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, 302 insertions, 0 deletions

diff --git a/drivers/mfd/wcd934x.c b/drivers/mfd/wcd934x.c
new file mode 100644
index 000000000..3c3080e8c
--- /dev/null
+++ b/drivers/mfd/wcd934x.c
@@ -0,0 +1,302 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2019, Linaro Limited
+
+#include <linux/clk.h>
+#include <linux/gpio/consumer.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/wcd934x/registers.h>
+#include <linux/mfd/wcd934x/wcd934x.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slimbus.h>
+
+#define WCD934X_REGMAP_IRQ_REG(_irq, _off, _mask)		\
+	[_irq] = {						\
+		.reg_offset = (_off),				\
+		.mask = (_mask),				\
+		.type = {					\
+			.type_reg_offset = (_off),		\
+			.types_supported = IRQ_TYPE_EDGE_BOTH,	\
+			.type_reg_mask  = (_mask),		\
+			.type_level_low_val = (_mask),		\
+			.type_level_high_val = (_mask),		\
+			.type_falling_val = 0,			\
+			.type_rising_val = 0,			\
+		},						\
+	}
+
+static const struct mfd_cell wcd934x_devices[] = {
+	{
+		.name = "wcd934x-codec",
+	}, {
+		.name = "wcd934x-gpio",
+		.of_compatible = "qcom,wcd9340-gpio",
+	}, {
+		.name = "wcd934x-soundwire",
+		.of_compatible = "qcom,soundwire-v1.3.0",
+	},
+};
+
+static const struct regmap_irq wcd934x_irqs[] = {
+	WCD934X_REGMAP_IRQ_REG(WCD934X_IRQ_SLIMBUS, 0, BIT(0)),
+	WCD934X_REGMAP_IRQ_REG(WCD934X_IRQ_HPH_PA_OCPL_FAULT, 0, BIT(2)),
+	WCD934X_REGMAP_IRQ_REG(WCD934X_IRQ_HPH_PA_OCPR_FAULT, 0, BIT(3)),
+	WCD934X_REGMAP_IRQ_REG(WCD934X_IRQ_MBHC_SW_DET, 1, BIT(0)),
+	WCD934X_REGMAP_IRQ_REG(WCD934X_IRQ_MBHC_ELECT_INS_REM_DET, 1, BIT(1)),
+	WCD934X_REGMAP_IRQ_REG(WCD934X_IRQ_MBHC_BUTTON_PRESS_DET, 1, BIT(2)),
+	WCD934X_REGMAP_IRQ_REG(WCD934X_IRQ_MBHC_BUTTON_RELEASE_DET, 1, BIT(3)),
+	WCD934X_REGMAP_IRQ_REG(WCD934X_IRQ_MBHC_ELECT_INS_REM_LEG_DET, 1, BIT(4)),
+	WCD934X_REGMAP_IRQ_REG(WCD934X_IRQ_SOUNDWIRE, 2, BIT(4)),
+};
+
+static const unsigned int wcd934x_config_regs[] = {
+	WCD934X_INTR_LEVEL0,
+};
+
+static const struct regmap_irq_chip wcd934x_regmap_irq_chip = {
+	.name = "wcd934x_irq",
+	.status_base = WCD934X_INTR_PIN1_STATUS0,
+	.mask_base = WCD934X_INTR_PIN1_MASK0,
+	.ack_base = WCD934X_INTR_PIN1_CLEAR0,
+	.num_regs = 4,
+	.irqs = wcd934x_irqs,
+	.num_irqs = ARRAY_SIZE(wcd934x_irqs),
+	.config_base = wcd934x_config_regs,
+	.num_config_bases = ARRAY_SIZE(wcd934x_config_regs),
+	.num_config_regs = 4,
+	.set_type_config = regmap_irq_set_type_config_simple,
+};
+
+static bool wcd934x_is_volatile_register(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case WCD934X_INTR_PIN1_STATUS0...WCD934X_INTR_PIN2_CLEAR3:
+	case WCD934X_SWR_AHB_BRIDGE_RD_DATA_0:
+	case WCD934X_SWR_AHB_BRIDGE_RD_DATA_1:
+	case WCD934X_SWR_AHB_BRIDGE_RD_DATA_2:
+	case WCD934X_SWR_AHB_BRIDGE_RD_DATA_3:
+	case WCD934X_SWR_AHB_BRIDGE_ACCESS_STATUS:
+	case WCD934X_ANA_MBHC_RESULT_3:
+	case WCD934X_ANA_MBHC_RESULT_2:
+	case WCD934X_ANA_MBHC_RESULT_1:
+	case WCD934X_ANA_MBHC_MECH:
