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, 345 insertions, 0 deletions

diff --git a/drivers/memory/mvebu-devbus.c b/drivers/memory/mvebu-devbus.c
new file mode 100644
index 000000000..406fddcdb
--- /dev/null
+++ b/drivers/memory/mvebu-devbus.c
@@ -0,0 +1,345 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Marvell EBU SoC Device Bus Controller
+ * (memory controller for NOR/NAND/SRAM/FPGA devices)
+ *
+ * Copyright (C) 2013-2014 Marvell
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/mbus.h>
+#include <linux/of_platform.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+
+/* Register definitions */
+#define ARMADA_DEV_WIDTH_SHIFT		30
+#define ARMADA_BADR_SKEW_SHIFT		28
+#define ARMADA_RD_HOLD_SHIFT		23
+#define ARMADA_ACC_NEXT_SHIFT		17
+#define ARMADA_RD_SETUP_SHIFT		12
+#define ARMADA_ACC_FIRST_SHIFT		6
+
+#define ARMADA_SYNC_ENABLE_SHIFT	24
+#define ARMADA_WR_HIGH_SHIFT		16
+#define ARMADA_WR_LOW_SHIFT		8
+
+#define ARMADA_READ_PARAM_OFFSET	0x0
+#define ARMADA_WRITE_PARAM_OFFSET	0x4
+
+#define ORION_RESERVED			(0x2 << 30)
+#define ORION_BADR_SKEW_SHIFT		28
+#define ORION_WR_HIGH_EXT_BIT		BIT(27)
+#define ORION_WR_HIGH_EXT_MASK		0x8
+#define ORION_WR_LOW_EXT_BIT		BIT(26)
+#define ORION_WR_LOW_EXT_MASK		0x8
+#define ORION_ALE_WR_EXT_BIT		BIT(25)
+#define ORION_ALE_WR_EXT_MASK		0x8
+#define ORION_ACC_NEXT_EXT_BIT		BIT(24)
+#define ORION_ACC_NEXT_EXT_MASK		0x10
+#define ORION_ACC_FIRST_EXT_BIT		BIT(23)
+#define ORION_ACC_FIRST_EXT_MASK	0x10
+#define ORION_TURN_OFF_EXT_BIT		BIT(22)
+#define ORION_TURN_OFF_EXT_MASK		0x8
+#define ORION_DEV_WIDTH_SHIFT		20
+#define ORION_WR_HIGH_SHIFT		17
+#define ORION_WR_HIGH_MASK		0x7
+#define ORION_WR_LOW_SHIFT		14
+#define ORION_WR_LOW_MASK		0x7
+#define ORION_ALE_WR_SHIFT		11
+#define ORION_ALE_WR_MASK		0x7
+#define ORION_ACC_NEXT_SHIFT		7
+#define ORION_ACC_NEXT_MASK		0xF
+#define ORION_ACC_FIRST_SHIFT		3
+#define ORION_ACC_FIRST_MASK		0xF
+#define ORION_TURN_OFF_SHIFT		0
+#define ORION_TURN_OFF_MASK		0x7
+
+struct devbus_read_params {
+	u32 bus_width;
+	u32 badr_skew;
+	u32 turn_off;
+	u32 acc_first;
+	u32 acc_next;
+	u32 rd_setup;
+	u32 rd_hold;
+};
+
+struct devbus_write_params {
+	u32 sync_enable;
+	u32 wr_high;
+	u32 wr_low;
+	u32 ale_wr;
+};
+
+struct devbus {
+	struct device *dev;
+	void __iomem *base;
+	unsigned long tick_ps;
+};
+
+static int get_timing_param_ps(struct devbus *devbus,
+			       struct device_node *node,
+			       const char *name,
+			       u32 *ticks)
+{
+	u32 time_ps;
+	int err;
+
+	err = of_property_read_u32(node, name, &time_ps);
+	if (err < 0) {
+		dev_err(devbus->dev, "%pOF has no '%s' property\n",
+			node, name);
+		return err;
+	}
+
+	*ticks = (time_ps + devbus->tick_ps - 1) / devbus->tick_ps;
+
+	dev_dbg(devbus->dev, "%s: %u ps -> 0x%x\n",
+		name, time_ps, *ticks);
+	return 0;
+}
+
+static int devbus_get_timing_params(struct devbus *devbus,
+				    struct device_node *node,
+				    struct devbus_read_params *r,
+				    struct devbus_write_params *w)
+{
+	int err;
+
+	err = of_property_read_u32(node, "devbus,bus-width", &r->bus_width);
+	if (err < 0) {
+		dev_err(devbus->dev,
+			"%pOF has no 'devbus,bus-width' property\n",
+			node);
+		return err;
+	}
+
+	/*
+	 * The bus width is encoded into the register as 0 for 8 bits,
+	 * and 1 for 16 bits, so we do the necessary conversion here.
