arm64: Add compile-time asserts for siginfo_t offsets

To help catch ABI breaks at compile-time, add compile-time assertions to
verify the siginfo_t layout.

Link: https://lkml.kernel.org/r/20210505141101.11519-3-ebiederm@xmission.com
Link: https://lkml.kernel.org/r/20210429190734.624918-3-elver@google.com
Link: https://lkml.kernel.org/r/87sg0fxx92.fsf_-_@disp2133
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index f8192f4..4413b6a 100644 (file)
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -999,3 +999,40 @@ void __init minsigstksz_setup(void)
                round_up(sizeof(struct frame_record), 16) +
                16; /* max alignment padding */
 }
+
+/*
+ * 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_addr_lsb) == 0x18);
+static_assert(offsetof(siginfo_t, si_lower)    == 0x20);
+static_assert(offsetof(siginfo_t, si_upper)    == 0x28);
+static_assert(offsetof(siginfo_t, si_pkey)     == 0x20);
+static_assert(offsetof(siginfo_t, si_perf_data)        == 0x18);
+static_assert(offsetof(siginfo_t, si_perf_type)        == 0x20);
+static_assert(offsetof(siginfo_t, si_band)     == 0x10);
+static_assert(offsetof(siginfo_t, si_fd)       == 0x18);
+static_assert(offsetof(siginfo_t, si_call_addr)        == 0x10);
+static_assert(offsetof(siginfo_t, si_syscall)  == 0x18);
+static_assert(offsetof(siginfo_t, si_arch)     == 0x1c);

diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c
index 2f507f5..ab17752 100644 (file)
--- a/arch/arm64/kernel/signal32.c
+++ b/arch/arm64/kernel/signal32.c
@@ -457,3 +457,40 @@ void compat_setup_restart_syscall(struct pt_regs *regs)
 {
        regs->regs[7] = __NR_compat_restart_syscall;
 }
+
+/*
+ * 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_addr_lsb)  == 0x10);
+static_assert(offsetof(compat_siginfo_t, si_lower)     == 0x14);
+static_assert(offsetof(compat_siginfo_t, si_upper)     == 0x18);
+static_assert(offsetof(compat_siginfo_t, si_pkey)      == 0x14);
+static_assert(offsetof(compat_siginfo_t, si_perf_data) == 0x10);
+static_assert(offsetof(compat_siginfo_t, si_perf_type) == 0x14);
+static_assert(offsetof(compat_siginfo_t, si_band)      == 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_fd)                == 0x10);
+static_assert(offsetof(compat_siginfo_t, si_call_addr) == 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_syscall)   == 0x10);
+static_assert(offsetof(compat_siginfo_t, si_arch)      == 0x14);