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, 112 insertions, 0 deletions

diff --git a/drivers/mfd/rohm-pwrbutton.c b/drivers/mfd/rohm-pwrbutton.c
new file mode 100644
index 000000000..96a6d1f01
--- /dev/null
+++ b/drivers/mfd/rohm-pwrbutton.c
@@ -0,0 +1,112 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Shared helper for ROHM PMIC power button registration
+ *
+ * Copyright 2018, 2019 ROHM Semiconductors
+ * Copyright 2026 Google LLC
+ */
+
+#include <linux/device/devres.h>
+#include <linux/gfp_types.h>
+#include <linux/input.h>
+#include <linux/mfd/core.h>
+#include <linux/module.h>
+#include <linux/property.h>
+#include <linux/slab.h>
+
+#include "rohm-pwrbutton.h"
+
+#define GPIO_KEYS  0	/* Node corresponding to gpio-keys device itself */
+#define PWRON_KEY  1	/* Node describing power button in gpio-keys */
+
+static int rohm_pwrbutton_register_swnodes(const struct software_node *nodes)
+{
+	const struct software_node * const node_group[] = {
+		&nodes[GPIO_KEYS], &nodes[PWRON_KEY], NULL
+	};
+
+	return software_node_register_node_group(node_group);
+}
+
+static void rohm_pwrbutton_unregister_swnodes(void *data)
+{
+	const struct software_node *nodes = data;
+	const struct software_node * const node_group[] = {
+		&nodes[GPIO_KEYS], &nodes[PWRON_KEY], NULL
+	};
+
+	software_node_unregister_node_group(node_group);
+}
+
+int rohm_register_pwrbutton(struct device *dev, int irq, const char *name,
+			    bool wakeup, struct irq_domain *irq_domain)
+{
+	const struct resource res[] = {
+		DEFINE_RES_IRQ_NAMED(irq, name),
+	};
+	struct mfd_cell gpio_keys_cell = {
+		.name = "gpio-keys",
+		.resources = res,
+		.num_resources = ARRAY_SIZE(res),
+	};
+	struct property_entry *parent_props;
+	struct property_entry *child_props;
+	struct software_node *nodes;
+	int n_props;
+	int ret;
+
+	if (irq <= 0)
+		return -EINVAL;
+
+	nodes = devm_kcalloc(dev, 2, sizeof(*nodes), GFP_KERNEL);
+	if (!nodes)
+		return -ENOMEM;
+
+	nodes[GPIO_KEYS].name = devm_kasprintf(dev, GFP_KERNEL, "%s-power-key", dev_name(dev));
+	if (!nodes[GPIO_KEYS].name)
+		return -ENOMEM;
+
+	parent_props = devm_kcalloc(dev, 2, sizeof(*parent_props), GFP_KERNEL);
+	if (!parent_props)
+		return -ENOMEM;
+
+	parent_props[0] = PROPERTY_ENTRY_STRING("label", name);
+	nodes[GPIO_KEYS].properties = parent_props;
+
+	n_props = 2; /* linux,code and terminator */
+	if (wakeup)
+		n_props++;
+
+	child_props = devm_kcalloc(dev, n_props, sizeof(*child_props), GFP_KERNEL);
+	if (!child_props)
+		return -ENOMEM;
+
+	child_props[0] = PROPERTY_ENTRY_U32("linux,code", KEY_POWER);
+	if (wakeup)
+		child_props[1] = PROPERTY_ENTRY_BOOL("wakeup-source");
+
+	nodes[PWRON_KEY].parent = &nodes[GPIO_KEYS];
+	nodes[PWRON_KEY].properties = child_props;
+
+	ret = rohm_pwrbutton_register_swnodes(nodes);
+	if (ret)
+		return ret;
+
+	ret = devm_add_action_or_reset(dev, rohm_pwrbutton_unregister_swnodes, nodes);
+	if (ret)
+		return ret;
+
+	gpio_keys_cell.swnode = &nodes[GPIO_KEYS];
+
+	ret = devm_mfd_add_devices(dev, PLATFORM_DEVID_AUTO, &gpio_keys_cell, 1,
+				   NULL, 0, irq_domain);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to register power-button");
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(rohm_register_pwrbutton);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Dmitry Torokhov <dmitry.torokhov@gmail.com>");
+MODULE_DESCRIPTION("Shared helper for ROHM PMIC power button registration");