From a5f7a5bb3b7f28ba7e4fa246775b29a0e5537255 Mon Sep 17 00:00:00 2001 From: Jinke Han Date: Tue, 8 Sep 2026 15:37:42 +0800 Subject: x86/kprobes: Fix crash when probing CS CALL instructions 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) Signed-off-by: Jinke Han Signed-off-by: Ingo Molnar Reviewed-by: Masami Hiramatsu (Google) Acked-by: Yafang Shao Acked-by: Borislav Petkov Cc: Peter Zijlstra Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000 --- drivers/phy/phy-google-usb.c | 296 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 296 insertions(+) create mode 100644 drivers/phy/phy-google-usb.c (limited to 'drivers/phy/phy-google-usb.c') diff --git a/drivers/phy/phy-google-usb.c b/drivers/phy/phy-google-usb.c new file mode 100644 index 000000000..ab20bc20f --- /dev/null +++ b/drivers/phy/phy-google-usb.c @@ -0,0 +1,296 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * phy-google-usb.c - Google USB PHY driver + * + * Copyright (C) 2025, Google LLC + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define USBCS_USB2PHY_CFG19_OFFSET 0x0 +#define USBCS_USB2PHY_CFG19_PHY_CFG_PLL_FB_DIV GENMASK(19, 8) + +#define USBCS_USB2PHY_CFG21_OFFSET 0x8 +#define USBCS_USB2PHY_CFG21_PHY_ENABLE BIT(12) +#define USBCS_USB2PHY_CFG21_REF_FREQ_SEL GENMASK(15, 13) +#define USBCS_USB2PHY_CFG21_PHY_TX_DIG_BYPASS_SEL BIT(19) + +#define USBCS_PHY_CFG1_OFFSET 0x28 +#define USBCS_PHY_CFG1_SYS_VBUSVALID BIT(17) + +enum google_usb_phy_id { + GOOGLE_USB2_PHY, + GOOGLE_USB_PHY_NUM, +}; + +struct google_usb_phy_instance { + struct google_usb_phy *parent; + unsigned int index; + struct phy *phy; + unsigned int num_clks; + struct clk_bulk_data *clks; + unsigned int num_rsts; + struct reset_control_bulk_data *rsts; +}; + +struct google_usb_phy { + struct device *dev; + struct regmap *usb_cfg_regmap; + unsigned int usb2_cfg_offset; + void __iomem *usbdp_top_base; + struct google_usb_phy_instance *insts; + /* + * Protect phy registers from concurrent access, specifically via + * google_usb_set_orientation callback. + */ + struct mutex phy_mutex; + struct typec_switch_dev *sw; + enum typec_orientation orientation; +}; + +static void set_vbus_valid(struct google_usb_phy *gphy) +{ + u32 reg; + + if (gphy->orientation == TYPEC_ORIENTATION_NONE) { + reg = readl(gphy->usbdp_top_base + USBCS_PHY_CFG1_OFFSET); + reg &= ~USBCS_PHY_CFG1_SYS_VBUSVALID; + writel(reg, gphy->usbdp_top_base + USBCS_PHY_CFG1_OFFSET); + } else { + reg = readl(gphy->usbdp_top_base + USBCS_PHY_CFG1_OFFSET); + reg |= USBCS_PHY_CFG1_SYS_VBUSVALID; + writel(reg, gphy->usbdp_top_base + USBCS_PHY_CFG1_OFFSET); + } +} + +static int google_usb_set_orientation(struct typec_switch_dev *sw, + enum typec_orientation orientation) +{ + struct google_usb_phy *gphy = typec_switch_get_drvdata(sw); + + dev_dbg(gphy->dev, "set orientation %d\n", orientation); + + gphy->orientation = orientation; + + if (pm_runtime_suspended(gphy->dev)) + return 0; + + guard(mutex)(&gphy->phy_mutex); + + set_vbus_valid(gphy); + + return 