1 files changed, 90 insertions, 43 deletions

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 87a57b7642d3..7d372db8bee1 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -405,12 +405,32 @@ static void __init print_xstate_offset_size(void)
 }
 
 /*
+ * All supported features have either init state all zeros or are
+ * handled in setup_init_fpu() individually. This is an explicit
+ * feature list and does not use XFEATURE_MASK*SUPPORTED to catch
+ * newly added supported features at build time and make people
+ * actually look at the init state for the new feature.
+ */
+#define XFEATURES_INIT_FPSTATE_HANDLED		\
+	(XFEATURE_MASK_FP |			\
+	 XFEATURE_MASK_SSE |			\
+	 XFEATURE_MASK_YMM |			\
+	 XFEATURE_MASK_OPMASK |			\
+	 XFEATURE_MASK_ZMM_Hi256 |		\
+	 XFEATURE_MASK_Hi16_ZMM	 |		\
+	 XFEATURE_MASK_PKRU |			\
+	 XFEATURE_MASK_BNDREGS |		\
+	 XFEATURE_MASK_BNDCSR)
+
+/*
  * setup the xstate image representing the init state
  */
 static void __init setup_init_fpu_buf(void)
 {
 	static int on_boot_cpu __initdata = 1;
 
+	BUILD_BUG_ON(XCNTXT_MASK != XFEATURES_INIT_FPSTATE_HANDLED);
+
 	WARN_ON_FPU(!on_boot_cpu);
 	on_boot_cpu = 0;
 
@@ -429,10 +449,22 @@ static void __init setup_init_fpu_buf(void)
 	copy_kernel_to_xregs_booting(&init_fpstate.xsave);
 
 	/*
-	 * Dump the init state again. This is to identify the init state
-	 * of any feature which is not represented by all zero's.
+	 * All components are now in init state. Read the state back so
+	 * that init_fpstate contains all non-zero init state. This only
+	 * works with XSAVE, but not with XSAVEOPT and XSAVES because
+	 * those use the init optimization which skips writing data for
+	 * components in init state.
+	 *
+	 * XSAVE could be used, but that would require to reshuffle the
+	 * data when XSAVES is available because XSAVES uses xstate
+	 * compaction. But doing so is a pointless exercise because most
+	 * components have an all zeros init state except for the legacy
+	 * ones (FP and SSE). Those can be saved with FXSAVE into the
+	 * legacy area. Adding new features requires to ensure that init
+	 * state is all zeroes or if not to add the necessary handling
+	 * here.
 	 */
-	copy_xregs_to_kernel_booting(&init_fpstate.xsave);
+	fxsave(&init_fpstate.fxsave);
 }
 
 static int xfeature_uncompacted_offset(int xfeature_nr)
@@ -907,8 +939,6 @@ const void *get_xsave_field_ptr(int xsave_state)
 
 #ifdef CONFIG_ARCH_HAS_PKEYS
 
-#define NR_VALID_PKRU_BITS (CONFIG_NR_PROTECTION_KEYS * 2)
-#define PKRU_VALID_MASK (NR_VALID_PKRU_BITS - 1)
 /*
  * This will go out and modify PKRU register to set the access
  * rights for @pkey to @init_val.
@@ -927,6 +957,13 @@ int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
 	if (!boot_cpu_has(X86_FEATURE_OSPKE))
 		return -EINVAL;
 
+	/*
+	 * This code should only be called with valid 'pkey'
+	 * values originating from in-kernel users.  Complain
+	 * if a bad value is observed.
+	 */
+	WARN_ON_ONCE(pkey >= arch_max_pkey());
+
 	/* Set the bits we need in PKRU:  */
 	if (init_val & PKEY_DISABLE_ACCESS)
 		new_pkru_bits |= PKRU_AD_BIT;
@@ -964,18 +1001,31 @@ static inline bool xfeatures_mxcsr_quirk(u64 xfeatures)
 	return true;
 }
 
-/*
- * This is similar to user_regset_copyout(), but will not add offset to
- * the source data pointer or increment pos, count, kbuf, and ubuf.
- */
-static inline void
-__copy_xstate_to_kernel(void *kbuf, const void *data,
-			unsigned int offset, unsigned int size, unsigned int size_total)
+static void fill_gap(unsigned to, void **kbuf, unsigned *pos, unsigned *count)
 {
-	if (offset < size_total) {
-		unsigned int copy = min(size, size_total - offset);
+	if (*pos < to) {
+		unsigned size = to - *pos;
+
+		if (size > *count)
+			size = *count;
+		memcpy(*kbuf, (void *)&init_fpstate.xsave + *pos, size);
+		*kbuf += size;
+		*pos += size;
+		*count -= size;
+	}
+}
 
