Note how CWD and TWD are off their usual init state (0x037f and 0xffff),
and how FP0 and FP1 has non-zero content.
This is normally not a problem, because any user-space FPU state
is initalized properly - but it can complicate the use of FPU
instructions in kernel code via kernel_fpu_begin()/end(): if
the FPU using code does not initialize registers itself, it
might generate spurious exceptions depending on which CPU it
executes on.
Fix this by initializing the x87 state via the FNINIT instruction.
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>
x86/fpu: Clarify ancient comments in fpu__restore()
So this function still had ancient language about 'saving current
math information' - but we haven't been doing lazy FPU saves for
quite some time, we are doing lazy FPU restores.
Also remove IRQ13 related comment, which we don't support anymore
either.
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>
x86/fpu: Rename save_xstate_sig() to copy_fpstate_to_sigframe()
Standardize the naming of save_xstate_sig() by renaming it to
copy_fpstate_to_sigframe(): this tells us at a glance that
the function copies an FPU fpstate to a signal frame.
This naming also follows the naming of copy_fpregs_to_fpstate().
Don't put 'xstate' into the name: since this is a generic name,
it's expected that the function is able to handle xstate frames
as well, beyond legacy frames.
xstate used to be the odd case in the x86 FPU code - now it's the
common case.
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>
x86/fpu: Pass 'struct fpu' to fpstate_sanitize_xstate()
Currently fpstate_sanitize_xstate() has a task_struct input parameter,
but it only uses the fpu structure from it - so pass in a 'struct fpu'
pointer only and update all call sites.
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>
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.
x86/fpu: Rename sanitize_i387_state() to fpstate_sanitize_xstate()
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>
x86/fpu, crypto x86/serpent_avx2: Simplify the init() xfeature checks
Use the new 'cpu_has_xfeatures()' function to query AVX CPU support.
This has the following advantages to the driver:
- Decouples the driver from FPU internals: it's now only using <asm/fpu/api.h>.
- Removes detection complexity from the driver, no more raw XGETBV instruction
- Shrinks the code a bit.
- Standardizes feature name error message printouts across drivers
There are also advantages to the x86 FPU code: once all drivers
are decoupled from internals we can move them out of common
headers and we'll also be able to remove xcr.h.
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>
x86/fpu, crypto x86/sha1_ssse3: Simplify the sha1_ssse3_mod_init() xfeature checks
Use the new 'cpu_has_xfeatures()' function to query AVX CPU support.
This has the following advantages to the driver:
- Decouples the driver from FPU internals: it's now only using <asm/fpu/api.h>.
- Removes detection complexity from the driver, no more raw XGETBV instruction
- Shrinks the code a bit.
- Standardizes feature name error message printouts across drivers
There are also advantages to the x86 FPU code: once all drivers
are decoupled from internals we can move them out of common
headers and we'll also be able to remove xcr.h.
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>
x86/fpu, crypto x86/cast6_avx: Simplify the cast6_init() xfeature checks
Use the new 'cpu_has_xfeatures()' function to query AVX CPU support.
This has the following advantages to the driver:
- Decouples the driver from FPU internals: it's now only using <asm/fpu/api.h>.
- Removes detection complexity from the driver, no more raw XGETBV instruction
- Shrinks the code a bit.
- Standardizes feature name error message printouts across drivers
There are also advantages to the x86 FPU code: once all drivers
are decoupled from internals we can move them out of common
headers and we'll also be able to remove xcr.h.
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>
x86/fpu, crypto x86/sha512_ssse3: Simplify the sha512_ssse3_mod_init() xfeature checks
Use the new 'cpu_has_xfeatures()' function to query AVX CPU support.
This has the following advantages to the driver:
- Decouples the driver from FPU internals: it's now only using <asm/fpu/api.h>.
- Removes detection complexity from the driver, no more raw XGETBV instruction
- Shrinks the code a bit.
- Standardizes feature name error message printouts across drivers
There are also advantages to the x86 FPU code: once all drivers
are decoupled from internals we can move them out of common
headers and we'll also be able to remove xcr.h.
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>
x86/fpu, crypto x86/cast5_avx: Simplify the cast5_init() xfeature checks
Use the new 'cpu_has_xfeatures()' function to query AVX CPU support.
