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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 v6 11/26] x86/fpu/xstate: Update the XSTATE context copy function to support dynamic states
Date: Tue, 29 Jun 2021 23:02:11 -0700	[thread overview]
Message-ID: <20210630060226.24652-12-chang.seok.bae@intel.com> (raw)
In-Reply-To: <20210630060226.24652-1-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
init fpstate is not always large enough to cover all the states.

Adjust the helpers to find a component's offset correctly. Also, update the
copy loop in the ptrace read path to support dynamic states.

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 v5:
* Updated to ensure xstate_bv aligned with the target.
* Rewrote the xstate copy loop, for the ptrace() read path, in an open
  code.
* Adjusted the changelog.

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 | 30 +++++++++++++++++++++++++-----
 1 file changed, 25 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 58e7567dc3cc..8939345778a7 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -1287,6 +1287,7 @@ void copy_xstate_to_uabi_buf(struct membuf to, struct task_struct *tsk,
 	zerofrom = offsetof(struct xregs_state, extended_state_area);
 
 	for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
+		u64 mask = BIT_ULL(i);
 		/*
 		 * The ptrace buffer is in non-compacted XSAVE format.
 		 * In non-compacted format disabled features still occupy
@@ -1294,7 +1295,7 @@ void copy_xstate_to_uabi_buf(struct membuf to, struct task_struct *tsk,
 		 * compacted init_fpstate. The gap tracking will zero this
 		 * later.
 		 */
-		if (!(xfeatures_mask_uabi() & BIT_ULL(i)))
+		if (!(xfeatures_mask_uabi() & mask))
 			continue;
 
 		/*
@@ -1314,10 +1315,24 @@ void copy_xstate_to_uabi_buf(struct membuf to, struct task_struct *tsk,
 			pkru.pkru = tsk->thread.pkru;
 			membuf_write(&to, &pkru, sizeof(pkru));
 		} else {
-			copy_feature(header.xfeatures & BIT_ULL(i), &to,
-				     __raw_xsave_addr(&tsk->thread.fpu, i),
-				     __raw_xsave_addr(NULL, i),
-				     xstate_sizes[i]);
+			unsigned int size = xstate_sizes[i];
+			void *from = NULL;
+
+			/*
+			 * Copy the xstate if available. Otherwise, copy the
+			 * non-zero init states for legacy states (FP and
+			 * SSE) or fill zeros.
+			 */
+
+			if (header.xfeatures & mask)
+				from = __raw_xsave_addr(&tsk->thread.fpu, i);
+			else if (XFEATURE_MASK_FPSSE & mask)
+				from = __raw_xsave_addr(NULL, i);
+
+			if (from)
+				membuf_write(&to, from, size);
+			else
+				membuf_zero(&to, size);
 		}
 		/*
 		 * Keep track of the last copied state in the non-compacted
@@ -1359,6 +1374,8 @@ static int copy_uabi_to_xstate(struct fpu *fpu, const void *kbuf,
 	if (validate_user_xstate_header(&hdr))
 		return -EINVAL;
 
+	hdr.xfeatures &= fpu->state_mask;
+
 	/* Validate MXCSR when any of the related features is in use */
 	mask = XFEATURE_MASK_FP | XFEATURE_MASK_SSE | XFEATURE_MASK_YMM;
 	if (hdr.xfeatures & mask) {
@@ -1385,6 +1402,9 @@ static int copy_uabi_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];
 
