On Fri, 30 Apr 2021 at 19:42, Eric W. Biederman [off-list ref] wrote:

Marco Elver [off-list ref] writes:

quoted

To help catch ABI breaks at compile-time, add compile-time assertions to
verify the siginfo_t layout. Unlike other architectures, sparc64 is
special, because it is one of few architectures requiring si_trapno.
ABI breaks around that field would only be caught here.

Arnd Bergman recently pointed out that we can move si_trapno into the
union and make it specific to a handful of signals.  Like we do other
items in the union.

Given that the code of perf_sigtrap is pretty much broken if si_trapno
needs to be filled out.  I think we should make that change before
we set this ABI in stone like this.

Otherwise this looks good.

Thanks, that's reasonable -- I'll reply to the other thread in a few minutes.

-- Marco

Eric

quoted

Link: https://lkml.kernel.org/r/m11rat9f85.fsf@fess.ebiederm.org
Suggested-by: Eric W. Biederman <redacted>
Signed-off-by: Marco Elver <elver@google.com>
---
 arch/sparc/kernel/signal32.c  | 34 ++++++++++++++++++++++++++++++++++
 arch/sparc/kernel/signal_64.c | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 67 insertions(+)

diff --git a/arch/sparc/kernel/signal32.c b/arch/sparc/kernel/signal32.c
index e9695a06492f..778ed5c26d4a 100644
--- a/arch/sparc/kernel/signal32.c
+++ b/arch/sparc/kernel/signal32.c

@@ -745,3 +745,37 @@ asmlinkage int do_sys32_sigstack(u32 u_ssptr, u32 u_ossptr, unsigned long sp)
 out:
      return ret;
 }
+
+/*
+ * Compile-time assertions for siginfo_t offsets. Check NSIG* as well, as
+ * changes likely come with new fields that should be added below.
+ */
+static_assert(NSIGILL        == 11);
+static_assert(NSIGFPE        == 15);
+static_assert(NSIGSEGV       == 9);
+static_assert(NSIGBUS        == 5);
+static_assert(NSIGTRAP       == 6);
+static_assert(NSIGCHLD       == 6);
+static_assert(NSIGSYS        == 2);
+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);
+static_assert(offsetof(compat_siginfo_t, si_pid)     == 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_uid)     == 0x10);
+static_assert(offsetof(compat_siginfo_t, si_tid)     == 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_overrun) == 0x10);
+static_assert(offsetof(compat_siginfo_t, si_status)  == 0x14);
+static_assert(offsetof(compat_siginfo_t, si_utime)   == 0x18);
+static_assert(offsetof(compat_siginfo_t, si_stime)   == 0x1c);
+static_assert(offsetof(compat_siginfo_t, si_value)   == 0x14);
+static_assert(offsetof(compat_siginfo_t, si_int)     == 0x14);
+static_assert(offsetof(compat_siginfo_t, si_ptr)     == 0x14);
+static_assert(offsetof(compat_siginfo_t, si_addr)    == 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_trapno)  == 0x10);
+static_assert(offsetof(compat_siginfo_t, si_addr_lsb)        == 0x14);
+static_assert(offsetof(compat_siginfo_t, si_lower)   == 0x18);
+static_assert(offsetof(compat_siginfo_t, si_upper)   == 0x1c);
+static_assert(offsetof(compat_siginfo_t, si_pkey)    == 0x18);
+static_assert(offsetof(compat_siginfo_t, si_perf)    == 0x14);
+static_assert(offsetof(compat_siginfo_t, si_band)    == 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_fd)              == 0x10);

diff --git a/arch/sparc/kernel/signal_64.c b/arch/sparc/kernel/signal_64.c
index a0eec62c825d..c9bbf5f29078 100644
--- a/arch/sparc/kernel/signal_64.c
+++ b/arch/sparc/kernel/signal_64.c

@@ -556,3 +556,36 @@ void do_notify_resume(struct pt_regs *regs, unsigned long orig_i0, unsigned long
      user_enter();
 }

+/*
+ * Compile-time assertions for siginfo_t offsets. Check NSIG* as well, as
+ * changes likely come with new fields that should be added below.
+ */
+static_assert(NSIGILL        == 11);
+static_assert(NSIGFPE        == 15);
+static_assert(NSIGSEGV       == 9);
+static_assert(NSIGBUS        == 5);
+static_assert(NSIGTRAP       == 6);
+static_assert(NSIGCHLD       == 6);
+static_assert(NSIGSYS        == 2);
+static_assert(offsetof(siginfo_t, si_signo)  == 0x00);
+static_assert(offsetof(siginfo_t, si_errno)  == 0x04);
+static_assert(offsetof(siginfo_t, si_code)   == 0x08);
+static_assert(offsetof(siginfo_t, si_pid)    == 0x10);
+static_assert(offsetof(siginfo_t, si_uid)    == 0x14);
+static_assert(offsetof(siginfo_t, si_tid)    == 0x10);
+static_assert(offsetof(siginfo_t, si_overrun)        == 0x14);
+static_assert(offsetof(siginfo_t, si_status) == 0x18);
+static_assert(offsetof(siginfo_t, si_utime)  == 0x20);
+static_assert(offsetof(siginfo_t, si_stime)  == 0x28);
+static_assert(offsetof(siginfo_t, si_value)  == 0x18);
+static_assert(offsetof(siginfo_t, si_int)    == 0x18);
+static_assert(offsetof(siginfo_t, si_ptr)    == 0x18);
+static_assert(offsetof(siginfo_t, si_addr)   == 0x10);
+static_assert(offsetof(siginfo_t, si_trapno) == 0x18);
+static_assert(offsetof(siginfo_t, si_addr_lsb)       == 0x20);
+static_assert(offsetof(siginfo_t, si_lower)  == 0x28);
+static_assert(offsetof(siginfo_t, si_upper)  == 0x30);
+static_assert(offsetof(siginfo_t, si_pkey)   == 0x28);
+static_assert(offsetof(siginfo_t, si_perf)   == 0x20);
+static_assert(offsetof(siginfo_t, si_band)   == 0x10);
+static_assert(offsetof(siginfo_t, si_fd)     == 0x14);

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