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From: "Chang S. Bae" <chang.seok.bae@intel.com>
To: bp@suse.de, luto@kernel.org, tglx@linutronix.de,
	mingo@kernel.org, x86@kernel.org
Cc: len.brown@intel.com, dave.hansen@intel.com, jing2.liu@intel.com,
	ravi.v.shankar@intel.com, linux-kernel@vger.kernel.org,
	chang.seok.bae@intel.com
Subject: [PATCH v5 13/28] x86/fpu/xstate: Update the xstate context copy function to support dynamic states
Date: Sun, 23 May 2021 12:32:44 -0700	[thread overview]
Message-ID: <20210523193259.26200-14-chang.seok.bae@intel.com> (raw)
In-Reply-To: <20210523193259.26200-1-chang.seok.bae@intel.com>

ptrace() and signal return paths use xstate context copy functions. They
allow callers to read (or write) xstate values in the target's buffer. With
dynamic user states, a component's position in the buffer may vary and the
initial value is not always stored in init_fpstate.

Change the helpers to find a component's offset accordingly.

When copying an initial value, explicitly check the init_fpstate coverage.
If not found, reset the memory in the destination. Otherwise, copy values
from init_fpstate.

Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Reviewed-by: Len Brown <len.brown@intel.com>
Cc: x86@kernel.org
Cc: linux-kernel@vger.kernel.org
---
Changes from v3:
* Cleaned up the code change with more comments.
* Removed 'no functional change' in the changelog. (Borislav Petkov)

Changes from v2:
* Updated the changelog with task->fpu removed. (Borislav Petkov)
---
 arch/x86/kernel/fpu/xstate.c | 69 ++++++++++++++++++++++++++++--------
 1 file changed, 55 insertions(+), 14 deletions(-)

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 9d3cd9775b76..299373669a5d 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -301,7 +301,7 @@ void fpstate_sanitize_xstate(struct fpu *fpu)
 	 * in a special way already:
 	 */
 	feature_bit = 0x2;
-	xfeatures = (xfeatures_mask_user() & ~xfeatures) >> 2;
+	xfeatures = (xfeatures_mask_user() & fpu->state_mask & ~xfeatures) >> feature_bit;
 
 	/*
 	 * Update all the remaining memory layouts according to their
@@ -310,12 +310,19 @@ void fpstate_sanitize_xstate(struct fpu *fpu)
 	 */
 	while (xfeatures) {
 		if (xfeatures & 0x1) {
-			int offset = xstate_comp_offsets[feature_bit];
+			int offset = get_xstate_comp_offset(fpu->state_mask, feature_bit);
 			int size = xstate_sizes[feature_bit];
 
-			memcpy((void *)fx + offset,
-			       (void *)&init_fpstate.xsave + offset,
-			       size);
+			/*
+			 * init_fpstate does not include the dynamic user states
+			 * as having initial values with zeros.
+			 */
+			if (xfeatures_mask_user_dynamic & BIT_ULL(feature_bit))
+				memset((void *)fx + offset, 0, size);
+			else
+				memcpy((void *)fx + offset,
+				       (void *)&init_fpstate.xsave + offset,
+				       size);
 		}
 
 		xfeatures >>= 1;
@@ -1297,15 +1304,31 @@ static void fill_gap(struct membuf *to, unsigned *last, unsigned offset)
 {
 	if (*last >= offset)
 		return;
-	membuf_write(to, (void *)&init_fpstate.xsave + *last, offset - *last);
+
+	/*
+	 * Copy initial data.
+	 *
+	 * init_fpstate buffer has the minimum size as excluding the dynamic user
+	 * states. But their initial values are zeros.
+	 */
+	if (offset <= get_xstate_config(XSTATE_MIN_SIZE))
+		membuf_write(to, (void *)&init_fpstate.xsave + *last, offset - *last);
+	else
+		membuf_zero(to, offset - *last);
 	*last = offset;
 }
 
+/*
+ * @from: If NULL, copy zeros.
+ */
 static void copy_part(struct membuf *to, unsigned *last, unsigned offset,
 		      unsigned size, void *from)
 {
 	fill_gap(to, last, offset);
-	membuf_write(to, from, size);
+	if (from)
+		membuf_write(to, from, size);
+	else
+		membuf_zero(to, size);
 	*last = offset + size;
 }
 
