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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org, Borislav Petkov <bp@suse.de>
Subject: [PATCH 5.15 30/41] x86/mce: Remove noinstr annotation from mce_setup()
Date: Fri, 14 Jan 2022 09:16:30 +0100	[thread overview]
Message-ID: <20220114081546.160146929@linuxfoundation.org> (raw)
In-Reply-To: <20220114081545.158363487@linuxfoundation.org>

From: Borislav Petkov <bp@suse.de>

commit 487d654db3edacc31dee86b10258cc740640fad8 upstream.

Instead, sandwitch around the call which is done in noinstr context and
mark the caller - mce_gather_info() - as noinstr.

Also, document what the whole instrumentation strategy with #MC is going
to be in the future and where it all is supposed to be going to.

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211208111343.8130-5-bp@alien8.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/x86/kernel/cpu/mce/core.c |   26 ++++++++++++++++++++------
 1 file changed, 20 insertions(+), 6 deletions(-)

--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -130,7 +130,7 @@ static void (*quirk_no_way_out)(int bank
 BLOCKING_NOTIFIER_HEAD(x86_mce_decoder_chain);
 
 /* Do initial initialization of a struct mce */
-noinstr void mce_setup(struct mce *m)
+void mce_setup(struct mce *m)
 {
 	memset(m, 0, sizeof(struct mce));
 	m->cpu = m->extcpu = smp_processor_id();
@@ -479,9 +479,15 @@ static noinstr void mce_wrmsrl(u32 msr,
  * check into our "mce" struct so that we can use it later to assess
  * the severity of the problem as we read per-bank specific details.
  */
-static inline void mce_gather_info(struct mce *m, struct pt_regs *regs)
+static noinstr void mce_gather_info(struct mce *m, struct pt_regs *regs)
 {
+	/*
+	 * Enable instrumentation around mce_setup() which calls external
+	 * facilities.
+	 */
+	instrumentation_begin();
 	mce_setup(m);
+	instrumentation_end();
 
 	m->mcgstatus = mce_rdmsrl(MSR_IA32_MCG_STATUS);
 	if (regs) {
@@ -1327,11 +1333,11 @@ static void queue_task_work(struct mce *
 }
 
 /*
- * The actual machine check handler. This only handles real
- * exceptions when something got corrupted coming in through int 18.
+ * The actual machine check handler. This only handles real exceptions when
+ * something got corrupted coming in through int 18.
  *
- * This is executed in NMI context not subject to normal locking rules. This
- * implies that most kernel services cannot be safely used. Don't even
+ * This is executed in #MC context not subject to normal locking rules.
+ * This implies that most kernel services cannot be safely used. Don't even
  * think about putting a printk in there!
  *
  * On Intel systems this is entered on all CPUs in parallel through
@@ -1343,6 +1349,14 @@ static void queue_task_work(struct mce *
  * issues: if the machine check was due to a failure of the memory
  * backing the user stack, tracing that reads the user stack will cause
  * potentially infinite recursion.
+ *
+ * Currently, the #MC handler calls out to a number of external facilities
+ * and, therefore, allows instrumentation around them. The optimal thing to
+ * have would be to do the absolutely minimal work required in #MC context
+ * and have instrumentation disabled only around that. Further processing can
+ * then happen in process context where instrumentation is allowed. Achieving
+ * that requires careful auditing and modifications. Until then, the code
+ * allows instrumentation temporarily, where required. *
  */
 noinstr void do_machine_check(struct pt_regs *regs)
 {



  parent reply	other threads:[~2022-01-14  8:22 UTC|newest]

