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, 412 insertions, 0 deletions

diff --git a/drivers/firmware/xilinx/zynqmp-debug.c b/drivers/firmware/xilinx/zynqmp-debug.c
new file mode 100644
index 000000000..36efb827f
--- /dev/null
+++ b/drivers/firmware/xilinx/zynqmp-debug.c
@@ -0,0 +1,412 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Xilinx Zynq MPSoC Firmware layer for debugfs APIs
+ *
+ *  Copyright (C) 2014-2018 Xilinx, Inc.
+ *  Copyright (C) 2022 - 2025 Advanced Micro Devices, Inc.
+ *
+ *  Michal Simek <michal.simek@amd.com>
+ *  Davorin Mista <davorin.mista@aggios.com>
+ *  Jolly Shah <jollys@xilinx.com>
+ *  Rajan Vaja <rajanv@xilinx.com>
+ */
+
+#include <linux/compiler.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/debugfs.h>
+#include <linux/uaccess.h>
+
+#include <linux/firmware/xlnx-zynqmp.h>
+#include "zynqmp-debug.h"
+
+#define PM_API_NAME_LEN			50
+
+struct pm_api_info {
+	u32 api_id;
+	char api_name[PM_API_NAME_LEN];
+	char api_name_len;
+};
+
+static char debugfs_buf[PAGE_SIZE];
+
+#define PM_API(id)		 {id, #id, strlen(#id)}
+static struct pm_api_info pm_api_list[] = {
+	PM_API(PM_FORCE_POWERDOWN),
+	PM_API(PM_REQUEST_WAKEUP),
+	PM_API(PM_SYSTEM_SHUTDOWN),
+	PM_API(PM_REQUEST_NODE),
+	PM_API(PM_RELEASE_NODE),
+	PM_API(PM_SET_REQUIREMENT),
+	PM_API(PM_GET_API_VERSION),
+	PM_API(PM_GET_NODE_STATUS),
+	PM_API(PM_REGISTER_NOTIFIER),
+	PM_API(PM_RESET_ASSERT),
+	PM_API(PM_RESET_GET_STATUS),
+	PM_API(PM_GET_CHIPID),
+	PM_API(PM_PINCTRL_SET_FUNCTION),
+	PM_API(PM_PINCTRL_CONFIG_PARAM_GET),
+	PM_API(PM_PINCTRL_CONFIG_PARAM_SET),
+	PM_API(PM_IOCTL),
+	PM_API(PM_CLOCK_ENABLE),
+	PM_API(PM_CLOCK_DISABLE),
+	PM_API(PM_CLOCK_GETSTATE),
+	PM_API(PM_CLOCK_SETDIVIDER),
+	PM_API(PM_CLOCK_GETDIVIDER),
+	PM_API(PM_CLOCK_SETPARENT),
+	PM_API(PM_CLOCK_GETPARENT),
+	PM_API(PM_QUERY_DATA),
+};
+
+static struct dentry *firmware_debugfs_root;
+
+/**
+ * zynqmp_pm_ioctl - PM IOCTL for device control and configs
+ * @node:	Node ID of the device
+ * @ioctl:	ID of the requested IOCTL
+ * @arg1:	Argument 1 of requested IOCTL call
+ * @arg2:	Argument 2 of requested IOCTL call
+ * @arg3:	Argument 3 of requested IOCTL call
+ * @out:	Returned output value
+ *
+ * Return:	Returns status, either success or error+reason
+ */
+static int zynqmp_pm_ioctl(const u32 node, const u32 ioctl, const u32 arg1,
+			   const u32 arg2, const u32 arg3, u32 *out)
+{
+	return zynqmp_pm_invoke_fn(PM_IOCTL, out, 5, node, ioctl, arg1, arg2, arg3);
+}
+
+/**
+ * zynqmp_pm_argument_value() - Extract argument value from a PM-API request
+ * @arg:	Entered PM-API argument in string format
+ *
+ * Return: Argument value in unsigned integer format on success
+ *	   0 otherwise
+ */
+static u64 zynqmp_pm_argument_value(char *arg)
+{
+	u64 value;
+
+	if (!arg)
+		return 0;
