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, 289 insertions, 0 deletions

diff --git a/drivers/amba/tegra-ahb.c b/drivers/amba/tegra-ahb.c
new file mode 100644
index 000000000..f23c3ed01
--- /dev/null
+++ b/drivers/amba/tegra-ahb.c
@@ -0,0 +1,289 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2012, NVIDIA CORPORATION.  All rights reserved.
+ * Copyright (C) 2011 Google, Inc.
+ *
+ * Author:
+ *	Jay Cheng <jacheng@nvidia.com>
+ *	James Wylder <james.wylder@motorola.com>
+ *	Benoit Goby <benoit@android.com>
+ *	Colin Cross <ccross@android.com>
+ *	Hiroshi DOYU <hdoyu@nvidia.com>
+ */
+
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <linux/of.h>
+
+#include <soc/tegra/ahb.h>
+
+#define DRV_NAME "tegra-ahb"
+
+#define AHB_ARBITRATION_DISABLE		0x04
+#define AHB_ARBITRATION_PRIORITY_CTRL	0x08
+#define   AHB_PRIORITY_WEIGHT(x)	(((x) & 0x7) << 29)
+#define   PRIORITY_SELECT_USB BIT(6)
+#define   PRIORITY_SELECT_USB2 BIT(18)
+#define   PRIORITY_SELECT_USB3 BIT(17)
+
+#define AHB_GIZMO_AHB_MEM		0x10
+#define   ENB_FAST_REARBITRATE BIT(2)
+#define   DONT_SPLIT_AHB_WR     BIT(7)
+
+#define AHB_GIZMO_APB_DMA		0x14
+#define AHB_GIZMO_IDE			0x1c
+#define AHB_GIZMO_USB			0x20
+#define AHB_GIZMO_AHB_XBAR_BRIDGE	0x24
+#define AHB_GIZMO_CPU_AHB_BRIDGE	0x28
+#define AHB_GIZMO_COP_AHB_BRIDGE	0x2c
+#define AHB_GIZMO_XBAR_APB_CTLR		0x30
+#define AHB_GIZMO_VCP_AHB_BRIDGE	0x34
+#define AHB_GIZMO_NAND			0x40
+#define AHB_GIZMO_SDMMC4		0x48
+#define AHB_GIZMO_XIO			0x4c
+#define AHB_GIZMO_BSEV			0x64
+#define AHB_GIZMO_BSEA			0x74
+#define AHB_GIZMO_NOR			0x78
+#define AHB_GIZMO_USB2			0x7c
+#define AHB_GIZMO_USB3			0x80
+#define   IMMEDIATE	BIT(18)
+
+#define AHB_GIZMO_SDMMC1		0x84
+#define AHB_GIZMO_SDMMC2		0x88
+#define AHB_GIZMO_SDMMC3		0x8c
+#define AHB_MEM_PREFETCH_CFG_X		0xdc
+#define AHB_ARBITRATION_XBAR_CTRL	0xe0
+#define AHB_MEM_PREFETCH_CFG3		0xe4
+#define AHB_MEM_PREFETCH_CFG4		0xe8
+#define AHB_MEM_PREFETCH_CFG1		0xf0
+#define AHB_MEM_PREFETCH_CFG2		0xf4
+#define   PREFETCH_ENB	BIT(31)
+#define   MST_ID(x)	(((x) & 0x1f) << 26)
+#define   AHBDMA_MST_ID	MST_ID(5)
+#define   USB_MST_ID	MST_ID(6)
+#define   USB2_MST_ID	MST_ID(18)
+#define   USB3_MST_ID	MST_ID(17)
+#define   ADDR_BNDRY(x)	(((x) & 0xf) << 21)
+#define   INACTIVITY_TIMEOUT(x)	(((x) & 0xffff) << 0)
+
+#define AHB_ARBITRATION_AHB_MEM_WRQUE_MST_ID	0xfc
+
+#define AHB_ARBITRATION_XBAR_CTRL_SMMU_INIT_DONE BIT(17)
+
+/*
+ * INCORRECT_BASE_ADDR_LOW_BYTE: Legacy kernel DT files for Tegra SoCs
+ * prior to Tegra124 generally use a physical base address ending in
+ * 0x4 for the AHB IP block.  According to the TRM, the low byte
+ * should be 0x0.  During device probing, this macro is used to detect
+ * whether the passed-in physical address is incorrect, and if so, to
+ * correct it.