This has the following advantages to the driver:
- Decouples the driver from FPU internals: it's now only using <asm/fpu/api.h>.
- Removes detection complexity from the driver, no more raw XGETBV instruction
- Shrinks the code a bit.
- Standardizes feature name error message printouts across drivers
There are also advantages to the x86 FPU code: once all drivers
are decoupled from internals we can move them out of common
headers and we'll also be able to remove xcr.h.
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>
x86/fpu, crypto x86/serpent_avx: Simplify the serpent_init() xfeature checks
Use the new 'cpu_has_xfeatures()' function to query AVX CPU support.
This has the following advantages to the driver:
- Decouples the driver from FPU internals: it's now only using <asm/fpu/api.h>.
- Removes detection complexity from the driver, no more raw XGETBV instruction
- Shrinks the code a bit.
- Standardizes feature name error message printouts across drivers
There are also advantages to the x86 FPU code: once all drivers
are decoupled from internals we can move them out of common
headers and we'll also be able to remove xcr.h.
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>
x86/fpu, crypto x86/twofish_avx: Simplify the twofish_init() xfeature checks
Use the new 'cpu_has_xfeatures()' function to query AVX CPU support.
This has the following advantages to the driver:
- Decouples the driver from FPU internals: it's now only using <asm/fpu/api.h>.
- Removes detection complexity from the driver, no more raw XGETBV instruction
- Shrinks the code a bit.
- Standardizes feature name error message printouts across drivers
There are also advantages to the x86 FPU code: once all drivers
are decoupled from internals we can move them out of common
headers and we'll also be able to remove xcr.h.
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>
x86/fpu, crypto x86/camellia_aesni_avx2: Simplify the camellia_aesni_init() xfeature checks
Use the new 'cpu_has_xfeatures()' function to query AVX CPU support.
This has the following advantages to the driver:
- Decouples the driver from FPU internals: it's now only using <asm/fpu/api.h>.
- Removes detection complexity from the driver, no more raw XGETBV instruction
- Shrinks the code a bit.
- Standardizes feature name error message printouts across drivers
There are also advantages to the x86 FPU code: once all drivers
are decoupled from internals we can move them out of common
headers and we'll also be able to remove xcr.h.
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>
x86/fpu, crypto x86/sha256_ssse3: Simplify the sha256_ssse3_mod_init() xfeature checks
Use the new 'cpu_has_xfeatures()' function to query AVX CPU support.
This has the following advantages to the driver:
- Decouples the driver from FPU internals: it's now only using <asm/fpu/api.h>.
- Removes detection complexity from the driver, no more raw XGETBV instruction
- Shrinks the code a bit.
- Standardizes feature name error message printouts across drivers
There are also advantages to the x86 FPU code: once all drivers
are decoupled from internals we can move them out of common
headers and we'll also be able to remove xcr.h.
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>
x86/fpu, crypto x86/camellia_aesni_avx: Simplify the camellia_aesni_init() xfeature checks
Use the new 'cpu_has_xfeatures()' function to query AVX CPU support.
This has the following advantages to the driver:
- Decouples the driver from FPU internals: it's now only using <asm/fpu/api.h>.
- Removes detection complexity from the driver, no more raw XGETBV instruction
- Shrinks the code a bit:
text data bss dec hex filename
2128 2896 0 5024 13a0 camellia_aesni_avx_glue.o.before
2067 2896 0 4963 1363 camellia_aesni_avx_glue.o.after
- Standardizes feature name error message printouts across drivers
There are also advantages to the x86 FPU code: once all drivers
are decoupled from internals we can move them out of common
headers and we'll also be able to remove xcr.h.
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>
We do a boot time printout of xfeatures in print_xstate_features(),
simplify this code to make use of the recently introduced cpu_has_xfeature()
method.
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>
'xsave' is an x86 instruction name to most people - but xsave.h is
about a lot more than just the XSAVE instruction: it includes
definitions and support, both internal and external, related to
xstate and xfeatures support.
As a first step in cleaning up the various xstate uses rename this
header to 'fpu/xstate.h' to better reflect what this header file
is about.
