diff options
Diffstat (limited to 'arch/x86/kernel')
| -rw-r--r-- | arch/x86/kernel/fpu/signal.c | 67 |
1 files changed, 33 insertions, 34 deletions
diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c index aa268d9cf228..4c252d0c8e6a 100644 --- a/arch/x86/kernel/fpu/signal.c +++ b/arch/x86/kernel/fpu/signal.c @@ -272,11 +272,17 @@ static int __restore_fpregs_from_user(void __user *buf, u64 xrestore, } } -static int restore_fpregs_from_user(void __user *buf, u64 xrestore, bool fx_only) +/* + * Attempt to restore the FPU registers directly from user memory. + * Pagefaults are handled and any errors returned are fatal. + */ +static int restore_fpregs_from_user(void __user *buf, u64 xrestore, + bool fx_only, unsigned int size) { struct fpu *fpu = ¤t->thread.fpu; int ret; +retry: fpregs_lock(); pagefault_disable(); ret = __restore_fpregs_from_user(buf, xrestore, fx_only); @@ -293,14 +299,18 @@ static int restore_fpregs_from_user(void __user *buf, u64 xrestore, bool fx_only * invalidate the FPU register state otherwise the task * might preempt current and return to user space with * corrupted FPU registers. - * - * In case current owns the FPU registers then no further - * action is required. The fixup in the slow path will - * handle it correctly. */ if (test_thread_flag(TIF_NEED_FPU_LOAD)) __cpu_invalidate_fpregs_state(); fpregs_unlock(); + + /* Try to handle #PF, but anything else is fatal. */ + if (ret != -EFAULT) + return -EINVAL; + + ret = fault_in_pages_readable(buf, size); + if (!ret) + goto retry; return ret; } @@ -311,9 +321,7 @@ static int restore_fpregs_from_user(void __user *buf, u64 xrestore, bool fx_only * * It would be optimal to handle this with a single XRSTORS, but * this does not work because the rest of the FPU registers have - * been restored from a user buffer directly. The single XRSTORS - * happens below, when the user buffer has been copied to the - * kernel one. + * been restored from a user buffer directly. */ if (test_thread_flag(TIF_NEED_FPU_LOAD) && xfeatures_mask_supervisor()) os_xrstor(&fpu->state.xsave, xfeatures_mask_supervisor()); @@ -326,14 +334,13 @@ static int restore_fpregs_from_user(void __user *buf, u64 xrestore, bool fx_only static int __fpu_restore_sig(void __user *buf, void __user *buf_fx, bool ia32_fxstate) { - struct user_i387_ia32_struct *envp = NULL; int state_size = fpu_kernel_xstate_size; struct task_struct *tsk = current; struct fpu *fpu = &tsk->thread.fpu; struct user_i387_ia32_struct env; u64 user_xfeatures = 0; bool fx_only = false; - int ret = 0; + int ret; if (use_xsave()) { struct _fpx_sw_bytes fx_sw_user; @@ -354,21 +361,20 @@ static int __fpu_restore_sig(void __user *buf, void __user *buf_fx, * faults. If it does, fall back to the slow path below, going * through the kernel buffer with the enabled pagefault handler. */ - ret = restore_fpregs_from_user(buf_fx, user_xfeatures, fx_only); - if (likely(!ret)) - return 0; - } else { - /* - * For 32-bit frames with fxstate, copy the fxstate so it can - * be reconstructed later. - */ - ret = __copy_from_user(&env, buf, sizeof(env)); - if (ret) - return ret; - envp = &env; + return restore_fpregs_from_user(buf_fx, user_xfeatures, fx_only, + state_size); } /* + * Copy the legacy state because the FP portion of the FX frame has + * to be ignored for histerical raisins. The legacy state is folded + * in once the larger state has been copied. + */ + ret = __copy_from_user(&env, buf, sizeof(env)); + if (ret) + return ret; + + /* * By setting TIF_NEED_FPU_LOAD it is ensured that our xstate is * not modified on context switch and that the xstate is considered * to be loaded again on return to userland (overriding last_cpu avoids @@ -382,8 +388,7 @@ static int __fpu_restore_sig(void __user *buf, void __user *buf_fx, * supervisor state is preserved. Save the full state for * simplicity. There is no point in optimizing this by only * saving the supervisor states and then shuffle them to - * the right place in memory. This is the slow path and the - * above XRSTOR failed or ia32_fxstate is true. Shrug. + * the right place in memory. It's ia32 mode. Shrug. */ if (xfeatures_mask_supervisor()) os_xsave(&fpu->state.xsave); @@ -399,7 +404,7 @@ static int __fpu_restore_sig(void __user *buf, void __user *buf_fx, if (ret) return ret; - sanitize_restored_user_xstate(&fpu->state, envp, user_xfeatures); + sanitize_restored_user_xstate(&fpu->state, &env, user_xfeatures); fpregs_lock(); if (unlikely(init_bv)) @@ -412,12 +417,12 @@ static int __fpu_restore_sig(void __user *buf, void __user *buf_fx, ret = os_xrstor_safe(&fpu->state.xsave, user_xfeatures | xfeatures_mask_supervisor()); - } else if (use_fxsr()) { + } else { ret = __copy_from_user(&fpu->state.fxsave, buf_fx, state_size); if (ret) return -EFAULT; - sanitize_restored_user_xstate(&fpu->state, envp, user_xfeatures); + sanitize_restored_user_xstate(&fpu->state, &env, user_xfeatures); fpregs_lock(); if (use_xsave()) { @@ -428,14 +433,8 @@ static int __fpu_restore_sig(void __user *buf, void __user *buf_fx, } ret = fxrstor_safe(&fpu->state.fxsave); - } else { - ret = __copy_from_user(&fpu->state.fsave, buf_fx, state_size); - if (ret) - return ret; - - fpregs_lock(); - ret = frstor_safe(&fpu->state.fsave); } + if (!ret) fpregs_mark_activate(); else |