miri/shims/unix/linux_like/
syscall.rs

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1use rustc_middle::ty::Ty;
2use rustc_span::Symbol;
3use rustc_target::callconv::{Conv, FnAbi};
4
5use crate::helpers::check_min_vararg_count;
6use crate::shims::unix::linux_like::eventfd::EvalContextExt as _;
7use crate::shims::unix::linux_like::sync::futex;
8use crate::*;
9
10pub fn syscall<'tcx>(
11    ecx: &mut MiriInterpCx<'tcx>,
12    link_name: Symbol,
13    abi: &FnAbi<'tcx, Ty<'tcx>>,
14    args: &[OpTy<'tcx>],
15    dest: &MPlaceTy<'tcx>,
16) -> InterpResult<'tcx> {
17    let ([op], varargs) = ecx.check_shim_variadic(abi, Conv::C, link_name, args)?;
18    // The syscall variadic function is legal to call with more arguments than needed,
19    // extra arguments are simply ignored. The important check is that when we use an
20    // argument, we have to also check all arguments *before* it to ensure that they
21    // have the right type.
22
23    let sys_getrandom = ecx.eval_libc("SYS_getrandom").to_target_usize(ecx)?;
24    let sys_futex = ecx.eval_libc("SYS_futex").to_target_usize(ecx)?;
25    let sys_eventfd2 = ecx.eval_libc("SYS_eventfd2").to_target_usize(ecx)?;
26
27    match ecx.read_target_usize(op)? {
28        // `libc::syscall(NR_GETRANDOM, buf.as_mut_ptr(), buf.len(), GRND_NONBLOCK)`
29        // is called if a `HashMap` is created the regular way (e.g. HashMap<K, V>).
30        num if num == sys_getrandom => {
31            // Used by getrandom 0.1
32            // The first argument is the syscall id, so skip over it.
33            let [ptr, len, flags] = check_min_vararg_count("syscall(SYS_getrandom, ...)", varargs)?;
34
35            let ptr = ecx.read_pointer(ptr)?;
36            let len = ecx.read_target_usize(len)?;
37            // The only supported flags are GRND_RANDOM and GRND_NONBLOCK,
38            // neither of which have any effect on our current PRNG.
39            // See <https://github.com/rust-lang/rust/pull/79196> for a discussion of argument sizes.
40            let _flags = ecx.read_scalar(flags)?.to_i32()?;
41
42            ecx.gen_random(ptr, len)?;
43            ecx.write_scalar(Scalar::from_target_usize(len, ecx), dest)?;
44        }
45        // `futex` is used by some synchronization primitives.
46        num if num == sys_futex => {
47            futex(ecx, varargs, dest)?;
48        }
49        num if num == sys_eventfd2 => {
50            let [initval, flags] = check_min_vararg_count("syscall(SYS_evetfd2, ...)", varargs)?;
51
52            let result = ecx.eventfd(initval, flags)?;
53            ecx.write_int(result.to_i32()?, dest)?;
54        }
55        num => {
56            throw_unsup_format!("syscall: unsupported syscall number {num}");
57        }
58    };
59
60    interp_ok(())
61}
miri/shims/unix/linux_like/syscall.rs

miri/shims/unix/linux_like/
syscall.rs
