x86/fpu/state: Fix XSAVES issues - Part 1

index 38951b0..16df2c4 100644
@@ -39,7 +39,6 @@
 #define REX_PREFIX
 #endif
 
-extern unsigned int xstate_size;
 extern u64 xfeatures_mask;
 extern u64 xstate_fx_sw_bytes[USER_XSTATE_FX_SW_WORDS];
 

index 9264476..8d5df3f 100644
@@ -368,6 +368,7 @@ DECLARE_PER_CPU(struct irq_stack *, softirq_stack);
 #endif	/* X86_64 */
 
 extern unsigned int xstate_size;
+extern unsigned int fpu_user_xstate_size;
 
 struct perf_event;
 

index 54c86ff..824d422 100644
@@ -195,7 +195,7 @@ static void __init fpu__init_task_struct_size(void)
 }
 
 /*
- * Set up the xstate_size based on the legacy FPU context size.
+ * Set up the user and kernel xstate_size based on the legacy FPU context size.
  *
  * We set this up first, and later it will be overwritten by
  * fpu__init_system_xstate() if the CPU knows about xstates.

@@ -226,6 +226,9 @@ static void __init fpu__init_system_xstate_size_legacy(void)
 		else
 			xstate_size = sizeof(struct fregs_state);
 	}
+
+	fpu_user_xstate_size = xstate_size;
+
 	/*
 	 * Quirk: we don't yet handle the XSAVES* instructions
 	 * correctly, as we don't correctly convert between

index 31c6a60..23572a9 100644
@@ -31,7 +31,7 @@ static inline int check_for_xstate(struct fxregs_state __user *buf,
 	/* Check for the first magic field and other error scenarios. */
 	if (fx_sw->magic1 != FP_XSTATE_MAGIC1 ||
 	    fx_sw->xstate_size < min_xstate_size ||
-	    fx_sw->xstate_size > xstate_size ||
+	    fx_sw->xstate_size > fpu_user_xstate_size ||
 	    fx_sw->xstate_size > fx_sw->extended_size)
 		return -1;
 

@@ -88,7 +88,8 @@ static inline int save_xstate_epilog(void __user *buf, int ia32_frame)
 	if (!use_xsave())
 		return err;
 
-	err |= __put_user(FP_XSTATE_MAGIC2, (__u32 *)(buf + xstate_size));
+	err |= __put_user(FP_XSTATE_MAGIC2,
+			  (__u32 *)(buf + fpu_user_xstate_size));
 
 	/*
 	 * Read the xfeatures which we copied (directly from the cpu or

@@ -125,7 +126,7 @@ static inline int copy_fpregs_to_sigframe(struct xregs_state __user *buf)
 	else
 		err = copy_fregs_to_user((struct fregs_state __user *) buf);
 
-	if (unlikely(err) && __clear_user(buf, xstate_size))
+	if (unlikely(err) && __clear_user(buf, fpu_user_xstate_size))
 		err = -EFAULT;
 	return err;
 }

@@ -175,8 +176,19 @@ int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size)
 		if (ia32_fxstate)
 			copy_fxregs_to_kernel(&tsk->thread.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;
+		}
+
 		fpstate_sanitize_xstate(&tsk->thread.fpu);
-		if (__copy_to_user(buf_fx, xsave, xstate_size))
+		if (__copy_to_user(buf_fx, xsave, fpu_user_xstate_size))
 			return -1;
 	}
 

@@ -341,7 +353,8 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
 
 static inline int xstate_sigframe_size(void)
 {
-	return use_xsave() ? xstate_size + FP_XSTATE_MAGIC2_SIZE : xstate_size;
+	return use_xsave() ? fpu_user_xstate_size + FP_XSTATE_MAGIC2_SIZE :
+			fpu_user_xstate_size;
 }
 
 /*

@@ -385,12 +398,12 @@ fpu__alloc_mathframe(unsigned long sp, int ia32_frame,
  */
 void fpu__init_prepare_fx_sw_frame(void)
 {
-	int size = xstate_size + FP_XSTATE_MAGIC2_SIZE;
+	int size = fpu_user_xstate_size + FP_XSTATE_MAGIC2_SIZE;
 
 	fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1;
 	fx_sw_reserved.extended_size = size;
 	fx_sw_reserved.xfeatures = xfeatures_mask;
-	fx_sw_reserved.xstate_size = xstate_size;
+	fx_sw_reserved.xstate_size = fpu_user_xstate_size;
 
 	if (config_enabled(CONFIG_IA32_EMULATION) ||
 	    config_enabled(CONFIG_X86_32)) {

