diff options
| author | Eric W. Biederman <ebiederm@xmission.com> | 2021-05-04 11:25:22 -0500 |
|---|---|---|
| committer | Eric W. Biederman <ebiederm@xmission.com> | 2021-07-23 13:15:31 -0500 |
| commit | 50ae81305c7a3ee802f0a1988503ce913c79cd6e (patch) | |
| tree | 8564c815a010b129d6af244f1570ad55f763757f /arch/x86/kernel/signal_compat.c | |
| parent | c7fff9288dce1ee5fa9de8d656e09cc8e0e3281b (diff) | |
signal: Verify the alignment and size of siginfo_t
Update the static assertions about siginfo_t to also describe
it's alignment and size.
While investigating if it was possible to add a 64bit field into
siginfo_t[1] it became apparent that the alignment of siginfo_t
is as much a part of the ABI as the size of the structure.
If the alignment changes siginfo_t when embedded in another structure
can move to a different offset. Which is not acceptable from an ABI
structure.
So document that fact and add static assertions to notify developers
if they change change the alignment by accident.
[1] https://lkml.kernel.org/r/YJEZdhe6JGFNYlum@elver.google.com
Acked-by: Marco Elver <elver@google.com>
v1: https://lkml.kernel.org/r/20210505141101.11519-4-ebiederm@xmission.co
Link: https://lkml.kernel.org/r/875yxaxmyl.fsf_-_@disp2133
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Diffstat (limited to 'arch/x86/kernel/signal_compat.c')
| -rw-r--r-- | arch/x86/kernel/signal_compat.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/arch/x86/kernel/signal_compat.c b/arch/x86/kernel/signal_compat.c index 06743ec054d2..b52407c56000 100644 --- a/arch/x86/kernel/signal_compat.c +++ b/arch/x86/kernel/signal_compat.c @@ -34,7 +34,13 @@ static inline void signal_compat_build_tests(void) BUILD_BUG_ON(NSIGSYS != 2); /* This is part of the ABI and can never change in size: */ + BUILD_BUG_ON(sizeof(siginfo_t) != 128); BUILD_BUG_ON(sizeof(compat_siginfo_t) != 128); + + /* This is a part of the ABI and can never change in alignment */ + BUILD_BUG_ON(__alignof__(siginfo_t) != 8); + BUILD_BUG_ON(__alignof__(compat_siginfo_t) != 4); + /* * The offsets of all the (unioned) si_fields are fixed * in the ABI, of course. Make sure none of them ever |