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, 113 insertions, 0 deletions

diff --git a/drivers/cpufreq/tegra20-cpufreq.c b/drivers/cpufreq/tegra20-cpufreq.c
new file mode 100644
index 000000000..a57318670
--- /dev/null
+++ b/drivers/cpufreq/tegra20-cpufreq.c
@@ -0,0 +1,113 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2010 Google, Inc.
+ *
+ * Author:
+ *	Colin Cross <ccross@google.com>
+ *	Based on arch/arm/plat-omap/cpu-omap.c, (C) 2005 Nokia Corporation
+ */
+
+#include <linux/bits.h>
+#include <linux/cpu.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm_opp.h>
+#include <linux/types.h>
+
+#include <soc/tegra/common.h>
+#include <soc/tegra/fuse.h>
+
+static bool cpu0_node_has_opp_v2_prop(void)
+{
+	struct device_node *np = of_cpu_device_node_get(0);
+	bool ret = false;
+
+	if (of_property_present(np, "operating-points-v2"))
+		ret = true;
+
+	of_node_put(np);
+	return ret;
+}
+
+static void tegra20_cpufreq_put_supported_hw(void *opp_token)
+{
+	dev_pm_opp_put_supported_hw((unsigned long) opp_token);
+}
+
+static void tegra20_cpufreq_dt_unregister(void *cpufreq_dt)
+{
+	platform_device_unregister(cpufreq_dt);
+}
+
+static int tegra20_cpufreq_probe(struct platform_device *pdev)
+{
+	struct platform_device *cpufreq_dt;
+	struct device *cpu_dev;
+	u32 versions[2];
+	int err;
+
+	if (!cpu0_node_has_opp_v2_prop()) {
+		dev_err(&pdev->dev, "operating points not found\n");
+		dev_err(&pdev->dev, "please update your device tree\n");
+		return -ENODEV;
+	}
+
+	if (of_machine_is_compatible("nvidia,tegra20")) {
+		versions[0] = BIT(tegra_sku_info.cpu_process_id);
+		versions[1] = BIT(tegra_sku_info.soc_speedo_id);
+	} else {
+		versions[0] = BIT(tegra_sku_info.cpu_process_id);
+		versions[1] = BIT(tegra_sku_info.cpu_speedo_id);
+	}
+
+	dev_info(&pdev->dev, "hardware version 0x%x 0x%x\n",
+		 versions[0], versions[1]);
+
+	cpu_dev = get_cpu_device(0);
+	if (WARN_ON(!cpu_dev))
+		return -ENODEV;
+
+	err = dev_pm_opp_set_supported_hw(cpu_dev, versions, 2);
+	if (err < 0) {
+		dev_err(&pdev->dev, "failed to set supported hw: %d\n", err);
+		return err;
+	}
+
+	err = devm_add_action_or_reset(&pdev->dev,
+				       tegra20_cpufreq_put_supported_hw,
+				       (void *)((unsigned long) err));
+	if (err)
+		return err;
+
+	cpufreq_dt = platform_device_register_simple("cpufreq-dt", -1, NULL, 0);
+	err = PTR_ERR_OR_ZERO(cpufreq_dt);
+	if (err) {
+		dev_err(&pdev->dev,
+			"failed to create cpufreq-dt device: %d\n", err);
+		return err;
+	}
+
+	err = devm_add_action_or_reset(&pdev->dev,
+				       tegra20_cpufreq_dt_unregister,
+				       cpufreq_dt);
+	if (err)
+		return err;
+
+	return 0;
+}
+
+static struct platform_driver tegra20_cpufreq_driver = {
+	.probe		= tegra20_cpufreq_probe,
+	.driver		= {
+		.name	= "tegra20-cpufreq",
+	},
+};
+module_platform_driver(tegra20_cpufreq_driver);
+
+MODULE_ALIAS("platform:tegra20-cpufreq");
+MODULE_AUTHOR("Colin Cross <ccross@android.com>");
+MODULE_DESCRIPTION("NVIDIA Tegra20 cpufreq driver");
+MODULE_LICENSE("GPL");