x86/kprobes: Fix crash when probing CS CALL instructionsgrafted

When using eBPF to probe CS CALL instructions within a function,
a crash can be triggered.

The eBPF tool probes offset 257 of the __hrtimer_run_queues()
function:

<__hrtimer_run_queues+249>:  nopl   0x0(%rax,%rax,1)
<__hrtimer_run_queues+254>:  mov    %r14,%rdi
<__hrtimer_run_queues+257>:  cs call <__x86_indirect_thunk_r12>
<__hrtimer_run_queues+263>:  mov    %eax,%r12d
<__hrtimer_run_queues+266>:  xchg   %ax,%ax
<__hrtimer_run_queues+268>:  mov    %r13,%rdi

Which triggers this crash:

  BUG: unable to handle page fault for address: 00000000000f41c9
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 0 P4D 0
  Oops: 0002 [#1] SMP NOPTI
  CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P
  RIP: 0010:__hrtimer_run_queues+0x106/0x230

Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is
at the 6th byte of the above CS CALL instruction. Since the CS CALL
instruction occupies 6 bytes, the exception occurred in the middle of that
call instruction.

The root cause is that when using eBPF tools to probe in the middle of a
function, a kprobe with INT3 is used as the underlying implementation.

During single-step emulation of the original CALL instruction,
int3_emulate_call() assumes that the probed CALL instruction is 5 bytes
long. However, the actual CS-prefixed CALL instruction occupies 6 bytes,
so it constructs an incorrect exception return address. When the CPU
returns from the kprobe handler, the next instruction to be executed is at
the address of the last byte of that CS CALL instruction. Coincidentally,
starting from that address, the CPU fetches and decodes a completely
different instruction, which ultimately triggers a kernel crash.

Fix the issue by using the actual instruction length obtained from
the instruction decoder when constructing the exception return
address, rather than relying on the hardcoded CALL_INSN_SIZE macro.

[ mingo: Refined the changelog ]

Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000

1 files changed, 399 insertions, 0 deletions

diff --git a/drivers/crypto/ccp/sev-dev-tsm.c b/drivers/crypto/ccp/sev-dev-tsm.c
new file mode 100644
index 000000000..46f2539d2
--- /dev/null
+++ b/drivers/crypto/ccp/sev-dev-tsm.c
@@ -0,0 +1,399 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+// Interface to CCP/SEV-TIO for generic PCIe TDISP module
+
+#include <linux/pci.h>
+#include <linux/device.h>
+#include <linux/tsm.h>
+#include <linux/iommu.h>
+#include <linux/pci-doe.h>
+#include <linux/bitfield.h>
+#include <linux/module.h>
+
+#include <asm/sev-common.h>
+#include <asm/sev.h>
+
+#include "psp-dev.h"
+#include "sev-dev.h"
+#include "sev-dev-tio.h"
+
+MODULE_IMPORT_NS("PCI_IDE");
+
+#define dev_to_sp(dev)		((struct sp_device *)dev_get_drvdata(dev))
+#define dev_to_psp(dev)		((struct psp_device *)(dev_to_sp(dev)->psp_data))
+#define dev_to_sev(dev)		((struct sev_device *)(dev_to_psp(dev)->sev_data))
+#define tsm_dev_to_sev(tsmdev)	dev_to_sev((tsmdev)->dev.parent)
+
+#define pdev_to_tio_dsm(pdev)	(container_of((pdev)->tsm, struct tio_dsm, tsm.base_tsm))
+
+static int sev_tio_spdm_cmd(struct tio_dsm *dsm, int ret)
+{
+	struct tsm_dsm_tio *dev_data = &dsm->data;
+	struct tsm_spdm *spdm = &dev_data->spdm;
+
+	/* Check the main command handler response before entering the loop */
+	if (ret == 0 && dev_data->psp_ret != SEV_RET_SUCCESS)
+		return -EINVAL;
+
+	if (ret <= 0)
+		return ret;
+
+	/* ret > 0 means "SPDM requested" */
+	while (ret == PCI_DOE_FEATURE_CMA || ret == PCI_DOE_FEATURE_SSESSION) {
+		ret = pci_doe(dsm->tsm.doe_mb, PCI_VENDOR_ID_PCI_SIG, ret,
+			      spdm->req, spdm->req_len, spdm->rsp, spdm->rsp_len);
+		if (ret < 0)
+			break;
+
+		WARN_ON_ONCE(ret == 0); /* The response should never be empty */
+		spdm->rsp_len = ret;
+		ret = sev_tio_continue(dev_data);
+	}
+
+	return ret;
+}
+
+static int stream_enable(struct pci_ide *ide)
+{
+	struct pci_dev *rp = pcie_find_root_port(ide->pdev);
+	int ret;
+
+	ret = pci_ide_stream_enable(ide->pdev, ide);
+	if (ret && ret != -ENXIO)
+		return ret;
+
+	ret = pci_ide_stream_enable(rp, ide);
+	if (ret && ret != -ENXIO)
+		pci_ide_stream_disable(ide->pdev, ide);
+
+	return ret;
+}
+
+static int streams_enable(struct pci_ide **ide)
+{
+	int ret = 0;
+
+	for (int i = 0; i < TIO_IDE_MAX_TC; ++i) {
+		if (ide[i]) {
+			ret = stream_enable(ide[i]);
+			if (ret)
+				break;
+		}
+	}
+
+	return ret;
+}
+
+static void stream_disable(struct pci_ide *ide)
+{
+	pci_ide_stream_disable(ide->pdev, ide);
+	pci_ide_stream_disable(pcie_find_root_port(ide->pdev), ide);
+}
+
+static void streams_disable(struct pci_ide **ide)
+{
+	for (int i = 0; i < TIO_IDE_MAX_TC; ++i)
+		if (ide[i])
+			stream_disable(ide[i]);
+}
+
+static void stream_setup(struct pci_ide *ide)
+{
+	struct pci_dev *rp = pcie_find_root_port(ide->pdev);
+
+	ide->partner[PCI_IDE_EP].rid_start = 0;
+	ide->partner[PCI_IDE_EP].rid_end = 0xffff;
+	ide->partner[PCI_IDE_RP].rid_start = 0;
+	ide->partner[PCI_IDE_RP].rid_end = 0xffff;
+
+	ide->pdev->ide_cfg = 0;
+	ide->pdev->ide_tee_limit = 1;
+	rp->ide_cfg = 1;
+	rp->ide_tee_limit = 0;