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>
x86/fpu: Optimize fpu_copy() some more on lazy switching systems
The current fpu_copy() code on lazy switching CPUs always saves
into the current fpstate and then copies it over into the child
context:
preempt_disable();
if (!copy_fpregs_to_fpstate(src_fpu))
fpregs_deactivate(src_fpu);
preempt_enable();
memcpy(&dst_fpu->state, &src_fpu->state, xstate_size);
That memcpy() can be avoided on all lazy switching setups except
really old FNSAVE-only systems: change fpu_copy() to directly save
into the child context, for both the lazy and the eager context
switching case.
Note that we still have to do a memcpy() back into the parent
context in the FNSAVE case, but this won't be executed on the
majority of x86 systems that got built in the last 10 years or so.
Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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>
copy_fpregs_to_fpstate(fpu);
if (!use_eager_fpu())
fpregs_deactivate(fpu);
... which deactivates the FPU on lazy switching systems unconditionally.
Both usecases of fpu__save() use this function to save the
FPU state into a fpstate: fork()/clone() and math error signal handling.
The unconditional disabling of FPU registers in the lazy switching
case is probably a mistaken conversion of old FNSAVE code (that had
to disable FPU registers).
So speed up this code by only disabling FPU registers when absolutely
necessary: when indicated by the copy_fpregs_to_fpstate() return
code:
if (!copy_fpregs_to_fpstate(fpu))
fpregs_deactivate(fpu);
Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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>
if (use_xsave()) {
xsave_state(&fpu->state.xsave);
} else {
fpu_fxsave(fpu);
}
Is actually a simplified version of copy_fpregs_to_fpstate(),
if use_eager_fpu() is true.
But all call sites of __save_fpu() call it only it when use_eager_fpu()
is true.
So we can eliminate __save_fpu() altogether and use the standard
copy_fpregs_to_fpstate() function. This cleans up the code
by making it use fewer variants of FPU register saving.
Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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>
x86/fpu: Rename fpu__unlazy_stopped() to fpu__activate_stopped()
In line with the fpstate_activate() change, name
fpu__unlazy_stopped() in a similar fashion as well: its purpose
is to make the fpstate of a stopped task the current and active FPU
context, which may require unlazying and initialization.
The unlazying is just part of the job, the main concept is to make
the fpstate active.
Also clarify the function's description to clarify its exact
usage and the background behind it all.
Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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>
Now that fpstate_init() cannot fail the error return of fx_init()
has lost its purpose. Eliminate the error return and propagate this
change to all callers.
Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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>
x86/fpu: Rename fpstate_alloc_init() to fpstate_init_curr()
Now that there are no FPU context allocations, rename fpstate_alloc_init()
to fpstate_init_curr(), to signal that it initializes the fpstate and
marks it active, for the current task.
Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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>
x86/fpu: Remove failure paths from fpstate-alloc low level functions
Now that we always allocate the FPU context as part of task_struct there's
no need for separate allocations - remove them and their primary failure
handling code.
( Note that there's still secondary error codes that have become superfluous,
those will be removed in separate patches. )
Move the somewhat misplaced setup_xstate_comp() call to the core.
Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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>
x86/fpu: Simplify FPU handling by embedding the fpstate in task_struct (again)
So 6 years ago we made the FPU fpstate dynamically allocated:
aa283f49276e ("x86, fpu: lazy allocation of FPU area - v5") 61c4628b5386 ("x86, fpu: split FPU state from task struct - v5")
In hindsight this was a mistake:
- it complicated context allocation failure handling, such as:
/* kthread execs. TODO: cleanup this horror. */
if (WARN_ON(fpstate_alloc_init(fpu)))
force_sig(SIGKILL, tsk);
- it caused us to enable irqs in fpu__restore():
local_irq_enable();
/*
* does a slab alloc which can sleep
*/
if (fpstate_alloc_init(fpu)) {
/*
* ran out of memory!
*/
do_group_exit(SIGKILL);
return;
}
local_irq_disable();
- it (slightly) slowed down task creation/destruction by adding
slab allocation/free pattens.
- it made access to context contents (slightly) slower by adding
one more pointer dereference.
The motivation for the dynamic allocation was two-fold:
- reduce memory consumption by non-FPU tasks
- allocate and handle only the necessary amount of context for
various XSAVE processors that have varying hardware frame
sizes.