+	case WCD934X_ANA_MBHC_ELECT:
+	case WCD934X_ANA_MBHC_ZDET:
+	case WCD934X_ANA_MICB2:
+	case WCD934X_ANA_RCO:
+	case WCD934X_ANA_BIAS:
+		return true;
+	default:
+		return false;
+	}
+};
+
+static const struct regmap_range_cfg wcd934x_ranges[] = {
+	{	.name = "WCD934X",
+		.range_min =  0x0,
+		.range_max =  WCD934X_MAX_REGISTER,
+		.selector_reg = WCD934X_SEL_REGISTER,
+		.selector_mask = WCD934X_SEL_MASK,
+		.selector_shift = WCD934X_SEL_SHIFT,
+		.window_start = WCD934X_WINDOW_START,
+		.window_len = WCD934X_WINDOW_LENGTH,
+	},
+};
+
+static const struct regmap_config wcd934x_regmap_config = {
+	.reg_bits = 16,
+	.val_bits = 8,
+	.cache_type = REGCACHE_MAPLE,
+	.max_register = 0xffff,
+	.can_multi_write = true,
+	.ranges = wcd934x_ranges,
+	.num_ranges = ARRAY_SIZE(wcd934x_ranges),
+	.volatile_reg = wcd934x_is_volatile_register,
+};
+
+static int wcd934x_bring_up(struct wcd934x_ddata *ddata)
+{
+	struct regmap *regmap = ddata->regmap;
+	u16 id_minor, id_major;
+	int ret;
+
+	ret = regmap_bulk_read(regmap, WCD934X_CHIP_TIER_CTRL_CHIP_ID_BYTE0,
+			       (u8 *)&id_minor, sizeof(u16));
+	if (ret)
+		return ret;
+
+	ret = regmap_bulk_read(regmap, WCD934X_CHIP_TIER_CTRL_CHIP_ID_BYTE2,
+			       (u8 *)&id_major, sizeof(u16));
+	if (ret)
+		return ret;
+
+	dev_info(ddata->dev, "WCD934x chip id major 0x%x, minor 0x%x\n",
+		 id_major, id_minor);
+
+	regmap_write(regmap, WCD934X_CODEC_RPM_RST_CTL, 0x01);
+	regmap_write(regmap, WCD934X_SIDO_NEW_VOUT_A_STARTUP, 0x19);
+	regmap_write(regmap, WCD934X_SIDO_NEW_VOUT_D_STARTUP, 0x15);
+	/* Add 1msec delay for VOUT to settle */
+	usleep_range(1000, 1100);
+	regmap_write(regmap, WCD934X_CODEC_RPM_PWR_CDC_DIG_HM_CTL, 0x5);
+	regmap_write(regmap, WCD934X_CODEC_RPM_PWR_CDC_DIG_HM_CTL, 0x7);
+	regmap_write(regmap, WCD934X_CODEC_RPM_RST_CTL, 0x3);
+	regmap_write(regmap, WCD934X_CODEC_RPM_RST_CTL, 0x7);
+	regmap_write(regmap, WCD934X_CODEC_RPM_PWR_CDC_DIG_HM_CTL, 0x3);
+
+	return 0;
+}
+
+static int wcd934x_slim_status_up(struct slim_device *sdev)
+{
+	struct device *dev = &sdev->dev;
+	struct wcd934x_ddata *ddata;
+	int ret;
+
+	ddata = dev_get_drvdata(dev);
+
+	ddata->regmap = regmap_init_slimbus(sdev, &wcd934x_regmap_config);
+	if (IS_ERR(ddata->regmap)) {
+		dev_err(dev, "Error allocating slim regmap\n");
+		return PTR_ERR(ddata->regmap);
+	}
+
+	ret = wcd934x_bring_up(ddata);
+	if (ret) {
+		dev_err(dev, "Failed to bring up WCD934X: err = %d\n", ret);
+		return ret;
+	}
+
+	ret = devm_regmap_add_irq_chip(dev, ddata->regmap, ddata->irq,
+				       IRQF_TRIGGER_HIGH, 0,
+				       &wcd934x_regmap_irq_chip,
+				       &ddata->irq_data);
+	if (ret) {
+		dev_err(dev, "Failed to add IRQ chip: err = %d\n", ret);
+		return ret;
+	}
+
+	ret = mfd_add_devices(dev, PLATFORM_DEVID_AUTO, wcd934x_devices,
+			      ARRAY_SIZE(wcd934x_devices), NULL, 0, NULL);
+	if (ret) {
+		dev_err(dev, "Failed to add child devices: err = %d\n",
+			ret);
+		return ret;
+	}
+
+	return ret;
+}