@@ -1357,15 +1380,27 @@ void copy_xstate_to_kernel(struct membuf to, struct fpu *fpu)
 		  sizeof(header), &header);
 
 	for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
+		u64 mask = BIT_ULL(i);
+		void *src;
+
+		if (!(xfeatures_mask_user() & mask))
+			continue;
+
 		/*
-		 * Copy only in-use xstates:
+		 * Copy states if used. Otherwise, copy the initial data.
 		 */
-		if ((header.xfeatures >> i) & 1) {
-			void *src = __raw_xsave_addr(fpu, i);
 
-			copy_part(&to, &last, xstate_offsets[i],
-				  xstate_sizes[i], src);
-		}
+		if (header.xfeatures & mask)
+			src = __raw_xsave_addr(fpu, i);
+		else
+			/*
+			 * init_fpstate buffer does not include the dynamic
+			 * user state data as having initial values with zeros.
+			 */
+			src = (xfeatures_mask_user_dynamic & mask) ?
+			      NULL : (void *)&init_fpstate.xsave + last;
+
+		copy_part(&to, &last, xstate_offsets[i], xstate_sizes[i], src);
 
 	}
 	fill_gap(&to, &last, size);
@@ -1398,6 +1433,9 @@ int copy_kernel_to_xstate(struct fpu *fpu, const void *kbuf)
 		if (hdr.xfeatures & mask) {
 			void *dst = __raw_xsave_addr(fpu, i);
 
+			if (!dst)
+				continue;
+
 			offset = xstate_offsets[i];
 			size = xstate_sizes[i];
 
@@ -1455,6 +1493,9 @@ int copy_user_to_xstate(struct fpu *fpu, const void __user *ubuf)
 		if (hdr.xfeatures & mask) {
 			void *dst = __raw_xsave_addr(fpu, i);
 
+			if (!dst)
+				continue;
+
 			offset = xstate_offsets[i];
 			size = xstate_sizes[i];
 
@@ -1535,7 +1576,7 @@ void copy_supervisor_to_kernel(struct fpu *fpu)
 			continue;
 
 		/* Move xfeature 'i' into its normal location */
-		memmove(xbuf + xstate_comp_offsets[i],
+		memmove(xbuf + get_xstate_comp_offset(fpu->state_mask, i),
 			xbuf + xstate_supervisor_only_offsets[i],
 			xstate_sizes[i]);
 	}
-- 
2.17.1


  parent reply	other threads:[~2021-05-23 19:39 UTC|newest]

