_elem = bpf_fd_inode_storage_update_elem,
 	.map_delete_elem = bpf_fd_inode_storage_delete_elem,
 	.map_check_btf = bpf_local_storage_map_check_btf,
-	.map_btf_id = &inode_storage_map_btf_ids[0],
+	.map_btf_id = &bpf_local_storage_map_btf_id[0],
 	.map_owner_storage_ptr = inode_storage_ptr,
 };
 
diff --git a/kernel/bpf/bpf_task_storage.c b/kernel/bpf/bpf_task_storage.c
index 8e832db8151a..1e486055a523 100644
--- a/kernel/bpf/bpf_task_storage.c
+++ b/kernel/bpf/bpf_task_storage.c
@@ -324,7 +324,7 @@ static void task_storage_map_free(struct bpf_map *map)
 	bpf_local_storage_map_free(map, &task_cache, &bpf_task_storage_busy);
 }
 
-BTF_ID_LIST_SINGLE(task_storage_map_btf_ids, struct, bpf_local_storage_map)
+BTF_ID_LIST_GLOBAL_SINGLE(bpf_local_storage_map_btf_id, struct, bpf_local_storage_map)
 const struct bpf_map_ops task_storage_map_ops = {
 	.map_meta_equal = bpf_map_meta_equal,
 	.map_alloc_check = bpf_local_storage_map_alloc_check,
@@ -335,7 +335,7 @@ const struct bpf_map_ops task_storage_map_ops = {
 	.map_update_elem = bpf_pid_task_storage_update_elem,
 	.map_delete_elem = bpf_pid_task_storage_delete_elem,
 	.map_check_btf = bpf_local_storage_map_check_btf,
-	.map_btf_id = &task_storage_map_btf_ids[0],
+	.map_btf_id = &bpf_local_storage_map_btf_id[0],
 	.map_owner_storage_ptr = task_storage_ptr,
 };
 
diff --git a/net/core/bpf_sk_storage.c b/net/core/bpf_sk_storage.c
index 9d2288c0736e..bb378c33f542 100644
--- a/net/core/bpf_sk_storage.c
+++ b/net/core/bpf_sk_storage.c
@@ -310,7 +310,6 @@ bpf_sk_storage_ptr(void *owner)
 	return &sk->sk_bpf_storage;
 }
 
-BTF_ID_LIST_SINGLE(sk_storage_map_btf_ids, struct, bpf_local_storage_map)
 const struct bpf_map_ops sk_storage_map_ops = {
 	.map_meta_equal = bpf_map_meta_equal,
 	.map_alloc_check = bpf_local_storage_map_alloc_check,
@@ -321,7 +320,7 @@ const struct bpf_map_ops sk_storage_map_ops = {
 	.map_update_elem = bpf_fd_sk_storage_update_elem,
 	.map_delete_elem = bpf_fd_sk_storage_delete_elem,
 	.map_check_btf = bpf_local_storage_map_check_btf,
-	.map_btf_id = &sk_storage_map_btf_ids[0],
+	.map_btf_id = &bpf_local_storage_map_btf_id[0],
 	.map_local_storage_charge = bpf_sk_storage_charge,
 	.map_local_storage_uncharge = bpf_sk_storage_uncharge,
 	.map_owner_storage_ptr = bpf_sk_storage_ptr,
-- 
2.30.2

Re: [PATCH bpf-next] bpf: Fix a compilation failure with clang lto build

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to bpf/bpf-next.git (master)
by Andrii Nakryiko <andrii@kernel.org>:

On Tue, 29 Nov 2022 21:21:47 -0800 you wrote:
> When building the kernel with clang lto (CONFIG_LTO_CLANG_FULL=y), the
> following compilation error will appear:
> 
>   $ make LLVM=1 LLVM_IAS=1 -j
>   ...
>   ld.lld: error: ld-temp.o <inline asm>:26889:1: symbol 'cgroup_storage_map_btf_ids' is already defined
>   cgroup_storage_map_btf_ids:;
>   ^
>   make[1]: *** [/.../bpf-next/scripts/Makefile.vmlinux_o:61: vmlinux.o] Error 1
> 
> [...]

Here is the summary with links:
  - [bpf-next] bpf: Fix a compilation failure with clang lto build
    https://git.kernel.org/bpf/bpf-next/c/3144bfa5078e

You are awesome, thank you!
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