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, 355 insertions, 0 deletions

diff --git a/drivers/pinctrl/mediatek/pinctrl-mtmips.c b/drivers/pinctrl/mediatek/pinctrl-mtmips.c
new file mode 100644
index 000000000..b2d7a79ff
--- /dev/null
+++ b/drivers/pinctrl/mediatek/pinctrl-mtmips.c
@@ -0,0 +1,355 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  Copyright (C) 2013 John Crispin <blogic@openwrt.org>
+ */
+
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/pinctrl/pinctrl.h>
+#include <linux/pinctrl/pinconf.h>
+#include <linux/pinctrl/pinconf-generic.h>
+#include <linux/pinctrl/pinmux.h>
+#include <linux/pinctrl/consumer.h>
+#include <linux/pinctrl/machine.h>
+
+#include <asm/mach-ralink/ralink_regs.h>
+#include <asm/mach-ralink/mt7620.h>
+
+#include "pinctrl-mtmips.h"
+#include "../core.h"
+#include "../pinctrl-utils.h"
+
+#define SYSC_REG_GPIO_MODE	0x60
+#define SYSC_REG_GPIO_MODE2	0x64
+
+struct mtmips_priv {
+	struct device *dev;
+
+	struct pinctrl_pin_desc *pads;
+	struct pinctrl_desc *desc;
+
+	struct mtmips_pmx_func **func;
+	int func_count;
+
+	struct mtmips_pmx_group *groups;
+	const char **group_names;
+	int group_count;
+
+	u8 *gpio;
+	int max_pins;
+};
+
+static int mtmips_get_group_count(struct pinctrl_dev *pctrldev)
+{
+	struct mtmips_priv *p = pinctrl_dev_get_drvdata(pctrldev);
+
+	return p->group_count;
+}
+
+static const char *mtmips_get_group_name(struct pinctrl_dev *pctrldev,
+					 unsigned int group)
+{
+	struct mtmips_priv *p = pinctrl_dev_get_drvdata(pctrldev);
+
+	return (group >= p->group_count) ? NULL : p->group_names[group];
+}
+
+static int mtmips_get_group_pins(struct pinctrl_dev *pctrldev,
+				 unsigned int group,
+				 const unsigned int **pins,
+				 unsigned int *num_pins)
+{
+	struct mtmips_priv *p = pinctrl_dev_get_drvdata(pctrldev);
+
+	if (group >= p->group_count)
+		return -EINVAL;
+
+	*pins = p->groups[group].func[0].pins;
+	*num_pins = p->groups[group].func[0].pin_count;
+
+	return 0;
+}
+
+static const struct pinctrl_ops mtmips_pctrl_ops = {
+	.get_groups_count	= mtmips_get_group_count,
+	.get_group_name		= mtmips_get_group_name,
+	.get_group_pins		= mtmips_get_group_pins,
+	.dt_node_to_map		= pinconf_generic_dt_node_to_map_all,
+	.dt_free_map		= pinconf_generic_dt_free_map,
+};
+
+static int mtmips_pmx_func_count(struct pinctrl_dev *pctrldev)
+{
+	struct mtmips_priv *p = pinctrl_dev_get_drvdata(pctrldev);
+
+	return p->func_count;
+}
+
+static const char *mtmips_pmx_func_name(struct pinctrl_dev *pctrldev,
+					unsigned int func)
+{
+	struct mtmips_priv *p = pinctrl_dev_get_drvdata(pctrldev);
+
+	return p->func[func]->name;
+}
+
+static int mtmips_pmx_group_get_groups(struct pinctrl_dev *pctrldev,
+				       unsigned int func,
+				       const char * const **groups,
+				       unsigned int * const num_groups)
+{
+	struct mtmips_priv *p = pinctrl_dev_get_drvdata(pctrldev);
+
+	if (p->func[func]->group_count == 1)
+		*groups = &p->group_names[p->func[func]->groups[0]];
+	else
+		*groups = p->group_names;
+
+	*num_groups = p->func[func]->group_count;
+
+	return 0;
+}
+
+static int mtmips_pmx_group_enable(struct pinctrl_dev *pctrldev,
+				   unsigned int func, unsigned int group)
+{
+	struct mtmips_priv *p = pinctrl_dev_get_drvdata(pctrldev);
+	u32 mode = 0;
+	u32 reg = SYSC_REG_GPIO_MODE;
+	int i;
+	int shift;
+
+	/* dont allow double use */
+	if (p->groups[group].enabled) {