-- 
2.17.1


  parent reply	other threads:[~2021-06-30  6:08 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-30  6:02 [PATCH v6 00/26] x86: Support Intel Advanced Matrix Extensions Chang S. Bae
2021-06-30  6:02 ` [PATCH v6 01/26] x86/fpu/xstate: Modify the initialization helper to handle both static and dynamic buffers Chang S. Bae
2021-06-30  6:02 ` [PATCH v6 02/26] x86/fpu/xstate: Modify state copy helpers " Chang S. Bae
2021-06-30  6:02 ` [PATCH v6 03/26] x86/fpu/xstate: Modify address finders " Chang S. Bae
2021-06-30  6:02 ` [PATCH v6 04/26] x86/fpu/xstate: Add a new variable to indicate dynamic user states Chang S. Bae
2021-06-30  6:02 ` [PATCH v6 05/26] x86/fpu/xstate: Add new variables to indicate dynamic XSTATE buffer size Chang S. Bae
2021-06-30  6:02 ` [PATCH v6 06/26] x86/fpu/xstate: Calculate and remember dynamic XSTATE buffer sizes Chang S. Bae
2021-07-02 15:19   ` Bae, Chang Seok
2021-07-02 15:17     ` [PATCH v6-fix " Chang S. Bae
2021-07-02 17:46       ` Dave Hansen
2021-06-30  6:02 ` [PATCH v6 07/26] x86/fpu/xstate: Convert the struct fpu 'state' field to a pointer Chang S. Bae
2021-06-30  6:02 ` [PATCH v6 08/26] x86/fpu/xstate: Introduce helpers to manage the XSTATE buffer dynamically Chang S. Bae
2021-06-30  6:02 ` [PATCH v6 09/26] x86/fpu/xstate: Update the XSTATE save function to support dynamic states Chang S. Bae
2021-06-30  6:02 ` [PATCH v6 10/26] x86/fpu/xstate: Update the XSTATE buffer address finder " Chang S. Bae
2021-06-30  6:02 ` Chang S. Bae [this message]
2021-06-30  6:02 ` [PATCH v6 12/26] x86/fpu/xstate: Use feature disable (XFD) to protect dynamic user state Chang S. Bae
2021-06-30  6:02 ` [PATCH v6 13/26] x86/fpu/xstate: Support ptracer-induced XSTATE buffer expansion Chang S. Bae
2021-06-30  6:02 ` [PATCH v6 14/26] x86/arch_prctl: Create ARCH_ENABLE_XSTATE Chang S. Bae
2021-06-30  6:02 ` [PATCH v6 15/26] x86/fpu/xstate: Support both legacy and expanded signal XSTATE size Chang S. Bae
2021-06-30  6:02 ` [PATCH v6 16/26] x86/fpu/xstate: Adjust the XSAVE feature table to address gaps in state component numbers Chang S. Bae
2021-06-30  6:02 ` [PATCH v6 17/26] x86/fpu/xstate: Disable XSTATE support if an inconsistent state is detected Chang S. Bae
2021-06-30  6:02 ` [PATCH v6 18/26] x86/cpufeatures/amx: Enumerate Advanced Matrix Extension (AMX) feature bits Chang S. Bae
2021-06-30  6:02 ` [PATCH v6 19/26] x86/fpu/amx: Define AMX state components and have it used for boot-time checks Chang S. Bae
2021-06-30  6:02 ` [PATCH v6 20/26] x86/fpu/amx: Initialize child's AMX state Chang S. Bae
2021-06-30  6:02 ` [PATCH v6 21/26] x86/fpu/amx: Enable the AMX feature in 64-bit mode Chang S. Bae
2021-06-30  6:02 ` [PATCH v6 22/26] x86/fpu/xstate: Skip writing zeros to signal frame for dynamic user states if in INIT-state Chang S. Bae
2021-06-30  6:02 ` [PATCH v6 23/26] selftest/x86/amx: Test cases for the AMX state management Chang S. Bae
2021-06-30  6:02 ` [PATCH v6 24/26] x86/insn/amx: Add TILERELEASE instruction to the opcode map Chang S. Bae
2021-06-30  6:02 ` [PATCH v6 25/26] intel_idle/amx: Clear the AMX state before entering idle Chang S. Bae
2021-06-30 13:11   ` Rafael J. Wysocki
2021-06-30  6:02 ` [PATCH v6 26/26] x86/fpu/xstate: Add a sanity check for XFD state when saving XSTATE Chang S. Bae

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