+
+	if (!kstrtou64(arg, 0, &value))
+		return value;
+
+	return 0;
+}
+
+/**
+ * get_pm_api_id() - Extract API-ID from a PM-API request
+ * @pm_api_req:		Entered PM-API argument in string format
+ * @pm_id:		API-ID
+ *
+ * Return: 0 on success else error code
+ */
+static int get_pm_api_id(char *pm_api_req, u32 *pm_id)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(pm_api_list) ; i++) {
+		if (!strncasecmp(pm_api_req, pm_api_list[i].api_name,
+				 pm_api_list[i].api_name_len)) {
+			*pm_id = pm_api_list[i].api_id;
+			break;
+		}
+	}
+
+	/* If no name was entered look for PM-API ID instead */
+	if (i == ARRAY_SIZE(pm_api_list) && kstrtouint(pm_api_req, 10, pm_id))
+		return -EINVAL;
+
+	return 0;
+}
+
+static int process_api_request(u32 pm_id, u64 *pm_api_arg, u32 *pm_api_ret)
+{
+	u32 pm_api_version;
+	int ret;
+	struct zynqmp_pm_query_data qdata = {0};
+
+	switch (pm_id) {
+	case PM_GET_API_VERSION:
+		ret = zynqmp_pm_get_api_version(&pm_api_version);
+		sprintf(debugfs_buf, "PM-API Version = %d.%d\n",
+			pm_api_version >> 16, pm_api_version & 0xffff);
+		break;
+	case PM_FORCE_POWERDOWN:
+		ret = zynqmp_pm_force_pwrdwn(pm_api_arg[0],
+					     pm_api_arg[1] ? pm_api_arg[1] :
+					     ZYNQMP_PM_REQUEST_ACK_NO);
+		break;
+	case PM_REQUEST_WAKEUP:
+		ret = zynqmp_pm_request_wake(pm_api_arg[0],
+					     pm_api_arg[1], pm_api_arg[2],
+					     pm_api_arg[3] ? pm_api_arg[3] :
+					     ZYNQMP_PM_REQUEST_ACK_NO);
+		break;
+	case PM_SYSTEM_SHUTDOWN:
+		ret = zynqmp_pm_system_shutdown(pm_api_arg[0], pm_api_arg[1]);
+		break;
+	case PM_REQUEST_NODE:
+		ret = zynqmp_pm_request_node(pm_api_arg[0],
+					     pm_api_arg[1] ? pm_api_arg[1] :
+					     ZYNQMP_PM_CAPABILITY_ACCESS,
+					     pm_api_arg[2] ? pm_api_arg[2] : 0,
+					     pm_api_arg[3] ? pm_api_arg[3] :
+					     ZYNQMP_PM_REQUEST_ACK_BLOCKING);
+		break;
+	case PM_RELEASE_NODE:
+		ret = zynqmp_pm_release_node(pm_api_arg[0]);
+		break;
+	case PM_SET_REQUIREMENT:
+		ret = zynqmp_pm_set_requirement(pm_api_arg[0],
+						pm_api_arg[1] ? pm_api_arg[1] :
+						ZYNQMP_PM_CAPABILITY_CONTEXT,
+						pm_api_arg[2] ?
+						pm_api_arg[2] : 0,
+						pm_api_arg[3] ? pm_api_arg[3] :
+						ZYNQMP_PM_REQUEST_ACK_BLOCKING);
+		break;
+	case PM_GET_NODE_STATUS:
+		ret = zynqmp_pm_get_node_status(pm_api_arg[0],
+						&pm_api_ret[0],
+						&pm_api_ret[1],
+						&pm_api_ret[2]);
+		if (!ret)
+			sprintf(debugfs_buf,
+				"GET_NODE_STATUS:\n\tNodeId: %llu\n\tStatus: %u\n\tRequirements: %u\n\tUsage: %u\n",
+				pm_api_arg[0], pm_api_ret[0],
+				pm_api_ret[1], pm_api_ret[2]);
+		break;
+	case PM_REGISTER_NOTIFIER:
+		ret = zynqmp_pm_register_notifier(pm_api_arg[0],
+						  pm_api_arg[1] ?
+						  pm_api_arg[1] : 0,
+						  pm_api_arg[2] ?
+						  pm_api_arg[2] : 0,
+						  pm_api_arg[3] ?