-		memcpy(kbuf + offset, data, copy);
+static void copy_part(unsigned offset, unsigned size, void *from,
+			void **kbuf, unsigned *pos, unsigned *count)
+{
+	fill_gap(offset, kbuf, pos, count);
+	if (size > *count)
+		size = *count;
+	if (size) {
+		memcpy(*kbuf, from, size);
+		*kbuf += size;
+		*pos += size;
+		*count -= size;
 	}
 }
 
@@ -988,8 +1038,9 @@ __copy_xstate_to_kernel(void *kbuf, const void *data,
  */
 int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int offset_start, unsigned int size_total)
 {
-	unsigned int offset, size;
 	struct xstate_header header;
+	const unsigned off_mxcsr = offsetof(struct fxregs_state, mxcsr);
+	unsigned count = size_total;
 	int i;
 
 	/*
@@ -1005,46 +1056,42 @@ int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int of
 	header.xfeatures = xsave->header.xfeatures;
 	header.xfeatures &= ~XFEATURE_MASK_SUPERVISOR;
 
+	if (header.xfeatures & XFEATURE_MASK_FP)
+		copy_part(0, off_mxcsr,
+			  &xsave->i387, &kbuf, &offset_start, &count);
+	if (header.xfeatures & (XFEATURE_MASK_SSE | XFEATURE_MASK_YMM))
+		copy_part(off_mxcsr, MXCSR_AND_FLAGS_SIZE,
+			  &xsave->i387.mxcsr, &kbuf, &offset_start, &count);
+	if (header.xfeatures & XFEATURE_MASK_FP)
+		copy_part(offsetof(struct fxregs_state, st_space), 128,
+			  &xsave->i387.st_space, &kbuf, &offset_start, &count);
+	if (header.xfeatures & XFEATURE_MASK_SSE)
+		copy_part(xstate_offsets[XFEATURE_SSE], 256,
+			  &xsave->i387.xmm_space, &kbuf, &offset_start, &count);
+	/*
+	 * Fill xsave->i387.sw_reserved value for ptrace frame:
+	 */
+	copy_part(offsetof(struct fxregs_state, sw_reserved), 48,
+		  xstate_fx_sw_bytes, &kbuf, &offset_start, &count);
 	/*
 	 * Copy xregs_state->header:
 	 */
-	offset = offsetof(struct xregs_state, header);
-	size = sizeof(header);
-
-	__copy_xstate_to_kernel(kbuf, &header, offset, size, size_total);
+	copy_part(offsetof(struct xregs_state, header), sizeof(header),
+		  &header, &kbuf, &offset_start, &count);
 
-	for (i = 0; i < XFEATURE_MAX; i++) {
+	for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
 		/*
 		 * Copy only in-use xstates:
 		 */
 		if ((header.xfeatures >> i) & 1) {
 			void *src = __raw_xsave_addr(xsave, 1 << i);
 
-			offset = xstate_offsets[i];
-			size = xstate_sizes[i];
-
-			/* The next component has to fit fully into the output buffer: */
-			if (offset + size > size_total)
-				break;
-
-			__copy_xstate_to_kernel(kbuf, src, offset, size, size_total);
+			copy_part(xstate_offsets[i], xstate_sizes[i],
+				  src, &kbuf, &offset_start, &count);
 		}
 
 	}
-
-	if (xfeatures_mxcsr_quirk(header.xfeatures)) {
-		offset = offsetof(struct fxregs_state, mxcsr);
-		size = MXCSR_AND_FLAGS_SIZE;
-		__copy_xstate_to_kernel(kbuf, &xsave->i387.mxcsr, offset, size, size_total);
-	}
-
-	/*
-	 * Fill xsave->i387.sw_reserved value for ptrace frame:
-	 */
-	offset = offsetof(struct fxregs_state, sw_reserved);
-	size = sizeof(xstate_fx_sw_bytes);
-
-	__copy_xstate_to_kernel(kbuf, xstate_fx_sw_bytes, offset, size, size_total);
+	fill_gap(size_total, &kbuf, &offset_start, &count);
 
 	return 0;
 }