+	 */
+	if (r->bus_width == 8) {
+		r->bus_width = 0;
+	} else if (r->bus_width == 16) {
+		r->bus_width = 1;
+	} else {
+		dev_err(devbus->dev, "invalid bus width %d\n", r->bus_width);
+		return -EINVAL;
+	}
+
+	err = get_timing_param_ps(devbus, node, "devbus,badr-skew-ps",
+				  &r->badr_skew);
+	if (err < 0)
+		return err;
+
+	err = get_timing_param_ps(devbus, node, "devbus,turn-off-ps",
+				  &r->turn_off);
+	if (err < 0)
+		return err;
+
+	err = get_timing_param_ps(devbus, node, "devbus,acc-first-ps",
+				  &r->acc_first);
+	if (err < 0)
+		return err;
+
+	err = get_timing_param_ps(devbus, node, "devbus,acc-next-ps",
+				  &r->acc_next);
+	if (err < 0)
+		return err;
+
+	if (of_device_is_compatible(devbus->dev->of_node, "marvell,mvebu-devbus")) {
+		err = get_timing_param_ps(devbus, node, "devbus,rd-setup-ps",
+					  &r->rd_setup);
+		if (err < 0)
+			return err;
+
+		err = get_timing_param_ps(devbus, node, "devbus,rd-hold-ps",
+					  &r->rd_hold);
+		if (err < 0)
+			return err;
+
+		err = of_property_read_u32(node, "devbus,sync-enable",
+					   &w->sync_enable);
+		if (err < 0) {
+			dev_err(devbus->dev,
+				"%pOF has no 'devbus,sync-enable' property\n",
+				node);
+			return err;
+		}
+	}
+
+	err = get_timing_param_ps(devbus, node, "devbus,ale-wr-ps",
+				  &w->ale_wr);
+	if (err < 0)
+		return err;
+
+	err = get_timing_param_ps(devbus, node, "devbus,wr-low-ps",
+				  &w->wr_low);
+	if (err < 0)
+		return err;
+
+	err = get_timing_param_ps(devbus, node, "devbus,wr-high-ps",
+				  &w->wr_high);
+	if (err < 0)
+		return err;
+
+	return 0;
+}
+
+static void devbus_orion_set_timing_params(struct devbus *devbus,
+					  struct device_node *node,
+					  struct devbus_read_params *r,
+					  struct devbus_write_params *w)
+{
+	u32 value;
+
+	/*
+	 * The hardware designers found it would be a good idea to
+	 * split most of the values in the register into two fields:
+	 * one containing all the low-order bits, and another one
+	 * containing just the high-order bit. For all of those
+	 * fields, we have to split the value into these two parts.
+	 */
+	value =	(r->turn_off   & ORION_TURN_OFF_MASK)  << ORION_TURN_OFF_SHIFT  |
+		(r->acc_first  & ORION_ACC_FIRST_MASK) << ORION_ACC_FIRST_SHIFT |
+		(r->acc_next   & ORION_ACC_NEXT_MASK)  << ORION_ACC_NEXT_SHIFT  |
+		(w->ale_wr     & ORION_ALE_WR_MASK)    << ORION_ALE_WR_SHIFT    |
+		(w->wr_low     & ORION_WR_LOW_MASK)    << ORION_WR_LOW_SHIFT    |
+		(w->wr_high    & ORION_WR_HIGH_MASK)   << ORION_WR_HIGH_SHIFT   |
+		r->bus_width                           << ORION_DEV_WIDTH_SHIFT |
+		((r->turn_off  & ORION_TURN_OFF_EXT_MASK)  ? ORION_TURN_OFF_EXT_BIT  : 0) |
+		((r->acc_first & ORION_ACC_FIRST_EXT_MASK) ? ORION_ACC_FIRST_EXT_BIT : 0) |
+		((r->acc_next  & ORION_ACC_NEXT_EXT_MASK)  ? ORION_ACC_NEXT_EXT_BIT  : 0) |
+		((w->ale_wr    & ORION_ALE_WR_EXT_MASK)    ? ORION_ALE_WR_EXT_BIT    : 0) |
+		((w->wr_low    & ORION_WR_LOW_EXT_MASK)    ? ORION_WR_LOW_EXT_BIT    : 0) |
+		((w->wr_high   & ORION_WR_HIGH_EXT_MASK)   ? ORION_WR_HIGH_EXT_BIT   : 0) |
+		(r->badr_skew << ORION_BADR_SKEW_SHIFT) |
+		ORION_RESERVED;
+
+	writel(value, devbus->base);
+}
+
+static void devbus_armada_set_timing_params(struct devbus *devbus,
+					   struct device_node *node,
