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linux: Fix clock_gettime on systems w/o VDSO

master
LemonBoy 2019-05-11 10:33:41 +02:00
parent d065f297ab
commit 715d808f14
1 changed files with 16 additions and 8 deletions
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24
std/os/linux.zig
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@ -959,10 +959,13 @@ pub fn waitpid(pid: i32, status: *i32, options: i32) usize {
return syscall4(SYS_wait4, @bitCast(usize, isize(pid)), @ptrToInt(status), @bitCast(usize, isize(options)), 0); return syscall4(SYS_wait4, @bitCast(usize, isize(pid)), @ptrToInt(status), @bitCast(usize, isize(options)), 0);
} }
var vdso_clock_gettime = @ptrCast(?*const c_void, init_vdso_clock_gettime);
pub fn clock_gettime(clk_id: i32, tp: *timespec) usize { pub fn clock_gettime(clk_id: i32, tp: *timespec) usize {
if (VDSO_CGT_SYM.len != 0) { if (VDSO_CGT_SYM.len != 0) {
const f = @atomicLoad(@typeOf(init_vdso_clock_gettime), &vdso_clock_gettime, builtin.AtomicOrder.Unordered); const ptr = @atomicLoad(?*const c_void, &vdso_clock_gettime, .Unordered);
if (@ptrToInt(f) != 0) { if (ptr) |fn_ptr| {
const f = @ptrCast(@typeOf(clock_gettime), fn_ptr);
const rc = f(clk_id, tp); const rc = f(clk_id, tp);
switch (rc) { switch (rc) {
0, @bitCast(usize, isize(-EINVAL)) => return rc, 0, @bitCast(usize, isize(-EINVAL)) => return rc,
@ -972,13 +975,18 @@ pub fn clock_gettime(clk_id: i32, tp: *timespec) usize {
} }
return syscall2(SYS_clock_gettime, @bitCast(usize, isize(clk_id)), @ptrToInt(tp)); return syscall2(SYS_clock_gettime, @bitCast(usize, isize(clk_id)), @ptrToInt(tp));
} }
var vdso_clock_gettime = init_vdso_clock_gettime;
extern fn init_vdso_clock_gettime(clk: i32, ts: *timespec) usize { extern fn init_vdso_clock_gettime(clk: i32, ts: *timespec) usize {
const addr = vdso.lookup(VDSO_CGT_VER, VDSO_CGT_SYM); const ptr = @intToPtr(?*const c_void, vdso.lookup(VDSO_CGT_VER, VDSO_CGT_SYM));
var f = @intToPtr(@typeOf(init_vdso_clock_gettime), addr); // Note that we may not have a VDSO at all, update the stub address anyway
_ = @cmpxchgStrong(@typeOf(init_vdso_clock_gettime), &vdso_clock_gettime, init_vdso_clock_gettime, f, builtin.AtomicOrder.Monotonic, builtin.AtomicOrder.Monotonic); // so that clock_gettime will fall back on the good old (and slow) syscall
if (@ptrToInt(f) == 0) return @bitCast(usize, isize(-ENOSYS)); _ = @cmpxchgStrong(?*const c_void, &vdso_clock_gettime, &init_vdso_clock_gettime, ptr, .Monotonic, .Monotonic);
return f(clk, ts); // Call into the VDSO if available
if (ptr) |fn_ptr| {
const f = @ptrCast(@typeOf(clock_gettime), fn_ptr);
return f(clk, ts);
}
return @bitCast(usize, isize(-ENOSYS));
} }
pub fn clock_getres(clk_id: i32, tp: *timespec) usize { pub fn clock_getres(clk_id: i32, tp: *timespec) usize {