+ */
+#define INCORRECT_BASE_ADDR_LOW_BYTE		0x4
+
+static struct platform_driver tegra_ahb_driver;
+
+static const u32 tegra_ahb_gizmo[] = {
+	AHB_ARBITRATION_DISABLE,
+	AHB_ARBITRATION_PRIORITY_CTRL,
+	AHB_GIZMO_AHB_MEM,
+	AHB_GIZMO_APB_DMA,
+	AHB_GIZMO_IDE,
+	AHB_GIZMO_USB,
+	AHB_GIZMO_AHB_XBAR_BRIDGE,
+	AHB_GIZMO_CPU_AHB_BRIDGE,
+	AHB_GIZMO_COP_AHB_BRIDGE,
+	AHB_GIZMO_XBAR_APB_CTLR,
+	AHB_GIZMO_VCP_AHB_BRIDGE,
+	AHB_GIZMO_NAND,
+	AHB_GIZMO_SDMMC4,
+	AHB_GIZMO_XIO,
+	AHB_GIZMO_BSEV,
+	AHB_GIZMO_BSEA,
+	AHB_GIZMO_NOR,
+	AHB_GIZMO_USB2,
+	AHB_GIZMO_USB3,
+	AHB_GIZMO_SDMMC1,
+	AHB_GIZMO_SDMMC2,
+	AHB_GIZMO_SDMMC3,
+	AHB_MEM_PREFETCH_CFG_X,
+	AHB_ARBITRATION_XBAR_CTRL,
+	AHB_MEM_PREFETCH_CFG3,
+	AHB_MEM_PREFETCH_CFG4,
+	AHB_MEM_PREFETCH_CFG1,
+	AHB_MEM_PREFETCH_CFG2,
+	AHB_ARBITRATION_AHB_MEM_WRQUE_MST_ID,
+};
+
+struct tegra_ahb {
+	void __iomem	*regs;
+	struct device	*dev;
+	u32		ctx[];
+};
+
+static inline u32 gizmo_readl(struct tegra_ahb *ahb, u32 offset)
+{
+	return readl(ahb->regs + offset);
+}
+
+static inline void gizmo_writel(struct tegra_ahb *ahb, u32 value, u32 offset)
+{
+	writel(value, ahb->regs + offset);
+}
+
+#ifdef CONFIG_TEGRA_IOMMU_SMMU
+int tegra_ahb_enable_smmu(struct device_node *dn)
+{
+	struct device *dev;
+	u32 val;
+	struct tegra_ahb *ahb;
+
+	dev = driver_find_device_by_of_node(&tegra_ahb_driver.driver, dn);
+	if (!dev)
+		return -EPROBE_DEFER;
+	ahb = dev_get_drvdata(dev);
+	put_device(dev);
+	val = gizmo_readl(ahb, AHB_ARBITRATION_XBAR_CTRL);
+	val |= AHB_ARBITRATION_XBAR_CTRL_SMMU_INIT_DONE;
+	gizmo_writel(ahb, val, AHB_ARBITRATION_XBAR_CTRL);
+	return 0;
+}
+EXPORT_SYMBOL(tegra_ahb_enable_smmu);
+#endif
+
+static int __maybe_unused tegra_ahb_suspend(struct device *dev)
+{
+	int i;
+	struct tegra_ahb *ahb = dev_get_drvdata(dev);
+
+	for (i = 0; i < ARRAY_SIZE(tegra_ahb_gizmo); i++)
+		ahb->ctx[i] = gizmo_readl(ahb, tegra_ahb_gizmo[i]);
+	return 0;
+}
+
+static int __maybe_unused tegra_ahb_resume(struct device *dev)
+{
+	int i;
+	struct tegra_ahb *ahb = dev_get_drvdata(dev);
+
+	for (i = 0; i < ARRAY_SIZE(tegra_ahb_gizmo); i++)
+		gizmo_writel(ahb, ahb->ctx[i], tegra_ahb_gizmo[i]);
+	return 0;
+}
+
+static UNIVERSAL_DEV_PM_OPS(tegra_ahb_pm,
+			    tegra_ahb_suspend,
+			    tegra_ahb_resume, NULL);
+
+static void tegra_ahb_gizmo_init(struct tegra_ahb *ahb)
+{
+	u32 val;
+
+	val = gizmo_readl(ahb, AHB_GIZMO_AHB_MEM);
+	val |= ENB_FAST_REARBITRATE | IMMEDIATE | DONT_SPLIT_AHB_WR;
+	gizmo_writel(ahb, val, AHB_GIZMO_AHB_MEM);
+
+	val = gizmo_readl(ahb, AHB_GIZMO_USB);
+	val |= IMMEDIATE;
+	gizmo_writel(ahb, val, AHB_GIZMO_USB);
+
+	val = gizmo_readl(ahb, AHB_GIZMO_USB2);