These days, with glibc using SSE memcpy by default and GCC optimizing
for SSE/AVX by default, the scope of FPU using apps on an x86 system is
much larger than it was 6 years ago.
For example on a freshly installed Fedora 21 desktop system, with a
recent kernel, all non-kthread tasks have used the FPU shortly after
bootup.
Also, even modern embedded x86 CPUs try to support the latest vector
instruction set - so they'll too often use the larger xstate frame
sizes.
So remove the dynamic allocation complication by embedding the FPU
fpstate in task_struct again. This should make the FPU a lot more
accessible to all sorts of atomic contexts.
We could still optimize for the xstate frame size in the future,
by moving the state structure to the last element of task_struct,
and allocating only a part of that.
This change is kept minimal by still keeping the ctx_alloc()/free()
routines (that now do nothing substantial) - we'll remove them in
the following patches.
Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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>
x86/fpu: Optimize copy_fpregs_to_fpstate() by removing the FNCLEX synchronization with FP exceptions
So we have the following ancient code in copy_fpregs_to_fpstate():
if (unlikely(fpu->state->fxsave.swd & X87_FSW_ES)) {
asm volatile("fnclex");
goto drop_fpregs;
}
which clears pending FPU exceptions and then drops registers, which
causes the next FP instruction of the saved context to re-load the
saved FPU state, with all pending exceptions marked properly, and
will re-start the exception handling mechanism in the hardware.
Since FPU exceptions are always issued on instruction boundaries,
in particular on the next FP instruction following the exception
generating instruction, there's no fear of getting an FP exception
asynchronously.
They were truly asynchronous back in the IRQ13 days, when the FPU was
a weird and expensive co-processor that did its own processing, and we
had to synchronize with them, but that code is not working anymore:
we don't have IRQ13 mapped in the IDT anymore.
With the introduction of optimized XSAVE support there's a new
complication: if the xstate features bit indicates that a particular
state component is unused (in 'init state'), then the hardware does
not guarantee that the XSAVE (et al) instruction keeps the underlying
FPU state image in memory valid and current. In practice this means
that the hardware won't write it, and the exceptions flag in the
state might be an older version, with it still being set. This
meant that we had to check the xfeatures flag as well, adding
another memory load and branch to a critical hot path of the scheduler.
So optimize all this by removing both the old quirk and the new check,
and straight-line optimizing the most common cases with likely()
hints. Quite a bit of code gets removed this way:
arch/x86/kernel/process_64.o:
text data bss dec filename
5484 8 0 5492 process_64.o.before
5416 8 0 5424 process_64.o.after
Now there's also a chance that some weird behavior or erratum was
masked by our IRQ13 handling quirk (or that I misunderstood the
nature of the quirk), and that this change triggers some badness.
There's no real good way to protect against that possibility other
than keeping this change well isolated, well commented and well
bisectable. If you bisect a weird (or not so weird) breakage to
this commit then please let us know!
Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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>
x86/fpu: Rename fpu_save_init() to copy_fpregs_to_fpstate()
So fpu_save_init() is a historic name that got its name when the only
way the FPU state was FNSAVE, which cleared (well, destroyed) the FPU
state after saving it.
Nowadays the name is misleading, because ever since the introduction of
FXSAVE (and more modern FPU saving instructions) the 'we need to reload
the FPU state' part is only true if there's a pending FPU exception [*],
which is almost never the case.
So rename it to copy_fpregs_to_fpstate() to make it clear what's
happening. Also add a few comments about why we cannot keep registers
in certain cases.
Also clean up the control flow a bit, to make it more apparent when
we are dropping/keeping FP registers, and to optimize the common
case (of keeping fpregs) some more.
[*] Probably not true anymore, modern instructions always leave the FPU
state intact, even if exceptions are pending: because pending FP
exceptions are posted on the next FP instruction, not asynchronously.
They were truly asynchronous back in the IRQ13 case, and we had to
synchronize with them, but that code is not working anymore: we don't
have IRQ13 mapped in the IDT anymore.
But a cleanup patch is obviously not the place to change subtle behavior.
Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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>
x86/fpu: Move various internal function prototypes to fpu/internal.h
There are a number of FPU internal function prototypes and an inline function
in fpu/api.h, mostly placed so historically as the code grew over the years.
