Re: [PATCH -next v15 13/19] riscv: signal: Add sigcontext save/restore for vector

[Andy Chiu <andy.chiu@sifive.com>]

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On Mon, Mar 20, 2023 at 9:37 PM Conor Dooley <conor.dooley@microchip.com> wrote:
> Sparse, or at least Palmer's hacked up version of it that I am running
> [1] complains a bit about this patch, that you've added a few:
> +      1 ../arch/riscv/kernel/signal.c:145:29: warning: incorrect type in initializer (different address spaces)
> +      1 ../arch/riscv/kernel/signal.c:171:24: warning: incorrect type in initializer (different address spaces)
> +      1 ../arch/riscv/kernel/signal.c:172:24: warning: incorrect type in initializer (different address spaces)
> +      1 ../arch/riscv/kernel/signal.c:268:47: warning: incorrect type in initializer (different address spaces)
> +      1 ../arch/riscv/kernel/signal.c:282:16: warning: incorrect type in initializer (different address spaces)
> +      1 ../arch/riscv/kernel/signal.c:283:16: warning: incorrect type in initializer (different address spaces)
> Please have a look at those, and check whether they're valid complaints.

Yes, they are valid. Meanwhile, running sparse locally, I found the 
following, which are also reported at 19/19 patch:
arch/riscv/kernel/signal.c:78:13: warning: incorrect type in assignment (different address spaces)                                                                                                                                                                              
arch/riscv/kernel/signal.c:80:18: warning: cast removes address space '__user' of expression
arch/riscv/kernel/signal.c:92:16: warning: incorrect type in initializer (different address spaces)
arch/riscv/kernel/signal.c:114:51: warning: incorrect type in initializer (different address spaces)

And these need to be fixed, while not found by your sparse:
arch/riscv/kernel/vector.c:81:28: warning: incorrect type in initializer (different address spaces)
arch/riscv/kernel/vector.c:81:28:    expected unsigned int [noderef] [usertype] __user *epc
arch/riscv/kernel/vector.c:81:28:    got unsigned int [usertype] *

However, there is no way to get around signal.c:92 though. The copying of
__user pointer to a __user address should be valid.

+static long save_v_state(struct pt_regs *regs, void **sc_vec)
+{
...
+	/* Copy the pointer datap itself. */
+	err |= __put_user(datap, &state->v_state.datap); 
...

>
> Otherwise, this version of this patch seems a lot nicer than the last
> version, so that makes me happy at least, even if sparse isn't..
>
> Acked-by: Conor Dooley <conor.dooley@microchip.com>
>
> Cheers,
> Conor.

Thanks,
Andy