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/reset/reset-sunplus.c | 206 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 206 insertions(+) create mode 100644 drivers/reset/reset-sunplus.c (limited to 'drivers/reset/reset-sunplus.c') diff --git a/drivers/reset/reset-sunplus.c b/drivers/reset/reset-sunplus.c new file mode 100644 index 000000000..c136a1f07 --- /dev/null +++ b/drivers/reset/reset-sunplus.c @@ -0,0 +1,206 @@ +// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +/* + * SP7021 reset driver + * + * Copyright (C) Sunplus Technology Co., Ltd. + * All rights reserved. + */ + +#include +#include +#include +#include +#include + +/* HIWORD_MASK_REG BITS */ +#define BITS_PER_HWM_REG 16 + +/* resets HW info: reg_index_shift */ +static const u32 sp_resets[] = { +/* SP7021: mo_reset0 ~ mo_reset9 */ + 0x00, + 0x02, + 0x03, + 0x04, + 0x05, + 0x06, + 0x07, + 0x08, + 0x09, + 0x0a, + 0x0b, + 0x0d, + 0x0e, + 0x0f, + 0x10, + 0x12, + 0x14, + 0x15, + 0x16, + 0x17, + 0x18, + 0x19, + 0x1a, + 0x1b, + 0x1c, + 0x1d, + 0x1e, + 0x1f, + 0x20, + 0x21, + 0x22, + 0x23, + 0x24, + 0x25, + 0x26, + 0x2a, + 0x2b, + 0x2d, + 0x2e, + 0x30, + 0x31, + 0x32, + 0x33, + 0x3d, + 0x3e, + 0x3f, + 0x42, + 0x44, + 0x4b, + 0x4c, + 0x4d, + 0x4e, + 0x4f, + 0x50, + 0x55, + 0x60, + 0x61, + 0x6a, + 0x6f, + 0x70, + 0x73, + 0x74, + 0x86, + 0x8a, + 0x8b, + 0x8d, + 0x8e, + 0x8f, + 0x90, + 0x92, + 0x93, + 0x94, + 0x95, + 0x96, + 0x97, + 0x98, + 0x99, +}; + +struct sp_reset { + struct reset_controller_dev rcdev; + void __iomem *base; +}; + +static inline struct sp_reset *to_sp_reset(struct reset_controller_dev *rcdev) +{ + return container_of(rcdev, struct sp_reset, rcdev); +} + +static int sp_reset_update(struct reset_controller_dev *rcdev, + unsigned long id, bool assert) +{ + struct sp_reset *reset = to_sp_reset(rcdev); + int index = sp_resets[id] / BITS_PER_HWM_REG; + int shift = sp_resets[id] % BITS_PER_HWM_REG; + u32 val; + + val = (1 << (16 + shift)) | (assert << shift); + writel(val, reset->base + (index * 4)); + + return 0; +} + +static int sp_reset_assert(struct reset_controller_dev *rcdev, + unsigned long id) +{ + return sp_reset_update(rcdev, id, true); +} + +static int sp_reset_deassert(struct reset_controller_dev *rcdev, + unsigned long id) +{ + return sp_reset_update(rcdev, id, false); +} + +static int sp_reset_status(struct reset_controller_dev *rcdev, + unsigned long id) +{ + struct sp_reset *reset = to_sp_reset(rcdev); + int index = sp_resets[id] / BITS_PER_HWM_REG; + int shift = sp_resets[id] % BITS_PER_HWM_REG; + u32 reg; + + reg = readl(reset->base + (index * 4)); + + return !!(reg & BIT(shift)); +} + +static const struct reset_control_ops sp_reset_ops = { + .assert = sp_reset_assert, + .deassert = sp_reset_deassert, + .status = sp_reset_status, +}; + +static int sp_restart(struct sys_off_data *data) +{ + struct sp_reset *reset = data->cb_data; + + sp_reset_assert(&reset->rcdev, 0); + sp_reset_deassert(&reset->rcdev, 0); + + return NOTIFY_DONE; +} + +static int sp_reset_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct sp_reset *reset; + struct resource *res; + int ret; + + reset = devm_kzalloc(dev, sizeof(*reset), GFP_KERNEL); + if (!reset) + return -ENOMEM; + + reset->base = devm_platform_get_and_ioremap_resource(pdev, 0, &res); + if (IS_ERR(reset->base)) + return PTR_ERR(reset->base); + + reset->rcdev.ops = &sp_reset_ops; + reset->rcdev.owner = THIS_MODULE; + reset->rcdev.of_node = dev->of_node; + reset->rcdev.nr_resets = resource_size(res) / 4 * BITS_PER_HWM_REG; + + ret = devm_reset_controller_register(dev, &reset->rcdev); + if (ret) + return ret; + + return devm_register_sys_off_handler(&pdev->dev, SYS_OFF_MODE_RESTART, + 192, sp_restart, reset); +} + +static const struct of_device_id sp_reset_dt_ids[] = { + {.compatible = "sunplus,sp7021-reset",}, + { /* sentinel */ }, +}; + +static struct platform_driver sp_reset_driver = { + .probe = sp_reset_probe, + .driver = { + .name = "sunplus-reset", + .of_match_table = sp_reset_dt_ids, + .suppress_bind_attrs = true, + }, +}; +builtin_platform_driver(sp_reset_driver); -- cgit v1.3.1