Move them over into fpu/internal.h where they belong. (Add sched.h include
to stackprotector.h which incorrectly relied on getting it from fpu/api.h.)
fpu/api.h is now a pure file that only contains FPU APIs intended for driver
use.
Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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>
Now that fpu__detect() has become an empty layer around
fpu__init_system(), eliminate it and make fpu__init_system()
the main system initialization routine.
Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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>
Ingo Molnar [Tue, 5 May 2015 08:54:04 +0000 (10:54 +0200)]
x86/fpu: Make check_fpu() init ordering independent
check_fpu() currently relies on being called early in the init sequence,
when CR0::TS has not been set up yet.
Save/restore CR0::TS across this function, to make it invariant to
init ordering. This way we'll be able to move the generic FPU setup
routines earlier in the init sequence.
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>
There's a !FPU related sanity check in fpu__init_cpu_generic(),
which is executed on every CPU onlining - even though we should do
this only once, and during system init.
Move this check to fpu__init_system_early_generic().
Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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>
fpu__cpu_init() is called on every CPU, so it is the wrong place
to call fpu__init_system() from. Call it from fpu__detect():
this is early CPU init code, but we already have CPU features detected,
so we can call the system-wide FPU init code from here.
Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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>
x86/fpu: Call fpu__init_cpu_ctx_switch() from fpu__init_cpu()
fpu__init_cpu() is currently called from fpu__init_system(),
which is the wrong place for it: call it from the proper high level
per CPU init function, fpu__init_cpu().
Note, we still keep the old call site as well, because it depends
on having proper CR0::TS setup. We'll fix this in the next patch.
Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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>
x86/fpu: Move the fpstate_xstate_init_size() call into fpu__init_system()
The fpstate_xstate_init_size() function sets up a basic xstate_size, called
during fpu__detect() currently.
Its real dependency is to be called before fpu__init_system_xstate().
So move the function call site into fpu__init_system(), to right before the
fpu__init_system_xstate() call.
Also add a once-per-boot flag to fpstate_xstate_init_size(), we'll remove
this quirk later once we've cleaned up the init dependencies.
This moves the two related functions closer to each other and makes them
both part of the _init_system() functionality.
Currently we do the fpstate_xstate_init_size() Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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>
x86/fpu: Split fpu__ctx_switch_init() into _cpu() and _system() portions
So fpu__ctx_switch_init() has two aspects: a once per bootup functionality
that sets up a capability flag, and a per CPU functionality that sets CR0::TS.
Split the function.
Note that at this stage we still have duplicate calls into these methods, as
both the _system() and the _cpu() methods are run on all CPUs, with lower
level on_boot_cpu flags filtering out the duplicates where needed. So add
TS flag clearing as well, to handle the aftermath of early CPU init sequences
that might call in without having eager-fpu set - don't assume the TS flag
is cleared.
Calling each from its respective init level will happen later on.
Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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>
x86/fpu: Move all eager-fpu setup code to eager_fpu_init()
The FPU context switch type (lazy or eager) setup code is split into
two places currently - move it all to eager_fpu_init().
Note that the code we move will now be executed on non-xstate CPUs
as well, but this should be safe: both xfeatures_mask and
cpu_has_xsaveopt is 0 there.
Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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>
x86/fpu: Move legacy check to fpu__init_system_xstate()
Now that legacy code can execute fpu__init_cpu_xstate() in
xsave_init(), we can move the once per boot legacy check into
fpu__init_system_xstate(), where it belongs.
Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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>
x86/fpu: Move CPU capability check into fpu__init_cpu_xstate()
fpu__init_system_xstate() does an FPU capability check that is better
done in fpu__init_cpu_xstate(). This will allow us to call
fpu__init_cpu_xstate() directly on legacy CPUs as well.
Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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>
x86/fpu: Split fpu__cpu_init() into early-boot and cpu-boot parts
There are two kinds of FPU initialization sequences necessary to bring FPU
functionality up: once per system bootup activities, such as detection,
feature initialization, etc. of attributes that are shared by all CPUs
in the system - and per cpu initialization sequences run when a CPU is
brought online (either during bootup or during CPU hotplug onlining),
such as CR0/CR4 register setting, etc.
The FPU code is mixing these roles together, with no clear distinction.