+
+	pci_warn(ide->pdev, "Forcing CFG/TEE for %s", pci_name(rp));
+	pci_ide_stream_setup(ide->pdev, ide);
+	pci_ide_stream_setup(rp, ide);
+}
+
+static u8 streams_setup(struct pci_ide **ide, u8 *ids)
+{
+	bool def = false;
+	u8 tc_mask = 0;
+	int i;
+
+	for (i = 0; i < TIO_IDE_MAX_TC; ++i) {
+		if (!ide[i]) {
+			ids[i] = 0xFF;
+			continue;
+		}
+
+		tc_mask |= BIT(i);
+		ids[i] = ide[i]->stream_id;
+
+		if (!def) {
+			struct pci_ide_partner *settings;
+
+			settings = pci_ide_to_settings(ide[i]->pdev, ide[i]);
+			settings->default_stream = 1;
+			def = true;
+		}
+
+		stream_setup(ide[i]);
+	}
+
+	return tc_mask;
+}
+
+static int streams_register(struct pci_ide **ide)
+{
+	int ret = 0, i;
+
+	for (i = 0; i < TIO_IDE_MAX_TC; ++i) {
+		if (ide[i]) {
+			ret = pci_ide_stream_register(ide[i]);
+			if (ret)
+				break;
+		}
+	}
+
+	return ret;
+}
+
+static void streams_unregister(struct pci_ide **ide)
+{
+	for (int i = 0; i < TIO_IDE_MAX_TC; ++i)
+		if (ide[i])
+			pci_ide_stream_unregister(ide[i]);
+}
+
+static void stream_teardown(struct pci_ide *ide)
+{
+	pci_ide_stream_teardown(ide->pdev, ide);
+	pci_ide_stream_teardown(pcie_find_root_port(ide->pdev), ide);
+}
+
+static void streams_teardown(struct pci_ide **ide)
+{
+	for (int i = 0; i < TIO_IDE_MAX_TC; ++i) {
+		if (ide[i]) {
+			stream_teardown(ide[i]);
+			pci_ide_stream_free(ide[i]);
+			ide[i] = NULL;
+		}
+	}
+}
+
+static int stream_alloc(struct pci_dev *pdev, struct pci_ide **ide,
+			unsigned int tc)
+{
+	struct pci_ide *ide1;
+
+	if (ide[tc]) {
+		pci_err(pdev, "Stream for class=%d already registered", tc);
+		return -EBUSY;
+	}
+
+	ide1 = pci_ide_stream_alloc(pdev);
+	if (!ide1)
+		return -EFAULT;
+
+	ide1->stream_id = ide1->host_bridge_stream;
+
+	ide[tc] = ide1;
+
+	return 0;
+}
+
+static struct pci_tsm *tio_pf0_probe(struct pci_dev *pdev, struct sev_device *sev)
+{
+	struct tio_dsm *dsm __free(kfree) = kzalloc_obj(*dsm);
+	int rc;
+
+	if (!dsm)
+		return NULL;
+
+	rc = pci_tsm_pf0_constructor(pdev, &dsm->tsm, sev->tsmdev);
+	if (rc)
+		return NULL;
+
+	pci_dbg(pdev, "TSM enabled\n");
+	dsm->sev = sev;
+	return &no_free_ptr(dsm)->tsm.base_tsm;
+}
+
+static struct pci_tsm *dsm_probe(struct tsm_dev *tsmdev, struct pci_dev *pdev)
+{
+	struct sev_device *sev = tsm_dev_to_sev(tsmdev);
+
+	if (is_pci_tsm_pf0(pdev))
+		return tio_pf0_probe(pdev, sev);
+	return NULL;
+}
+
+static void dsm_remove(struct pci_tsm *tsm)
+{
+	struct pci_dev *pdev = tsm->pdev;
+
+	pci_dbg(pdev, "TSM disabled\n");
+
+	if (is_pci_tsm_pf0(pdev)) {
+		struct tio_dsm *dsm = container_of(tsm, struct tio_dsm, tsm.base_tsm);
+
+		pci_tsm_pf0_destructor(&dsm->tsm);
+		kfree(dsm);
+	}
+}
+
+static int dsm_create(struct tio_dsm *dsm)
+{
+	struct pci_dev *pdev = dsm->tsm.base_tsm.pdev;
+	struct pci_dev *rootport;
+	u8 segment_id;
+	u16 device_id;
+	u16 root_port_id;
+	u32 lnkcap = 0;
+
+	if (!pdev->bus)
+		return -ENODEV;
+
+	segment_id = pci_domain_nr(pdev->bus);
+	rootport = pcie_find_root_port(pdev);
+	device_id = pci_dev_id(pdev);
+
+	if (pci_read_config_dword(rootport, pci_pcie_cap(rootport) + PCI_EXP_LNKCAP,
+				  &lnkcap))
+		return -ENODEV;
