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 v4 15/22] x86/fpu/xstate: Support ptracer-induced xstate buffer expansion
Date: Sun, 21 Feb 2021 10:56:30 -0800 [thread overview]
Message-ID: <20210221185637.19281-16-chang.seok.bae@intel.com> (raw)
In-Reply-To: <20210221185637.19281-1-chang.seok.bae@intel.com>
ptrace() may update xstate data before the target task has taken an XFD
fault and expanded the xstate buffer. Detect this case and allocate a
sufficient buffer to support the request. Also, disable the (now
unnecessary) associated first-use fault.
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:
* Removed 'no functional changes' in the changelog. (Borislav Petkov)
Changes from v2:
* Updated the changelog with task->fpu removed. (Borislav Petkov)
* Updated the code comments.
---
arch/x86/kernel/fpu/regset.c | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/arch/x86/kernel/fpu/regset.c b/arch/x86/kernel/fpu/regset.c
index ee27df4caed6..ec6cbb75010e 100644
--- a/arch/x86/kernel/fpu/regset.c
+++ b/arch/x86/kernel/fpu/regset.c
@@ -122,6 +122,35 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset,
xsave = &fpu->state->xsave;
+ /*
+ * When a ptracer attempts to write any state in the target buffer but not
+ * sufficiently allocated, it dynamically expands the buffer.
+ */
+ if (count > get_xstate_size(fpu->state_mask)) {
+ unsigned int offset, size;
+ struct xstate_header hdr;
+ u64 mask;
+
+ offset = offsetof(struct xregs_state, header);
+ size = sizeof(hdr);
+
+ /* Retrieve XSTATE_BV */
+ if (kbuf) {
+ memcpy(&hdr, kbuf + offset, size);
+ } else {
+ ret = __copy_from_user(&hdr, ubuf + offset, size);
+ if (ret)
+ return ret;
+ }
+
+ mask = hdr.xfeatures & xfeatures_mask_user_dynamic;
+ if (!mask) {
+ ret = alloc_xstate_buffer(fpu, mask);
+ if (ret)
+ return ret;
+ }
+ }
+
fpu__prepare_write(fpu);
if (using_compacted_format()) {
--
2.17.1
next prev parent reply other threads:[~2021-02-21 19:07 UTC|newest]
Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-21 18:56 [PATCH v4 00/22] x86: Support Intel Advanced Matrix Extensions Chang S. Bae
2021-02-21 18:56 ` [PATCH v4 01/22] x86/fpu/xstate: Modify the initialization helper to handle both static and dynamic buffers Chang S. Bae
2021-03-10 13:40 ` Borislav Petkov
2021-02-21 18:56 ` [PATCH v4 02/22] x86/fpu/xstate: Modify state copy helpers " Chang S. Bae
2021-02-21 18:56 ` [PATCH v4 03/22] x86/fpu/xstate: Modify address finders " Chang S. Bae
2021-02-21 18:56 ` [PATCH v4 04/22] x86/fpu/xstate: Modify the context restore helper " Chang S. Bae
2021-02-21 18:56 ` [PATCH v4 05/22] x86/fpu/xstate: Add a new variable to indicate dynamic user states Chang S. Bae
2021-02-21 18:56 ` [PATCH v4 06/22] x86/fpu/xstate: Add new variables to indicate dynamic xstate buffer size Chang S. Bae
2021-02-21 18:56 ` [PATCH v4 07/22] x86/fpu/xstate: Calculate and remember dynamic xstate buffer sizes Chang S. Bae
2021-02-21 18:56 ` [PATCH v4 08/22] x86/fpu/xstate: Convert the struct fpu 'state' field to a pointer Chang S. Bae
2021-02-21 18:56 ` [PATCH v4 09/22] x86/fpu/xstate: Introduce helpers to manage the xstate buffer dynamically Chang S. Bae