+	val |= IMMEDIATE;
+	gizmo_writel(ahb, val, AHB_GIZMO_USB2);
+
+	val = gizmo_readl(ahb, AHB_GIZMO_USB3);
+	val |= IMMEDIATE;
+	gizmo_writel(ahb, val, AHB_GIZMO_USB3);
+
+	val = gizmo_readl(ahb, AHB_ARBITRATION_PRIORITY_CTRL);
+	val |= PRIORITY_SELECT_USB |
+		PRIORITY_SELECT_USB2 |
+		PRIORITY_SELECT_USB3 |
+		AHB_PRIORITY_WEIGHT(7);
+	gizmo_writel(ahb, val, AHB_ARBITRATION_PRIORITY_CTRL);
+
+	val = gizmo_readl(ahb, AHB_MEM_PREFETCH_CFG1);
+	val &= ~MST_ID(~0);
+	val |= PREFETCH_ENB |
+		AHBDMA_MST_ID |
+		ADDR_BNDRY(0xc) |
+		INACTIVITY_TIMEOUT(0x1000);
+	gizmo_writel(ahb, val, AHB_MEM_PREFETCH_CFG1);
+
+	val = gizmo_readl(ahb, AHB_MEM_PREFETCH_CFG2);
+	val &= ~MST_ID(~0);
+	val |= PREFETCH_ENB |
+		USB_MST_ID |
+		ADDR_BNDRY(0xc) |
+		INACTIVITY_TIMEOUT(0x1000);
+	gizmo_writel(ahb, val, AHB_MEM_PREFETCH_CFG2);
+
+	val = gizmo_readl(ahb, AHB_MEM_PREFETCH_CFG3);
+	val &= ~MST_ID(~0);
+	val |= PREFETCH_ENB |
+		USB3_MST_ID |
+		ADDR_BNDRY(0xc) |
+		INACTIVITY_TIMEOUT(0x1000);
+	gizmo_writel(ahb, val, AHB_MEM_PREFETCH_CFG3);
+
+	val = gizmo_readl(ahb, AHB_MEM_PREFETCH_CFG4);
+	val &= ~MST_ID(~0);
+	val |= PREFETCH_ENB |
+		USB2_MST_ID |
+		ADDR_BNDRY(0xc) |
+		INACTIVITY_TIMEOUT(0x1000);
+	gizmo_writel(ahb, val, AHB_MEM_PREFETCH_CFG4);
+}
+
+static int tegra_ahb_probe(struct platform_device *pdev)
+{
+	struct resource *res;
+	struct tegra_ahb *ahb;
+	size_t bytes;
+
+	bytes = sizeof(*ahb) + sizeof(u32) * ARRAY_SIZE(tegra_ahb_gizmo);
+	ahb = devm_kzalloc(&pdev->dev, bytes, GFP_KERNEL);
+	if (!ahb)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+
+	/* Correct the IP block base address if necessary */
+	if (res &&
+	    (res->start & INCORRECT_BASE_ADDR_LOW_BYTE) ==
+	    INCORRECT_BASE_ADDR_LOW_BYTE) {
+		dev_warn(&pdev->dev, "incorrect AHB base address in DT data - enabling workaround\n");
+		res->start -= INCORRECT_BASE_ADDR_LOW_BYTE;
+	}
+
+	ahb->regs = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(ahb->regs))
+		return PTR_ERR(ahb->regs);
+
+	ahb->dev = &pdev->dev;
+	platform_set_drvdata(pdev, ahb);
+	tegra_ahb_gizmo_init(ahb);
+	return 0;
+}
+
+static const struct of_device_id tegra_ahb_of_match[] = {
+	{ .compatible = "nvidia,tegra30-ahb", },
+	{ .compatible = "nvidia,tegra20-ahb", },
+	{},
+};
+
+static struct platform_driver tegra_ahb_driver = {
+	.probe = tegra_ahb_probe,
+	.driver = {
+		.name = DRV_NAME,
+		.of_match_table = tegra_ahb_of_match,
+		.pm = &tegra_ahb_pm,
+	},
+};
+module_platform_driver(tegra_ahb_driver);
+
+MODULE_AUTHOR("Hiroshi DOYU <hdoyu@nvidia.com>");
+MODULE_DESCRIPTION("Tegra AHB driver");
+MODULE_ALIAS("platform:" DRV_NAME);