diff options
| -rw-r--r-- | arch/x86/include/asm/fpu/types.h | 8 | ||||
| -rw-r--r-- | arch/x86/kernel/fpu/xstate.c | 18 |
2 files changed, 16 insertions, 10 deletions
diff --git a/arch/x86/include/asm/fpu/types.h b/arch/x86/include/asm/fpu/types.h index 97310df3ea13..e64db0eb9d27 100644 --- a/arch/x86/include/asm/fpu/types.h +++ b/arch/x86/include/asm/fpu/types.h @@ -416,9 +416,11 @@ struct fpu_state_perm { /* * @__state_perm: * - * This bitmap indicates the permission for state components, which - * are available to a thread group. The permission prctl() sets the - * enabled state bits in thread_group_leader()->thread.fpu. + * This bitmap indicates the permission for state components + * available to a thread group, including both user and supervisor + * components and software-defined bits like FPU_GUEST_PERM_LOCKED. + * The permission prctl() sets the enabled state bits in + * thread_group_leader()->thread.fpu. * * All run time operations use the per thread information in the * currently active fpu.fpstate which contains the xfeature masks diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 8b14c9d3a1df..1c8410b68108 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -1656,16 +1656,20 @@ static int __xstate_request_perm(u64 permitted, u64 requested, bool guest) if ((permitted & requested) == requested) return 0; - /* Calculate the resulting kernel state size */ + /* + * Calculate the resulting kernel state size. Note, @permitted also + * contains supervisor xfeatures even though supervisor are always + * permitted for kernel and guest FPUs, and never permitted for user + * FPUs. + */ mask = permitted | requested; - /* Take supervisor states into account on the host */ - if (!guest) - mask |= xfeatures_mask_supervisor(); ksize = xstate_calculate_size(mask, compacted); - /* Calculate the resulting user state size */ - mask &= XFEATURE_MASK_USER_SUPPORTED; - usize = xstate_calculate_size(mask, false); + /* + * Calculate the resulting user state size. Take care not to clobber + * the supervisor xfeatures in the new mask! + */ + usize = xstate_calculate_size(mask & XFEATURE_MASK_USER_SUPPORTED, false); if (!guest) { ret = validate_sigaltstack(usize); |