From f1c8cd0176078c7bcafdc89cac447cab672a0b5e Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Sat, 23 Sep 2017 15:00:01 +0200 Subject: [PATCH] x86/fpu: Change fpu->fpregs_active users to fpu->fpstate_active We want to simplify the FPU state machine by eliminating fpu->fpregs_active, and we can do that because the two state flags (::fpregs_active and ::fpstate_active) are set essentially together. The old lazy FPU switching code used to make a distinction - but there's no lazy switching code anymore, we always switch in an 'eager' fashion. Do this by first changing all substantial uses of fpu->fpregs_active to fpu->fpstate_active and adding a few debug checks to double check our assumption is correct. Cc: Andrew Morton Cc: Andy Lutomirski Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Dave Hansen Cc: Eric Biggers Cc: Fenghua Yu Cc: Linus Torvalds Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Rik van Riel Cc: Thomas Gleixner Cc: Yu-cheng Yu Link: http://lkml.kernel.org/r/20170923130016.21448-19-mingo@kernel.org Signed-off-by: Ingo Molnar --- arch/x86/include/asm/fpu/internal.h | 4 +++- arch/x86/kernel/fpu/core.c | 16 ++++++++++------ arch/x86/kernel/fpu/signal.c | 4 +++- arch/x86/mm/pkeys.c | 3 +-- 4 files changed, 17 insertions(+), 10 deletions(-) diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h index b223c57dd5dc..7fa676f93ac1 100644 --- a/arch/x86/include/asm/fpu/internal.h +++ b/arch/x86/include/asm/fpu/internal.h @@ -556,7 +556,9 @@ static inline void fpregs_activate(struct fpu *fpu) static inline void switch_fpu_prepare(struct fpu *old_fpu, int cpu) { - if (old_fpu->fpregs_active) { + WARN_ON_FPU(old_fpu->fpregs_active != old_fpu->fpstate_active); + + if (old_fpu->fpstate_active) { if (!copy_fpregs_to_fpstate(old_fpu)) old_fpu->last_cpu = -1; else diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index 815dfba7781a..eab244622402 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -100,7 +100,7 @@ void __kernel_fpu_begin(void) kernel_fpu_disable(); - if (fpu->fpregs_active) { + if (fpu->fpstate_active) { /* * Ignore return value -- we don't care if reg state * is clobbered. @@ -116,7 +116,7 @@ void __kernel_fpu_end(void) { struct fpu *fpu = ¤t->thread.fpu; - if (fpu->fpregs_active) + if (fpu->fpstate_active) copy_kernel_to_fpregs(&fpu->state); kernel_fpu_enable(); @@ -147,8 +147,10 @@ void fpu__save(struct fpu *fpu) WARN_ON_FPU(fpu != ¤t->thread.fpu); preempt_disable(); + WARN_ON_FPU(fpu->fpstate_active != fpu->fpregs_active); + trace_x86_fpu_before_save(fpu); - if (fpu->fpregs_active) { + if (fpu->fpstate_active) { if (!copy_fpregs_to_fpstate(fpu)) { copy_kernel_to_fpregs(&fpu->state); } @@ -262,11 +264,12 @@ EXPORT_SYMBOL_GPL(fpu__activate_curr); */ void fpu__activate_fpstate_read(struct fpu *fpu) { + WARN_ON_FPU(fpu->fpstate_active != fpu->fpregs_active); /* * If fpregs are active (in the current CPU), then * copy them to the fpstate: */ - if (fpu->fpregs_active) { + if (fpu->fpstate_active) { fpu__save(fpu); } else { if (!fpu->fpstate_active) { @@ -362,12 +365,13 @@ void fpu__current_fpstate_write_end(void) { struct fpu *fpu = ¤t->thread.fpu; + WARN_ON_FPU(fpu->fpstate_active != fpu->fpregs_active); /* * 'fpu' now has an updated copy of the state, but the * registers may still be out of date. Update them with * an XRSTOR if they are active. */ - if (fpu->fpregs_active) + if (fpu->fpstate_active) copy_kernel_to_fpregs(&fpu->state); /* @@ -417,7 +421,7 @@ void fpu__drop(struct fpu *fpu) if (fpu == ¤t->thread.fpu) { WARN_ON_FPU(fpu->fpstate_active != fpu->fpregs_active); - if (fpu->fpregs_active) { + if (fpu->fpstate_active) { /* Ignore delayed exceptions from user space */ asm volatile("1: fwait\n" "2:\n" diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c index 684025654d0c..a88083ba7f8b 100644 --- a/arch/x86/kernel/fpu/signal.c +++ b/arch/x86/kernel/fpu/signal.c @@ -171,7 +171,9 @@ int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size) sizeof(struct user_i387_ia32_struct), NULL, (struct _fpstate_32 __user *) buf) ? -1 : 1; - if (fpu->fpregs_active || using_compacted_format()) { + WARN_ON_FPU(fpu->fpstate_active != fpu->fpregs_active); + + if (fpu->fpstate_active || using_compacted_format()) { /* Save the live register state to the user directly. */ if (copy_fpregs_to_sigframe(buf_fx)) return -1; diff --git a/arch/x86/mm/pkeys.c b/arch/x86/mm/pkeys.c index e2c23472233e..4d24269c071f 100644 --- a/arch/x86/mm/pkeys.c +++ b/arch/x86/mm/pkeys.c @@ -18,7 +18,6 @@ #include /* boot_cpu_has, ... */ #include /* vma_pkey() */ -#include /* fpregs_active() */ int __execute_only_pkey(struct mm_struct *mm) { @@ -45,7 +44,7 @@ int __execute_only_pkey(struct mm_struct *mm) */ preempt_disable(); if (!need_to_set_mm_pkey && - current->thread.fpu.fpregs_active && + current->thread.fpu.fpstate_active && !__pkru_allows_read(read_pkru(), execute_only_pkey)) { preempt_enable(); return execute_only_pkey;