+						  pm_api_arg[3] : 0);
+		break;
+	case PM_RESET_ASSERT:
+		ret = zynqmp_pm_reset_assert(pm_api_arg[0], pm_api_arg[1]);
+		break;
+	case PM_RESET_GET_STATUS:
+		ret = zynqmp_pm_reset_get_status(pm_api_arg[0], &pm_api_ret[0]);
+		if (!ret)
+			sprintf(debugfs_buf, "Reset status: %u\n",
+				pm_api_ret[0]);
+		break;
+	case PM_GET_CHIPID:
+		ret = zynqmp_pm_get_chipid(&pm_api_ret[0], &pm_api_ret[1]);
+		if (!ret)
+			sprintf(debugfs_buf, "Idcode: %#x, Version:%#x\n",
+				pm_api_ret[0], pm_api_ret[1]);
+		break;
+	case PM_PINCTRL_SET_FUNCTION:
+		ret = zynqmp_pm_pinctrl_set_function(pm_api_arg[0],
+						     pm_api_arg[1]);
+		break;
+	case PM_PINCTRL_CONFIG_PARAM_GET:
+		ret = zynqmp_pm_pinctrl_get_config(pm_api_arg[0], pm_api_arg[1],
+						   &pm_api_ret[0]);
+		if (!ret)
+			sprintf(debugfs_buf,
+				"Pin: %llu, Param: %llu, Value: %u\n",
+				pm_api_arg[0], pm_api_arg[1],
+				pm_api_ret[0]);
+		break;
+	case PM_PINCTRL_CONFIG_PARAM_SET:
+		ret = zynqmp_pm_pinctrl_set_config(pm_api_arg[0],
+						   pm_api_arg[1],
+						   pm_api_arg[2]);
+		break;
+	case PM_IOCTL:
+		ret = zynqmp_pm_ioctl(pm_api_arg[0], pm_api_arg[1],
+				      pm_api_arg[2], pm_api_arg[3],
+				      pm_api_arg[4], &pm_api_ret[0]);
+		if (!ret && (pm_api_arg[1] == IOCTL_GET_RPU_OPER_MODE ||
+			     pm_api_arg[1] == IOCTL_GET_PLL_FRAC_MODE ||
+			     pm_api_arg[1] == IOCTL_GET_PLL_FRAC_DATA ||
+			     pm_api_arg[1] == IOCTL_READ_GGS ||
+			     pm_api_arg[1] == IOCTL_READ_PGGS ||
+			     pm_api_arg[1] == IOCTL_READ_REG))
+			sprintf(debugfs_buf, "IOCTL return value: %u\n",
+				pm_api_ret[1]);
+		if (!ret && pm_api_arg[1] == IOCTL_GET_QOS)
+			sprintf(debugfs_buf, "Default QoS: %u\nCurrent QoS: %u\n",
+				pm_api_ret[1], pm_api_ret[2]);
+		break;
+	case PM_CLOCK_ENABLE:
+		ret = zynqmp_pm_clock_enable(pm_api_arg[0]);
+		break;
+	case PM_CLOCK_DISABLE:
+		ret = zynqmp_pm_clock_disable(pm_api_arg[0]);
+		break;
+	case PM_CLOCK_GETSTATE:
+		ret = zynqmp_pm_clock_getstate(pm_api_arg[0], &pm_api_ret[0]);
+		if (!ret)
+			sprintf(debugfs_buf, "Clock state: %u\n",
+				pm_api_ret[0]);
+		break;
+	case PM_CLOCK_SETDIVIDER:
+		ret = zynqmp_pm_clock_setdivider(pm_api_arg[0], pm_api_arg[1]);
+		break;
+	case PM_CLOCK_GETDIVIDER:
+		ret = zynqmp_pm_clock_getdivider(pm_api_arg[0], &pm_api_ret[0]);
+		if (!ret)
+			sprintf(debugfs_buf, "Divider Value: %d\n",
+				pm_api_ret[0]);
+		break;
+	case PM_CLOCK_SETPARENT:
+		ret = zynqmp_pm_clock_setparent(pm_api_arg[0], pm_api_arg[1]);
+		break;
+	case PM_CLOCK_GETPARENT:
+		ret = zynqmp_pm_clock_getparent(pm_api_arg[0], &pm_api_ret[0]);
+		if (!ret)
+			sprintf(debugfs_buf,
+				"Clock parent Index: %u\n", pm_api_ret[0]);
+		break;
+	case PM_QUERY_DATA:
+		qdata.qid = pm_api_arg[0];
+		qdata.arg1 = pm_api_arg[1];
+		qdata.arg2 = pm_api_arg[2];
+		qdata.arg3 = pm_api_arg[3];
+
+		ret = zynqmp_pm_query_data(qdata, pm_api_ret);
+		if (ret)
+			break;
+
+		switch (qdata.qid) {
+		case PM_QID_CLOCK_GET_NAME:
+			sprintf(debugfs_buf, "Clock name = %s\n",
+				(char *)pm_api_ret);
+			break;
+		case PM_QID_CLOCK_GET_FIXEDFACTOR_PARAMS:
+			sprintf(debugfs_buf, "Multiplier = %d, Divider = %d\n",
+				pm_api_ret[1], pm_api_ret[2]);
