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, 244 insertions, 0 deletions

diff --git a/drivers/mfd/stpmic1.c b/drivers/mfd/stpmic1.c
new file mode 100644
index 000000000..7c677b034
--- /dev/null
+++ b/drivers/mfd/stpmic1.c
@@ -0,0 +1,244 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) STMicroelectronics 2018
+// Author: Pascal Paillet <p.paillet@st.com>
+
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/stpmic1.h>
+#include <linux/module.h>
+#include <linux/reboot.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/of_platform.h>
+#include <linux/pm_wakeirq.h>
+#include <linux/regmap.h>
+
+#include <dt-bindings/mfd/st,stpmic1.h>
+
+#define STPMIC1_MAX_RETRIES 2
+
+#define STPMIC1_MAIN_IRQ 0
+
+static const struct regmap_range stpmic1_readable_ranges[] = {
+	regmap_reg_range(TURN_ON_SR, VERSION_SR),
+	regmap_reg_range(MAIN_CR, LDO6_STDBY_CR),
+	regmap_reg_range(BST_SW_CR, BST_SW_CR),
+	regmap_reg_range(INT_PENDING_R1, INT_PENDING_R4),
+	regmap_reg_range(INT_CLEAR_R1, INT_CLEAR_R4),
+	regmap_reg_range(INT_MASK_R1, INT_MASK_R4),
+	regmap_reg_range(INT_SET_MASK_R1, INT_SET_MASK_R4),
+	regmap_reg_range(INT_CLEAR_MASK_R1, INT_CLEAR_MASK_R4),
+	regmap_reg_range(INT_SRC_R1, INT_SRC_R1),
+};
+
+static const struct regmap_range stpmic1_writeable_ranges[] = {
+	regmap_reg_range(MAIN_CR, LDO6_STDBY_CR),
+	regmap_reg_range(BST_SW_CR, BST_SW_CR),
+	regmap_reg_range(INT_CLEAR_R1, INT_CLEAR_R4),
+	regmap_reg_range(INT_SET_MASK_R1, INT_SET_MASK_R4),
+	regmap_reg_range(INT_CLEAR_MASK_R1, INT_CLEAR_MASK_R4),
+};
+
+static const struct regmap_range stpmic1_volatile_ranges[] = {
+	regmap_reg_range(TURN_ON_SR, VERSION_SR),
+	regmap_reg_range(WCHDG_CR, WCHDG_CR),
+	regmap_reg_range(INT_PENDING_R1, INT_PENDING_R4),
+	regmap_reg_range(INT_SRC_R1, INT_SRC_R4),
+};
+
+static const struct regmap_access_table stpmic1_readable_table = {
+	.yes_ranges = stpmic1_readable_ranges,
+	.n_yes_ranges = ARRAY_SIZE(stpmic1_readable_ranges),
+};
+
+static const struct regmap_access_table stpmic1_writeable_table = {
+	.yes_ranges = stpmic1_writeable_ranges,
+	.n_yes_ranges = ARRAY_SIZE(stpmic1_writeable_ranges),
+};
+
+static const struct regmap_access_table stpmic1_volatile_table = {
+	.yes_ranges = stpmic1_volatile_ranges,
+	.n_yes_ranges = ARRAY_SIZE(stpmic1_volatile_ranges),
+};
+
