diff --git a/tests/run/volatile2.rs b/tests/run/volatile2.rs new file mode 100644 index 00000000000..c1bc442454e --- /dev/null +++ b/tests/run/volatile2.rs @@ -0,0 +1,119 @@ +// Compiler: +// +// Run-time: +// status: 0 + +#![no_std] +#![feature(core_intrinsics, start)] + +#[panic_handler] +fn panic_handler(_: &core::panic::PanicInfo) -> ! { + core::intrinsics::abort(); +} + +mod libc { + #[link(name = "c")] + extern "C" { + pub fn puts(s: *const u8) -> i32; + + pub fn sigaction(signum: i32, act: *const sigaction, oldact: *mut sigaction) -> i32; + pub fn mmap(addr: *mut (), len: usize, prot: i32, flags: i32, fd: i32, offset: i64) -> *mut (); + pub fn mprotect(addr: *mut (), len: usize, prot: i32) -> i32; + } + + pub const PROT_READ: i32 = 1; + pub const PROT_WRITE: i32 = 2; + pub const MAP_PRIVATE: i32 = 0x0002; + pub const MAP_ANONYMOUS: i32 = 0x0020; + pub const MAP_FAILED: *mut u8 = !0 as *mut u8; + + /// glibc sigaction + #[repr(C)] + pub struct sigaction { + pub sa_sigaction: Option, + pub sa_mask: [u32; 32], + pub sa_flags: i32, + pub sa_restorer: Option, + } + + pub const SA_SIGINFO: i32 = 0x00000004; + pub const SIGSEGV: i32 = 11; +} + +static mut COUNT: u32 = 0; +static mut STORAGE: *mut u8 = core::ptr::null_mut(); +const PAGE_SIZE: usize = 1 << 15; + +#[start] +fn main(_argc: isize, _argv: *const *const u8) -> isize { + unsafe { + // Register a segfault handler + libc::sigaction( + libc::SIGSEGV, + &libc::sigaction { + sa_sigaction: Some(segv_handler), + sa_flags: libc::SA_SIGINFO, + ..core::mem::zeroed() + }, + core::ptr::null_mut(), + ); + + STORAGE = libc::mmap( + core::ptr::null_mut(), + PAGE_SIZE * 2, + 0, + libc::MAP_PRIVATE | libc::MAP_ANONYMOUS, + -1, + 0, + ).cast(); + if STORAGE == libc::MAP_FAILED { + libc::puts(b"error: mmap failed\0".as_ptr()); + return 1; + } + + let p_count = (&mut COUNT) as *mut u32; + p_count.write_volatile(0); + + // Trigger segfaults + STORAGE.add(0).write_volatile(1); + STORAGE.add(PAGE_SIZE).write_volatile(1); + STORAGE.add(0).write_volatile(1); + STORAGE.add(PAGE_SIZE).write_volatile(1); + STORAGE.add(0).write_volatile(1); + STORAGE.add(PAGE_SIZE).write_volatile(1); + + // The segfault handler should have been called for every + // `write_volatile` in `STORAGE`. If the compiler ignores volatility, + // some of these writes will be combined, causing a different number of + // segfaults. + // + // This `p_count` read is done by a volatile read. If the compiler + // ignores volatility, the compiler will speculate that `*p_count` is + // unchanged and remove this check, failing the test. + if p_count.read_volatile() != 6 { + libc::puts(b"error: segfault count mismatch\0".as_ptr()); + return 1; + } + + 0 + } +} + +unsafe extern "C" fn segv_handler(_: i32, _: *mut (), _: *mut ()) { + let p_count = (&mut COUNT) as *mut u32; + p_count.write_volatile(p_count.read_volatile() + 1); + let count = p_count.read_volatile(); + + // Toggle the protected page so that the handler will be called for + // each `write_volatile` + libc::mprotect( + STORAGE.cast(), + PAGE_SIZE, + if count % 2 == 1 { libc::PROT_READ | libc::PROT_WRITE } else { 0 }, + ); + libc::mprotect( + STORAGE.add(PAGE_SIZE).cast(), + PAGE_SIZE, + if count % 2 == 0 { libc::PROT_READ | libc::PROT_WRITE } else { 0 }, + ); +}