2021-02-21 18:56 ` [PATCH v4 10/22] x86/fpu/xstate: Define the scope of the initial xstate data Chang S. Bae
2021-02-21 18:56 ` [PATCH v4 11/22] x86/fpu/xstate: Update the xstate save function to support dynamic states Chang S. Bae
2021-02-21 18:56 ` [PATCH v4 12/22] x86/fpu/xstate: Update the xstate buffer address finder " Chang S. Bae
2021-02-21 18:56 ` [PATCH v4 13/22] x86/fpu/xstate: Update the xstate context copy function " Chang S. Bae
2021-02-21 18:56 ` [PATCH v4 14/22] x86/fpu/xstate: Expand the xstate buffer on the first use of dynamic user state Chang S. Bae
2021-03-20 22:13 ` Thomas Gleixner
2021-03-20 22:21 ` Andy Lutomirski
2021-03-23 21:01 ` Len Brown
2021-03-24 3:14 ` Liu, Jing2
2021-03-24 21:09 ` Len Brown
2021-03-24 21:26 ` Andy Lutomirski
2021-03-24 21:30 ` Dave Hansen
2021-03-24 21:42 ` Andy Lutomirski
2021-03-24 21:58 ` Dave Hansen
2021-03-24 22:12 ` Andy Lutomirski
2021-03-25 5:12 ` Liu, Jing2
2021-03-25 6:59 ` Bae, Chang Seok
2021-03-25 7:26 ` Liu, Jing2
2021-03-23 21:52 ` Bae, Chang Seok
2021-03-24 14:24 ` Dave Hansen
2021-03-29 13:14 ` Len Brown
2021-03-29 13:33 ` Thomas Gleixner
2021-03-29 15:43 ` Len Brown
2021-03-29 16:06 ` Len Brown
2021-03-29 17:43 ` Andy Lutomirski
2021-03-29 18:57 ` Len Brown
2021-03-29 18:49 ` Thomas Gleixner
2021-03-29 22:16 ` Len Brown
2021-03-30 8:28 ` Thomas Gleixner
2021-03-30 16:38 ` Len Brown
2021-03-26 16:34 ` Jann Horn
2021-03-29 18:14 ` Bae, Chang Seok
2021-02-21 18:56 ` Chang S. Bae [this message]
2021-02-21 18:56 ` [PATCH v4 16/22] x86/fpu/xstate: Extend the table to map state components with features Chang S. Bae
2021-03-20 21:25 ` Thomas Gleixner
2021-03-23 21:52 ` Bae, Chang Seok
2021-02-21 18:56 ` [PATCH v4 17/22] x86/cpufeatures/amx: Enumerate Advanced Matrix Extension (AMX) feature bits Chang S. Bae
2021-02-21 18:56 ` [PATCH v4 18/22] x86/fpu/amx: Define AMX state components and have it used for boot-time checks Chang S. Bae
2021-03-20 21:31 ` Thomas Gleixner
2021-03-23 21:52 ` Bae, Chang Seok
2021-02-21 18:56 ` [PATCH v4 19/22] x86/fpu/amx: Enable the AMX feature in 64-bit mode Chang S. Bae
2021-03-20 21:26 ` Thomas Gleixner
2021-03-23 21:51 ` Bae, Chang Seok
2021-02-21 18:56 ` [PATCH v4 20/22] selftest/x86/amx: Include test cases for the AMX state management Chang S. Bae
2021-02-21 18:56 ` [PATCH v4 21/22] x86/fpu/xstate: Support dynamic user state in the signal handling path Chang S. Bae
2021-02-21 18:56 ` [PATCH v4 22/22] x86/fpu/xstate: Introduce boot-parameters to control state component support Chang S. Bae
2021-02-21 19:30 ` Randy Dunlap
2021-02-21 20:10 ` Bae, Chang Seok
2021-02-21 20:37 ` Randy Dunlap
2021-03-20 20:56 ` Thomas Gleixner
2021-03-25 22:59 ` Len Brown
2021-03-25 23:10 ` Dave Hansen
2021-03-26 15:27 ` Len Brown
2021-03-26 19:22 ` Thomas Gleixner
2021-03-26 1:41 ` Andy Lutomirski
2021-03-26 15:33 ` Len Brown
2021-03-26 15:48 ` Andy Lutomirski
2021-03-26 17:53 ` Len Brown
2021-03-26 18:12 ` Andy Lutomirski
2021-03-27 4:53 ` Len Brown
2021-03-27 22:20 ` Thomas Gleixner
2021-03-29 13:31 ` Len Brown
2021-03-29 14:10 ` Thomas Gleixner
2021-03-26 18:17 ` Borislav Petkov
2021-03-27 4:41 ` Len Brown
2021-03-26 1:50 ` Thomas Gleixner
2021-03-26 15:36 ` Len Brown
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