diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/include/asm/fpu/xstate.h | 2 | ||||
| -rw-r--r-- | arch/x86/kernel/fpu/xstate.c | 47 | ||||
| -rw-r--r-- | arch/x86/kernel/traps.c | 38 |
3 files changed, 87 insertions, 0 deletions
diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h index cf285464eabe..b7b145cad019 100644 --- a/arch/x86/include/asm/fpu/xstate.h +++ b/arch/x86/include/asm/fpu/xstate.h @@ -99,6 +99,8 @@ int xfeature_size(int xfeature_nr); void xsaves(struct xregs_state *xsave, u64 mask); void xrstors(struct xregs_state *xsave, u64 mask); +int xfd_enable_feature(u64 xfd_err); + #ifdef CONFIG_X86_64 DECLARE_STATIC_KEY_FALSE(__fpu_state_size_dynamic); #endif diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 77739b0a56d5..3d38558d594f 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -1464,6 +1464,53 @@ static int xstate_request_perm(unsigned long idx) spin_unlock_irq(¤t->sighand->siglock); return ret; } + +/* Place holder for now */ +static int fpstate_realloc(u64 xfeatures, unsigned int ksize, + unsigned int usize) +{ + return -ENOMEM; +} + +int xfd_enable_feature(u64 xfd_err) +{ + u64 xfd_event = xfd_err & XFEATURE_MASK_USER_DYNAMIC; + unsigned int ksize, usize; + struct fpu *fpu; + + if (!xfd_event) { + pr_err_once("XFD: Invalid xfd error: %016llx\n", xfd_err); + return 0; + } + + /* Protect against concurrent modifications */ + spin_lock_irq(¤t->sighand->siglock); + + /* If not permitted let it die */ + if ((xstate_get_host_group_perm() & xfd_event) != xfd_event) { + spin_unlock_irq(¤t->sighand->siglock); + return -EPERM; + } + + fpu = ¤t->group_leader->thread.fpu; + ksize = fpu->perm.__state_size; + usize = fpu->perm.__user_state_size; + /* + * The feature is permitted. State size is sufficient. Dropping + * the lock is safe here even if more features are added from + * another task, the retrieved buffer sizes are valid for the + * currently requested feature(s). + */ + spin_unlock_irq(¤t->sighand->siglock); + + /* + * Try to allocate a new fpstate. If that fails there is no way + * out. + */ + if (fpstate_realloc(xfd_event, ksize, usize)) + return -EFAULT; + return 0; +} #else /* CONFIG_X86_64 */ static inline int xstate_request_perm(unsigned long idx) { diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index bae7582c58f5..6ca1454a65d4 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -1108,10 +1108,48 @@ DEFINE_IDTENTRY(exc_spurious_interrupt_bug) */ } +static bool handle_xfd_event(struct pt_regs *regs) +{ + u64 xfd_err; + int err; + + if (!IS_ENABLED(CONFIG_X86_64) || !cpu_feature_enabled(X86_FEATURE_XFD)) + return false; + + rdmsrl(MSR_IA32_XFD_ERR, xfd_err); + if (!xfd_err) + return false; + + wrmsrl(MSR_IA32_XFD_ERR, 0); + + /* Die if that happens in kernel space */ + if (WARN_ON(!user_mode(regs))) + return false; + + local_irq_enable(); + + err = xfd_enable_feature(xfd_err); + + switch (err) { + case -EPERM: + force_sig_fault(SIGILL, ILL_ILLOPC, error_get_trap_addr(regs)); + break; + case -EFAULT: + force_sig(SIGSEGV); + break; + } + + local_irq_disable(); + return true; +} + DEFINE_IDTENTRY(exc_device_not_available) { unsigned long cr0 = read_cr0(); + if (handle_xfd_event(regs)) + return; + #ifdef CONFIG_MATH_EMULATION if (!boot_cpu_has(X86_FEATURE_FPU) && (cr0 & X86_CR0_EM)) { struct math_emu_info info = { }; |