116 lines not on this page · raw message

index 8d5df3f..5fd59c6 100644
@@ -367,7 +367,7 @@ DECLARE_PER_CPU(struct irq_stack *, hardirq_stack);
 DECLARE_PER_CPU(struct irq_stack *, softirq_stack);
 #endif	/* X86_64 */
 
-extern unsigned int xstate_size;
+extern unsigned int fpu_kernel_xstate_size;
 extern unsigned int fpu_user_xstate_size;
 
 struct perf_event;

index 8e37cc8..dfd29ac 100644
@@ -222,7 +222,7 @@ void fpstate_init(union fpregs_state *state)
 		return;
 	}
 
-	memset(state, 0, xstate_size);
+	memset(state, 0, fpu_kernel_xstate_size);
 
 	if (cpu_has_fxsr)
 		fpstate_init_fxstate(&state->fxsave);

@@ -247,7 +247,7 @@ int fpu__copy(struct fpu *dst_fpu, struct fpu *src_fpu)
 	 * leak into the child task:
 	 */
 	if (use_eager_fpu())
-		memset(&dst_fpu->state.xsave, 0, xstate_size);
+		memset(&dst_fpu->state.xsave, 0, fpu_kernel_xstate_size);
 
 	/*
 	 * Save current FPU registers directly into the child

@@ -266,7 +266,8 @@ int fpu__copy(struct fpu *dst_fpu, struct fpu *src_fpu)
 	 */
 	preempt_disable();
 	if (!copy_fpregs_to_fpstate(dst_fpu)) {
-		memcpy(&src_fpu->state, &dst_fpu->state, xstate_size);
+		memcpy(&src_fpu->state, &dst_fpu->state,
+		       fpu_kernel_xstate_size);
 
 		if (use_eager_fpu())
 			copy_kernel_to_fpregs(&src_fpu->state);

index 824d422..eccc36b 100644
@@ -145,8 +145,8 @@ static void __init fpu__init_system_generic(void)
  * This is inherent to the XSAVE architecture which puts all state
  * components into a single, continuous memory block:
  */
-unsigned int xstate_size;
-EXPORT_SYMBOL_GPL(xstate_size);
+unsigned int fpu_kernel_xstate_size;
+EXPORT_SYMBOL_GPL(fpu_kernel_xstate_size);
 
 /* Get alignment of the TYPE. */
 #define TYPE_ALIGN(TYPE) offsetof(struct { char x; TYPE test; }, test)

@@ -178,7 +178,7 @@ static void __init fpu__init_task_struct_size(void)
 	 * Add back the dynamically-calculated register state
 	 * size.
 	 */
-	task_size += xstate_size;
+	task_size += fpu_kernel_xstate_size;
 
 	/*
 	 * We dynamically size 'struct fpu', so we require that

@@ -195,7 +195,7 @@ static void __init fpu__init_task_struct_size(void)
 }
 
 /*
- * Set up the user and kernel xstate_size based on the legacy FPU context size.
+ * Set up the user and kernel xstate sizes based on the legacy FPU context size.
  *
  * We set this up first, and later it will be overwritten by
  * fpu__init_system_xstate() if the CPU knows about xstates.

@@ -208,7 +208,7 @@ static void __init fpu__init_system_xstate_size_legacy(void)
 	on_boot_cpu = 0;
 
 	/*
-	 * Note that xstate_size might be overwriten later during
+	 * Note that xstate sizes might be overwritten later during
 	 * fpu__init_system_xstate().
 	 */
 

@@ -219,15 +219,17 @@ static void __init fpu__init_system_xstate_size_legacy(void)
 		 */
 		setup_clear_cpu_cap(X86_FEATURE_XSAVE);
 		setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT);
-		xstate_size = sizeof(struct swregs_state);
+		fpu_kernel_xstate_size = sizeof(struct swregs_state);
 	} else {
 		if (cpu_has_fxsr)
-			xstate_size = sizeof(struct fxregs_state);
+			fpu_kernel_xstate_size =
+				sizeof(struct fxregs_state);
 		else
-			xstate_size = sizeof(struct fregs_state);
+			fpu_kernel_xstate_size =
+				sizeof(struct fregs_state);
 	}
 
