kernel.git/arch/x86/kernel/fpu/init.c, branch linux-4.8.y

x86/fpu/xstate: Re-enable XSAVES

2016-07-11T14:44:01Z

We did not handle XSAVES instructions correctly. There were issues in converting between standard and compacted format when interfacing with user-space. These issues have been corrected. Add a WARN_ONCE() to make it clear that XSAVES supervisor states are not yet implemented. Signed-off-by: Yu-cheng Yu Signed-off-by: Fenghua Yu Reviewed-by: Dave Hansen Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Ravi V Shankar Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1468253937-40008-5-git-send-email-fenghua.yu@intel.com Signed-off-by: Ingo Molnar

x86/fpu/xstate: Rename 'xstate_size' to 'fpu_kernel_xstate_size', to distinguish it from 'fpu_user_xstate_size'

2016-06-18T08:10:18Z

User space uses standard format xsave area. fpstate in signal frame should have standard format size. To explicitly distinguish between xstate size in kernel space and the one in user space, we rename 'xstate_size' to 'fpu_kernel_xstate_size'. Cleanup only, no change in functionality. Signed-off-by: Fenghua Yu [ Rebased the patch and cleaned up the naming. ] Signed-off-by: Yu-cheng Yu Reviewed-by: Dave Hansen Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Quentin Casasnovas Cc: Ravi V. Shankar Cc: Sai Praneeth Prakhya Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/2ecbae347a5152d94be52adf7d0f3b7305d90d99.1463760376.git.yu-cheng.yu@intel.com Signed-off-by: Ingo Molnar

x86/fpu/xstate: Define and use 'fpu_user_xstate_size'

2016-06-18T08:10:18Z

The kernel xstate area can be in standard or compacted format; it is always in standard format for user mode. When XSAVES is enabled, the kernel uses the compacted format and it is necessary to use a separate fpu_user_xstate_size for signal/ptrace frames. Signed-off-by: Fenghua Yu [ Rebased the patch and cleaned up the naming. ] Signed-off-by: Yu-cheng Yu Reviewed-by: Dave Hansen Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Quentin Casasnovas Cc: Ravi V. Shankar Cc: Sai Praneeth Prakhya Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/8756ec34dabddfc727cda5743195eb81e8caf91c.1463760376.git.yu-cheng.yu@intel.com Signed-off-by: Ingo Molnar

x86/cpufeature: Replace cpu_has_fxsr with boot_cpu_has() usage

2016-04-13T09:37:41Z

Signed-off-by: Borislav Petkov Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1459801503-15600-9-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar

x86/cpufeature: Replace cpu_has_fpu with boot_cpu_has() usage

2016-04-13T09:37:40Z

Use static_cpu_has() in the timing-sensitive paths in fpstate_init() and fpu__copy(). While at it, simplify the use in init_cyrix() and get rid of the ternary operator. Signed-off-by: Borislav Petkov Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1459801503-15600-6-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar

x86/cpufeature: Replace cpu_has_xmm with boot_cpu_has() usage

2016-04-13T09:37:40Z

Signed-off-by: Borislav Petkov Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1459801503-15600-5-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar

Merge branch 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2016-03-15T17:23:56Z

Pull x86 fpu updates from Ingo Molnar: "The biggest change in terms of impact is the changing of the FPU context switch model to 'eagerfpu' for all CPU types, via: commit 58122bf1d856: "x86/fpu: Default eagerfpu=on on all CPUs" This makes all FPU saves and restores synchronous and makes the FPU code a lot more obvious to read. In the next cycle, if this change is problem free, we'll remove the old lazy FPU restore code altogether. This change flushed out some old bugs, which should all be fixed by now, BYMMV" * 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/fpu: Default eagerfpu=on on all CPUs x86/fpu: Speed up lazy FPU restores slightly x86/fpu: Fold fpu_copy() into fpu__copy() x86/fpu: Fix FNSAVE usage in eagerfpu mode x86/fpu: Fix math emulation in eager fpu mode

x86/fpu: Fix eager-FPU handling on legacy FPU machines

2016-03-12T15:13:55Z

i486 derived cores like Intel Quark support only the very old, legacy x87 FPU (FSAVE/FRSTOR, CPUID bit FXSR is not set), and our FPU code wasn't handling the saving and restoring there properly in the 'eagerfpu' case. So after we made eagerfpu the default for all CPU types: 58122bf1d856 x86/fpu: Default eagerfpu=on on all CPUs these old FPU designs broke. First, Andy Shevchenko reported a splat: WARNING: CPU: 0 PID: 823 at arch/x86/include/asm/fpu/internal.h:163 fpu__clear+0x8c/0x160 which was us trying to execute FXRSTOR on those machines even though they don't support it. After taking care of that, Bryan O'Donoghue reported that a simple FPU test still failed because we weren't initializing the FPU state properly on those machines. Take care of all that. Reported-and-tested-by: Bryan O'Donoghue Reported-by: Andy Shevchenko Signed-off-by: Borislav Petkov Acked-by: Linus Torvalds Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: Denys Vlasenko Cc: Fenghua Yu Cc: H. Peter Anvin Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Quentin Casasnovas Cc: Thomas Gleixner Cc: Yu-cheng Link: http://lkml.kernel.org/r/20160311113206.GD4312@pd.tnic Signed-off-by: Ingo Molnar

x86/fpu: Revert ("x86/fpu: Disable AVX when eagerfpu is off")

2016-03-10T09:15:58Z

Leonid Shatz noticed that the SDM interpretation of the following recent commit: 394db20ca240741 ("x86/fpu: Disable AVX when eagerfpu is off") ... is incorrect and that the original behavior of the FPU code was correct. Because AVX is not stated in CR0 TS bit description, it was mistakenly believed to be not supported for lazy context switch. This turns out to be false: Intel Software Developer's Manual Vol. 3A, Sec. 2.5 Control Registers: 'TS Task Switched bit (bit 3 of CR0) -- Allows the saving of the x87 FPU/ MMX/SSE/SSE2/SSE3/SSSE3/SSE4 context on a task switch to be delayed until an x87 FPU/MMX/SSE/SSE2/SSE3/SSSE3/SSE4 instruction is actually executed by the new task.' Intel Software Developer's Manual Vol. 2A, Sec. 2.4 Instruction Exception Specification: 'AVX instructions refer to exceptions by classes that include #NM "Device Not Available" exception for lazy context switch.' So revert the commit. Reported-by: Leonid Shatz Signed-off-by: Yu-cheng Yu Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Dave Hansen Cc: Fenghua Yu Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Ravi V. Shankar Cc: Sai Praneeth Prakhya Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1457569734-3785-1-git-send-email-yu-cheng.yu@intel.com Signed-off-by: Ingo Molnar

x86/fpu: Fix 'no387' regression

2016-03-09T12:54:40Z

After fixing FPU option parsing, we now parse the 'no387' boot option too early: no387 clears X86_FEATURE_FPU before it's even probed, so the boot CPU promptly re-enables it. I suspect it gets even more confused on SMP. Fix the probing code to leave X86_FEATURE_FPU off if it's been disabled by setup_clear_cpu_cap(). Signed-off-by: Andy Lutomirski Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: Denys Vlasenko Cc: Fenghua Yu Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Quentin Casasnovas Cc: Sai Praneeth Prakhya Cc: Thomas Gleixner Cc: yu-cheng yu Fixes: 4f81cbafcce2 ("x86/fpu: Fix early FPU command-line parsing") Signed-off-by: Ingo Molnar