On Fri, Apr 03, 2015 at 11:42:10AM +0200, Borislav Petkov wrote:
> From: Borislav Petkov <[email protected]>
> 
> Commit
> 
>   d56fe4bf5f3c ("x86/asm/entry/64: Always set up SYSENTER MSRs")
> 
> missed to add "ULL" to the 0 and wrmsrl_safe() complains:
> 
>   arch/x86/kernel/cpu/common.c: In function ‘syscall_init’:
>   arch/x86/kernel/cpu/common.c:1226:2: warning: right shift count >= width of 
> type
>     wrmsrl_safe(MSR_IA32_SYSENTER_CS, 0);
> 
> Fix it.
> 
> Signed-off-by: Borislav Petkov <[email protected]>
> Cc: Denys Vlasenko <[email protected]>
> Cc: Andy Lutomirski <[email protected]>
> Cc: Alexei Starovoitov <[email protected]>
> Cc: Frederic Weisbecker <[email protected]>
> Cc: H. Peter Anvin <[email protected]>
> Cc: Kees Cook <[email protected]>
> Cc: Linus Torvalds <[email protected]>
> Cc: Oleg Nesterov <[email protected]>
> Cc: Steven Rostedt <[email protected]>
> Cc: Will Drewry <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> ---
>  arch/x86/kernel/cpu/common.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
> index bb6633a87a19..2c249b57e4b5 100644
> --- a/arch/x86/kernel/cpu/common.c
> +++ b/arch/x86/kernel/cpu/common.c
> @@ -1223,7 +1223,7 @@ void syscall_init(void)
>       wrmsrl_safe(MSR_IA32_SYSENTER_EIP, (u64)ia32_sysenter_target);
>  #else
>       wrmsrl(MSR_CSTAR, ignore_sysret);
> -     wrmsrl_safe(MSR_IA32_SYSENTER_CS, 0);
> +     wrmsrl_safe(MSR_IA32_SYSENTER_CS, 0ULL);

Btw, we probably should define an invalid segment

#define GDT_ENTRY_INVALID_SEGMENT               0ULL

and use that value instead of the naked 0.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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