[PATCH 3/3] arm64: Add compile-time asserts for siginfo_t offsets

Marco Elver
2021-04-29T19:17:01Z

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

Signed-off-by: Marco Elver <elver@google.com>
---
arch/arm64/kernel/signal.c | 36 ++++++++++++++++++++++++++++++++++++
arch/arm64/kernel/signal32.c | 36 ++++++++++++++++++++++++++++++++++++
2 files changed, 72 insertions(+)

diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index 6237486ff6bb..af8bd2af1298 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -973,3 +973,39 @@ 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) == 0x18);
+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 2f507f565c48..b6afb646515f 100644
--- a/arch/arm64/kernel/signal32.c
+++ b/arch/arm64/kernel/signal32.c
@@ -457,3 +457,39 @@ 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) == 0x10);
+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);
--
2.31.1.527.g47e6f16901-goog