Start sorting this out by splitting the main FPU detection routine
(fpu__cpu_init()) into two parts: fpu__init_system() for
one per system init activities, and fpu__init_cpu() for the
per CPU onlining init activities.
Note that xstate_init() is called from both variants for the time being,
because it has a dual nature as well. We'll fix that in upcoming patches.
Just do the split and call it as we used to before, don't introduce any
change in initialization behavior yet, beyond duplicate (and harmless)
fpu__init_cpu() and xstate_init() calls - which we'll fix in later
patches.
Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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>
Make init_xstate_buf allocated statically at build time.
This structure's maximum size is around 1KB - and it's allocated even on
most modern embedded x86 CPUs which strive for FPU instruction set parity
with desktop and server CPUs, so it's not like we can save much on smaller
systems.
This removes the last bootmem allocation from the FPU init path, allowing
it to be called earlier in the boot sequence.
Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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>
x86/fpu: Make setup_init_fpu_buf() run-once explicitly
Remove the dependency on the init_xstate_buf == NULL check to
implement once-per-bootup logic in eager_fpu_init(), by making
setup_init_fpu_buf() run once per bootup explicitly.
This is in preparation to make init_xstate_buf statically
allocated.
The various boot-once quirks in the FPU init code will be removed
in a later cleanup stage.
Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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>
There's only 8 xstate bits at the moment, and it's not like we
can support unknown bits - so put xstate_offsets[] and
xstate_sizes[] into static allocation.
This is in preparation to be able to call the FPU init code
earlier, when there's no bootmem available yet.
Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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>
x86/fpu: Rename fpu->has_fpu to fpu->fpregs_active
So the current code uses fpu->has_cpu to determine whether a given
user FPU context is actively loaded into the FPU's registers [*] and
that those registers represent the task's current FPU state.
But this term is not unambiguous: especially the distinction between
fpu->has_fpu, PF_USED_MATH and fpu_fpregs_owner_ctx is not clear.
Increase clarity by unambigously signalling that it's about
hardware registers being active right now, by renaming it to
fpu->fpregs_active.
( In later patches we'll use more of the 'fpregs' naming, which will
make it easier to grep for as well. )
[*] There's the kernel_fpu_begin()/end() primitive that also
activates FPU hw registers as well and uses them, without
touching the fpu->fpregs_active flag.
Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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>
- it uses a single global 'fx_scratch' area that multiple CPUs could
write into simultaneously, in theory.
- it wastes 512 bytes of .data for something that is only rarely used.
Fix this by moving the state buffer to the stack. Note that while
this is 512 bytes, we don't ever call this function in very deep
callchains, so its stack usage should not be a problem.
Also add comments to explain the magic 0x0000ffbf default value.
Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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>
x86/fpu: Rename xsave.header::xstate_bv to 'xfeatures'
'xsave.header::xstate_bv' is a misnomer - what does 'bv' stand for?
It probably comes from the 'XGETBV' instruction name, but I could
not find in the Intel documentation where that abbreviation comes
from. It could mean 'bit vector' - or something else?
But how about - instead of guessing about a weird name - we named
the field in an obvious and descriptive way that tells us exactly
what it does?
So rename it to 'xfeatures', which is a bitmask of the
xfeatures that are fpstate_active in that context structure.
is an eyesore, because not only is the words 'xsave' and 'state'
are repeated twice times (!), but also because of the 'hdr' and 'bv'
abbreviations that are pretty meaningless at a first glance.
Start cleaning this up by renaming 'xsave_hdr' to 'header'.
Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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>
x86/fpu: Rename 'xstate_features' to 'xfeatures_nr'
The name 'xstate_features' does not tell us whether it's a bitmap
or any other value. That it's a count of features is only obvious
if you read the code that calculates it.
Rename it to the more descriptive 'xfeatures_nr' name.
Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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>
asm/fpu/api.h does not contain any defines useful to assembly code,
and no assembly code includes asm/fpu/api.h. Remove the historic
#ifndef __ASSEMBLY__ leftover guard.
Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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 this code surprised me - and being surprised when reading FPU code
does not help maintainability of an already overly complex subsystem.
Remove the obfuscation and just don't use __init annotation for now.
Anyone who wants to free these ~600 bytes of xstate_enable_boot_cpu()
should implement it cleanly.
Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> 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>
projects / linux-beck.git / log