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/chipidea/debug.c | 313 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 313 insertions(+) create mode 100644 drivers/usb/chipidea/debug.c (limited to 'drivers/usb/chipidea/debug.c') diff --git a/drivers/usb/chipidea/debug.c b/drivers/usb/chipidea/debug.c new file mode 100644 index 000000000..e72c43615 --- /dev/null +++ b/drivers/usb/chipidea/debug.c @@ -0,0 +1,313 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "ci.h" +#include "udc.h" +#include "bits.h" +#include "otg.h" + +/* + * ci_device_show: prints information about device capabilities and status + */ +static int ci_device_show(struct seq_file *s, void *data) +{ + struct ci_hdrc *ci = s->private; + struct usb_gadget *gadget = &ci->gadget; + + seq_printf(s, "speed = %d\n", gadget->speed); + seq_printf(s, "max_speed = %d\n", gadget->max_speed); + seq_printf(s, "is_otg = %d\n", gadget->is_otg); + seq_printf(s, "is_a_peripheral = %d\n", gadget->is_a_peripheral); + seq_printf(s, "b_hnp_enable = %d\n", gadget->b_hnp_enable); + seq_printf(s, "a_hnp_support = %d\n", gadget->a_hnp_support); + seq_printf(s, "a_alt_hnp_support = %d\n", gadget->a_alt_hnp_support); + seq_printf(s, "name = %s\n", + (gadget->name ? gadget->name : "")); + + if (!ci->driver) + return 0; + + seq_printf(s, "gadget function = %s\n", + (ci->driver->function ? ci->driver->function : "")); + seq_printf(s, "gadget max speed = %d\n", ci->driver->max_speed); + + return 0; +} +DEFINE_SHOW_ATTRIBUTE(ci_device); + +/* + * ci_port_test_show: reads port test mode + */ +static int ci_port_test_show(struct seq_file *s, void *data) +{ + struct ci_hdrc *ci = s->private; + unsigned long flags; + unsigned mode; + + pm_runtime_get_sync(ci->dev); + spin_lock_irqsave(&ci->lock, flags); + mode = hw_port_test_get(ci); + spin_unlock_irqrestore(&ci->lock, flags); + pm_runtime_put_sync(ci->dev); + + seq_printf(s, "mode = %u\n", mode); + + return 0; +} + +/* + * ci_port_test_write: writes port test mode + */ +static ssize_t ci_port_test_write(struct file *file, const char __user *ubuf, + size_t count, loff_t *ppos) +{ + struct seq_file *s = file->private_data; + struct ci_hdrc *ci = s->private; + unsigned long flags; + unsigned mode; + char buf[32]; + int ret; + + count = min_t(size_t, sizeof(buf) - 1, count); + if (copy_from_user(buf, ubuf, count)) + return -EFAULT; + + /* sscanf requires a zero terminated string */ + buf[count] = '\0'; + + if (sscanf(buf, "%u", &mode) != 1) + return -EINVAL; + + if (mode > 255) + return -EBADRQC; + + pm_runtime_get_sync(ci->dev); + spin_lock_irqsave(&ci->lock, flags); + ret = hw_port_test_set(ci, mode); + spin_unlock_irqrestore(&ci->lock, flags); + pm_runtime_put_sync(ci->dev); + + return ret ? ret : count; +} + +static int ci_port_test_open(struct inode *inode, struct file *file) +{ + return single_open(file, ci_port_test_show, inode->i_private); +} + +static const struct file_operations ci_port_test_fops = { + .open = ci_port_test_open, + .write = ci_port_test_write, + .read = seq_read, + .llseek = seq_lseek, + .release = single_release, +}; + +/* + * ci_qheads_show: DMA contents of all queue heads + */ +static int ci_qheads_show(struct seq_file *s, void *data) +{ + struct ci_hdrc *ci = s->private; + unsigned long flags; + unsigned i, j; + + if (ci->role != CI_ROLE_GADGET) { + seq_printf(s, "not in gadget mode\n"); + return 0; + } + + spin_lock_irqsave(&ci->lock, flags); + for (i = 0; i < ci->hw_ep_max/2; i++) { + struct ci_hw_ep *hweprx = &ci->ci_hw_ep[i]; + struct ci_hw_ep *hweptx = + &ci->ci_hw_ep[i + ci->hw_ep_max/2]; + seq_printf(s, "EP=%02i: RX=%08X TX=%08X\n", + i, (u32)hweprx->qh.dma, (u32)hweptx->qh.dma); + for (j = 0; j < (sizeof(struct ci_hw_qh)/sizeof(u32)); j++) + seq_printf(s, " %04X: %08X %08X\n", j, + *((u32 *)hweprx->qh.ptr + j), + *((u32 *)hweptx->qh.ptr + j)); + } + spin_unlock_irqrestore(&ci->lock, flags); + + return 0; +} +DEFINE_SHOW_ATTRIBUTE(ci_qheads); + +/* + * ci_requests_show: DMA contents of all requests currently queued (all endpts) + */ +static int ci_requests_show(struct seq_file *s, void *data) +{ + struct ci_hdrc *ci = s->private; + unsigned long flags; + struct ci_hw_req *req = NULL; + struct td_node *node, *tmpnode; + unsigned i, j, qsize = sizeof(struct ci_hw_td)/sizeof(u32); + + if (ci->role != CI_ROLE_GADGET) { + seq_printf(s, "not in gadget mode\n"); + return 0; + } + + spin_lock_irqsave(&ci->lock, flags); + for (i = 0; i < ci->hw_ep_max; i++) + list_for_each_entry(req, &ci->ci_hw_ep[i].qh.queue, queue) { + list_for_each_entry_safe(node, tmpnode, &req->tds, td) { + seq_printf(s, "EP=%02i: TD=%08X %s\n", + i % (ci->hw_ep_max / 2), + (u32)node->dma, + ((i < ci->hw_ep_max/2) ? + "RX" : "TX")); + + for (j = 0; j < qsize; j++) + seq_printf(s, " %04X: %08X\n", j, + *((u32 *)node->ptr + j)); + } + } + spin_unlock_irqrestore(&ci->lock, flags); + + return 0; +} +DEFINE_SHOW_ATTRIBUTE(ci_requests); + +static int ci_otg_show(struct seq_file *s, void *unused) +{ + struct ci_hdrc *ci = s->private; + struct otg_fsm *fsm; + + if (!ci || !ci_otg_is_fsm_mode(ci)) + return 0; + + fsm = &ci->fsm; + + /* ------ State ----- */ + seq_printf(s, "OTG state: %s\n\n", + usb_otg_state_string(ci->otg.state)); + + /* ------ State Machine Variables ----- */ + seq_printf(s, "a_bus_drop: %d\n", fsm->a_bus_drop); + + seq_printf(s, "a_bus_req: %d\n", fsm->a_bus_req); + + seq_printf(s, "a_srp_det: %d\n", fsm->a_srp_det); + + seq_printf(s, "a_vbus_vld: %d\n", fsm->a_vbus_vld); + + seq_printf(s, "b_conn: %d\n", fsm->b_conn); + + seq_printf(s, "adp_change: %d\n", fsm->adp_change); + + seq_printf(s, "power_up: %d\n", fsm->power_up); + + seq_printf(s, "a_bus_resume: %d\n", fsm->a_bus_resume); + + seq_printf(s, "a_bus_suspend: %d\n", fsm->a_bus_suspend); + + seq_printf(s, "a_conn: %d\n", fsm->a_conn); + + seq_printf(s, "b_bus_req: %d\n", fsm->b_bus_req); + + seq_printf(s, "b_bus_suspend: %d\n", fsm->b_bus_suspend); + + seq_printf(s, "b_se0_srp: %d\n", fsm->b_se0_srp); + + seq_printf(s, "b_ssend_srp: %d\n", fsm->b_ssend_srp); + + seq_printf(s, "b_sess_vld: %d\n", fsm->b_sess_vld); + + seq_printf(s, "b_srp_done: %d\n", fsm->b_srp_done); + + seq_printf(s, "drv_vbus: %d\n", fsm->drv_vbus); + + seq_printf(s, "loc_conn: %d\n", fsm->loc_conn); + + seq_printf(s, "loc_sof: %d\n", fsm->loc_sof); + + seq_printf(s, "adp_prb: %d\n", fsm->adp_prb); + + seq_printf(s, "id: %d\n", fsm->id); + + seq_printf(s, "protocol: %d\n", fsm->protocol); + + return 0; +} +DEFINE_SHOW_ATTRIBUTE(ci_otg); + +static int ci_registers_show(struct seq_file *s, void *unused) +{ + struct ci_hdrc *ci = s->private; + u32 tmp_reg; + + if (!ci || ci->in_lpm) + return -EPERM; + + /* ------ Registers ----- */ + tmp_reg = hw_read_intr_enable(ci); + seq_printf(s, "USBINTR reg: %08x\n", tmp_reg); + + tmp_reg = hw_read_intr_status(ci); + seq_printf(s, "USBSTS reg: %08x\n", tmp_reg); + + tmp_reg = hw_read(ci, OP_USBMODE, ~0); + seq_printf(s, "USBMODE reg: %08x\n", tmp_reg); + + tmp_reg = hw_read(ci, OP_USBCMD, ~0); + seq_printf(s, "USBCMD reg: %08x\n", tmp_reg); + + tmp_reg = hw_read(ci, OP_PORTSC, ~0); + seq_printf(s, "PORTSC reg: %08x\n", tmp_reg); + + if (ci->is_otg) { + tmp_reg = hw_read_otgsc(ci, ~0); + seq_printf(s, "OTGSC reg: %08x\n", tmp_reg); + } + + return 0; +} +DEFINE_SHOW_ATTRIBUTE(ci_registers); + +/** + * dbg_create_files: initializes the attribute interface + * @ci: device + * + * This function returns an error code + */ +void dbg_create_files(struct ci_hdrc *ci) +{ + struct dentry *dir; + + dir = debugfs_create_dir(dev_name(ci->dev), usb_debug_root); + + debugfs_create_file("device", S_IRUGO, dir, ci, &ci_device_fops); + debugfs_create_file("port_test", S_IRUGO | S_IWUSR, dir, ci, &ci_port_test_fops); + debugfs_create_file("qheads", S_IRUGO, dir, ci, &ci_qheads_fops); + debugfs_create_file("requests", S_IRUGO, dir, ci, &ci_requests_fops); + + if (ci_otg_is_fsm_mode(ci)) + debugfs_create_file("otg", S_IRUGO, dir, ci, &ci_otg_fops); + + debugfs_create_file("registers", S_IRUGO, dir, ci, &ci_registers_fops); +} + +/** + * dbg_remove_files: destroys the attribute interface + * @ci: device + */ +void dbg_remove_files(struct ci_hdrc *ci) +{ + debugfs_lookup_and_remove(dev_name(ci->dev), usb_debug_root); +} -- cgit v1.3.1