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, 434 insertions, 0 deletions

diff --git a/drivers/acpi/pfr_telemetry.c b/drivers/acpi/pfr_telemetry.c
new file mode 100644
index 000000000..238737683
--- /dev/null
+++ b/drivers/acpi/pfr_telemetry.c
@@ -0,0 +1,434 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ACPI Platform Firmware Runtime Telemetry driver
+ *
+ * Copyright (C) 2021 Intel Corporation
+ * Author: Chen Yu <yu.c.chen@intel.com>
+ *
+ * This driver allows user space to fetch telemetry data from the
+ * firmware with the help of the Platform Firmware Runtime Telemetry
+ * interface.
+ */
+#include <linux/acpi.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/mm.h>
+#include <linux/platform_device.h>
+#include <linux/string.h>
+#include <linux/uaccess.h>
+#include <linux/uio.h>
+#include <linux/uuid.h>
+
+#include <uapi/linux/pfrut.h>
+
+#define PFRT_LOG_EXEC_IDX	0
+#define PFRT_LOG_HISTORY_IDX	1
+
+#define PFRT_LOG_ERR		0
+#define PFRT_LOG_WARN	1
+#define PFRT_LOG_INFO	2
+#define PFRT_LOG_VERB	4
+
+#define PFRT_FUNC_SET_LEV		1
+#define PFRT_FUNC_GET_LEV		2
+#define PFRT_FUNC_GET_DATA		3
+
+#define PFRT_REVID_1		1
+#define PFRT_REVID_2		2
+#define PFRT_DEFAULT_REV_ID	PFRT_REVID_1
+
+enum log_index {
+	LOG_STATUS_IDX = 0,
+	LOG_EXT_STATUS_IDX = 1,
+	LOG_MAX_SZ_IDX = 2,
+	LOG_CHUNK1_LO_IDX = 3,
+	LOG_CHUNK1_HI_IDX = 4,
+	LOG_CHUNK1_SZ_IDX = 5,
+	LOG_CHUNK2_LO_IDX = 6,
+	LOG_CHUNK2_HI_IDX = 7,
+	LOG_CHUNK2_SZ_IDX = 8,
+	LOG_ROLLOVER_CNT_IDX = 9,
+	LOG_RESET_CNT_IDX = 10,
+	LOG_NR_IDX
+};
+
+struct pfrt_log_device {
+	int index;
+	struct pfrt_log_info info;
+	struct device *parent_dev;
+	struct miscdevice miscdev;
+};
+
+/* pfrt_guid is the parameter for _DSM method */
+static const guid_t pfrt_log_guid =
+	GUID_INIT(0x75191659, 0x8178, 0x4D9D, 0xB8, 0x8F, 0xAC, 0x5E,
+		  0x5E, 0x93, 0xE8, 0xBF);
+
+static DEFINE_IDA(pfrt_log_ida);
+
+static inline struct pfrt_log_device *to_pfrt_log_dev(struct file *file)
+{
+	return container_of(file->private_data, struct pfrt_log_device, miscdev);
+}
+
+static int get_pfrt_log_data_info(struct pfrt_log_data_info *data_info,
+				  struct pfrt_log_device *pfrt_log_dev)
+{
+	acpi_handle handle = ACPI_HANDLE(pfrt_log_dev->parent_dev);
+	union acpi_object *out_obj, in_obj, in_buf;
+	int ret = -EBUSY;
+
+	memset(data_info, 0, sizeof(*data_info));
+	memset(&in_obj, 0, sizeof(in_obj));
+	memset(&in_buf, 0, sizeof(in_buf));
+	in_obj.type = ACPI_TYPE_PACKAGE;
+	in_obj.package.count = 1;
+	in_obj.package.elements = &in_buf;
+	in_buf.type = ACPI_TYPE_INTEGER;
+	in_buf.integer.value = pfrt_log_dev->info.log_type;
+
+	out_obj = acpi_evaluate_dsm_typed(handle, &pfrt_log_guid,
+					  pfrt_log_dev->info.log_revid, PFRT_FUNC_GET_DATA,
+					  &in_obj, ACPI_TYPE_PACKAGE);
+	if (!out_obj)
+		return -EINVAL;
+
+	if (out_obj->package.count < LOG_NR_IDX ||
