[GIT PULL] siginfo: ABI fixes for v5.13-rc2

[Eric W. Biederman]

Linus,

Please pull the for-v5.13-rc2 branch from the git tree:

  git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace.git for-v5.13-rc2

  HEAD: addd6821190ebf1e9fece0b7848db667fd280e2e signalfd: Remove SIL_FAULT_PERF_EVENT fields from signalfd_siginfo

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.

- BUILD_BUG_ONs are added and various helpers are modified to
  accommodate this change.

- Unnecessary additions to signalfd_siginfo are removed.

v3: https://lkml.kernel.org/r/m1tuni8ano.fsf_-_@xxxxxxxxxxxxxxxxx
v2: https://lkml.kernel.org/r/m14kfjh8et.fsf_-_@xxxxxxxxxxxxxxxxx
v1: https://lkml.kernel.org/r/m1zgxfs7zq.fsf_-_@xxxxxxxxxxxxxxxxx

You might notice a recent rebase.  This code has been sitting in
linux-next as  ef566ba2d7d9 ("signal: Remove the last few si_perf
references").  Which results in the exact same code as the branch
I am sending you but the commits differ to keep git bisect working.

The difference is that I squashed a fix for a mips BUILD_BUG_ON about
si_perf into the commit that replaces si_perf with si_perf_data and
si_perf_type.  This keeps the kernel building on all architectures for
all commits keeping git-bisect working for everyone.

Eric W. Biederman (9):
      signal: Verify the alignment and size of siginfo_t
      siginfo: Move si_trapno inside the union inside _si_fault
      signal: Implement SIL_FAULT_TRAPNO
      signal: Use dedicated helpers to send signals with si_trapno set
      signal: Remove __ARCH_SI_TRAPNO
      signal: Rename SIL_PERF_EVENT SIL_FAULT_PERF_EVENT for consistency
      signal: Factor force_sig_perf out of perf_sigtrap
      signal: Deliver all of the siginfo perf data in _perf
      signalfd: Remove SIL_FAULT_PERF_EVENT fields from signalfd_siginfo

Marco Elver (3):
      sparc64: Add compile-time asserts for siginfo_t offsets
      arm: Add compile-time asserts for siginfo_t offsets
      arm64: Add compile-time asserts for siginfo_t offsets

 arch/alpha/include/uapi/asm/siginfo.h              |   2 -
 arch/alpha/kernel/osf_sys.c                        |   2 +-
 arch/alpha/kernel/signal.c                         |   4 +-
 arch/alpha/kernel/traps.c                          |  24 ++---
 arch/alpha/mm/fault.c                              |   4 +-
 arch/arm/kernel/signal.c                           |  39 +++++++
 arch/arm64/kernel/signal.c                         |  39 +++++++
 arch/arm64/kernel/signal32.c                       |  39 +++++++
 arch/m68k/kernel/signal.c                          |   3 +-
 arch/mips/include/uapi/asm/siginfo.h               |   2 -
 arch/sparc/include/uapi/asm/siginfo.h              |   3 -
 arch/sparc/kernel/process_64.c                     |   2 +-
 arch/sparc/kernel/signal32.c                       |  37 +++++++
 arch/sparc/kernel/signal_64.c                      |  36 +++++++
 arch/sparc/kernel/sys_sparc_32.c                   |   2 +-
 arch/sparc/kernel/sys_sparc_64.c                   |   2 +-
 arch/sparc/kernel/traps_32.c                       |  22 ++--
 arch/sparc/kernel/traps_64.c                       |  44 ++++----
 arch/sparc/kernel/unaligned_32.c                   |   2 +-
 arch/sparc/mm/fault_32.c                           |   2 +-
 arch/sparc/mm/fault_64.c                           |   2 +-
 arch/x86/kernel/signal_compat.c                    |  15 ++-
 fs/signalfd.c                                      |  23 ++---
 include/linux/compat.h                             |  10 +-
 include/linux/sched/signal.h                       |  13 +--
 include/linux/signal.h                             |   3 +-
 include/uapi/asm-generic/siginfo.h                 |  20 ++--
 include/uapi/linux/perf_event.h                    |   2 +-
 include/uapi/linux/signalfd.h                      |   4 +-
 kernel/events/core.c                               |  11 +-
 kernel/signal.c                                    | 113 +++++++++++++--------
 .../selftests/perf_events/sigtrap_threads.c        |  14 +--
 32 files changed, 377 insertions(+), 163 deletions(-)

Eric