Re: [PATCH v6 1/1] linux-user: add openat2 support in linux-user

[Richard Henderson <richard.henderson@linaro.org>]

On 9/20/24 11:22, Michael Vogt wrote:
> +static int do_openat2(CPUArchState *cpu_env, abi_long dirfd,
> +                      abi_ptr guest_pathname, abi_ptr guest_open_how,
> +                      abi_long guest_size)

abi_ulong guest_size, as the "real" type is the unsigned size_t.

> +            qemu_log_mask(LOG_UNIMP,
> +                          "Unimplemented openat2 open_how size: %lu\n",
> +                          guest_size);

Use of %lu, and host "long" in general, is always wrong in qemu.

You did not build test everything: this errors out for 32-bit guests.
We must use TARGET_ABI_LONG_lu here.

> @@ -9197,6 +9296,11 @@ static abi_long do_syscall1(CPUArchState *cpu_env, int num, abi_long arg1,
>           fd_trans_unregister(ret);
>           unlock_user(p, arg2, 0);
>           return ret;
> +#if defined(TARGET_NR_openat2)
> +    case TARGET_NR_openat2:
> +        ret = do_openat2(cpu_env, arg1, arg2, arg3, arg4);
> +        return ret;
> +#endif

TARGET_NR_openat2 is universally defined.
This ifdef is not required.

An update to strace.list is missing.

Finally, this does not pass LTP.  In particular,

src/testcases/kernel/syscalls/openat2/openat202.c:62: TFAIL: resolve-no-magiclinks: 
openat2() passed unexpectedly

With RESOLVE_NO_MAGICLINKS, the open of /proc/self/exe handled by maybe_do_fake_open 
should fail with ELOOP.  I *think* that's the only magic link that we handle there, but 
please double check.


r~