+	    out_obj->package.elements[LOG_STATUS_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[LOG_EXT_STATUS_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[LOG_MAX_SZ_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[LOG_CHUNK1_LO_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[LOG_CHUNK1_HI_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[LOG_CHUNK1_SZ_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[LOG_CHUNK2_LO_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[LOG_CHUNK2_HI_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[LOG_CHUNK2_SZ_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[LOG_ROLLOVER_CNT_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[LOG_RESET_CNT_IDX].type != ACPI_TYPE_INTEGER)
+		goto free_acpi_buffer;
+
+	data_info->status = out_obj->package.elements[LOG_STATUS_IDX].integer.value;
+	data_info->ext_status =
+		out_obj->package.elements[LOG_EXT_STATUS_IDX].integer.value;
+	if (data_info->status != DSM_SUCCEED) {
+		dev_dbg(pfrt_log_dev->parent_dev, "Error Status:%d\n", data_info->status);
+		dev_dbg(pfrt_log_dev->parent_dev, "Error Extend Status:%d\n",
+			data_info->ext_status);
+		goto free_acpi_buffer;
+	}
+
+	data_info->max_data_size =
+		out_obj->package.elements[LOG_MAX_SZ_IDX].integer.value;
+	data_info->chunk1_addr_lo =
+		out_obj->package.elements[LOG_CHUNK1_LO_IDX].integer.value;
+	data_info->chunk1_addr_hi =
+		out_obj->package.elements[LOG_CHUNK1_HI_IDX].integer.value;
+	data_info->chunk1_size =
+		out_obj->package.elements[LOG_CHUNK1_SZ_IDX].integer.value;
+	data_info->chunk2_addr_lo =
+		out_obj->package.elements[LOG_CHUNK2_LO_IDX].integer.value;
+	data_info->chunk2_addr_hi =
+		out_obj->package.elements[LOG_CHUNK2_HI_IDX].integer.value;
+	data_info->chunk2_size =
+		out_obj->package.elements[LOG_CHUNK2_SZ_IDX].integer.value;
+	data_info->rollover_cnt =
+		out_obj->package.elements[LOG_ROLLOVER_CNT_IDX].integer.value;
+	data_info->reset_cnt =
+		out_obj->package.elements[LOG_RESET_CNT_IDX].integer.value;
+
+	ret = 0;
+
+free_acpi_buffer:
+	ACPI_FREE(out_obj);
+
+	return ret;
+}
+
+static int set_pfrt_log_level(int level, struct pfrt_log_device *pfrt_log_dev)
+{
+	acpi_handle handle = ACPI_HANDLE(pfrt_log_dev->parent_dev);
+	union acpi_object *out_obj, *obj, in_obj, in_buf;
+	enum pfru_dsm_status status, ext_status;
+	int ret = 0;
+
+	memset(&in_obj, 0, sizeof(in_obj));
+	memset(&in_buf, 0, sizeof(in_buf));
+	in_obj.type = ACPI_TYPE_PACKAGE;
+	in_obj.package.count = 1;
+	in_obj.package.elements = &in_buf;
+	in_buf.type = ACPI_TYPE_INTEGER;
+	in_buf.integer.value = level;
+
+	out_obj = acpi_evaluate_dsm_typed(handle, &pfrt_log_guid,
+					  pfrt_log_dev->info.log_revid, PFRT_FUNC_SET_LEV,
+					  &in_obj, ACPI_TYPE_PACKAGE);
+	if (!out_obj)
+		return -EINVAL;
+
+	obj = &out_obj->package.elements[0];
+	status = obj->integer.value;
+	if (status != DSM_SUCCEED) {
+		obj = &out_obj->package.elements[1];
+		ext_status = obj->integer.value;
+		dev_dbg(pfrt_log_dev->parent_dev, "Error Status:%d\n", status);
+		dev_dbg(pfrt_log_dev->parent_dev, "Error Extend Status:%d\n", ext_status);
+		ret = -EBUSY;
+	}
+
+	ACPI_FREE(out_obj);
+
+	return ret;
+}
+
+static int get_pfrt_log_level(struct pfrt_log_device *pfrt_log_dev)
+{
+	acpi_handle handle = ACPI_HANDLE(pfrt_log_dev->parent_dev);
