From 50ae81305c7a3ee802f0a1988503ce913c79cd6e Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Tue, 4 May 2021 11:25:22 -0500 Subject: 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 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" --- arch/sparc/kernel/signal32.c | 2 ++ arch/sparc/kernel/signal_64.c | 2 ++ 2 files changed, 4 insertions(+) (limited to 'arch/sparc') diff --git a/arch/sparc/kernel/signal32.c b/arch/sparc/kernel/signal32.c index 65fd26ae9d25..4276b9e003ca 100644 --- a/arch/sparc/kernel/signal32.c +++ b/arch/sparc/kernel/signal32.c @@ -757,6 +757,8 @@ static_assert(NSIGBUS == 5); static_assert(NSIGTRAP == 6); static_assert(NSIGCHLD == 6); static_assert(NSIGSYS == 2); +static_assert(sizeof(compat_siginfo_t) == 128); +static_assert(__alignof__(compat_siginfo_t) == 4); static_assert(offsetof(compat_siginfo_t, si_signo) == 0x00); static_assert(offsetof(compat_siginfo_t, si_errno) == 0x04); static_assert(offsetof(compat_siginfo_t, si_code) == 0x08); diff --git a/arch/sparc/kernel/signal_64.c b/arch/sparc/kernel/signal_64.c index a58e0cc45d24..cea23cf95600 100644 --- a/arch/sparc/kernel/signal_64.c +++ b/arch/sparc/kernel/signal_64.c @@ -567,6 +567,8 @@ static_assert(NSIGBUS == 5); static_assert(NSIGTRAP == 6); static_assert(NSIGCHLD == 6); static_assert(NSIGSYS == 2); +static_assert(sizeof(siginfo_t) == 128); +static_assert(__alignof__(siginfo_t) == 8); static_assert(offsetof(siginfo_t, si_signo) == 0x00); static_assert(offsetof(siginfo_t, si_errno) == 0x04); static_assert(offsetof(siginfo_t, si_code) == 0x08); -- cgit v1.2.3