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/usb/cdns3/host.c | 168 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 168 insertions(+) create mode 100644 drivers/usb/cdns3/host.c (limited to 'drivers/usb/cdns3/host.c') diff --git a/drivers/usb/cdns3/host.c b/drivers/usb/cdns3/host.c new file mode 100644 index 000000000..f0df114c2 --- /dev/null +++ b/drivers/usb/cdns3/host.c @@ -0,0 +1,168 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Cadence USBSS and USBSSP DRD Driver - host side + * + * Copyright (C) 2018-2019 Cadence Design Systems. + * Copyright (C) 2017-2018 NXP + * + * Authors: Peter Chen + * Pawel Laszczak + */ + +#include +#include +#include "core.h" +#include "drd.h" +#include "host-export.h" +#include +#include "../host/xhci.h" +#include "../host/xhci-plat.h" + +/* + * The XECP_PORT_CAP_REG and XECP_AUX_CTRL_REG1 exist only + * in Cadence USB3 dual-role controller, so it can't be used + * with Cadence CDNSP dual-role controller. + */ +#define XECP_PORT_CAP_REG 0x8000 +#define XECP_AUX_CTRL_REG1 0x8120 + +#define CFG_RXDET_P3_EN BIT(15) +#define LPM_2_STB_SWITCH_EN BIT(25) + +static void xhci_cdns3_plat_start(struct usb_hcd *hcd) +{ + struct xhci_hcd *xhci = hcd_to_xhci(hcd); + u32 value; + + /* set usbcmd.EU3S */ + value = readl(&xhci->op_regs->command); + value |= CMD_PM_INDEX; + writel(value, &xhci->op_regs->command); + + if (hcd->regs) { + value = readl(hcd->regs + XECP_AUX_CTRL_REG1); + value |= CFG_RXDET_P3_EN; + writel(value, hcd->regs + XECP_AUX_CTRL_REG1); + + value = readl(hcd->regs + XECP_PORT_CAP_REG); + value |= LPM_2_STB_SWITCH_EN; + writel(value, hcd->regs + XECP_PORT_CAP_REG); + } +} + +static int xhci_cdns3_resume_quirk(struct usb_hcd *hcd) +{ + xhci_cdns3_plat_start(hcd); + return 0; +} + +static const struct xhci_plat_priv xhci_plat_cdns3_xhci = { + .quirks = XHCI_SKIP_PHY_INIT | XHCI_AVOID_BEI, + .plat_start = xhci_cdns3_plat_start, + .resume_quirk = xhci_cdns3_resume_quirk, +}; + +static const struct xhci_plat_priv xhci_plat_cdnsp_xhci = { + .quirks = XHCI_CDNS_SCTX_QUIRK, +}; + +static int __cdns_host_init(struct cdns *cdns) +{ + struct platform_device *xhci; + int ret; + struct usb_hcd *hcd; + + cdns_drd_host_on(cdns); + + xhci = platform_device_alloc("xhci-hcd", PLATFORM_DEVID_AUTO); + if (!xhci) { + dev_err(cdns->dev, "couldn't allocate xHCI device\n"); + return -ENOMEM; + } + + xhci->dev.parent = cdns->dev; + cdns->host_dev = xhci; + + ret = platform_device_add_resources(xhci, cdns->xhci_res, + CDNS_XHCI_RESOURCES_NUM); + if (ret) { + dev_err(cdns->dev, "couldn't add resources to xHCI device\n"); + goto err1; + } + + if (cdns->version < CDNSP_CONTROLLER_V2) + cdns->xhci_plat_data = kmemdup(&xhci_plat_cdns3_xhci, + sizeof(struct xhci_plat_priv), GFP_KERNEL); + else + cdns->xhci_plat_data = kmemdup(&xhci_plat_cdnsp_xhci, + sizeof(struct xhci_plat_priv), GFP_KERNEL); + + if (!cdns->xhci_plat_data) { + ret = -ENOMEM; + goto err1; + } + + if (cdns->pdata && (cdns->pdata->quirks & CDNS3_DEFAULT_PM_RUNTIME_ALLOW)) + cdns->xhci_plat_data->quirks |= XHCI_DEFAULT_PM_RUNTIME_ALLOW; + + ret = platform_device_add_data(xhci, cdns->xhci_plat_data, + sizeof(struct xhci_plat_priv)); + if (ret) + goto free_memory; + + ret = platform_device_add(xhci); + if (ret) { + dev_err(cdns->dev, "failed to register xHCI device\n"); + goto free_memory; + } + + /* Glue needs to access xHCI region register for Power management */ + hcd = platform_get_drvdata(xhci); + if (hcd) + cdns->xhci_regs = hcd->regs; + + return 0; + +free_memory: + kfree(cdns->xhci_plat_data); +err1: + platform_device_put(xhci); + return ret; +} + +static void cdns_host_exit(struct cdns *cdns) +{ + kfree(cdns->xhci_plat_data); + platform_device_unregister(cdns->host_dev); + cdns->host_dev = NULL; + cdns_drd_host_off(cdns); +} + +static int cdns_host_resume(struct cdns *cdns, bool power_lost) +{ + struct usb_hcd *hcd = platform_get_drvdata(cdns->host_dev); + struct xhci_plat_priv *priv = hcd_to_xhci_priv(hcd); + + priv->power_lost = power_lost; + + return 0; +} + +int cdns_host_init(struct cdns *cdns) +{ + struct cdns_role_driver *rdrv; + + rdrv = devm_kzalloc(cdns->dev, sizeof(*rdrv), GFP_KERNEL); + if (!rdrv) + return -ENOMEM; + + rdrv->start = __cdns_host_init; + rdrv->stop = cdns_host_exit; + rdrv->resume = cdns_host_resume; + rdrv->state = CDNS_ROLE_STATE_INACTIVE; + rdrv->name = "host"; + + cdns->roles[USB_ROLE_HOST] = rdrv; + + return 0; +} -- cgit v1.3.1