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 v3 14/21] x86/fpu/xstate: Support ptracer-induced xstate buffer expansion
Date: Wed, 23 Dec 2020 07:57:10 -0800 [thread overview]
Message-ID: <20201223155717.19556-15-chang.seok.bae@intel.com> (raw)
In-Reply-To: <20201223155717.19556-1-chang.seok.bae@intel.com>
ptrace() may update xstate data before the target task has taken an XFD
fault and expanded the context switch buffer. Detect this case and allocate
a sufficient buffer 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
---
Changes from v2:
* Updated the changelog with task->fpu removed. (Boris 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 8d863240b9c6..16ff8ac765c1 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 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:[~2020-12-23 16:03 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-23 15:56 [PATCH v3 00/21] x86: Support Intel Advanced Matrix Extensions Chang S. Bae
2020-12-23 15:56 ` [PATCH v3 01/21] x86/fpu/xstate: Modify initialization helper to handle both static and dynamic buffers Chang S. Bae
2021-01-15 12:40 ` Borislav Petkov
2020-12-23 15:56 ` [PATCH v3 02/21] x86/fpu/xstate: Modify state copy helpers " Chang S. Bae
2021-01-15 12:50 ` Borislav Petkov
2021-01-19 18:50 ` Bae, Chang Seok
2021-01-20 20:53 ` Borislav Petkov
2021-01-20 21:12 ` Bae, Chang Seok
2020-12-23 15:56 ` [PATCH v3 03/21] x86/fpu/xstate: Modify address finders " Chang S. Bae
2021-01-15 13:06 ` Borislav Petkov
2020-12-23 15:57 ` [PATCH v3 04/21] x86/fpu/xstate: Modify context switch helpers " Chang S. Bae
2021-01-15 13:18 ` Borislav Petkov
2021-01-19 18:49 ` Bae, Chang Seok
2020-12-23 15:57 ` [PATCH v3 05/21] x86/fpu/xstate: Add a new variable to indicate dynamic user states Chang S. Bae
2021-01-15 13:39 ` Borislav Petkov
2021-01-15 19:47 ` Bae, Chang Seok
2021-01-19 15:57 ` Borislav Petkov
2021-01-19 18:57 ` Bae, Chang Seok
2021-01-22 10:56 ` Borislav Petkov
2021-01-27 1:23 ` Bae, Chang Seok
2020-12-23 15:57 ` [PATCH v3 06/21] x86/fpu/xstate: Calculate and remember dynamic xstate buffer sizes Chang S. Bae
2021-01-22 11:44 ` Borislav Petkov
2021-01-27 1:23 ` Bae, Chang Seok
2021-01-27 9:38 ` Borislav Petkov
2021-02-03 2:54 ` Bae, Chang Seok
2020-12-23 15:57 ` [PATCH v3 07/21] x86/fpu/xstate: Introduce helpers to manage dynamic xstate buffers Chang S. Bae
2021-01-26 20:17 ` Borislav Petkov
2021-01-27 1:23 ` Bae, Chang Seok
2021-01-27 10:41 ` Borislav Petkov
2021-02-03 4:10 ` Bae, Chang Seok
2021-02-04 13:10 ` Borislav Petkov
2021-02-03 4:10 ` Bae, Chang Seok
2020-12-23 15:57 ` [PATCH v3 08/21] x86/fpu/xstate: Define the scope of the initial xstate data Chang S. Bae
2021-02-08 12:33 ` Borislav Petkov
2021-02-08 18:53 ` Bae, Chang Seok
2021-02-09 12:49 ` Borislav Petkov
2021-02-09 15:38 ` Bae, Chang Seok
2020-12-23 15:57 ` [PATCH v3 09/21] x86/fpu/xstate: Introduce wrapper functions to organize xstate buffer access Chang S. Bae
2021-02-08 12:33 ` Borislav Petkov
2021-02-09 15:50 ` Bae, Chang Seok
2020-12-23 15:57 ` [PATCH v3 10/21] x86/fpu/xstate: Update xstate save function to support dynamic xstate Chang S. Bae
2021-01-07 8:41 ` Liu, Jing2
2021-01-07 18:40 ` Bae, Chang Seok
2021-01-12 2:52 ` Liu, Jing2
2021-01-15 4:59 ` Bae, Chang Seok
2021-01-15 5:45 ` Liu, Jing2
2021-02-08 12:33 ` Borislav Petkov
2021-02-09 15:48 ` Bae, Chang Seok
2020-12-23 15:57 ` [PATCH v3 11/21] x86/fpu/xstate: Update xstate buffer address finder " Chang S. Bae
2021-02-19 15:00 ` Borislav Petkov
2021-02-19 19:19 ` Bae, Chang Seok
2020-12-23 15:57 ` [PATCH v3 12/21] x86/fpu/xstate: Update xstate context copy function to support dynamic buffer Chang S. Bae
2020-12-23 15:57 ` [PATCH v3 13/21] x86/fpu/xstate: Expand dynamic context switch buffer on first use Chang S. Bae
2020-12-23 15:57 ` Chang S. Bae [this message]
2020-12-23 15:57 ` [PATCH v3 15/21] x86/fpu/xstate: Extend the table to map xstate components with features Chang S. Bae
2020-12-23 15:57 ` [PATCH v3 16/21] x86/cpufeatures/amx: Enumerate Advanced Matrix Extension (AMX) feature bits Chang S. Bae
2020-12-23 15:57 ` [PATCH v3 17/21] x86/fpu/amx: Define AMX state components and have it used for boot-time checks Chang S. Bae
2020-12-23 15:57 ` [PATCH v3 18/21] x86/fpu/amx: Enable the AMX feature in 64-bit mode Chang S. Bae
2020-12-23 15:57 ` [PATCH v3 19/21] selftest/x86/amx: Include test cases for the AMX state management Chang S. Bae
2020-12-23 15:57 ` [PATCH v3 20/21] x86/fpu/xstate: Support dynamic user state in the signal handling path Chang S. Bae
2020-12-23 15:57 ` [PATCH v3 21/21] x86/fpu/xstate: Introduce boot-parameters to control some state component support Chang S. Bae
2020-12-23 18:37 ` Randy Dunlap
2021-01-14 21:31 ` Bae, Chang Seok
2021-01-14 21:31 ` [PATCH v3 00/21] x86: Support Intel Advanced Matrix Extensions Bae, Chang Seok
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20201223155717.19556-15-chang.seok.bae@intel.com \
--to=chang.seok.bae@intel.com \
--cc=bp@suse.de \
--cc=dave.hansen@intel.com \
--cc=jing2.liu@intel.com \
--cc=len.brown@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=mingo@kernel.org \
--cc=ravi.v.shankar@intel.com \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).