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, 262 insertions, 0 deletions

diff --git a/drivers/base/topology.c b/drivers/base/topology.c
new file mode 100644
index 000000000..c890e2a5b
--- /dev/null
+++ b/drivers/base/topology.c
@@ -0,0 +1,262 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * driver/base/topology.c - Populate sysfs with cpu topology information
+ *
+ * Written by: Zhang Yanmin, Intel Corporation
+ *
+ * Copyright (C) 2006, Intel Corp.
+ *
+ * All rights reserved.
+ */
+#include <linux/mm.h>
+#include <linux/cpu.h>
+#include <linux/module.h>
+#include <linux/hardirq.h>
+#include <linux/topology.h>
+
+#define define_id_show_func(name, fmt)					\
+static ssize_t name##_show(struct device *dev,				\
+			   struct device_attribute *attr, char *buf)	\
+{									\
+	return sysfs_emit(buf, fmt "\n", topology_##name(dev->id));	\
+}
+
+#define define_siblings_read_func(name, mask)					\
+static ssize_t name##_read(struct file *file, struct kobject *kobj,		\
+			   const struct bin_attribute *attr, char *buf,		\
+			   loff_t off, size_t count)				\
+{										\
+	struct device *dev = kobj_to_dev(kobj);                                 \
+	cpumask_var_t mask;							\
+	ssize_t n;								\
+										\
+	if (!alloc_cpumask_var(&mask, GFP_KERNEL))				\
+		return -ENOMEM;							\
+										\
+	cpumask_copy(mask, topology_##mask(dev->id));				\
+	n = cpumap_print_bitmask_to_buf(buf, mask, off, count);			\
+	free_cpumask_var(mask);							\
+										\
+	return n;								\
+}										\
+										\
+static ssize_t name##_list_read(struct file *file, struct kobject *kobj,	\
+				const struct bin_attribute *attr, char *buf,	\
+				loff_t off, size_t count)			\
+{										\
+	struct device *dev = kobj_to_dev(kobj);					\
+	cpumask_var_t mask;							\
+	ssize_t n;								\
+										\
+	if (!alloc_cpumask_var(&mask, GFP_KERNEL))				\
+		return -ENOMEM;							\
+										\
+	cpumask_copy(mask, topology_##mask(dev->id));				\
+	n = cpumap_print_list_to_buf(buf, mask, off, count);			\
+	free_cpumask_var(mask);							\
+										\
+	return n;								\
+}
+
+define_id_show_func(physical_package_id, "%d");
+static DEVICE_ATTR_RO(physical_package_id);
+
+#ifdef TOPOLOGY_DIE_SYSFS
+define_id_show_func(die_id, "%d");
+static DEVICE_ATTR_RO(die_id);
+#endif
+
+#ifdef TOPOLOGY_CLUSTER_SYSFS
+define_id_show_func(cluster_id, "%d");
+static DEVICE_ATTR_RO(cluster_id);
+#endif
+
+define_id_show_func(core_id, "%d");
+static DEVICE_ATTR_RO(core_id);
+
+define_id_show_func(ppin, "0x%llx");
+static DEVICE_ATTR_ADMIN_RO(ppin);
+
+define_siblings_read_func(thread_siblings, sibling_cpumask);
+static const BIN_ATTR_RO(thread_siblings, CPUMAP_FILE_MAX_BYTES);
+static const BIN_ATTR_RO(thread_siblings_list, CPULIST_FILE_MAX_BYTES);
+
+define_siblings_read_func(core_cpus, sibling_cpumask);
+static const BIN_ATTR_RO(core_cpus, CPUMAP_FILE_MAX_BYTES);
+static const BIN_ATTR_RO(core_cpus_list, CPULIST_FILE_MAX_BYTES);
+
+define_siblings_read_func(core_siblings, core_cpumask);
+static const BIN_ATTR_RO(core_siblings, CPUMAP_FILE_MAX_BYTES);
+static const BIN_ATTR_RO(core_siblings_list, CPULIST_FILE_MAX_BYTES);
+
+#ifdef TOPOLOGY_CLUSTER_SYSFS
+define_siblings_read_func(cluster_cpus, cluster_cpumask);
+static const BIN_ATTR_RO(cluster_cpus, CPUMAP_FILE_MAX_BYTES);
+static const BIN_ATTR_RO(cluster_cpus_list, CPULIST_FILE_MAX_BYTES);
+#endif
+
+#ifdef TOPOLOGY_DIE_SYSFS
+define_siblings_read_func(die_cpus, die_cpumask);
+static const BIN_ATTR_RO(die_cpus, CPUMAP_FILE_MAX_BYTES);
+static const BIN_ATTR_RO(die_cpus_list, CPULIST_FILE_MAX_BYTES);
+#endif
+
+define_siblings_read_func(package_cpus, core_cpumask);
+static const BIN_ATTR_RO(package_cpus, CPUMAP_FILE_MAX_BYTES);
+static const BIN_ATTR_RO(package_cpus_list, CPULIST_FILE_MAX_BYTES);
+
+#ifdef TOPOLOGY_BOOK_SYSFS
+define_id_show_func(book_id, "%d");
