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authorEric W. Biederman <ebiederm@xmission.com>2021-04-30 17:06:01 -0500
committerEric W. Biederman <ebiederm@xmission.com>2021-05-18 16:17:03 -0500
commitadd0b32ef9146a8559a60aed54c37692a5f9d34f (patch)
tree2fae531f39ba89ce5e1fb6ffc0212f83df8c0c6a /kernel/signal.c
parent42dec9a936e7696bea1f27d3c5a0068cd9aa95fd (diff)
siginfo: Move si_trapno inside the union inside _si_fault
It turns out that linux uses si_trapno very sparingly, and as such it can be considered extra information for a very narrow selection of signals, rather than information that is present with every fault reported in siginfo. As such move si_trapno inside the union inside of _si_fault. This results in no change in placement, and makes it eaiser to extend _si_fault in the future as this reduces the number of special cases. In particular with si_trapno included in the union it is no longer a concern that the union must be pointer aligned on most architectures because the union follows immediately after si_addr which is a pointer. This change results in a difference in siginfo field placement on sparc and alpha for the fields si_addr_lsb, si_lower, si_upper, si_pkey, and si_perf. These architectures do not implement the signals that would use si_addr_lsb, si_lower, si_upper, si_pkey, and si_perf. Further these architecture have not yet implemented the userspace that would use si_perf. The point of this change is in fact to correct these placement issues before sparc or alpha grow userspace that cares. This change was discussed[1] and the agreement is that this change is currently safe. [1]: https://lkml.kernel.org/r/CAK8P3a0+uKYwL1NhY6Hvtieghba2hKYGD6hcKx5n8=4Gtt+pHA@mail.gmail.com Acked-by: Marco Elver <elver@google.com> v1: https://lkml.kernel.org/r/m1tunns7yf.fsf_-_@fess.ebiederm.org v2: https://lkml.kernel.org/r/20210505141101.11519-5-ebiederm@xmission.com Link: https://lkml.kernel.org/r/20210517195748.8880-1-ebiederm@xmission.com Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Diffstat (limited to 'kernel/signal.c')
-rw-r--r--kernel/signal.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/signal.c b/kernel/signal.c
index c3017aa8024a..65888aec65a0 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -4607,6 +4607,7 @@ static inline void siginfo_buildtime_checks(void)
/* sigfault */
CHECK_OFFSET(si_addr);
+ CHECK_OFFSET(si_trapno);
CHECK_OFFSET(si_addr_lsb);
CHECK_OFFSET(si_lower);
CHECK_OFFSET(si_upper);

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