+					   struct devbus_read_params *r,
+					   struct devbus_write_params *w)
+{
+	u32 value;
+
+	/* Set read timings */
+	value = r->bus_width << ARMADA_DEV_WIDTH_SHIFT |
+		r->badr_skew << ARMADA_BADR_SKEW_SHIFT |
+		r->rd_hold   << ARMADA_RD_HOLD_SHIFT   |
+		r->acc_next  << ARMADA_ACC_NEXT_SHIFT  |
+		r->rd_setup  << ARMADA_RD_SETUP_SHIFT  |
+		r->acc_first << ARMADA_ACC_FIRST_SHIFT |
+		r->turn_off;
+
+	dev_dbg(devbus->dev, "read parameters register 0x%p = 0x%x\n",
+		devbus->base + ARMADA_READ_PARAM_OFFSET,
+		value);
+
+	writel(value, devbus->base + ARMADA_READ_PARAM_OFFSET);
+
+	/* Set write timings */
+	value = w->sync_enable  << ARMADA_SYNC_ENABLE_SHIFT |
+		w->wr_low       << ARMADA_WR_LOW_SHIFT      |
+		w->wr_high      << ARMADA_WR_HIGH_SHIFT     |
+		w->ale_wr;
+
+	dev_dbg(devbus->dev, "write parameters register: 0x%p = 0x%x\n",
+		devbus->base + ARMADA_WRITE_PARAM_OFFSET,
+		value);
+
+	writel(value, devbus->base + ARMADA_WRITE_PARAM_OFFSET);
+}
+
+static int mvebu_devbus_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *node = pdev->dev.of_node;
+	struct devbus_read_params r;
+	struct devbus_write_params w;
+	struct devbus *devbus;
+	struct clk *clk;
+	unsigned long rate;
+	int err;
+
+	devbus = devm_kzalloc(&pdev->dev, sizeof(struct devbus), GFP_KERNEL);
+	if (!devbus)
+		return -ENOMEM;
+
+	devbus->dev = dev;
+	devbus->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(devbus->base))
+		return PTR_ERR(devbus->base);
+
+	clk = devm_clk_get_enabled(&pdev->dev, NULL);
+	if (IS_ERR(clk))
+		return PTR_ERR(clk);
+
+	/*
+	 * Obtain clock period in picoseconds,
+	 * we need this in order to convert timing
+	 * parameters from cycles to picoseconds.
+	 */
+	rate = clk_get_rate(clk) / 1000;
+	devbus->tick_ps = 1000000000 / rate;
+
+	dev_dbg(devbus->dev, "Setting timing parameter, tick is %lu ps\n",
+		devbus->tick_ps);
+
+	if (!of_property_read_bool(node, "devbus,keep-config")) {
+		/* Read the Device Tree node */
+		err = devbus_get_timing_params(devbus, node, &r, &w);
+		if (err < 0)
+			return err;
+
+		/* Set the new timing parameters */
+		if (of_device_is_compatible(node, "marvell,orion-devbus"))
+			devbus_orion_set_timing_params(devbus, node, &r, &w);
+		else
+			devbus_armada_set_timing_params(devbus, node, &r, &w);
+	}
+
+	/*
+	 * We need to create a child device explicitly from here to
+	 * guarantee that the child will be probed after the timing
+	 * parameters for the bus are written.
+	 */
+	err = of_platform_populate(node, NULL, NULL, dev);
+	if (err < 0)
+		return err;
+
+	return 0;
+}
+
+static const struct of_device_id mvebu_devbus_of_match[] = {
+	{ .compatible = "marvell,mvebu-devbus" },
+	{ .compatible = "marvell,orion-devbus" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, mvebu_devbus_of_match);
+
+static struct platform_driver mvebu_devbus_driver = {
+	.probe		= mvebu_devbus_probe,
+	.driver		= {
+		.name	= "mvebu-devbus",
+		.of_match_table = mvebu_devbus_of_match,
+	},
+};
+
+static int __init mvebu_devbus_init(void)
+{
+	return platform_driver_register(&mvebu_devbus_driver);
+}
+module_init(mvebu_devbus_init);
+
+MODULE_AUTHOR("Ezequiel Garcia <ezequiel.garcia@free-electrons.com>");
+MODULE_DESCRIPTION("Marvell EBU SoC Device Bus controller");