Remove the extra layer of __fpstate_sanitize_xstate():
if (!use_xsaveopt())
return;
__fpstate_sanitize_xstate(tsk);
and move the check for use_xsaveopt() into fpstate_sanitize_xstate().
In general we optimize for the presence of CPU features, not for
the absence of them. Furthermore there's little point in this inlining,
as the call sites are not super hot code paths.
Doing this uninlining shrinks the code a bit:
text data bss dec hex filename
14108751 2573624 1634304 18316679 1177d87 vmlinux.before
14108627 2573624 1634304 18316555 1177d0b vmlinux.after
Also remove a pointless '!fx' check from fpstate_sanitize_xstate().
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
So the sanitize_i387_state() function has the following purpose:
on CPUs that support optimized xstate saving instructions, an
FPU fpstate might end up having partially uninitialized data.
This function initializes that data.
Note that the function name is a misnomer and confusing on two levels,
not only is it not i387 specific at all, but it is the exact opposite:
it only matters on xstate CPUs.
So rename sanitize_i387_state() and __sanitize_i387_state() to
fpstate_sanitize_xstate() and __fpstate_sanitize_xstate(),
to clearly express the purpose and usage of the function.
We'll further clean up this function in the next patch.
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
A lot of FPU using driver code is querying complex CPU features to be
able to figure out whether a given set of xstate features is supported
by the CPU or not.
Introduce a simplified API function that can be used on any CPU type
to get this information. Also add an error string return pointer,
so that the driver can print a meaningful error message with a
standardized feature name.
Also mark xfeatures_mask as __read_only.
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