-	fpu_user_xstate_size = xstate_size;
+	fpu_user_xstate_size = fpu_kernel_xstate_size;
 
 	/*
 	 * Quirk: we don't yet handle the XSAVES* instructions

index 23572a9..1454989 100644
@@ -262,7 +262,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
 	int ia32_fxstate = (buf != buf_fx);
 	struct task_struct *tsk = current;
 	struct fpu *fpu = &tsk->thread.fpu;
-	int state_size = xstate_size;
+	int state_size = fpu_kernel_xstate_size;
 	u64 xfeatures = 0;
 	int fx_only = 0;
 

index dfac87d..875afe9 100644
@@ -537,7 +537,7 @@ static void do_extra_xstate_size_checks(void)
 		 */
 		paranoid_xstate_size += xfeature_size(i);
 	}
-	XSTATE_WARN_ON(paranoid_xstate_size != xstate_size);
+	XSTATE_WARN_ON(paranoid_xstate_size != fpu_kernel_xstate_size);
 }
 
 

@@ -616,7 +616,7 @@ static int init_xstate_size(void)
 	 * The size is OK, we are definitely going to use xsave,
 	 * make it known to the world that we need more space.
 	 */
-	xstate_size = possible_xstate_size;
+	fpu_kernel_xstate_size = possible_xstate_size;
 	do_extra_xstate_size_checks();
 
 	/*

@@ -679,14 +679,14 @@ void __init fpu__init_system_xstate(void)
 		return;
 	}
 
-	update_regset_xstate_info(xstate_size, xfeatures_mask);
+	update_regset_xstate_info(fpu_kernel_xstate_size, xfeatures_mask);
 	fpu__init_prepare_fx_sw_frame();
 	setup_init_fpu_buf();
 	setup_xstate_comp();
 
 	pr_info("x86/fpu: Enabled xstate features 0x%llx, context size is %d bytes, using '%s' format.\n",
 		xfeatures_mask,
-		xstate_size,
+		fpu_kernel_xstate_size,
 		cpu_has_xsaves ? "compacted" : "standard");
 }
 

index 875afe9..5239d4d 100644
@@ -329,13 +329,11 @@ static void __init setup_init_fpu_buf(void)
 	setup_xstate_features();
 	print_xstate_features();
 
-	if (cpu_has_xsaves) {
+	if (cpu_has_xsaves)
 		init_fpstate.xsave.header.xcomp_bv = (u64)1 << 63 | xfeatures_mask;
-		init_fpstate.xsave.header.xfeatures = xfeatures_mask;
-	}
 
 	/*
-	 * Init all the features state with header_bv being 0x0
+	 * Init all the features state with header.xfeatures being 0x0
 	 */
 	copy_kernel_to_xregs_booting(&init_fpstate.xsave);
 

index 16df2c4..d812cf3 100644
@@ -47,5 +47,6 @@ extern void update_regset_xstate_info(unsigned int size, u64 xstate_mask);
 void fpu__xstate_clear_all_cpu_caps(void);
 void *get_xsave_addr(struct xregs_state *xsave, int xstate);
 const void *get_xsave_field_ptr(int xstate_field);
+int using_compacted_format(void);
 
 #endif

index 1454989..9ce2963 100644
@@ -8,6 +8,7 @@
 #include <asm/fpu/internal.h>
 #include <asm/fpu/signal.h>
 #include <asm/fpu/regset.h>
+#include <asm/fpu/xstate.h>
 
 #include <asm/sigframe.h>
 

@@ -168,7 +169,7 @@ int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size)
 			sizeof(struct user_i387_ia32_struct), NULL,
 			(struct _fpstate_32 __user *) buf) ? -1 : 1;
 
-	if (fpregs_active()) {
+	if (fpregs_active() || using_compacted_format()) {
 		/* Save the live register state to the user directly. */
 		if (copy_fpregs_to_sigframe(buf_fx))
 			return -1;

index 5239d4d..e00ec6a 100644
@@ -420,7 +420,7 @@ static int xfeature_size(int xfeature_nr)
  * that it is obvious which aspect of 'XSAVES' is being handled
  * by the calling code.
  */
-static int using_compacted_format(void)
+int using_compacted_format(void)
 {
 	return cpu_has_xsaves;
 }