# Re: \[PATCH v4 0/5\] siginfo: ABI fixes for TRAP\_PERF - List: linux-api - 2 messages, 2 authors - Page: https://ratatoskr.run/linux-api/2021/05/1381518/t ## Re: \[PATCH v4 0/5\] siginfo: ABI fixes for TRAP\_PERF - From: Eric W. Biederman \ - Date: 2021-05-18 03:47:04 - Message: https://ratatoskr.run/linux-api/2021/05/1381518.md ```text Marco Elver [ref] writes: > On Mon, 17 May 2021 at 21:58, Eric W. Biederman [ref] wrote: >> >> During the merge window an issue with si_perf and the siginfo ABI came >> up. The alpha and sparc siginfo structure layout had changed with the >> addition of SIGTRAP TRAP_PERF and the new field si_perf. >> >> The reason only alpha and sparc were affected is that they are the >> only architectures that use si_trapno. >> >> Looking deeper it was discovered that si_trapno is used for only >> a few select signals on alpha and sparc, and that none of the >> other _sigfault fields past si_addr are used at all. Which means >> technically no regression on alpha and sparc. >> >> While the alignment concerns might be dismissed the abuse of >> si_errno by SIGTRAP TRAP_PERF does have the potential to cause >> regressions in existing userspace. >> >> While we still have time before userspace starts using and depending on >> the new definition siginfo for SIGTRAP TRAP_PERF this set of changes >> cleans up siginfo_t. >> >> - The si_trapno field is demoted from magic alpha and sparc status and >> made an ordinary union member of the _sigfault member of siginfo_t. >> Without moving it of course. >> >> - si_perf is replaced with si_perf_data and si_perf_type ending the >> abuse of si_errno. >> >> - Unnecessary additions to signalfd_siginfo are removed. >> >> v3: https://lkml.kernel.org/r/m1tuni8ano.fsf_-_@fess.ebiederm.org >> v2: https://lkml.kernel.org/r/m14kfjh8et.fsf_-_@fess.ebiederm.org >> v1: https://lkml.kernel.org/r/m1zgxfs7zq.fsf_-_@fess.ebiederm.org >> >> This version drops the tests and fine grained handling of si_trapno >> on alpha and sparc (replaced assuming si_trapno is valid for >> all but the faults that defined different data). > > And just to clarify, the rest of the series (including static-asserts) > for the next merge-window will be sent once this series is all sorted, > correct? That is the plan. I really wonder about alphas use of si_trapno, and alphas use send_sig instead of force_sig. It could be worth looking into those as it has the potential to simplify the code. >> Eric W. Biederman (5): >> siginfo: Move si_trapno inside the union inside _si_fault >> signal: Implement SIL_FAULT_TRAPNO >> signal: Factor force_sig_perf out of perf_sigtrap >> signal: Deliver all of the siginfo perf data in _perf >> signalfd: Remove SIL_PERF_EVENT fields from signalfd_siginfo > > Looks good, thank you! I build-tested (defconfig -- x86_64, i386, arm, > arm64, m68k, sparc, alpha) this series together with a local patch to > pull in the static asserts from v3. Also re-ran perf_events kselftests > on x86_64 (native and 32bit compat). Thanks, Can I have your Tested-by? Eric ``` ## Re: \[PATCH v4 0/5\] siginfo: ABI fixes for TRAP\_PERF - From: Marco Elver \ - Date: 2021-05-18 06:44:24 - Message: https://ratatoskr.run/linux-api/2021/05/1381617.md ```text On Tue, 18 May 2021 at 05:47, Eric W. Biederman [ref] wrote: > > Marco Elver [ref] writes: > > > On Mon, 17 May 2021 at 21:58, Eric W. Biederman [ref] wrote: > >> > >> During the merge window an issue with si_perf and the siginfo ABI came > >> up. The alpha and sparc siginfo structure layout had changed with the > >> addition of SIGTRAP TRAP_PERF and the new field si_perf. > >> > >> The reason only alpha and sparc were affected is that they are the > >> only architectures that use si_trapno. > >> > >> Looking deeper it was discovered that si_trapno is used for only > >> a few select signals on alpha and sparc, and that none of the > >> other _sigfault fields past si_addr are used at all. Which means > >> technically no regression on alpha and sparc. > >> > >> While the alignment concerns might be dismissed the abuse of > >> si_errno by SIGTRAP TRAP_PERF does have the potential to cause > >> regressions in existing userspace. > >> > >> While we still have time before userspace starts using and depending on > >> the new definition siginfo for SIGTRAP TRAP_PERF this set of changes > >> cleans up siginfo_t. > >> > >> - The si_trapno field is demoted from magic alpha and sparc status and > >> made an ordinary union member of the _sigfault member of siginfo_t. > >> Without moving it of course. > >> > >> - si_perf is replaced with si_perf_data and si_perf_type ending the > >> abuse of si_errno. > >> > >> - Unnecessary additions to signalfd_siginfo are removed. > >> > >> v3: https://lkml.kernel.org/r/m1tuni8ano.fsf_-_@fess.ebiederm.org > >> v2: https://lkml.kernel.org/r/m14kfjh8et.fsf_-_@fess.ebiederm.org > >> v1: https://lkml.kernel.org/r/m1zgxfs7zq.fsf_-_@fess.ebiederm.org > >> > >> This version drops the tests and fine grained handling of si_trapno > >> on alpha and sparc (replaced assuming si_trapno is valid for > >> all but the faults that defined different data). > > > > And just to clarify, the rest of the series (including static-asserts) > > for the next merge-window will be sent once this series is all sorted, > > correct? > > That is the plan. > > I really wonder about alphas use of si_trapno, and alphas use send_sig > instead of force_sig. It could be worth looking into those as it > has the potential to simplify the code. > > >> Eric W. Biederman (5): > >> siginfo: Move si_trapno inside the union inside _si_fault > >> signal: Implement SIL_FAULT_TRAPNO > >> signal: Factor force_sig_perf out of perf_sigtrap > >> signal: Deliver all of the siginfo perf data in _perf > >> signalfd: Remove SIL_PERF_EVENT fields from signalfd_siginfo > > > > Looks good, thank you! I build-tested (defconfig -- x86_64, i386, arm, > > arm64, m68k, sparc, alpha) this series together with a local patch to > > pull in the static asserts from v3. Also re-ran perf_events kselftests > > on x86_64 (native and 32bit compat). > > Thanks, > > Can I have your Tested-by? Of course, Tested-by: Marco Elver [ref] Thanks, -- Marco ```