+	union acpi_object *out_obj, *obj;
+	enum pfru_dsm_status status, ext_status;
+	int ret = -EBUSY;
+
+	out_obj = acpi_evaluate_dsm_typed(handle, &pfrt_log_guid,
+					  pfrt_log_dev->info.log_revid, PFRT_FUNC_GET_LEV,
+					  NULL, ACPI_TYPE_PACKAGE);
+	if (!out_obj)
+		return -EINVAL;
+
+	obj = &out_obj->package.elements[0];
+	if (obj->type != ACPI_TYPE_INTEGER)
+		goto free_acpi_buffer;
+
+	status = obj->integer.value;
+	if (status != DSM_SUCCEED) {
+		obj = &out_obj->package.elements[1];
+		ext_status = obj->integer.value;
+		dev_dbg(pfrt_log_dev->parent_dev, "Error Status:%d\n", status);
+		dev_dbg(pfrt_log_dev->parent_dev, "Error Extend Status:%d\n", ext_status);
+		goto free_acpi_buffer;
+	}
+
+	obj = &out_obj->package.elements[2];
+	if (obj->type != ACPI_TYPE_INTEGER)
+		goto free_acpi_buffer;
+
+	ret = obj->integer.value;
+
+free_acpi_buffer:
+	ACPI_FREE(out_obj);
+
+	return ret;
+}
+
+static int valid_log_level(u32 level)
+{
+	return level == PFRT_LOG_ERR || level == PFRT_LOG_WARN ||
+	       level == PFRT_LOG_INFO || level == PFRT_LOG_VERB;
+}
+
+static int valid_log_type(u32 type)
+{
+	return type == PFRT_LOG_EXEC_IDX || type == PFRT_LOG_HISTORY_IDX;
+}
+
+static inline int valid_log_revid(u32 id)
+{
+	return id == PFRT_REVID_1 || id == PFRT_REVID_2;
+}
+
+static long pfrt_log_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct pfrt_log_device *pfrt_log_dev = to_pfrt_log_dev(file);
+	struct pfrt_log_data_info data_info;
+	struct pfrt_log_info info;
+	void __user *p;
+	int ret = 0;
+
+	p = (void __user *)arg;
+
+	switch (cmd) {
+	case PFRT_LOG_IOC_SET_INFO:
+		if (copy_from_user(&info, p, sizeof(info)))
+			return -EFAULT;
+
+		if (valid_log_revid(info.log_revid))
+			pfrt_log_dev->info.log_revid = info.log_revid;
+
+		if (valid_log_level(info.log_level)) {
+			ret = set_pfrt_log_level(info.log_level, pfrt_log_dev);
+			if (ret < 0)
+				return ret;
+
+			pfrt_log_dev->info.log_level = info.log_level;
+		}
+
+		if (valid_log_type(info.log_type))
+			pfrt_log_dev->info.log_type = info.log_type;
+
+		return 0;
+
+	case PFRT_LOG_IOC_GET_INFO:
+		info.log_level = get_pfrt_log_level(pfrt_log_dev);
+		info.log_type = pfrt_log_dev->info.log_type;
+		info.log_revid = pfrt_log_dev->info.log_revid;
+		if (copy_to_user(p, &info, sizeof(info)))
+			return -EFAULT;
+
+		return 0;
+
+	case PFRT_LOG_IOC_GET_DATA_INFO:
+		ret = get_pfrt_log_data_info(&data_info, pfrt_log_dev);
+		if (ret)
+			return ret;
+
+		if (copy_to_user(p, &data_info, sizeof(struct pfrt_log_data_info)))
+			return -EFAULT;
+
+		return 0;
+
+	default:
+		return -ENOTTY;
+	}
+}
+
+static int
+pfrt_log_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	struct pfrt_log_device *pfrt_log_dev;
+	struct pfrt_log_data_info info;
+	unsigned long psize, vsize;
+	phys_addr_t base_addr;
+	int ret;
+
+	if (vma->vm_flags & VM_WRITE)
+		return -EROFS;
+
+	/* changing from read to write with mprotect is not allowed */
+	vm_flags_clear(vma, VM_MAYWRITE);
+
+	pfrt_log_dev = to_pfrt_log_dev(file);
+
+	ret = get_pfrt_log_data_info(&info, pfrt_log_dev);
