x86-fpu-revert-x86-fpu-disable-avx-when-eagerfpu-is-off.patch
x86-fpu-fix-eager-fpu-handling-on-legacy-fpu-machines.patch
x86-fpu-hard-disable-lazy-fpu-mode.patch
+x86-fpu-fix-fnsave-usage-in-eagerfpu-mode.patch
+x86-fpu-fix-math-emulation-in-eager-fpu-mode.patch
--- /dev/null
+From 5ed73f40735c68d8a656b46d09b1885d3b8740ae Mon Sep 17 00:00:00 2001
+From: Andy Lutomirski <luto@kernel.org>
+Date: Sun, 24 Jan 2016 14:38:07 -0800
+Subject: x86/fpu: Fix FNSAVE usage in eagerfpu mode
+
+From: Andy Lutomirski <luto@kernel.org>
+
+commit 5ed73f40735c68d8a656b46d09b1885d3b8740ae upstream.
+
+In eager fpu mode, having deactivated FPU without immediately
+reloading some other context is illegal. Therefore, to recover from
+FNSAVE, we can't just deactivate the state -- we need to reload it
+if we're not actively context switching.
+
+We had this wrong in fpu__save() and fpu__copy(). Fix both.
+__kernel_fpu_begin() was fine -- add a comment.
+
+This fixes a warning triggerable with nofxsr eagerfpu=on.
+
+Signed-off-by: Andy Lutomirski <luto@kernel.org>
+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: Quentin Casasnovas <quentin.casasnovas@oracle.com>
+Cc: Rik van Riel <riel@redhat.com>
+Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
+Cc: Thomas Gleixner <tglx@linutronix.de>
+Cc: yu-cheng yu <yu-cheng.yu@intel.com>
+Link: http://lkml.kernel.org/r/60662444e13c76f06e23c15c5dcdba31b4ac3d67.1453675014.git.luto@kernel.org
+Signed-off-by: Ingo Molnar <mingo@kernel.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ arch/x86/kernel/fpu/core.c | 18 +++++++++++++++---
+ 1 file changed, 15 insertions(+), 3 deletions(-)
+
+--- a/arch/x86/kernel/fpu/core.c
++++ b/arch/x86/kernel/fpu/core.c
+@@ -114,6 +114,10 @@ void __kernel_fpu_begin(void)
+ kernel_fpu_disable();
+
+ if (fpu->fpregs_active) {
++ /*
++ * Ignore return value -- we don't care if reg state
++ * is clobbered.
++ */
+ copy_fpregs_to_fpstate(fpu);
+ } else {
+ this_cpu_write(fpu_fpregs_owner_ctx, NULL);
+@@ -189,8 +193,12 @@ void fpu__save(struct fpu *fpu)
+
+ preempt_disable();
+ if (fpu->fpregs_active) {
+- if (!copy_fpregs_to_fpstate(fpu))
+- fpregs_deactivate(fpu);
++ if (!copy_fpregs_to_fpstate(fpu)) {
++ if (use_eager_fpu())
++ copy_kernel_to_fpregs(&fpu->state);
++ else
++ fpregs_deactivate(fpu);
++ }
+ }
+ preempt_enable();
+ }
+@@ -259,7 +267,11 @@ static void fpu_copy(struct fpu *dst_fpu
+ preempt_disable();
+ if (!copy_fpregs_to_fpstate(dst_fpu)) {
+ memcpy(&src_fpu->state, &dst_fpu->state, xstate_size);
+- fpregs_deactivate(src_fpu);
++
++ if (use_eager_fpu())
++ copy_kernel_to_fpregs(&src_fpu->state);
++ else
++ fpregs_deactivate(src_fpu);
+ }
+ preempt_enable();
+ }
--- /dev/null
+From 4ecd16ec7059390b430af34bd8bc3ca2b5dcef9a Mon Sep 17 00:00:00 2001
+From: Andy Lutomirski <luto@kernel.org>
+Date: Sun, 24 Jan 2016 14:38:06 -0800
+Subject: x86/fpu: Fix math emulation in eager fpu mode
+
+From: Andy Lutomirski <luto@kernel.org>
+
+commit 4ecd16ec7059390b430af34bd8bc3ca2b5dcef9a upstream.
+
+Systems without an FPU are generally old and therefore use lazy FPU
+switching. Unsurprisingly, math emulation in eager FPU mode is a
+bit buggy. Fix it.
+
+There were two bugs involving kernel code trying to use the FPU
+registers in eager mode even if they didn't exist and one BUG_ON()
+that was incorrect.
+
+Signed-off-by: Andy Lutomirski <luto@kernel.org>
+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: Quentin Casasnovas <quentin.casasnovas@oracle.com>
+Cc: Rik van Riel <riel@redhat.com>
+Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
+Cc: Thomas Gleixner <tglx@linutronix.de>
+Cc: yu-cheng yu <yu-cheng.yu@intel.com>
+Link: http://lkml.kernel.org/r/b4b8d112436bd6fab866e1b4011131507e8d7fbe.1453675014.git.luto@kernel.org
+Signed-off-by: Ingo Molnar <mingo@kernel.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ arch/x86/include/asm/fpu/internal.h | 3 ++-
+ arch/x86/kernel/fpu/core.c | 2 +-
+ arch/x86/kernel/traps.c | 1 -
+ 3 files changed, 3 insertions(+), 3 deletions(-)
+
+--- a/arch/x86/include/asm/fpu/internal.h
++++ b/arch/x86/include/asm/fpu/internal.h
+@@ -596,7 +596,8 @@ switch_fpu_prepare(struct fpu *old_fpu,
+ * If the task has used the math, pre-load the FPU on xsave processors
+ * or if the past 5 consecutive context-switches used math.
+ */
+- fpu.preload = new_fpu->fpstate_active &&
++ fpu.preload = static_cpu_has(X86_FEATURE_FPU) &&
++ new_fpu->fpstate_active &&
+ (use_eager_fpu() || new_fpu->counter > 5);
+
+ if (old_fpu->fpregs_active) {
+--- a/arch/x86/kernel/fpu/core.c
++++ b/arch/x86/kernel/fpu/core.c
+@@ -437,7 +437,7 @@ void fpu__clear(struct fpu *fpu)
+ {
+ WARN_ON_FPU(fpu != ¤t->thread.fpu); /* Almost certainly an anomaly */
+
+- if (!use_eager_fpu()) {
++ if (!use_eager_fpu() || !static_cpu_has(X86_FEATURE_FPU)) {
+ /* FPU state will be reallocated lazily at the first use. */
+ fpu__drop(fpu);
+ } else {
+--- a/arch/x86/kernel/traps.c
++++ b/arch/x86/kernel/traps.c
+@@ -751,7 +751,6 @@ dotraplinkage void
+ do_device_not_available(struct pt_regs *regs, long error_code)
+ {
+ RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
+- BUG_ON(use_eager_fpu());
+
+ #ifdef CONFIG_MATH_EMULATION
+ if (read_cr0() & X86_CR0_EM) {
projects / thirdparty / kernel / stable-queue.git / commitdiff