+			break;
+		default:
+			sprintf(debugfs_buf,
+				"data[0] = 0x%08x\ndata[1] = 0x%08x\n data[2] = 0x%08x\ndata[3] = 0x%08x\n",
+				pm_api_ret[0], pm_api_ret[1],
+				pm_api_ret[2], pm_api_ret[3]);
+		}
+		break;
+	default:
+		sprintf(debugfs_buf, "Unsupported PM-API request\n");
+		ret = -EINVAL;
+	}
+
+	return ret;
+}
+
+/**
+ * zynqmp_pm_debugfs_api_write() - debugfs write function
+ * @file:	User file
+ * @ptr:	User entered PM-API string
+ * @len:	Length of the userspace buffer
+ * @off:	Offset within the file
+ *
+ * Used for triggering pm api functions by writing
+ * echo <pm_api_id>	> /sys/kernel/debug/zynqmp_pm/power or
+ * echo <pm_api_name>	> /sys/kernel/debug/zynqmp_pm/power
+ *
+ * Return: Number of bytes copied if PM-API request succeeds,
+ *	   the corresponding error code otherwise
+ */
+static ssize_t zynqmp_pm_debugfs_api_write(struct file *file,
+					   const char __user *ptr, size_t len,
+					   loff_t *off)
+{
+	char *kern_buff, *tmp_buff;
+	char *pm_api_req;
+	u32 pm_id = 0;
+	u64 pm_api_arg[5] = {0, 0, 0, 0, 0};
+	/* Return values from PM APIs calls */
+	u32 pm_api_ret[4] = {0, 0, 0, 0};
+
+	int ret;
+	int i = 0;
+
+	strcpy(debugfs_buf, "");
+
+	if (*off != 0 || len <= 1 || len > PAGE_SIZE - 1)
+		return -EINVAL;
+
+	kern_buff = memdup_user_nul(ptr, len);
+	if (IS_ERR(kern_buff))
+		return PTR_ERR(kern_buff);
+	tmp_buff = kern_buff;
+
+	/* Read the API name from a user request */
+	pm_api_req = strsep(&kern_buff, " ");
+
+	ret = get_pm_api_id(pm_api_req, &pm_id);
+	if (ret < 0)
+		goto err;
+
+	/* Read node_id and arguments from the PM-API request */
+	pm_api_req = strsep(&kern_buff, " ");
+	while ((i < ARRAY_SIZE(pm_api_arg)) && pm_api_req) {
+		pm_api_arg[i++] = zynqmp_pm_argument_value(pm_api_req);
+		pm_api_req = strsep(&kern_buff, " ");
+	}
+
+	ret = process_api_request(pm_id, pm_api_arg, pm_api_ret);
+
+err:
+	kfree(tmp_buff);
+	if (ret)
+		return ret;
+
+	return len;
+}
+
+/**
+ * zynqmp_pm_debugfs_api_read() - debugfs read function
+ * @file:	User file
+ * @ptr:	Requested pm_api_version string
+ * @len:	Length of the userspace buffer
+ * @off:	Offset within the file
+ *
+ * Return: Length of the version string on success
+ *	   else error code
+ */
+static ssize_t zynqmp_pm_debugfs_api_read(struct file *file, char __user *ptr,
+					  size_t len, loff_t *off)
+{
+	return simple_read_from_buffer(ptr, len, off, debugfs_buf,
+				       strlen(debugfs_buf));
+}
+
+/* Setup debugfs fops */
+static const struct file_operations fops_zynqmp_pm_dbgfs = {
+	.owner = THIS_MODULE,
+	.write = zynqmp_pm_debugfs_api_write,
+	.read = zynqmp_pm_debugfs_api_read,
+};
+
+/**
+ * zynqmp_pm_api_debugfs_init - Initialize debugfs interface
+ *
+ * Return:	None
+ */
+void zynqmp_pm_api_debugfs_init(void)
+{
+	/* Initialize debugfs interface */
+	firmware_debugfs_root = debugfs_create_dir("zynqmp-firmware", NULL);
+	debugfs_create_file("pm", 0660, firmware_debugfs_root, NULL,
+			    &fops_zynqmp_pm_dbgfs);
+}
+
+/**
+ * zynqmp_pm_api_debugfs_exit - Remove debugfs interface
+ *
+ * Return:	None
+ */
+void zynqmp_pm_api_debugfs_exit(void)
+{
+	debugfs_remove_recursive(firmware_debugfs_root);
+}