From: "Chang S. Bae" <chang.seok.bae@intel.com>
To: tglx@linutronix.de, mingo@kernel.org, bp@suse.de,
luto@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: [RFC PATCH 15/22] x86/fpu/xstate: Support ptracer-induced xstate area expansion
Date: Thu, 1 Oct 2020 13:39:06 -0700 [thread overview]
Message-ID: <20201001203913.9125-16-chang.seok.bae@intel.com> (raw)
In-Reply-To: <20201001203913.9125-1-chang.seok.bae@intel.com>
ptrace() may request an update to task->fpu that has not yet been
allocated. Detect this case and allocate task->fpu to support the request.
Also, disable the (now unnecessary) associated first-use fault.
No functional change until the kernel supports dynamic user 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
---
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 8d863240b9c6..6b9d0c0a266d 100644
--- a/arch/x86/kernel/fpu/regset.c
+++ b/arch/x86/kernel/fpu/regset.c
@@ -125,6 +125,35 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset,
xsave = __xsave(fpu);
+ /*
+ * When a ptracer attempts to write any state in task->fpu but not allocated,
+ * it dynamically expands the xstate area of fpu->state_ptr.
+ */
+ 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_area(fpu, mask, NULL);
+ if (ret)
+ return ret;
+ }
+ }
+
fpu__prepare_write(fpu);
if (using_compacted_format()) {
--
2.17.1
next prev parent reply other threads:[~2020-10-01 20:43 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-01 20:38 [RFC PATCH 00/22] x86: Support Intel Advanced Matrix Extensions Chang S. Bae
2020-10-01 20:38 ` [RFC PATCH 01/22] x86/fpu/xstate: Modify area init helper prototypes to access all the possible areas Chang S. Bae
2020-10-01 20:38 ` [RFC PATCH 02/22] x86/fpu/xstate: Modify xstate copy " Chang S. Bae
2020-10-01 20:38 ` [RFC PATCH 03/22] x86/fpu/xstate: Modify address finder " Chang S. Bae
2020-10-01 20:38 ` [RFC PATCH 04/22] x86/fpu/xstate: Modify save and restore helper " Chang S. Bae
2020-10-01 20:38 ` [RFC PATCH 05/22] x86/fpu/xstate: Introduce a new variable for dynamic user states Chang S. Bae
2020-10-01 20:38 ` [RFC PATCH 06/22] x86/fpu/xstate: Outline dynamic xstate area size in the task context Chang S. Bae
2020-10-01 20:38 ` [RFC PATCH 07/22] x86/fpu/xstate: Introduce helpers to manage an xstate area dynamically Chang S. Bae
2020-10-01 23:41 ` Andy Lutomirski
2020-10-13 22:00 ` Brown, Len
2020-10-01 20:38 ` [RFC PATCH 08/22] x86/fpu/xstate: Define the scope of the initial xstate data Chang S. Bae
2020-10-01 20:39 ` [RFC PATCH 09/22] x86/fpu/xstate: Introduce wrapper functions for organizing xstate area access Chang S. Bae
2020-10-01 20:39 ` [RFC PATCH 10/22] x86/fpu/xstate: Update xstate save function for supporting dynamic user xstate Chang S. Bae
2020-10-01 20:39 ` [RFC PATCH 11/22] x86/fpu/xstate: Update xstate area address finder " Chang S. Bae
2020-10-01 20:39 ` [RFC PATCH 12/22] x86/fpu/xstate: Update xstate context copy function for supporting dynamic area Chang S. Bae
2020-10-01 20:39 ` [RFC PATCH 13/22] x86/fpu/xstate: Expand dynamic user state area on first use Chang S. Bae
2020-10-01 23:39 ` Andy Lutomirski
2020-10-13 22:31 ` Brown, Len
2020-10-13 22:43 ` Dave Hansen
2020-10-14 1:11 ` Andy Lutomirski
2020-10-14 6:03 ` Dave Hansen
2020-10-14 16:10 ` Andy Lutomirski
2020-10-14 16:29 ` Dave Hansen
2020-11-03 21:32 ` Bae, Chang Seok
2020-11-03 21:41 ` Dave Hansen
2020-11-03 21:53 ` Bae, Chang Seok
2020-10-14 10:41 ` Peter Zijlstra
2020-10-14 1:47 ` Andy Lutomirski
2020-10-01 20:39 ` [RFC PATCH 14/22] x86/fpu/xstate: Inherit dynamic user state when used in the parent Chang S. Bae
2020-10-01 20:39 ` Chang S. Bae [this message]
2020-10-01 20:39 ` [RFC PATCH 16/22] x86/fpu/xstate: Support dynamic user state in the signal handling path Chang S. Bae
2020-10-01 20:39 ` [RFC PATCH 17/22] x86/fpu/xstate: Extend the table for mapping xstate components with features Chang S. Bae
2020-10-01 20:39 ` [RFC PATCH 18/22] x86/cpufeatures/amx: Enumerate Advanced Matrix Extension (AMX) feature bits Chang S. Bae
2020-10-01 20:39 ` [RFC PATCH 19/22] x86/fpu/amx: Define AMX state components and have it used for boot-time checks Chang S. Bae
2020-10-01 20:39 ` [RFC PATCH 20/22] x86/fpu/amx: Enable the AMX feature in 64-bit mode Chang S. Bae
2020-10-01 20:39 ` [RFC PATCH 21/22] selftest/x86/amx: Include test cases for the AMX state management Chang S. Bae
2020-10-01 20:39 ` [RFC PATCH 22/22] x86/fpu/xstate: Introduce boot-parameters for control some state component support Chang S. Bae
2020-10-02 2:09 ` Randy Dunlap
2020-10-13 23:00 ` Brown, Len
2020-10-02 17:15 ` Andy Lutomirski
2020-10-02 17:26 ` Dave Hansen
2020-10-13 23:38 ` Brown, Len
2020-10-02 17:25 ` Dave Hansen
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