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, 146 insertions, 0 deletions

diff --git a/drivers/misc/tps6594-esm.c b/drivers/misc/tps6594-esm.c
new file mode 100644
index 000000000..50e121669
--- /dev/null
+++ b/drivers/misc/tps6594-esm.c
@@ -0,0 +1,146 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ESM (Error Signal Monitor) driver for TI TPS6594/TPS6593/LP8764 PMICs
+ *
+ * Copyright (C) 2023 BayLibre Incorporated - https://www.baylibre.com/
+ */
+
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/regmap.h>
+
+#include <linux/mfd/tps6594.h>
+
+#define TPS6594_DEV_REV_1 0x08
+
+static irqreturn_t tps6594_esm_isr(int irq, void *dev_id)
+{
+	struct platform_device *pdev = dev_id;
+	int i;
+
+	for (i = 0 ; i < pdev->num_resources ; i++) {
+		if (irq == platform_get_irq_byname(pdev, pdev->resource[i].name)) {
+			dev_err(pdev->dev.parent, "%s error detected\n", pdev->resource[i].name);
+			return IRQ_HANDLED;
+		}
+	}
+
+	return IRQ_NONE;
+}
+
+static int tps6594_esm_probe(struct platform_device *pdev)
+{
+	struct tps6594 *tps = dev_get_drvdata(pdev->dev.parent);
+	struct device *dev = &pdev->dev;
+	unsigned int rev;
+	int irq;
+	int ret;
+	int i;
+
+	/*
+	 * Due to a bug in revision 1 of the PMIC, the GPIO3 used for the
+	 * SoC ESM function is used to power the load switch instead.
+	 * As a consequence, ESM can not be used on those PMIC.
+	 * Check the version and return an error in case of revision 1.
+	 */
+	ret = regmap_read(tps->regmap, TPS6594_REG_DEV_REV, &rev);
+	if (ret)
+		return dev_err_probe(dev, ret,
+				     "Failed to read PMIC revision\n");
+	if (rev == TPS6594_DEV_REV_1)
+		return dev_err_probe(dev, -ENODEV,
+			      "ESM not supported for revision 1 PMIC\n");
+
+	for (i = 0; i < pdev->num_resources; i++) {
+		irq = platform_get_irq_byname(pdev, pdev->resource[i].name);
+		if (irq < 0)
+			return irq;
+
+		ret = devm_request_threaded_irq(dev, irq, NULL,
+						tps6594_esm_isr, IRQF_ONESHOT,
+						pdev->resource[i].name, pdev);
+		if (ret)
+			return ret;
+	}
+
+	ret = regmap_set_bits(tps->regmap, TPS6594_REG_ESM_SOC_MODE_CFG,
+			      TPS6594_BIT_ESM_SOC_EN | TPS6594_BIT_ESM_SOC_ENDRV);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to configure ESM\n");
+
+	ret = regmap_set_bits(tps->regmap, TPS6594_REG_ESM_SOC_START_REG,
+			      TPS6594_BIT_ESM_SOC_START);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to start ESM\n");
+
+	pm_runtime_enable(dev);
+	pm_runtime_get_sync(dev);
+
+	return 0;
+}
+
+static void tps6594_esm_remove(struct platform_device *pdev)
+{
+	struct tps6594 *tps = dev_get_drvdata(pdev->dev.parent);
+	struct device *dev = &pdev->dev;
+	int ret;
+
+	ret = regmap_clear_bits(tps->regmap, TPS6594_REG_ESM_SOC_START_REG,
+				TPS6594_BIT_ESM_SOC_START);
+	if (ret) {
+		dev_err(dev, "Failed to stop ESM\n");
+		goto out;
+	}
+
+	ret = regmap_clear_bits(tps->regmap, TPS6594_REG_ESM_SOC_MODE_CFG,
+				TPS6594_BIT_ESM_SOC_EN | TPS6594_BIT_ESM_SOC_ENDRV);
+	if (ret)
+		dev_err(dev, "Failed to unconfigure ESM\n");
+
+out:
+	pm_runtime_put_sync(dev);
+	pm_runtime_disable(dev);
+}
+
+static int tps6594_esm_suspend(struct device *dev)
+{
+	struct tps6594 *tps = dev_get_drvdata(dev->parent);
+	int ret;
+
+	ret = regmap_clear_bits(tps->regmap, TPS6594_REG_ESM_SOC_START_REG,
+				TPS6594_BIT_ESM_SOC_START);
+
+	pm_runtime_put_sync(dev);
+
+	return ret;
+}
+
+static int tps6594_esm_resume(struct device *dev)
+{
+	struct tps6594 *tps = dev_get_drvdata(dev->parent);
+
+	pm_runtime_get_sync(dev);
+
+	return regmap_set_bits(tps->regmap, TPS6594_REG_ESM_SOC_START_REG,
+			       TPS6594_BIT_ESM_SOC_START);
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(tps6594_esm_pm_ops, tps6594_esm_suspend, tps6594_esm_resume);
+
+static struct platform_driver tps6594_esm_driver = {
+	.driver	= {
+		.name = "tps6594-esm",
+		.pm = pm_sleep_ptr(&tps6594_esm_pm_ops),
+	},
+	.probe = tps6594_esm_probe,
+	.remove = tps6594_esm_remove,
+};
+
+module_platform_driver(tps6594_esm_driver);
+
+MODULE_ALIAS("platform:tps6594-esm");
+MODULE_AUTHOR("Julien Panis <jpanis@baylibre.com>");
+MODULE_DESCRIPTION("TPS6594 Error Signal Monitor Driver");
+MODULE_LICENSE("GPL");