0; +} + +static int google_usb2_phy_init(struct phy *_phy) +{ + struct google_usb_phy_instance *inst = phy_get_drvdata(_phy); + struct google_usb_phy *gphy = inst->parent; + u32 reg; + int ret; + + dev_dbg(gphy->dev, "initializing usb2 phy\n"); + + guard(mutex)(&gphy->phy_mutex); + + regmap_read(gphy->usb_cfg_regmap, gphy->usb2_cfg_offset + USBCS_USB2PHY_CFG21_OFFSET, ®); + reg &= ~USBCS_USB2PHY_CFG21_PHY_TX_DIG_BYPASS_SEL; + reg &= ~USBCS_USB2PHY_CFG21_REF_FREQ_SEL; + reg |= FIELD_PREP(USBCS_USB2PHY_CFG21_REF_FREQ_SEL, 0); + regmap_write(gphy->usb_cfg_regmap, gphy->usb2_cfg_offset + USBCS_USB2PHY_CFG21_OFFSET, reg); + + regmap_read(gphy->usb_cfg_regmap, gphy->usb2_cfg_offset + USBCS_USB2PHY_CFG19_OFFSET, ®); + reg &= ~USBCS_USB2PHY_CFG19_PHY_CFG_PLL_FB_DIV; + reg |= FIELD_PREP(USBCS_USB2PHY_CFG19_PHY_CFG_PLL_FB_DIV, 368); + regmap_write(gphy->usb_cfg_regmap, gphy->usb2_cfg_offset + USBCS_USB2PHY_CFG19_OFFSET, reg); + + set_vbus_valid(gphy); + + ret = clk_bulk_prepare_enable(inst->num_clks, inst->clks); + if (ret) + return ret; + + ret = reset_control_bulk_deassert(inst->num_rsts, inst->rsts); + if (ret) { + clk_bulk_disable_unprepare(inst->num_clks, inst->clks); + return ret; + } + + regmap_read(gphy->usb_cfg_regmap, gphy->usb2_cfg_offset + USBCS_USB2PHY_CFG21_OFFSET, ®); + reg |= USBCS_USB2PHY_CFG21_PHY_ENABLE; + regmap_write(gphy->usb_cfg_regmap, gphy->usb2_cfg_offset + USBCS_USB2PHY_CFG21_OFFSET, reg); + + return 0; +} + +static int google_usb2_phy_exit(struct phy *_phy) +{ + struct google_usb_phy_instance *inst = phy_get_drvdata(_phy); + struct google_usb_phy *gphy = inst->parent; + u32 reg; + + dev_dbg(gphy->dev, "exiting usb2 phy\n"); + + guard(mutex)(&gphy->phy_mutex); + + regmap_read(gphy->usb_cfg_regmap, gphy->usb2_cfg_offset + USBCS_USB2PHY_CFG21_OFFSET, ®); + reg &= ~USBCS_USB2PHY_CFG21_PHY_ENABLE; + regmap_write(gphy->usb_cfg_regmap, gphy->usb2_cfg_offset + USBCS_USB2PHY_CFG21_OFFSET, reg); + + reset_control_bulk_assert(inst->num_rsts, inst->rsts); + clk_bulk_disable_unprepare(inst->num_clks, inst->clks); + + return 0; +} + +static const struct phy_ops google_usb2_phy_ops = { + .init = google_usb2_phy_init, + .exit = google_usb2_phy_exit, +}; + +static struct phy *google_usb_phy_xlate(struct device *dev, + const struct of_phandle_args *args) +{ + struct google_usb_phy *gphy = dev_get_drvdata(dev); + + if (args->args[0] >= GOOGLE_USB_PHY_NUM) { + dev_err(dev, "invalid PHY index requested from DT\n"); + return ERR_PTR(-ENODEV); + } + return gphy->insts[args->args[0]].phy; +} + +static int google_usb_phy_probe(struct platform_device *pdev) +{ + struct typec_switch_desc sw_desc = { }; + struct google_usb_phy_instance *inst; + struct phy_provider *phy_provider; + struct device *dev = &pdev->dev; + struct google_usb_phy *gphy; + struct phy *phy; + u32 args[1]; + int ret; + + gphy = devm_kzalloc(dev, sizeof(*gphy), GFP_KERNEL); + if (!gphy) + return -ENOMEM; + + dev_set_drvdata(dev, gphy); + gphy->dev = dev; + + ret = devm_mutex_init(dev, &gphy->phy_mutex); + if (ret) + return ret; + + gphy->usb_cfg_regmap = + syscon_regmap_lookup_by_phandle_args(dev->of_node, + "google,usb-cfg-csr", + ARRAY_SIZE(args), args); + if (IS_ERR(gphy->usb_cfg_regmap)) { + return dev_err_probe(dev, PTR_ERR(gphy->usb_cfg_regmap), + "invalid usb cfg csr\n"); + } + + gphy->usb2_cfg_offset = args[0]; + + gphy->usbdp_top_base = devm_platform_ioremap_resource_byname(pdev, + "usbdp_top"); + if (IS_ERR(gphy->usbdp_top_base)) + return dev_err_probe(dev, PTR_ERR(gphy->usbdp_top_base), + "invalid usbdp top\n"); + + gphy->insts = devm_kcalloc(dev, GOOGLE_USB_PHY_NUM, sizeof(*gphy->insts), GFP_KERNEL); + if (!gphy->insts) + return -ENOMEM; + + inst = &gphy->insts[GOOGLE_USB2_PHY]; + inst->parent = gphy; + inst->index = GOOGLE_USB2_PHY; + phy = devm_phy_create(dev, NULL, &google_usb2_phy_ops); + if (IS_ERR(phy)) + return dev_err_probe(dev, PTR_ERR(phy), + "failed to create usb2 phy instance\n"); + inst->phy = phy; + phy_set_drvdata(phy, inst); + + inst->num_clks = 2; + inst->clks = devm_kcalloc(dev, inst->num_clks, sizeof(*inst->clks), GFP_KERNEL); + if (!inst->clks) + return -ENOMEM; + inst->clks[0].id = "usb2"; + inst->clks[1].id = "usb2_apb"; + ret = devm_clk_bulk_get(dev, inst->num_clks, inst->clks); + if (ret) + return dev_err_probe(dev, ret, "failed to get u2 phy clks\n"); + + inst->num_rsts = 2; + inst->rsts = devm_kcalloc(dev, inst->num_rsts, sizeof(*inst->rsts), GFP_KERNEL); + if (!inst->rsts) + return -ENOMEM; + inst->rsts[0].id = "usb2"; + inst->rsts[1].id = "usb2_apb"; + ret = devm_reset_control_bulk_get_exclusive(dev, inst->num_rsts, inst->rsts); + if (ret) + return dev_err_probe(dev, ret, "failed to get u2 phy resets\n"); + + phy_provider = devm_of_phy_provider_register(dev, google_usb_phy_xlate); + if (IS_ERR(phy_provider)) + return dev_err_probe(dev, PTR_ERR(phy_provider), + "failed to register phy provider\n"); + + pm_runtime_enable(dev); + + sw_desc.fwnode = dev_fwnode(dev); + sw_desc.drvdata = gphy; + sw_desc.name = fwnode_get_name(dev_fwnode(dev)); + sw_desc.set = google_usb_set_orientation; + + gphy->sw = typec_switch_register(dev, &sw_desc); + if (IS_ERR(gphy->sw)) + return dev_err_probe(dev, PTR_ERR(gphy->sw), + "failed to register typec switch\n"); + + return 0; +} + +static void google_usb_phy_remove(struct platform_device *pdev) +{ + struct google_usb_phy *gphy = dev_get_drvdata(&pdev->dev); + + typec_switch_unregister(gphy->sw); + pm_runtime_disable(&pdev->dev); +} + +static const struct of_device_id google_usb_phy_of_match[] = { + { + .compatible = "google,lga-usb-phy", + }, + { } +}; +MODULE_DEVICE_TABLE(of, google_usb_phy_of_match); + +static struct platform_driver google_usb_phy = { + .probe = google_usb_phy_probe, + .remove = google_usb_phy_remove, + .driver = { + .name = "google-usb-phy", + .of_match_table = google_usb_phy_of_match, + } +}; + +module_platform_driver(google_usb_phy); +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("Google USB phy driver"); -- cgit v1.3.1