+
+static int wcd934x_slim_status(struct slim_device *sdev,
+			       enum slim_device_status status)
+{
+	switch (status) {
+	case SLIM_DEVICE_STATUS_UP:
+		return wcd934x_slim_status_up(sdev);
+	case SLIM_DEVICE_STATUS_DOWN:
+		mfd_remove_devices(&sdev->dev);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int wcd934x_slim_probe(struct slim_device *sdev)
+{
+	struct device *dev = &sdev->dev;
+	struct device_node *np = dev->of_node;
+	struct wcd934x_ddata *ddata;
+	struct gpio_desc *reset_gpio;
+	int ret;
+
+	ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);
+	if (!ddata)
+		return	-ENOMEM;
+
+	ddata->irq = of_irq_get(np, 0);
+	if (ddata->irq < 0)
+		return dev_err_probe(ddata->dev, ddata->irq,
+				     "Failed to get IRQ\n");
+
+	ddata->extclk = devm_clk_get(dev, "extclk");
+	if (IS_ERR(ddata->extclk))
+		return dev_err_probe(dev, PTR_ERR(ddata->extclk),
+				     "Failed to get extclk");
+
+	ddata->supplies[0].supply = "vdd-buck";
+	ddata->supplies[1].supply = "vdd-buck-sido";
+	ddata->supplies[2].supply = "vdd-tx";
+	ddata->supplies[3].supply = "vdd-rx";
+	ddata->supplies[4].supply = "vdd-io";
+
+	ret = regulator_bulk_get(dev, WCD934X_MAX_SUPPLY, ddata->supplies);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to get supplies\n");
+
+	ret = regulator_bulk_enable(WCD934X_MAX_SUPPLY, ddata->supplies);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to enable supplies\n");
+
+	/*
+	 * For WCD934X, it takes about 600us for the Vout_A and
+	 * Vout_D to be ready after BUCK_SIDO is powered up.
+	 * SYS_RST_N shouldn't be pulled high during this time
+	 */
+	usleep_range(600, 650);
+	reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
+	if (IS_ERR(reset_gpio)) {
+		ret = dev_err_probe(dev, PTR_ERR(reset_gpio),
+				    "Failed to get reset gpio\n");
+		goto err_disable_regulators;
+	}
+	msleep(20);
+	gpiod_set_value(reset_gpio, 1);
+	msleep(20);
+
+	ddata->dev = dev;
+	dev_set_drvdata(dev, ddata);
+
+	return 0;
+
+err_disable_regulators:
+	regulator_bulk_disable(WCD934X_MAX_SUPPLY, ddata->supplies);
+	return ret;
+}
+
+static void wcd934x_slim_remove(struct slim_device *sdev)
+{
+	struct wcd934x_ddata *ddata = dev_get_drvdata(&sdev->dev);
+
+	regulator_bulk_disable(WCD934X_MAX_SUPPLY, ddata->supplies);
+	mfd_remove_devices(&sdev->dev);
+}
+
+static const struct slim_device_id wcd934x_slim_id[] = {
+	{ SLIM_MANF_ID_QCOM, SLIM_PROD_CODE_WCD9340,
+	  SLIM_DEV_IDX_WCD9340, SLIM_DEV_INSTANCE_ID_WCD9340 },
+	{}
+};
+MODULE_DEVICE_TABLE(slim, wcd934x_slim_id);
+
+static struct slim_driver wcd934x_slim_driver = {
+	.driver = {
+		.name = "wcd934x-slim",
+	},
+	.probe = wcd934x_slim_probe,
+	.remove = wcd934x_slim_remove,
+	.device_status = wcd934x_slim_status,
+	.id_table = wcd934x_slim_id,
+};
+
+module_slim_driver(wcd934x_slim_driver);
+MODULE_DESCRIPTION("WCD934X slim driver");
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Srinivas Kandagatla <srinivas.kandagatla@linaro.org>");