+static const struct regmap_config stpmic1_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.cache_type = REGCACHE_MAPLE,
+	.max_register = PMIC_MAX_REGISTER_ADDRESS,
+	.rd_table = &stpmic1_readable_table,
+	.wr_table = &stpmic1_writeable_table,
+	.volatile_table = &stpmic1_volatile_table,
+};
+
+static const struct regmap_irq stpmic1_irqs[] = {
+	REGMAP_IRQ_REG(IT_PONKEY_F, 0, 0x01),
+	REGMAP_IRQ_REG(IT_PONKEY_R, 0, 0x02),
+	REGMAP_IRQ_REG(IT_WAKEUP_F, 0, 0x04),
+	REGMAP_IRQ_REG(IT_WAKEUP_R, 0, 0x08),
+	REGMAP_IRQ_REG(IT_VBUS_OTG_F, 0, 0x10),
+	REGMAP_IRQ_REG(IT_VBUS_OTG_R, 0, 0x20),
+	REGMAP_IRQ_REG(IT_SWOUT_F, 0, 0x40),
+	REGMAP_IRQ_REG(IT_SWOUT_R, 0, 0x80),
+
+	REGMAP_IRQ_REG(IT_CURLIM_BUCK1, 1, 0x01),
+	REGMAP_IRQ_REG(IT_CURLIM_BUCK2, 1, 0x02),
+	REGMAP_IRQ_REG(IT_CURLIM_BUCK3, 1, 0x04),
+	REGMAP_IRQ_REG(IT_CURLIM_BUCK4, 1, 0x08),
+	REGMAP_IRQ_REG(IT_OCP_OTG, 1, 0x10),
+	REGMAP_IRQ_REG(IT_OCP_SWOUT, 1, 0x20),
+	REGMAP_IRQ_REG(IT_OCP_BOOST, 1, 0x40),
+	REGMAP_IRQ_REG(IT_OVP_BOOST, 1, 0x80),
+
+	REGMAP_IRQ_REG(IT_CURLIM_LDO1, 2, 0x01),
+	REGMAP_IRQ_REG(IT_CURLIM_LDO2, 2, 0x02),
+	REGMAP_IRQ_REG(IT_CURLIM_LDO3, 2, 0x04),
+	REGMAP_IRQ_REG(IT_CURLIM_LDO4, 2, 0x08),
+	REGMAP_IRQ_REG(IT_CURLIM_LDO5, 2, 0x10),
+	REGMAP_IRQ_REG(IT_CURLIM_LDO6, 2, 0x20),
+	REGMAP_IRQ_REG(IT_SHORT_SWOTG, 2, 0x40),
+	REGMAP_IRQ_REG(IT_SHORT_SWOUT, 2, 0x80),
+
+	REGMAP_IRQ_REG(IT_TWARN_F, 3, 0x01),
+	REGMAP_IRQ_REG(IT_TWARN_R, 3, 0x02),
+	REGMAP_IRQ_REG(IT_VINLOW_F, 3, 0x04),
+	REGMAP_IRQ_REG(IT_VINLOW_R, 3, 0x08),
+	REGMAP_IRQ_REG(IT_SWIN_F, 3, 0x40),
+	REGMAP_IRQ_REG(IT_SWIN_R, 3, 0x80),
+};
+
+static const struct regmap_irq_chip stpmic1_regmap_irq_chip = {
+	.name = "pmic_irq",
+	.status_base = INT_PENDING_R1,
+	.mask_base = INT_SET_MASK_R1,
+	.unmask_base = INT_CLEAR_MASK_R1,
+	.mask_unmask_non_inverted = true,
+	.ack_base = INT_CLEAR_R1,
+	.num_regs = STPMIC1_PMIC_NUM_IRQ_REGS,
+	.irqs = stpmic1_irqs,
+	.num_irqs = ARRAY_SIZE(stpmic1_irqs),
+};
+
+static int stpmic1_power_off(struct sys_off_data *data)
+{
+	struct stpmic1 *ddata = data->cb_data;
+	int ret;
+
+	/*
+	 * Attempt to shut down again, in case the first attempt failed.
+	 * The STPMIC1 might get confused and the first regmap_update_bits()
+	 * returns with -ETIMEDOUT / -110 . If that or similar transient
+	 * failure occurs, try to shut down again. If the second attempt
+	 * fails, there is some bigger problem, report it to user.
