Update Linux to v5.4.2
Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c
index d99a8ee..0071b79 100644
--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -5,6 +5,7 @@
#include <linux/compat.h>
#include <linux/cpu.h>
+#include <linux/pagemap.h>
#include <asm/fpu/internal.h>
#include <asm/fpu/signal.h>
@@ -61,6 +62,11 @@
struct user_i387_ia32_struct env;
struct _fpstate_32 __user *fp = buf;
+ fpregs_lock();
+ if (!test_thread_flag(TIF_NEED_FPU_LOAD))
+ copy_fxregs_to_kernel(&tsk->thread.fpu);
+ fpregs_unlock();
+
convert_from_fxsr(&env, tsk);
if (__copy_to_user(buf, &env, sizeof(env)) ||
@@ -92,13 +98,13 @@
return err;
err |= __put_user(FP_XSTATE_MAGIC2,
- (__u32 *)(buf + fpu_user_xstate_size));
+ (__u32 __user *)(buf + fpu_user_xstate_size));
/*
* Read the xfeatures which we copied (directly from the cpu or
* from the state in task struct) to the user buffers.
*/
- err |= __get_user(xfeatures, (__u32 *)&x->header.xfeatures);
+ err |= __get_user(xfeatures, (__u32 __user *)&x->header.xfeatures);
/*
* For legacy compatible, we always set FP/SSE bits in the bit
@@ -113,7 +119,7 @@
*/
xfeatures |= XFEATURE_MASK_FPSSE;
- err |= __put_user(xfeatures, (__u32 *)&x->header.xfeatures);
+ err |= __put_user(xfeatures, (__u32 __user *)&x->header.xfeatures);
return err;
}
@@ -144,9 +150,10 @@
* buf == buf_fx for 64-bit frames and 32-bit fsave frame.
* buf != buf_fx for 32-bit frames with fxstate.
*
- * If the fpu, extended register state is live, save the state directly
- * to the user frame pointed by the aligned pointer 'buf_fx'. Otherwise,
- * copy the thread's fpu state to the user frame starting at 'buf_fx'.
+ * Try to save it directly to the user frame with disabled page fault handler.
+ * If this fails then do the slow path where the FPU state is first saved to
+ * task's fpu->state and then copy it to the user frame pointed to by the
+ * aligned pointer 'buf_fx'.
*
* If this is a 32-bit frame with fxstate, put a fsave header before
* the aligned state at 'buf_fx'.
@@ -156,15 +163,14 @@
*/
int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size)
{
- struct fpu *fpu = ¤t->thread.fpu;
- struct xregs_state *xsave = &fpu->state.xsave;
struct task_struct *tsk = current;
int ia32_fxstate = (buf != buf_fx);
+ int ret;
ia32_fxstate &= (IS_ENABLED(CONFIG_X86_32) ||
IS_ENABLED(CONFIG_IA32_EMULATION));
- if (!access_ok(VERIFY_WRITE, buf, size))
+ if (!access_ok(buf, size))
return -EACCES;
if (!static_cpu_has(X86_FEATURE_FPU))
@@ -172,28 +178,26 @@
sizeof(struct user_i387_ia32_struct), NULL,
(struct _fpstate_32 __user *) buf) ? -1 : 1;
- if (fpu->initialized || using_compacted_format()) {
- /* Save the live register state to the user directly. */
- if (copy_fpregs_to_sigframe(buf_fx))
- return -1;
- /* Update the thread's fxstate to save the fsave header. */
- if (ia32_fxstate)
- copy_fxregs_to_kernel(fpu);
- } else {
- /*
- * It is a *bug* if kernel uses compacted-format for xsave
- * area and we copy it out directly to a signal frame. It
- * should have been handled above by saving the registers
- * directly.
- */
- if (boot_cpu_has(X86_FEATURE_XSAVES)) {
- WARN_ONCE(1, "x86/fpu: saving compacted-format xsave area to a signal frame!\n");
- return -1;
- }
+retry:
+ /*
+ * Load the FPU registers if they are not valid for the current task.