+		dev_err(p->dev, "%s is already enabled\n",
+			p->groups[group].name);
+		return 0;
+	}
+
+	p->groups[group].enabled = 1;
+	p->func[func]->enabled = 1;
+
+	shift = p->groups[group].shift;
+	if (shift >= 32) {
+		shift -= 32;
+		reg = SYSC_REG_GPIO_MODE2;
+	}
+	mode = rt_sysc_r32(reg);
+	mode &= ~(p->groups[group].mask << shift);
+
+	/* mark the pins as gpio */
+	for (i = 0; i < p->groups[group].func[0].pin_count; i++)
+		p->gpio[p->groups[group].func[0].pins[i]] = 1;
+
+	/* function 0 is gpio and needs special handling */
+	if (func == 0) {
+		mode |= p->groups[group].gpio << shift;
+	} else {
+		for (i = 0; i < p->func[func]->pin_count; i++)
+			p->gpio[p->func[func]->pins[i]] = 0;
+		mode |= p->func[func]->value << shift;
+	}
+	rt_sysc_w32(mode, reg);
+
+	return 0;
+}
+
+static int mtmips_pmx_group_gpio_request_enable(struct pinctrl_dev *pctrldev,
+						struct pinctrl_gpio_range *range,
+						unsigned int pin)
+{
+	struct mtmips_priv *p = pinctrl_dev_get_drvdata(pctrldev);
+
+	if (!p->gpio[pin]) {
+		dev_err(p->dev, "pin %d is not set to gpio mux\n", pin);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static const struct pinmux_ops mtmips_pmx_group_ops = {
+	.get_functions_count	= mtmips_pmx_func_count,
+	.get_function_name	= mtmips_pmx_func_name,
+	.get_function_groups	= mtmips_pmx_group_get_groups,
+	.set_mux		= mtmips_pmx_group_enable,
+	.gpio_request_enable	= mtmips_pmx_group_gpio_request_enable,
+};
+
+static struct pinctrl_desc mtmips_pctrl_desc = {
+	.owner		= THIS_MODULE,
+	.name		= "mtmips-pinctrl",
+	.pctlops	= &mtmips_pctrl_ops,
+	.pmxops		= &mtmips_pmx_group_ops,
+};
+
+static struct mtmips_pmx_func gpio_func = {
+	.name = "gpio",
+};
+
+static int mtmips_pinctrl_index(struct mtmips_priv *p)
+{
+	struct mtmips_pmx_group *mux = p->groups;
+	int i, j, c = 0;
+
+	/* count the mux functions */
+	while (mux->name) {
+		p->group_count++;
+		mux++;
+	}
+
+	/* allocate the group names array needed by the gpio function */
+	p->group_names = devm_kcalloc(p->dev, p->group_count,
+				      sizeof(char *), GFP_KERNEL);
+	if (!p->group_names)
+		return -ENOMEM;
+
+	for (i = 0; i < p->group_count; i++) {
+		p->group_names[i] = p->groups[i].name;
+		p->func_count += p->groups[i].func_count;
+	}
+
+	/* we have a dummy function[0] for gpio */
+	p->func_count++;
+
+	/* allocate our function and group mapping index buffers */
+	p->func = devm_kcalloc(p->dev, p->func_count,
+			       sizeof(*p->func), GFP_KERNEL);
+	gpio_func.groups = devm_kcalloc(p->dev, p->group_count, sizeof(int),
+					GFP_KERNEL);
+	if (!p->func || !gpio_func.groups)
+		return -ENOMEM;
+
+	/* add a backpointer to the function so it knows its group */
+	gpio_func.group_count = p->group_count;
+	for (i = 0; i < gpio_func.group_count; i++)
+		gpio_func.groups[i] = i;
+
+	p->func[c] = &gpio_func;
+	c++;
+
+	/* add remaining functions */
+	for (i = 0; i < p->group_count; i++) {
+		for (j = 0; j < p->groups[i].func_count; j++) {
+			p->func[c] = &p->groups[i].func[j];
+			p->func[c]->groups = devm_kzalloc(p->dev, sizeof(int),
+						    GFP_KERNEL);
+			if (!p->func[c]->groups)
+				return -ENOMEM;
+			p->func[c]->groups[0] = i;
+			p->func[c]->group_count = 1;
+			c++;
+		}
+	}
+	return 0;
+}
+
+static int mtmips_pinctrl_pins(struct mtmips_priv *p)
+{
+	int i, j;
+
+	/*
+	 * loop over the functions and initialize the pins array.