+static DEVICE_ATTR_RO(book_id);
+define_siblings_read_func(book_siblings, book_cpumask);
+static const BIN_ATTR_RO(book_siblings, CPUMAP_FILE_MAX_BYTES);
+static const BIN_ATTR_RO(book_siblings_list, CPULIST_FILE_MAX_BYTES);
+#endif
+
+#ifdef TOPOLOGY_DRAWER_SYSFS
+define_id_show_func(drawer_id, "%d");
+static DEVICE_ATTR_RO(drawer_id);
+define_siblings_read_func(drawer_siblings, drawer_cpumask);
+static const BIN_ATTR_RO(drawer_siblings, CPUMAP_FILE_MAX_BYTES);
+static const BIN_ATTR_RO(drawer_siblings_list, CPULIST_FILE_MAX_BYTES);
+#endif
+
+static const struct bin_attribute *const bin_attrs[] = {
+	&bin_attr_core_cpus,
+	&bin_attr_core_cpus_list,
+	&bin_attr_thread_siblings,
+	&bin_attr_thread_siblings_list,
+	&bin_attr_core_siblings,
+	&bin_attr_core_siblings_list,
+#ifdef TOPOLOGY_CLUSTER_SYSFS
+	&bin_attr_cluster_cpus,
+	&bin_attr_cluster_cpus_list,
+#endif
+#ifdef TOPOLOGY_DIE_SYSFS
+	&bin_attr_die_cpus,
+	&bin_attr_die_cpus_list,
+#endif
+	&bin_attr_package_cpus,
+	&bin_attr_package_cpus_list,
+#ifdef TOPOLOGY_BOOK_SYSFS
+	&bin_attr_book_siblings,
+	&bin_attr_book_siblings_list,
+#endif
+#ifdef TOPOLOGY_DRAWER_SYSFS
+	&bin_attr_drawer_siblings,
+	&bin_attr_drawer_siblings_list,
+#endif
+	NULL
+};
+
+static struct attribute *default_attrs[] = {
+	&dev_attr_physical_package_id.attr,
+#ifdef TOPOLOGY_DIE_SYSFS
+	&dev_attr_die_id.attr,
+#endif
+#ifdef TOPOLOGY_CLUSTER_SYSFS
+	&dev_attr_cluster_id.attr,
+#endif
+	&dev_attr_core_id.attr,
+#ifdef TOPOLOGY_BOOK_SYSFS
+	&dev_attr_book_id.attr,
+#endif
+#ifdef TOPOLOGY_DRAWER_SYSFS
+	&dev_attr_drawer_id.attr,
+#endif
+	&dev_attr_ppin.attr,
+	NULL
+};
+
+static umode_t topology_is_visible(struct kobject *kobj,
+				   struct attribute *attr, int unused)
+{
+	if (attr == &dev_attr_ppin.attr && !topology_ppin(kobj_to_dev(kobj)->id))
+		return 0;
+
+	return attr->mode;
+}
+
+static const struct attribute_group topology_attr_group = {
+	.attrs = default_attrs,
+	.bin_attrs = bin_attrs,
+	.is_visible = topology_is_visible,
+	.name = "topology"
+};
+
+/* Add/Remove cpu_topology interface for CPU device */
+static int topology_add_dev(unsigned int cpu)
+{
+	struct device *dev = get_cpu_device(cpu);
+
+	return sysfs_create_group(&dev->kobj, &topology_attr_group);
+}
+
+static int topology_remove_dev(unsigned int cpu)
+{
+	struct device *dev = get_cpu_device(cpu);
+
+	sysfs_remove_group(&dev->kobj, &topology_attr_group);
+	return 0;
+}
+
+static int __init topology_sysfs_init(void)
+{
+	return cpuhp_setup_state(CPUHP_TOPOLOGY_PREPARE,
+				 "base/topology:prepare", topology_add_dev,
+				 topology_remove_dev);
+}
+
+device_initcall(topology_sysfs_init);
+
+DEFINE_PER_CPU(unsigned long, cpu_scale) = SCHED_CAPACITY_SCALE;
+EXPORT_PER_CPU_SYMBOL_GPL(cpu_scale);
+
+void topology_set_cpu_scale(unsigned int cpu, unsigned long capacity)
+{
+	per_cpu(cpu_scale, cpu) = capacity;
+}
+
+static ssize_t cpu_capacity_show(struct device *dev,
+				 struct device_attribute *attr,
+				 char *buf)
+{
+	struct cpu *cpu = container_of(dev, struct cpu, dev);
+
+	return sysfs_emit(buf, "%lu\n", topology_get_cpu_scale(cpu->dev.id));
+}
+
+static DEVICE_ATTR_RO(cpu_capacity);
+
+static int cpu_capacity_sysctl_add(unsigned int cpu)
+{
+	struct device *cpu_dev = get_cpu_device(cpu);
+
+	if (!cpu_dev)
+		return -ENOENT;
+
+	device_create_file(cpu_dev, &dev_attr_cpu_capacity);
+
+	return 0;
+}
+
+static int cpu_capacity_sysctl_remove(unsigned int cpu)
+{
+	struct device *cpu_dev = get_cpu_device(cpu);
+
+	if (!cpu_dev)
+		return -ENOENT;
+
+	device_remove_file(cpu_dev, &dev_attr_cpu_capacity);
+
+	return 0;
+}
+
+static int register_cpu_capacity_sysctl(void)
+{
+	cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "topology/cpu-capacity",
+			  cpu_capacity_sysctl_add, cpu_capacity_sysctl_remove);
+
+	return 0;
+}
+subsys_initcall(register_cpu_capacity_sysctl);