+ * With a valid FPU state we can attempt to save the state directly to
+ * userland's stack frame which will likely succeed. If it does not,
+ * resolve the fault in the user memory and try again.
+ */
+ fpregs_lock();
+ if (test_thread_flag(TIF_NEED_FPU_LOAD))
+ __fpregs_load_activate();
- fpstate_sanitize_xstate(fpu);
- if (__copy_to_user(buf_fx, xsave, fpu_user_xstate_size))
- return -1;
+ pagefault_disable();
+ ret = copy_fpregs_to_sigframe(buf_fx);
+ pagefault_enable();
+ fpregs_unlock();
+
+ if (ret) {
+ if (!fault_in_pages_writeable(buf_fx, fpu_user_xstate_size))
+ goto retry;
+ return -EFAULT;
}
/* Save the fsave header for the 32-bit frames. */
@@ -207,11 +211,11 @@
}
static inline void
-sanitize_restored_xstate(struct task_struct *tsk,
+sanitize_restored_xstate(union fpregs_state *state,
struct user_i387_ia32_struct *ia32_env,
u64 xfeatures, int fx_only)
{
- struct xregs_state *xsave = &tsk->thread.fpu.state.xsave;
+ struct xregs_state *xsave = &state->xsave;
struct xstate_header *header = &xsave->header;
if (use_xsave()) {
@@ -238,17 +242,18 @@
*/
xsave->i387.mxcsr &= mxcsr_feature_mask;
- convert_to_fxsr(tsk, ia32_env);
+ if (ia32_env)
+ convert_to_fxsr(&state->fxsave, ia32_env);
}
}
/*
* Restore the extended state if present. Otherwise, restore the FP/SSE state.
*/
-static inline int copy_user_to_fpregs_zeroing(void __user *buf, u64 xbv, int fx_only)
+static int copy_user_to_fpregs_zeroing(void __user *buf, u64 xbv, int fx_only)
{
if (use_xsave()) {
- if ((unsigned long)buf % 64 || fx_only) {
+ if (fx_only) {
u64 init_bv = xfeatures_mask & ~XFEATURE_MASK_FPSSE;
copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
return copy_user_to_fxregs(buf);
@@ -266,12 +271,15 @@
static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
{
+ struct user_i387_ia32_struct *envp = NULL;
+ int state_size = fpu_kernel_xstate_size;
int ia32_fxstate = (buf != buf_fx);
struct task_struct *tsk = current;
struct fpu *fpu = &tsk->thread.fpu;
- int state_size = fpu_kernel_xstate_size;
+ struct user_i387_ia32_struct env;
u64 xfeatures = 0;
int fx_only = 0;
+ int ret = 0;
ia32_fxstate &= (IS_ENABLED(CONFIG_X86_32) ||
IS_ENABLED(CONFIG_IA32_EMULATION));
@@ -281,11 +289,9 @@
return 0;
}
- if (!access_ok(VERIFY_READ, buf, size))
+ if (!access_ok(buf, size))
return -EACCES;
- fpu__initialize(fpu);
-
if (!static_cpu_has(X86_FEATURE_FPU))
return fpregs_soft_set(current, NULL,
0, sizeof(struct user_i387_ia32_struct),
@@ -308,61 +314,101 @@
}
}
+ /*
+ * The current state of the FPU registers does not matter. By setting
+ * TIF_NEED_FPU_LOAD unconditionally it is ensured that the 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
+ * the optimisation).
+ */
+ set_thread_flag(TIF_NEED_FPU_LOAD);
+ __fpu_invalidate_fpregs_state(fpu);
+
+ if ((unsigned long)buf_fx % 64)
+ fx_only = 1;
+ /*
+ * For 32-bit frames with fxstate, copy the fxstate so it can be
+ * reconstructed later.
+ */
if (ia32_fxstate) {
- /*
- * For 32-bit frames with fxstate, copy the user state to the
- * thread's fpu state, reconstruct fxstate from the fsave
- * header. Validate and sanitize the copied state.