+
+	root_port_id = FIELD_GET(PCI_EXP_LNKCAP_PN, lnkcap);
+
+	return sev_tio_dev_create(&dsm->data, device_id, root_port_id, segment_id);
+}
+
+static int dsm_connect(struct pci_dev *pdev)
+{
+	struct tio_dsm *dsm = pdev_to_tio_dsm(pdev);
+	struct tsm_dsm_tio *dev_data = &dsm->data;
+	u8 ids[TIO_IDE_MAX_TC];
+	u8 tc_mask;
+	int ret;
+
+	if (pci_find_doe_mailbox(pdev, PCI_VENDOR_ID_PCI_SIG,
+				 PCI_DOE_FEATURE_SSESSION) != dsm->tsm.doe_mb) {
+		pci_err(pdev, "CMA DOE MB must support SSESSION\n");
+		return -EFAULT;
+	}
+
+	ret = stream_alloc(pdev, dev_data->ide, 0);
+	if (ret)
+		return ret;
+
+	ret = dsm_create(dsm);
+	if (ret)
+		goto ide_free_exit;
+
+	tc_mask = streams_setup(dev_data->ide, ids);
+
+	ret = sev_tio_dev_connect(dev_data, tc_mask, ids, dev_data->cert_slot);
+	ret = sev_tio_spdm_cmd(dsm, ret);
+	if (ret)
+		goto free_exit;
+
+	streams_enable(dev_data->ide);
+
+	ret = streams_register(dev_data->ide);
+	if (ret)
+		goto free_exit;
+
+	return 0;
+
+free_exit:
+	sev_tio_dev_reclaim(dev_data);
+
+	streams_disable(dev_data->ide);
+ide_free_exit:
+
+	streams_teardown(dev_data->ide);
+
+	return ret;
+}
+
+static void dsm_disconnect(struct pci_dev *pdev)
+{
+	bool force = SYSTEM_HALT <= system_state && system_state <= SYSTEM_RESTART;
+	struct tio_dsm *dsm = pdev_to_tio_dsm(pdev);
+	struct tsm_dsm_tio *dev_data = &dsm->data;
+	int ret;
+
+	ret = sev_tio_dev_disconnect(dev_data, force);
+	ret = sev_tio_spdm_cmd(dsm, ret);
+	if (ret && !force) {
+		ret = sev_tio_dev_disconnect(dev_data, true);
+		sev_tio_spdm_cmd(dsm, ret);
+	}
+
+	sev_tio_dev_reclaim(dev_data);
+
+	streams_disable(dev_data->ide);
+	streams_unregister(dev_data->ide);
+	streams_teardown(dev_data->ide);
+}
+
+static struct pci_tsm_ops sev_tsm_ops = {
+	.probe = dsm_probe,
+	.remove = dsm_remove,
+	.connect = dsm_connect,
+	.disconnect = dsm_disconnect,
+};
+
+void sev_tsm_init_locked(struct sev_device *sev, void *tio_status_page)
+{
+	struct sev_tio_status *t = kzalloc_obj(*t);
+	struct tsm_dev *tsmdev;
+	int ret;
+
+	WARN_ON(sev->tio_status);
+
+	if (!t)
+		return;
+
+	ret = sev_tio_init_locked(tio_status_page);
+	if (ret) {
+		pr_warn("SEV-TIO STATUS failed with %d\n", ret);
+		goto error_exit;
+	}
+
+	tsmdev = tsm_register(sev->dev, &sev_tsm_ops);
+	if (IS_ERR(tsmdev))
+		goto error_exit;
+
+	memcpy(t, tio_status_page, sizeof(*t));
+
+	pr_notice("SEV-TIO status: EN=%d INIT_DONE=%d rq=%d..%d rs=%d..%d "
+		  "scr=%d..%d out=%d..%d dev=%d tdi=%d algos=%x\n",
+		  t->tio_en, t->tio_init_done,
+		  t->spdm_req_size_min, t->spdm_req_size_max,
+		  t->spdm_rsp_size_min, t->spdm_rsp_size_max,
+		  t->spdm_scratch_size_min, t->spdm_scratch_size_max,
+		  t->spdm_out_size_min, t->spdm_out_size_max,
+		  t->devctx_size, t->tdictx_size,
+		  t->tio_crypto_alg);
+
+	sev->tsmdev = tsmdev;
+	sev->tio_status = t;
+
+	return;
+
+error_exit:
+	pr_err("Failed to enable SEV-TIO: ret=%d en=%d initdone=%d SEV=%d\n",
+	       ret, t->tio_en, t->tio_init_done, boot_cpu_has(X86_FEATURE_SEV));
+	kfree(t);
+}
+
+void sev_tsm_uninit(struct sev_device *sev)
+{
+	if (sev->tsmdev)
+		tsm_unregister(sev->tsmdev);
+
+	sev->tsmdev = NULL;
+}