Re: [patch] x86: fix ESP corruption CPU bug

[Pavel Machek]

Hi!

> @@ -257,8 +265,31 @@
>  	movl TI_flags(%ebp), %ecx
>  	testw $_TIF_ALLWORK_MASK, %cx	# current->work
>  	jne syscall_exit_work
> +
>  restore_all:
> -	RESTORE_ALL
> +	movl EFLAGS(%esp), %eax		# mix EFLAGS, SS and CS
> +	movb OLDSS(%esp), %ah
> +	movb CS(%esp), %al
> +	andl $(VM_MASK | (4 << 8) | 3), %eax
> +	cmpl $((4 << 8) | 3), %eax
> +	je ldt_ss			# returning to user-space with LDT SS

All common linux apps use same %ss, no? Perhaps it would be more
efficient to just check if %ss == 0x7b, and proceed directly to
restore_nocheck if not?

Or perhaps we could only enable this code after application loads
custom ldt?

								Pavel

-- 
People were complaining that M$ turns users into beta-testers...
...jr ghea gurz vagb qrirybcref, naq gurl frrz gb yvxr vg gung jnl!
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