- */
- struct user_i387_ia32_struct env;
- int err = 0;
-
- /*
- * Drop the current fpu which clears fpu->initialized. This ensures
- * that any context-switch during the copy of the new state,
- * avoids the intermediate state from getting restored/saved.
- * Thus avoiding the new restored state from getting corrupted.
- * We will be ready to restore/save the state only after
- * fpu->initialized is again set.
- */
- fpu__drop(fpu);
-
- if (using_compacted_format()) {
- err = copy_user_to_xstate(&fpu->state.xsave, buf_fx);
- } else {
- err = __copy_from_user(&fpu->state.xsave, buf_fx, state_size);
-
- if (!err && state_size > offsetof(struct xregs_state, header))
- err = validate_xstate_header(&fpu->state.xsave.header);
- }
-
- if (err || __copy_from_user(&env, buf, sizeof(env))) {
- fpstate_init(&fpu->state);
- trace_x86_fpu_init_state(fpu);
- err = -1;
- } else {
- sanitize_restored_xstate(tsk, &env, xfeatures, fx_only);
- }
-
- local_bh_disable();
- fpu->initialized = 1;
- fpu__restore(fpu);
- local_bh_enable();
-
- return err;
+ ret = __copy_from_user(&env, buf, sizeof(env));
+ if (ret)
+ goto err_out;
+ envp = &env;
} else {
/*
- * For 64-bit frames and 32-bit fsave frames, restore the user
- * state to the registers directly (with exceptions handled).
+ * Attempt to restore the FPU registers directly from user
+ * memory. For that to succeed, the user access cannot cause
+ * page faults. If it does, fall back to the slow path below,
+ * going through the kernel buffer with the enabled pagefault
+ * handler.
*/
- user_fpu_begin();
- if (copy_user_to_fpregs_zeroing(buf_fx, xfeatures, fx_only)) {
- fpu__clear(fpu);
- return -1;
+ fpregs_lock();
+ pagefault_disable();
+ ret = copy_user_to_fpregs_zeroing(buf_fx, xfeatures, fx_only);
+ pagefault_enable();
+ if (!ret) {
+ fpregs_mark_activate();
+ fpregs_unlock();
+ return 0;
}
+ fpregs_unlock();
}
- return 0;
+
+ if (use_xsave() && !fx_only) {
+ u64 init_bv = xfeatures_mask & ~xfeatures;
+
+ if (using_compacted_format()) {
+ ret = copy_user_to_xstate(&fpu->state.xsave, buf_fx);
+ } else {
+ ret = __copy_from_user(&fpu->state.xsave, buf_fx, state_size);
+
+ if (!ret && state_size > offsetof(struct xregs_state, header))
+ ret = validate_xstate_header(&fpu->state.xsave.header);
+ }
+ if (ret)
+ goto err_out;
+
+ sanitize_restored_xstate(&fpu->state, envp, xfeatures, fx_only);
+
+ fpregs_lock();
+ if (unlikely(init_bv))
+ copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
+ ret = copy_kernel_to_xregs_err(&fpu->state.xsave, xfeatures);
+
+ } else if (use_fxsr()) {
+ ret = __copy_from_user(&fpu->state.fxsave, buf_fx, state_size);
+ if (ret) {
+ ret = -EFAULT;
+ goto err_out;
+ }
+
+ sanitize_restored_xstate(&fpu->state, envp, xfeatures, fx_only);
+
+ fpregs_lock();
+ if (use_xsave()) {
+ u64 init_bv = xfeatures_mask & ~XFEATURE_MASK_FPSSE;
+ copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
+ }
+
+ ret = copy_kernel_to_fxregs_err(&fpu->state.fxsave);
+ } else {
+ ret = __copy_from_user(&fpu->state.fsave, buf_fx, state_size);
+ if (ret)
+ goto err_out;
+
+ fpregs_lock();
+ ret = copy_kernel_to_fregs_err(&fpu->state.fsave);
+ }
+ if (!ret)
+ fpregs_mark_activate();
+ fpregs_unlock();
+
+err_out:
+ if (ret)
+ fpu__clear(fpu);
+ return ret;
}
static inline int xstate_sigframe_size(void)