+	if (ret)
+		return ret;
+
+	base_addr = (phys_addr_t)((info.chunk2_addr_hi << 32) | info.chunk2_addr_lo);
+	/* pfrt update has not been launched yet */
+	if (!base_addr)
+		return -ENODEV;
+
+	psize = info.max_data_size;
+	/* base address and total buffer size must be page aligned */
+	if (!PAGE_ALIGNED(base_addr) || !PAGE_ALIGNED(psize))
+		return -ENODEV;
+
+	vsize = vma->vm_end - vma->vm_start;
+	if (vsize > psize)
+		return -EINVAL;
+
+	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+	if (io_remap_pfn_range(vma, vma->vm_start, PFN_DOWN(base_addr),
+			       vsize, vma->vm_page_prot))
+		return -EAGAIN;
+
+	return 0;
+}
+
+static const struct file_operations acpi_pfrt_log_fops = {
+	.owner		= THIS_MODULE,
+	.mmap		= pfrt_log_mmap,
+	.unlocked_ioctl = pfrt_log_ioctl,
+	.llseek		= noop_llseek,
+};
+
+static void acpi_pfrt_log_remove(struct platform_device *pdev)
+{
+	struct pfrt_log_device *pfrt_log_dev = platform_get_drvdata(pdev);
+
+	misc_deregister(&pfrt_log_dev->miscdev);
+}
+
+static void pfrt_log_put_idx(void *data)
+{
+	struct pfrt_log_device *pfrt_log_dev = data;
+
+	ida_free(&pfrt_log_ida, pfrt_log_dev->index);
+}
+
+static int acpi_pfrt_log_probe(struct platform_device *pdev)
+{
+	struct pfrt_log_device *pfrt_log_dev;
+	acpi_handle handle;
+	int ret;
+
+	handle = ACPI_HANDLE(&pdev->dev);
+	if (!handle)
+		return -ENODEV;
+
+	if (!acpi_has_method(handle, "_DSM")) {
+		dev_dbg(&pdev->dev, "Missing _DSM\n");
+		return -ENODEV;
+	}
+
+	pfrt_log_dev = devm_kzalloc(&pdev->dev, sizeof(*pfrt_log_dev), GFP_KERNEL);
+	if (!pfrt_log_dev)
+		return -ENOMEM;
+
+	ret = ida_alloc(&pfrt_log_ida, GFP_KERNEL);
+	if (ret < 0)
+		return ret;
+
+	pfrt_log_dev->index = ret;
+	ret = devm_add_action_or_reset(&pdev->dev, pfrt_log_put_idx, pfrt_log_dev);
+	if (ret)
+		return ret;
+
+	pfrt_log_dev->info.log_revid = PFRT_DEFAULT_REV_ID;
+	pfrt_log_dev->parent_dev = &pdev->dev;
+
+	pfrt_log_dev->miscdev.minor = MISC_DYNAMIC_MINOR;
+	pfrt_log_dev->miscdev.name = devm_kasprintf(&pdev->dev, GFP_KERNEL,
+						    "pfrt%d",
+						    pfrt_log_dev->index);
+	if (!pfrt_log_dev->miscdev.name)
+		return -ENOMEM;
+
+	pfrt_log_dev->miscdev.nodename = devm_kasprintf(&pdev->dev, GFP_KERNEL,
+							"acpi_pfr_telemetry%d",
+							pfrt_log_dev->index);
+	if (!pfrt_log_dev->miscdev.nodename)
+		return -ENOMEM;
+
+	pfrt_log_dev->miscdev.fops = &acpi_pfrt_log_fops;
+	pfrt_log_dev->miscdev.parent = &pdev->dev;
+
+	ret = misc_register(&pfrt_log_dev->miscdev);
+	if (ret)
+		return ret;
+
+	platform_set_drvdata(pdev, pfrt_log_dev);
+
+	return 0;
+}
+
+static const struct acpi_device_id acpi_pfrt_log_ids[] = {
+	{"INTC1081"},
+	{}
+};
+MODULE_DEVICE_TABLE(acpi, acpi_pfrt_log_ids);
+
+static struct platform_driver acpi_pfrt_log_driver = {
+	.driver = {
+		.name = "pfr_telemetry",
+		.acpi_match_table = acpi_pfrt_log_ids,
+	},
+	.probe = acpi_pfrt_log_probe,
+	.remove = acpi_pfrt_log_remove,
+};
+module_platform_driver(acpi_pfrt_log_driver);
+
+MODULE_DESCRIPTION("Platform Firmware Runtime Update Telemetry driver");
+MODULE_LICENSE("GPL v2");