Re: [PATCH] um: Fix check for _xstate for older hosts

[Richard Weinberger]

On Wed, Jul 19, 2017 at 1:43 AM, Florian Fainelli <f.fainelli@xxxxxxxxx> wrote:
> Commit 0a987645672e ("um: Allow building and running on older
> hosts") attempted to check for PTRACE_{GET,SET}REGSET under the premise
> that these ptrace(2) parameters were directly linked with the presence
> of the _xstate structure.
>
> After Richard's commit 61e8d462457f ("um: Correctly check for
> PTRACE_GETRESET/SETREGSET") which properly included linux/ptrace.h
> instead of asm/ptrace.h, we could get into the original build failure
> that I reported:
>
> arch/x86/um/user-offsets.c: In function 'foo':
> arch/x86/um/user-offsets.c:54: error: invalid application of 'sizeof' to
> incomplete type 'struct _xstate'
>
> On this particular host, we do have PTRACE_GETREGSET and
> PTRACE_SETREGSET defined in linux/ptrace.h, but not the structure
> _xstate that should be pulled from the following include chain: signal.h
> -> bits/sigcontext.h.
>
> Correctly fix this by checking for FP_XSTATE_MAGIC1 which is the correct
> way to see if struct _xstate is available or not on the host.
>
> Fixes: 61e8d462457f ("um: Correctly check for PTRACE_GETRESET/SETREGSET")
> Fixes: 0a987645672e ("um: Allow building and running on older hosts")
> Signed-off-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
> ---
>  arch/x86/um/user-offsets.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/um/user-offsets.c b/arch/x86/um/user-offsets.c
> index ae4cd58c0c7a..02250b2633b8 100644
> --- a/arch/x86/um/user-offsets.c
> +++ b/arch/x86/um/user-offsets.c
> @@ -50,7 +50,7 @@ void foo(void)
>         DEFINE(HOST_GS, GS);
>         DEFINE(HOST_ORIG_AX, ORIG_EAX);
>  #else
> -#if defined(PTRACE_GETREGSET) && defined(PTRACE_SETREGSET)
> +#ifdef FP_XSTATE_MAGIC1
>         DEFINE(HOST_FP_SIZE, sizeof(struct _xstate) / sizeof(unsigned long));
>  #else
>         DEFINE(HOST_FP_SIZE, sizeof(struct _fpstate) / sizeof(unsigned long));
> --
> 2.9.3
>

Applied, thanks for fixing!

-- 
Thanks,
//richard