Thread overview: 75+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-23 19:32 [PATCH v5 00/28] x86: Support Intel Advanced Matrix Extensions Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 01/28] x86/fpu/xstate: Modify the initialization helper to handle both static and dynamic buffers Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 02/28] x86/fpu/xstate: Modify state copy helpers " Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 03/28] x86/fpu/xstate: Modify address finders " Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 04/28] x86/fpu/xstate: Modify the context restore helper " Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 05/28] x86/fpu/xstate: Add a new variable to indicate dynamic user states Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 06/28] x86/fpu/xstate: Add new variables to indicate dynamic xstate buffer size Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 07/28] x86/fpu/xstate: Calculate and remember dynamic xstate buffer sizes Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 08/28] x86/fpu/xstate: Convert the struct fpu 'state' field to a pointer Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 09/28] x86/fpu/xstate: Introduce helpers to manage the xstate buffer dynamically Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 10/28] x86/fpu/xstate: Define the scope of the initial xstate data Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 11/28] x86/fpu/xstate: Update the xstate save function to support dynamic states Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 12/28] x86/fpu/xstate: Update the xstate buffer address finder " Chang S. Bae
2021-05-23 19:32 ` Chang S. Bae [this message]
2021-05-23 19:32 ` [PATCH v5 14/28] x86/fpu/xstate: Prevent unauthorised use of dynamic user state Chang S. Bae
2021-06-16 16:17   ` Dave Hansen
2021-06-16 16:27   ` Dave Hansen
2021-06-16 18:12     ` Andy Lutomirski
2021-06-16 18:47       ` Bae, Chang Seok
2021-06-16 19:01         ` Dave Hansen
2021-06-16 19:23           ` Bae, Chang Seok
2021-06-16 19:28             ` Dave Hansen
2021-06-16 19:37               ` Bae, Chang Seok
2021-06-28 10:11               ` Liu, Jing2
2021-06-29 17:43           ` Bae, Chang Seok
2021-06-29 17:54             ` Dave Hansen
2021-06-29 18:35               ` Bae, Chang Seok
2021-06-29 18:50                 ` Dave Hansen
2021-06-29 19:13                   ` Bae, Chang Seok
2021-06-29 19:26                     ` Dave Hansen
2021-05-23 19:32 ` [PATCH v5 15/28] x86/arch_prctl: Create ARCH_GET_XSTATE/ARCH_PUT_XSTATE Chang S. Bae
2021-05-24 23:10   ` Len Brown
2021-05-25 17:27     ` Borislav Petkov
2021-05-25 17:33       ` Dave Hansen
2021-05-26  0:38     ` Len Brown
2021-05-27 11:14       ` second, sync-alloc syscall Borislav Petkov
2021-05-27 13:59         ` Len Brown
2021-05-27 19:35           ` Andy Lutomirski
2021-05-25 15:46   ` [PATCH v5 15/28] x86/arch_prctl: Create ARCH_GET_XSTATE/ARCH_PUT_XSTATE Dave Hansen
2021-05-23 19:32 ` [PATCH v5 16/28] x86/fpu/xstate: Support ptracer-induced xstate buffer expansion Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 17/28] x86/fpu/xstate: Adjust the XSAVE feature table to address gaps in state component numbers Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 18/28] x86/fpu/xstate: Disable xstate support if an inconsistent state is detected Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 19/28] x86/cpufeatures/amx: Enumerate Advanced Matrix Extension (AMX) feature bits Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 20/28] x86/fpu/amx: Define AMX state components and have it used for boot-time checks Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 21/28] x86/fpu/amx: Initialize child's AMX state Chang S. Bae
2021-05-24  3:09   ` Andy Lutomirski
2021-05-24 17:37     ` Len Brown
2021-05-24 18:13       ` Andy Lutomirski
2021-05-24 18:21         ` Len Brown
2021-05-25  3:44           ` Andy Lutomirski
2021-05-23 19:32 ` [PATCH v5 22/28] x86/fpu/amx: Enable the AMX feature in 64-bit mode Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 23/28] selftest/x86/amx: Test cases for the AMX state management Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 24/28] x86/fpu/xstate: Use per-task xstate mask for saving xstate in signal frame Chang S. Bae
2021-05-24  3:15   ` Andy Lutomirski
2021-05-24 18:06     ` Len Brown
2021-05-25  4:47       ` Andy Lutomirski
2021-05-25 14:04         ` Len Brown
2021-05-23 19:32 ` [PATCH v5 25/28] x86/fpu/xstate: Skip writing zeros to signal frame for dynamic user states if in INIT-state Chang S. Bae
2021-05-24  3:25   ` Andy Lutomirski
2021-05-24 18:15     ` Len Brown
2021-05-24 18:29       ` Dave Hansen
2021-05-25  4:46       ` Andy Lutomirski
2021-05-23 19:32 ` [PATCH v5 26/28] selftest/x86/amx: Test case for AMX state copy optimization in signal delivery Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 27/28] x86/insn/amx: Add TILERELEASE instruction to the opcode map Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 28/28] x86/fpu/amx: Clear the AMX state when appropriate Chang S. Bae
2021-05-24  3:13   ` Andy Lutomirski
2021-05-24 14:10     ` Dave Hansen
2021-05-24 17:32       ` Len Brown
2021-05-24 17:39         ` Dave Hansen
2021-05-24 18:24           ` Len Brown
2021-05-27 11:56             ` Peter Zijlstra
2021-05-27 14:02               ` Len Brown
2021-05-24 14:06   ` Dave Hansen
2021-05-24 17:34     ` Len Brown
2021-05-24 21:11       ` [PATCH v5-fix " Chang S. Bae

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