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/interconnect/samsung/Kconfig | 15 +++ drivers/interconnect/samsung/Makefile | 4 + drivers/interconnect/samsung/exynos.c | 196 ++++++++++++++++++++++++++++++++++ 3 files changed, 215 insertions(+) create mode 100644 drivers/interconnect/samsung/Kconfig create mode 100644 drivers/interconnect/samsung/Makefile create mode 100644 drivers/interconnect/samsung/exynos.c (limited to 'drivers/interconnect/samsung') diff --git a/drivers/interconnect/samsung/Kconfig b/drivers/interconnect/samsung/Kconfig new file mode 100644 index 000000000..fbee87e37 --- /dev/null +++ b/drivers/interconnect/samsung/Kconfig @@ -0,0 +1,15 @@ +# SPDX-License-Identifier: GPL-2.0-only +config INTERCONNECT_SAMSUNG + bool "Samsung SoC interconnect drivers" + depends on ARCH_EXYNOS || COMPILE_TEST + help + Interconnect drivers for Samsung SoCs. + +config INTERCONNECT_EXYNOS + tristate "Exynos SoC generic interconnect driver" + depends on INTERCONNECT_SAMSUNG + default y if ARCH_EXYNOS + help + Generic interconnect driver for Samsung Exynos SoCs (e.g. Exynos3250, + Exynos4210, Exynos4412, Exynos542x, Exynos5433). + Choose Y here only if you build for such Samsung SoC. diff --git a/drivers/interconnect/samsung/Makefile b/drivers/interconnect/samsung/Makefile new file mode 100644 index 000000000..e19d1df7d --- /dev/null +++ b/drivers/interconnect/samsung/Makefile @@ -0,0 +1,4 @@ +# SPDX-License-Identifier: GPL-2.0 +exynos-interconnect-objs := exynos.o + +obj-$(CONFIG_INTERCONNECT_EXYNOS) += exynos-interconnect.o diff --git a/drivers/interconnect/samsung/exynos.c b/drivers/interconnect/samsung/exynos.c new file mode 100644 index 000000000..8e8f56186 --- /dev/null +++ b/drivers/interconnect/samsung/exynos.c @@ -0,0 +1,196 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Exynos generic interconnect provider driver + * + * Copyright (c) 2020 Samsung Electronics Co., Ltd. + * + * Authors: Artur Świgoń + * Sylwester Nawrocki + */ +#include +#include +#include +#include +#include +#include +#include + +#define EXYNOS_ICC_DEFAULT_BUS_CLK_RATIO 8 + +struct exynos_icc_priv { + struct device *dev; + + /* One interconnect node per provider */ + struct icc_provider provider; + struct icc_node *node; + + struct dev_pm_qos_request qos_req; + u32 bus_clk_ratio; +}; + +static struct icc_node *exynos_icc_get_parent(struct device_node *np) +{ + struct of_phandle_args args; + struct icc_node_data *icc_node_data; + struct icc_node *icc_node; + int num, ret; + + num = of_count_phandle_with_args(np, "interconnects", + "#interconnect-cells"); + if (num < 1) + return NULL; /* parent nodes are optional */ + + /* Get the interconnect target node */ + ret = of_parse_phandle_with_args(np, "interconnects", + "#interconnect-cells", 0, &args); + if (ret < 0) + return ERR_PTR(ret); + + icc_node_data = of_icc_get_from_provider(&args); + of_node_put(args.np); + + if (IS_ERR(icc_node_data)) + return ERR_CAST(icc_node_data); + + icc_node = icc_node_data->node; + kfree(icc_node_data); + + return icc_node; +} + +static int exynos_generic_icc_set(struct icc_node *src, struct icc_node *dst) +{ + struct exynos_icc_priv *src_priv = src->data, *dst_priv = dst->data; + s32 src_freq = max(src->avg_bw, src->peak_bw) / src_priv->bus_clk_ratio; + s32 