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-hsdk.c | 135 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 135 insertions(+) create mode 100644 drivers/reset/reset-hsdk.c (limited to 'drivers/reset/reset-hsdk.c') diff --git a/drivers/reset/reset-hsdk.c b/drivers/reset/reset-hsdk.c new file mode 100644 index 000000000..98460e087 --- /dev/null +++ b/drivers/reset/reset-hsdk.c @@ -0,0 +1,135 @@ +/* + * Copyright (C) 2017 Synopsys. + * + * Synopsys HSDK Development platform reset driver. + * + * This file is licensed under the terms of the GNU General Public + * License version 2. This program is licensed "as is" without any + * warranty of any kind, whether express or implied. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define to_hsdk_rst(p) container_of((p), struct hsdk_rst, rcdev) + +struct hsdk_rst { + void __iomem *regs_ctl; + void __iomem *regs_rst; + spinlock_t lock; + struct reset_controller_dev rcdev; +}; + +static const u32 rst_map[] = { + BIT(16), /* APB_RST */ + BIT(17), /* AXI_RST */ + BIT(18), /* ETH_RST */ + BIT(19), /* USB_RST */ + BIT(20), /* SDIO_RST */ + BIT(21), /* HDMI_RST */ + BIT(22), /* GFX_RST */ + BIT(25), /* DMAC_RST */ + BIT(31), /* EBI_RST */ +}; + +#define HSDK_MAX_RESETS ARRAY_SIZE(rst_map) + +#define CGU_SYS_RST_CTRL 0x0 +#define CGU_IP_SW_RESET 0x0 +#define CGU_IP_SW_RESET_DELAY_SHIFT 16 +#define CGU_IP_SW_RESET_DELAY_MASK GENMASK(31, CGU_IP_SW_RESET_DELAY_SHIFT) +#define CGU_IP_SW_RESET_DELAY 0 +#define CGU_IP_SW_RESET_RESET BIT(0) +#define SW_RESET_TIMEOUT 10000 + +static void hsdk_reset_config(struct hsdk_rst *rst, unsigned long id) +{ + writel(rst_map[id], rst->regs_ctl + CGU_SYS_RST_CTRL); +} + +static int hsdk_reset_do(struct hsdk_rst *rst) +{ + u32 reg; + + reg = readl(rst->regs_rst + CGU_IP_SW_RESET); + reg &= ~CGU_IP_SW_RESET_DELAY_MASK; + reg |= CGU_IP_SW_RESET_DELAY << CGU_IP_SW_RESET_DELAY_SHIFT; + reg |= CGU_IP_SW_RESET_RESET; + writel(reg, rst->regs_rst + CGU_IP_SW_RESET); + + /* wait till reset bit is back to 0 */ + return readl_poll_timeout_atomic(rst->regs_rst + CGU_IP_SW_RESET, reg, + !(reg & CGU_IP_SW_RESET_RESET), 5, SW_RESET_TIMEOUT); +} + +static int hsdk_reset_reset(struct reset_controller_dev *rcdev, + unsigned long id) +{ + struct hsdk_rst *rst = to_hsdk_rst(rcdev); + unsigned long flags; + int ret; + + spin_lock_irqsave(&rst->lock, flags); + hsdk_reset_config(rst, id); + ret = hsdk_reset_do(rst); + spin_unlock_irqrestore(&rst->lock, flags); + + return ret; +} + +static const struct reset_control_ops hsdk_reset_ops = { + .reset = hsdk_reset_reset, + .deassert = hsdk_reset_reset, +}; + +static int hsdk_reset_probe(struct platform_device *pdev) +{ + struct hsdk_rst *rst; + + rst = devm_kzalloc(&pdev->dev, sizeof(*rst), GFP_KERNEL); + if (!rst) + return -ENOMEM; + + rst->regs_ctl = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(rst->regs_ctl)) + return PTR_ERR(rst->regs_ctl); + + rst->regs_rst = devm_platform_ioremap_resource(pdev, 1); + if (IS_ERR(rst->regs_rst)) + return PTR_ERR(rst->regs_rst); + + spin_lock_init(&rst->lock); + + rst->rcdev.owner = THIS_MODULE; + rst->rcdev.ops = &hsdk_reset_ops; + rst->rcdev.of_node = pdev->dev.of_node; + rst->rcdev.nr_resets = HSDK_MAX_RESETS; + rst->rcdev.of_reset_n_cells = 1; + + return reset_controller_register(&rst->rcdev); +} + +static const struct of_device_id hsdk_reset_dt_match[] = { + { .compatible = "snps,hsdk-reset" }, + { }, +}; + +static struct platform_driver hsdk_reset_driver = { + .probe = hsdk_reset_probe, + .driver = { + .name = "hsdk-reset", + .of_match_table = hsdk_reset_dt_match, + }, +}; +builtin_platform_driver(hsdk_reset_driver); + +MODULE_AUTHOR("Eugeniy Paltsev "); +MODULE_DESCRIPTION("Synopsys HSDK SDP reset driver"); +MODULE_LICENSE("GPL v2"); -- cgit v1.3.1