+	 * also work out the highest pin used.
+	 */
+	for (i = 0; i < p->func_count; i++) {
+		int pin;
+
+		if (!p->func[i]->pin_count)
+			continue;
+
+		p->func[i]->pins = devm_kcalloc(p->dev,
+						p->func[i]->pin_count,
+						sizeof(int),
+						GFP_KERNEL);
+		if (!p->func[i]->pins)
+			return -ENOMEM;
+		for (j = 0; j < p->func[i]->pin_count; j++)
+			p->func[i]->pins[j] = p->func[i]->pin_first + j;
+
+		pin = p->func[i]->pin_first + p->func[i]->pin_count;
+		if (pin > p->max_pins)
+			p->max_pins = pin;
+	}
+
+	/* the buffer that tells us which pins are gpio */
+	p->gpio = devm_kcalloc(p->dev, p->max_pins, sizeof(u8), GFP_KERNEL);
+	/* the pads needed to tell pinctrl about our pins */
+	p->pads = devm_kcalloc(p->dev, p->max_pins,
+			       sizeof(struct pinctrl_pin_desc), GFP_KERNEL);
+	if (!p->pads || !p->gpio)
+		return -ENOMEM;
+
+	memset(p->gpio, 1, sizeof(u8) * p->max_pins);
+	for (i = 0; i < p->func_count; i++) {
+		if (!p->func[i]->pin_count)
+			continue;
+
+		for (j = 0; j < p->func[i]->pin_count; j++)
+			p->gpio[p->func[i]->pins[j]] = 0;
+	}
+
+	/* pin 0 is always a gpio */
+	p->gpio[0] = 1;
+
+	/* set the pads */
+	for (i = 0; i < p->max_pins; i++) {
+		/* strlen("ioXY") + 1 = 5 */
+		char *name = devm_kzalloc(p->dev, 5, GFP_KERNEL);
+
+		if (!name)
+			return -ENOMEM;
+		snprintf(name, 5, "io%d", i);
+		p->pads[i].number = i;
+		p->pads[i].name = name;
+	}
+	p->desc->pins = p->pads;
+	p->desc->npins = p->max_pins;
+
+	return 0;
+}
+
+int mtmips_pinctrl_init(struct platform_device *pdev,
+			struct mtmips_pmx_group *data)
+{
+	struct mtmips_priv *p;
+	struct pinctrl_dev *dev;
+	int err;
+
+	if (!data)
+		return -ENOTSUPP;
+
+	/* setup the private data */
+	p = devm_kzalloc(&pdev->dev, sizeof(struct mtmips_priv), GFP_KERNEL);
+	if (!p)
+		return -ENOMEM;
+
+	p->dev = &pdev->dev;
+	p->desc = &mtmips_pctrl_desc;
+	p->groups = data;
+	platform_set_drvdata(pdev, p);
+
+	/* init the device */
+	err = mtmips_pinctrl_index(p);
+	if (err) {
+		dev_err(&pdev->dev, "failed to load index\n");
+		return err;
+	}
+
+	err = mtmips_pinctrl_pins(p);
+	if (err) {
+		dev_err(&pdev->dev, "failed to load pins\n");
+		return err;
+	}
+	dev = pinctrl_register(p->desc, &pdev->dev, p);
+
+	return PTR_ERR_OR_ZERO(dev);
+}
+EXPORT_SYMBOL_NS_GPL(mtmips_pinctrl_init, "MTK_PINCTRL");
+
+MODULE_DESCRIPTION("MediaTek MIPS Pinctrl Common Driver");
+MODULE_LICENSE("GPL v2");