+	 */
+	for (int retries = 0; retries < STPMIC1_MAX_RETRIES; retries++) {
+		ret = regmap_update_bits(ddata->regmap, MAIN_CR, SOFTWARE_SWITCH_OFF,
+					 SOFTWARE_SWITCH_OFF);
+		if (!ret)
+			return NOTIFY_DONE;
+	}
+
+	dev_err(ddata->dev, "Failed to access PMIC I2C bus (%d)\n", ret);
+
+	return NOTIFY_DONE;
+}
+
+static int stpmic1_probe(struct i2c_client *i2c)
+{
+	struct stpmic1 *ddata;
+	struct device *dev = &i2c->dev;
+	int ret;
+	struct device_node *np = dev->of_node;
+	u32 reg;
+
+	ddata = devm_kzalloc(dev, sizeof(struct stpmic1), GFP_KERNEL);
+	if (!ddata)
+		return -ENOMEM;
+
+	i2c_set_clientdata(i2c, ddata);
+	ddata->dev = dev;
+
+	ddata->regmap = devm_regmap_init_i2c(i2c, &stpmic1_regmap_config);
+	if (IS_ERR(ddata->regmap))
+		return PTR_ERR(ddata->regmap);
+
+	ddata->irq = of_irq_get(np, STPMIC1_MAIN_IRQ);
+	if (ddata->irq < 0) {
+		dev_err(dev, "Failed to get main IRQ: %d\n", ddata->irq);
+		return ddata->irq;
+	}
+
+	ret = regmap_read(ddata->regmap, VERSION_SR, &reg);
+	if (ret) {
+		dev_err(dev, "Unable to read PMIC version\n");
+		return ret;
+	}
+	dev_info(dev, "PMIC Chip Version: 0x%x\n", reg);
+
+	/* Initialize PMIC IRQ Chip & associated IRQ domains */
+	ret = devm_regmap_add_irq_chip(dev, ddata->regmap, ddata->irq,
+				       IRQF_ONESHOT | IRQF_SHARED,
+				       0, &stpmic1_regmap_irq_chip,
+				       &ddata->irq_data);
+	if (ret) {
+		dev_err(dev, "IRQ Chip registration failed: %d\n", ret);
+		return ret;
+	}
+
+	ret = devm_register_power_off_handler(ddata->dev, stpmic1_power_off, ddata);
+	if (ret) {
+		dev_err(ddata->dev, "failed to register sys-off handler: %d\n", ret);
+		return ret;
+	}
+
+	return devm_of_platform_populate(dev);
+}
+
+static int stpmic1_suspend(struct device *dev)
+{
+	struct i2c_client *i2c = to_i2c_client(dev);
+	struct stpmic1 *pmic_dev = i2c_get_clientdata(i2c);
+
+	disable_irq(pmic_dev->irq);
+
+	return 0;
+}
+
+static int stpmic1_resume(struct device *dev)
+{
+	struct i2c_client *i2c = to_i2c_client(dev);
+	struct stpmic1 *pmic_dev = i2c_get_clientdata(i2c);
+	int ret;
+
+	ret = regcache_sync(pmic_dev->regmap);
+	if (ret)
+		return ret;
+
+	enable_irq(pmic_dev->irq);
+
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(stpmic1_pm, stpmic1_suspend, stpmic1_resume);
+
+static const struct of_device_id stpmic1_of_match[] = {
+	{ .compatible = "st,stpmic1", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, stpmic1_of_match);
+
+static struct i2c_driver stpmic1_driver = {
+	.driver = {
+		.name = "stpmic1",
+		.of_match_table = stpmic1_of_match,
+		.pm = pm_sleep_ptr(&stpmic1_pm),
+	},
+	.probe = stpmic1_probe,
+};
+
+module_i2c_driver(stpmic1_driver);
+
+MODULE_DESCRIPTION("STPMIC1 PMIC Driver");
+MODULE_AUTHOR("Pascal Paillet <p.paillet@st.com>");
+MODULE_LICENSE("GPL v2");