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-14  8:16 [PATCH 5.15 00/41] 5.15.15-rc1 review Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 01/41] s390/kexec: handle R_390_PLT32DBL rela in arch_kexec_apply_relocations_add() Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 02/41] workqueue: Fix unbind_workers() VS wq_worker_running() race Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 03/41] staging: r8188eu: switch the led off during deinit Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 04/41] bpf: Fix out of bounds access from invalid *_or_null type verification Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 05/41] Bluetooth: btusb: Add protocol for MediaTek bluetooth devices(MT7922) Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 06/41] Bluetooth: btusb: Add the new support ID for Realtek RTL8852A Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 07/41] Bluetooth: btusb: Add support for IMC Networks Mediatek Chip(MT7921) Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 08/41] Bbluetooth: btusb: Add another Bluetooth part for Realtek 8852AE Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 09/41] Bluetooth: btusb: fix memory leak in btusb_mtk_submit_wmt_recv_urb() Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 10/41] Bluetooth: btusb: enable Mediatek to support AOSP extension Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 11/41] Bluetooth: btusb: Add one more Bluetooth part for the Realtek RTL8852AE Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 12/41] Bluetooth: btusb: Add the new support IDs for WCN6855 Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 13/41] fget: clarify and improve __fget_files() implementation Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 14/41] Bluetooth: btusb: Add one more Bluetooth part for WCN6855 Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 15/41] Bluetooth: btusb: Add two more Bluetooth parts " Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 16/41] Bluetooth: btusb: Add support for Foxconn MT7922A Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 17/41] Bluetooth: btintel: Fix broken LED quirk for legacy ROM devices Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 18/41] Bluetooth: btusb: Add support for Foxconn QCA 0xe0d0 Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 19/41] Bluetooth: bfusb: fix division by zero in send path Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 20/41] ARM: dts: exynos: Fix BCM4330 Bluetooth reset polarity in I9100 Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 21/41] USB: core: Fix bug in resuming hubs handling of wakeup requests Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 22/41] USB: Fix "slab-out-of-bounds Write" bug in usb_hcd_poll_rh_status Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 23/41] ath11k: Fix buffer overflow when scanning with extraie Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 24/41] mmc: sdhci-pci: Add PCI ID for Intel ADL Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 25/41] Bluetooth: add quirk disabling LE Read Transmit Power Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 26/41] Bluetooth: btbcm: disable read tx power for some Macs with the T2 Security chip Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 27/41] Bluetooth: btbcm: disable read tx power for MacBook Air 8,1 and 8,2 Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 28/41] veth: Do not record rx queue hint in veth_xmit Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 29/41] mfd: intel-lpss: Fix too early PM enablement in the ACPI ->probe() Greg Kroah-Hartman
2022-01-14  8:16 ` Greg Kroah-Hartman [this message]
2022-01-14  8:16 ` [PATCH 5.15 31/41] can: gs_usb: fix use of uninitialized variable, detach device on reception of invalid USB data Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 32/41] can: isotp: convert struct tpcon::{idx,len} to unsigned int Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 33/41] can: gs_usb: gs_can_start_xmit(): zero-initialize hf->{flags,reserved} Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 34/41] random: fix data race on crng_node_pool Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 35/41] random: fix data race on crng init time Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 36/41] random: fix crash on multiple early calls to add_bootloader_randomness() Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 37/41] platform/x86/intel: hid: add quirk to support Surface Go 3 Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 38/41] media: Revert "media: uvcvideo: Set unique vdev name based in type" Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 39/41] staging: wlan-ng: Avoid bitwise vs logical OR warning in hfa384x_usb_throttlefn() Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 40/41] drm/i915: Avoid bitwise vs logical OR warning in snb_wm_latency_quirk() Greg Kroah-Hartman
2022-01-14  8:16 ` [PATCH 5.15 41/41] staging: greybus: fix stack size warning with UBSAN Greg Kroah-Hartman
2022-01-14 17:43 ` [PATCH 5.15 00/41] 5.15.15-rc1 review Naresh Kamboju
2022-01-14 18:09 ` Jon Hunter
2022-01-14 19:59 ` Ron Economos
2022-01-15  8:14   ` Greg Kroah-Hartman
2022-01-15 11:52     ` Ron Economos
2022-01-15 12:15       ` Greg Kroah-Hartman
2022-01-15 12:31         ` Ron Economos
2022-01-14 22:29 ` Florian Fainelli
2022-01-14 23:32 ` Fox Chen
2022-01-15  0:24 ` Shuah Khan
2022-01-15 11:03 ` Sudip Mukherjee
2022-01-15 14:47 ` Andrei Rabusov
2022-01-15 16:39 ` Guenter Roeck
2022-01-15 16:48 ` Jeffrin Jose T

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