by tip-bot2 for Boqun Feng

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Subject: [tip: objtool/core] objtool: Include weak functions in global_noreturns check

The following commit has been merged into the objtool/core branch of tip:

Commit-ID: 1c47c8758a11345ac643fa68cb70b708a6668883
Gitweb: https://git.kernel.org/tip/1c47c8758a11345ac643fa68cb70b708a6668883
Author: Josh Poimboeuf <[email protected]>
AuthorDate: Wed, 12 Apr 2023 16:49:37 -07:00
Committer: Peter Zijlstra <[email protected]>
CommitterDate: Fri, 14 Apr 2023 17:31:26 +02:00

objtool: Include weak functions in global_noreturns check

If a global function doesn't return, and its prototype has the
__noreturn attribute, its weak counterpart must also not return so that
it matches the prototype and meets call site expectations.

To properly follow the compiled control flow at the call sites, change
the global_noreturns check to include both global and weak functions.

On the other hand, if a weak function isn't in global_noreturns, assume
the prototype doesn't have __noreturn. Even if the weak function
doesn't return, call sites treat it like a returnable function.

Fixes the following warning:

kernel/sched/build_policy.o: warning: objtool: do_idle() falls through to next function play_idle_precise()

Reported-by: kernel test robot <[email protected]>
Signed-off-by: Josh Poimboeuf <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Reviewed-by: Miroslav Benes <[email protected]>
Link: https://lore.kernel.org/r/ede3460d63f4a65d282c86f1175bd2662c2286ba.1681342859.git.jpoimboe@kernel.org
---
tools/objtool/check.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 8d073bf..ae0c942 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -236,14 +236,14 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
if (!func)
return false;

- if (func->bind == STB_WEAK)
- return false;
-
- if (func->bind == STB_GLOBAL)
+ if (func->bind == STB_GLOBAL || func->bind == STB_WEAK)
for (i = 0; i < ARRAY_SIZE(global_noreturns); i++)
if (!strcmp(func->name, global_noreturns[i]))
return true;

+ if (func->bind == STB_WEAK)
+ return false;
+
if (!func->len)
return false;

2023-04-17 10:52:58

by tip-bot2 for Boqun Feng

[permalink] [raw]

Subject: [tip: objtool/core] btrfs: Mark btrfs_assertfail() __noreturn

The following commit has been merged into the objtool/core branch of tip:

Commit-ID: 09c5ae30d007514a1be870fa5873ad55c3319f3a
Gitweb: https://git.kernel.org/tip/09c5ae30d007514a1be870fa5873ad55c3319f3a
Author: Josh Poimboeuf <[email protected]>
AuthorDate: Wed, 12 Apr 2023 16:49:38 -07:00
Committer: Peter Zijlstra <[email protected]>
CommitterDate: Fri, 14 Apr 2023 17:31:26 +02:00

btrfs: Mark btrfs_assertfail() __noreturn

Fixes a bunch of warnings including:

vmlinux.o: warning: objtool: select_reloc_root+0x314: unreachable instruction
vmlinux.o: warning: objtool: finish_inode_if_needed+0x15b1: unreachable instruction
vmlinux.o: warning: objtool: get_bio_sector_nr+0x259: unreachable instruction
vmlinux.o: warning: objtool: raid_wait_read_end_io+0xc26: unreachable instruction
vmlinux.o: warning: objtool: raid56_parity_alloc_scrub_rbio+0x37b: unreachable instruction
...

Reported-by: kernel test robot <[email protected]>
Signed-off-by: Josh Poimboeuf <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lore.kernel.org/r/960bd9c0c9e3cfc409ba9c35a17644b11b832956.1681342859.git.jpoimboe@kernel.org
---
fs/btrfs/messages.c | 2 +-
fs/btrfs/messages.h | 2 +-
tools/objtool/check.c | 1 +
3 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/messages.c b/fs/btrfs/messages.c
index fde5aaa..310a05c 100644
--- a/fs/btrfs/messages.c
+++ b/fs/btrfs/messages.c
@@ -253,7 +253,7 @@ void __cold _btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt,
#endif

#ifdef CONFIG_BTRFS_ASSERT
-void __cold btrfs_assertfail(const char *expr, const char *file, int line)
+void __cold __noreturn btrfs_assertfail(const char *expr, const char *file, int line)
{
pr_err("assertion failed: %s, in %s:%d\n", expr, file, line);
BUG();
diff --git a/fs/btrfs/messages.h b/fs/btrfs/messages.h
index 8c516ee..ac2d198 100644
--- a/fs/btrfs/messages.h
+++ b/fs/btrfs/messages.h
@@ -160,7 +160,7 @@ do { \
} while (0)

#ifdef CONFIG_BTRFS_ASSERT
-void __cold btrfs_assertfail(const char *expr, const char *file, int line);
+void __cold __noreturn btrfs_assertfail(const char *expr, const char *file, int line);

#define ASSERT(expr) \
(likely(expr) ? (void)0 : btrfs_assertfail(#expr, __FILE__, __LINE__))
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index ae0c942..ceb9848 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -204,6 +204,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
"__ubsan_handle_builtin_unreachable",
"arch_call_rest_init",
"arch_cpu_idle_dead",
+ "btrfs_assertfail",
"cpu_bringup_and_idle",
"cpu_startup_entry",
"do_exit",