On 6/20/22 20:56, gaosong wrote:
This is missing lock_user/unlock_user somewhere.
You can't use the double-underscore __get/__put_user without having done that.
My understanding is that the struct exctx need lock_user_struct/unlock_user_struct, then
we can use __get/__put the struct extctx.
No, extctx does not exist in target memory. It is purely local to the signal
implementation as a way of tracking the layout.
This is why I suggested statically allocating the extra
pieces of the signal frame *on write*. You obviously
cannot rely on the signal frame being identical on
signal return -- the guest is allowed to create any valid
context to give to rt_sigreturn.
I don’t know if my understanding is correct,
we can put the exctx or target_fpu_context into target_rt_sigframe, like this:
struct target_rt_sigframe {
struct target_siginfo rs_info;
struct target_ucontext rs_uc;
struct extctx_layout rs_ext;
};
No.
You need to look at what the code in setup_extcontext does.
It allocates two sctx_info and one fpu_context on the stack.
Thus the structure would look like
struct target_rt_sigframe {
struct target_siginfo rs_info;
struct target_ucontext rs_uc;
struct sctx_info rs_fpu_info QEMU_ALIGNED(16);
struct target_fp_context rs_fpu;
struct sctx_info rs_end_info QEMU_ALIGNED(16);
};
r~