dst_freq = max(dst->avg_bw, dst->peak_bw) / dst_priv->bus_clk_ratio; + int ret; + + ret = dev_pm_qos_update_request(&src_priv->qos_req, src_freq); + if (ret < 0) { + dev_err(src_priv->dev, "failed to update PM QoS of %s (src)\n", + src->name); + return ret; + } + + ret = dev_pm_qos_update_request(&dst_priv->qos_req, dst_freq); + if (ret < 0) { + dev_err(dst_priv->dev, "failed to update PM QoS of %s (dst)\n", + dst->name); + return ret; + } + + return 0; +} + +static struct icc_node *exynos_generic_icc_xlate(const struct of_phandle_args *spec, + void *data) +{ + struct exynos_icc_priv *priv = data; + + if (spec->np != priv->dev->parent->of_node) + return ERR_PTR(-EINVAL); + + return priv->node; +} + +static void exynos_generic_icc_remove(struct platform_device *pdev) +{ + struct exynos_icc_priv *priv = platform_get_drvdata(pdev); + + icc_provider_deregister(&priv->provider); + icc_nodes_remove(&priv->provider); +} + +static int exynos_generic_icc_probe(struct platform_device *pdev) +{ + struct device *bus_dev = pdev->dev.parent; + struct exynos_icc_priv *priv; + struct icc_provider *provider; + struct icc_node *icc_node, *icc_parent_node; + int ret; + + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + priv->dev = &pdev->dev; + platform_set_drvdata(pdev, priv); + + provider = &priv->provider; + + provider->set = exynos_generic_icc_set; + provider->aggregate = icc_std_aggregate; + provider->xlate = exynos_generic_icc_xlate; + provider->dev = bus_dev; + provider->inter_set = true; + provider->data = priv; + + icc_provider_init(provider); + + icc_node = icc_node_create(pdev->id); + if (IS_ERR(icc_node)) + return PTR_ERR(icc_node); + + priv->node = icc_node; + icc_node->name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "%pOFn", + bus_dev->of_node); + if (!icc_node->name) { + icc_node_destroy(pdev->id); + return -ENOMEM; + } + + if (of_property_read_u32(bus_dev->of_node, "samsung,data-clock-ratio", + &priv->bus_clk_ratio)) + priv->bus_clk_ratio = EXYNOS_ICC_DEFAULT_BUS_CLK_RATIO; + + icc_node->data = priv; + icc_node_add(icc_node, provider); + + /* + * Register a PM QoS request for the parent (devfreq) device. + */ + ret = dev_pm_qos_add_request(bus_dev, &priv->qos_req, + DEV_PM_QOS_MIN_FREQUENCY, 0); + if (ret < 0) + goto err_node_del; + + icc_parent_node = exynos_icc_get_parent(bus_dev->of_node); + if (IS_ERR(icc_parent_node)) { + ret = PTR_ERR(icc_parent_node); + goto err_pmqos_del; + } + if (icc_parent_node) { + ret = icc_link_create(icc_node, icc_parent_node->id); + if (ret < 0) + goto err_pmqos_del; + } + + ret = icc_provider_register(provider); + if (ret < 0) + goto err_pmqos_del; + + return 0; + +err_pmqos_del: + dev_pm_qos_remove_request(&priv->qos_req); +err_node_del: + icc_nodes_remove(provider); + + return ret; +} + +static struct platform_driver exynos_generic_icc_driver = { + .driver = { + .name = "exynos-generic-icc", + .sync_state = icc_sync_state, + }, + .probe = exynos_generic_icc_probe, + .remove = exynos_generic_icc_remove, +}; +module_platform_driver(exynos_generic_icc_driver); + +MODULE_DESCRIPTION("Exynos generic interconnect driver"); +MODULE_AUTHOR("Artur Świgoń "); +MODULE_AUTHOR("Sylwester Nawrocki "); +MODULE_LICENSE("GPL v2"); +MODULE_ALIAS("platform:exynos-generic-icc"); -- cgit v1.3.1