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/devfreq/mtk-cci-devfreq.c | 444 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 444 insertions(+) create mode 100644 drivers/devfreq/mtk-cci-devfreq.c (limited to 'drivers/devfreq/mtk-cci-devfreq.c') diff --git a/drivers/devfreq/mtk-cci-devfreq.c b/drivers/devfreq/mtk-cci-devfreq.c new file mode 100644 index 000000000..4c22be728 --- /dev/null +++ b/drivers/devfreq/mtk-cci-devfreq.c @@ -0,0 +1,444 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2022 MediaTek Inc. + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +struct mtk_ccifreq_platform_data { + int min_volt_shift; + int max_volt_shift; + int proc_max_volt; + int sram_min_volt; + int sram_max_volt; +}; + +struct mtk_ccifreq_drv { + struct device *dev; + struct devfreq *devfreq; + struct regulator *proc_reg; + struct regulator *sram_reg; + struct clk *cci_clk; + struct clk *inter_clk; + int inter_voltage; + unsigned long pre_freq; + /* Avoid race condition for regulators between notify and policy */ + struct mutex reg_lock; + struct notifier_block opp_nb; + const struct mtk_ccifreq_platform_data *soc_data; + int vtrack_max; +}; + +static int mtk_ccifreq_set_voltage(struct mtk_ccifreq_drv *drv, int new_voltage) +{ + const struct mtk_ccifreq_platform_data *soc_data = drv->soc_data; + struct device *dev = drv->dev; + int pre_voltage, pre_vsram, new_vsram, vsram, voltage, ret; + int retry_max = drv->vtrack_max; + + if (!drv->sram_reg) { + ret = regulator_set_voltage(drv->proc_reg, new_voltage, + drv->soc_data->proc_max_volt); + return ret; + } + + pre_voltage = regulator_get_voltage(drv->proc_reg); + if (pre_voltage < 0) { + dev_err(dev, "invalid vproc value: %d\n", pre_voltage); + return pre_voltage; + } + + pre_vsram = regulator_get_voltage(drv->sram_reg); + if (pre_vsram < 0) { + dev_err(dev, "invalid vsram value: %d\n", pre_vsram); + return pre_vsram; + } + + new_vsram = clamp(new_voltage + soc_data->min_volt_shift, + soc_data->sram_min_volt, soc_data->sram_max_volt); + + do { + if (pre_voltage <= new_voltage) { + vsram = clamp(pre_voltage + soc_data->max_volt_shift, + soc_data->sram_min_volt, new_vsram); + ret = regulator_set_voltage(drv->sram_reg, vsram, + soc_data->sram_max_volt); + if (ret) + return ret; + + if (vsram == soc_data->sram_max_volt || + new_vsram == soc_data->sram_min_volt) + voltage = new_voltage; + else + voltage = vsram - soc_data->min_volt_shift; + + ret = regulator_set_voltage(drv->proc_reg, voltage, + soc_data->proc_max_volt); + if (ret) { + regulator_set_voltage(drv->sram_reg, pre_vsram, + soc_data->sram_max_volt); + return ret; + } + } else { + voltage = max(new_voltage, + pre_vsram - soc_data->max_volt_shift); + ret = regulator_set_voltage(drv->proc_reg, voltage, + soc_data->proc_max_volt); + if (ret) + return ret; + + if (voltage == new_voltage) + vsram = new_vsram; + else + vsram = max(new_vsram, + voltage + soc_data->min_volt_shift); + + ret = regulator_set_voltage(drv->sram_reg, vsram, + soc_data->sram_max_volt); + if (ret) { + regulator_set_voltage(drv->proc_reg, pre_voltage, + soc_data->proc_max_volt); + return ret; + } + } + + pre_voltage = voltage; + pre_vsram = vsram; + + if (--retry_max < 0) { + dev_err(dev, + "over loop count, failed to set voltage\n"); + return -EINVAL; + } + } while (voltage != new_voltage || vsram != new_vsram); + + return 0; +} + +static int mtk_ccifreq_target(struct device *dev, unsigned long *freq, + u32 flags) +{ + struct mtk_ccifreq_drv *drv = dev_get_drvdata(dev); + struct clk *cci_pll; + struct dev_pm_opp *opp; + unsigned long opp_rate; + int voltage, pre_voltage, inter_voltage, target_voltage, ret; + + if (!drv) + return -EINVAL; + + if (drv->pre_freq == *freq) + return 0; + + mutex_lock(&drv->reg_lock); + + inter_voltage = drv->inter_voltage; + cci_pll = clk_get_parent(drv->cci_clk); + + opp_rate = *freq; + opp = devfreq_recommended_opp(dev, &opp_rate, 1); + if (IS_ERR(opp)) { + dev_err(dev, "failed to find opp for freq: %ld\n", opp_rate); + ret = PTR_ERR(opp); + goto out_unlock; + } + + voltage = dev_pm_opp_get_voltage(opp); + dev_pm_opp_put(opp); + + pre_voltage = regulator_get_voltage(drv->proc_reg); + if (pre_voltage < 0) { + dev_err(dev, "invalid vproc value: %d\n", pre_voltage); + ret = pre_voltage; + goto out_unlock; + } + + /* scale up: set voltage first then freq. */ + target_voltage = max(inter_voltage, voltage); + if (pre_voltage <= target_voltage) { + ret = mtk_ccifreq_set_voltage(drv, target_voltage); + if (ret) { + dev_err(dev, "failed to scale up voltage\n"); + goto out_restore_voltage; + } + } + + /* switch the cci clock to intermediate clock source. */ + ret = clk_set_parent(drv->cci_clk, drv->inter_clk); + if (ret) { + dev_err(dev, "failed to re-parent cci clock\n"); + goto out_restore_voltage; + } + + /* set the original clock to target rate. */ + ret = clk_set_rate(cci_pll, *freq); + if (ret) { + dev_err(dev, "failed to set cci pll rate: %d\n", ret); + clk_set_parent(drv->cci_clk, cci_pll); + goto out_restore_voltage; + } + + /* switch the cci clock back to the original clock source. */ + ret = clk_set_parent(drv->cci_clk, cci_pll); + if (ret) { + dev_err(dev, "failed to re-parent cci clock\n"); + mtk_ccifreq_set_voltage(drv, inter_voltage); + goto out_unlock; + } + + /* + * If the new voltage is lower than the intermediate voltage or the + * original voltage, scale down to the new voltage. + */ + if (voltage < inter_voltage || voltage < pre_voltage) { + ret = mtk_ccifreq_set_voltage(drv, voltage); + if (ret) { + dev_err(dev, "failed to scale down voltage\n"); + goto out_unlock; + } + } + + drv->pre_freq = *freq; + mutex_unlock(&drv->reg_lock); + + return 0; + +out_restore_voltage: + mtk_ccifreq_set_voltage(drv, pre_voltage); + +out_unlock: + mutex_unlock(&drv->reg_lock); + return ret; +} + +static int mtk_ccifreq_opp_notifier(struct notifier_block *nb, + unsigned long event, void *data) +{ + struct dev_pm_opp *opp = data; + struct mtk_ccifreq_drv *drv; + unsigned long freq, volt; + + drv = container_of(nb, struct mtk_ccifreq_drv, opp_nb); + + if (event == OPP_EVENT_ADJUST_VOLTAGE) { + mutex_lock(&drv->reg_lock); + freq = dev_pm_opp_get_freq(opp); + + /* current opp item is changed */ + if (freq == drv->pre_freq) { + volt = dev_pm_opp_get_voltage(opp); + mtk_ccifreq_set_voltage(drv, volt); + } + mutex_unlock(&drv->reg_lock); + } + + return 0; +} + +static struct devfreq_dev_profile mtk_ccifreq_profile = { + .target = mtk_ccifreq_target, +}; + +static int mtk_ccifreq_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct mtk_ccifreq_drv *drv; + struct devfreq_passive_data *passive_data; + struct dev_pm_opp *opp; + unsigned long rate, opp_volt; + int ret; + + drv = devm_kzalloc(dev, sizeof(*drv), GFP_KERNEL); + if (!drv) + return -ENOMEM; + + drv->dev = dev; + drv->soc_data = (const struct mtk_ccifreq_platform_data *) + of_device_get_match_data(&pdev->dev); + mutex_init(&drv->reg_lock); + platform_set_drvdata(pdev, drv); + + drv->cci_clk = devm_clk_get(dev, "cci"); + if (IS_ERR(drv->cci_clk)) { + ret = PTR_ERR(drv->cci_clk); + return dev_err_probe(dev, ret, "failed to get cci clk\n"); + } + + drv->inter_clk = devm_clk_get(dev, "intermediate"); + if (IS_ERR(drv->inter_clk)) { + ret = PTR_ERR(drv->inter_clk); + return dev_err_probe(dev, ret, + "failed to get intermediate clk\n"); + } + + drv->proc_reg = devm_regulator_get_optional(dev, "proc"); + if (IS_ERR(drv->proc_reg)) { + ret = PTR_ERR(drv->proc_reg); + return dev_err_probe(dev, ret, + "failed to get proc regulator\n"); + } + + ret = regulator_enable(drv->proc_reg); + if (ret) { + dev_err(dev, "failed to enable proc regulator\n"); + return ret; + } + + drv->sram_reg = devm_regulator_get_optional(dev, "sram"); + if (IS_ERR(drv->sram_reg)) { + ret = PTR_ERR(drv->sram_reg); + if (ret == -EPROBE_DEFER) + goto out_free_resources; + + drv->sram_reg = NULL; + } else { + ret = regulator_enable(drv->sram_reg); + if (ret) { + dev_err(dev, "failed to enable sram regulator\n"); + goto out_free_resources; + } + } + + /* + * We assume min voltage is 0 and tracking target voltage using + * min_volt_shift for each iteration. + * The retry_max is 3 times of expected iteration count. + */ + drv->vtrack_max = 3 * DIV_ROUND_UP(max(drv->soc_data->sram_max_volt, + drv->soc_data->proc_max_volt), + drv->soc_data->min_volt_shift); + + ret = clk_prepare_enable(drv->cci_clk); + if (ret) + goto out_free_resources; + + ret = dev_pm_opp_of_add_table(dev); + if (ret) { + dev_err(dev, "failed to add opp table: %d\n", ret); + goto out_disable_cci_clk; + } + + rate = clk_get_rate(drv->inter_clk); + opp = dev_pm_opp_find_freq_ceil(dev, &rate); + if (IS_ERR(opp)) { + ret = PTR_ERR(opp); + dev_err(dev, "failed to get intermediate opp: %d\n", ret); + goto out_remove_opp_table; + } + drv->inter_voltage = dev_pm_opp_get_voltage(opp); + dev_pm_opp_put(opp); + + rate = U32_MAX; + opp = dev_pm_opp_find_freq_floor(drv->dev, &rate); + if (IS_ERR(opp)) { + dev_err(dev, "failed to get opp\n"); + ret = PTR_ERR(opp); + goto out_remove_opp_table; + } + + opp_volt = dev_pm_opp_get_voltage(opp); + dev_pm_opp_put(opp); + ret = mtk_ccifreq_set_voltage(drv, opp_volt); + if (ret) { + dev_err(dev, "failed to scale to highest voltage %lu in proc_reg\n", + opp_volt); + goto out_remove_opp_table; + } + + passive_data = devm_kzalloc(dev, sizeof(*passive_data), GFP_KERNEL); + if (!passive_data) { + ret = -ENOMEM; + goto out_remove_opp_table; + } + + passive_data->parent_type = CPUFREQ_PARENT_DEV; + drv->devfreq = devm_devfreq_add_device(dev, &mtk_ccifreq_profile, + DEVFREQ_GOV_PASSIVE, + passive_data); + if (IS_ERR(drv->devfreq)) { + ret = -EPROBE_DEFER; + dev_err(dev, "failed to add devfreq device: %ld\n", + PTR_ERR(drv->devfreq)); + goto out_remove_opp_table; + } + + drv->opp_nb.notifier_call = mtk_ccifreq_opp_notifier; + ret = dev_pm_opp_register_notifier(dev, &drv->opp_nb); + if (ret) { + dev_err(dev, "failed to register opp notifier: %d\n", ret); + goto out_remove_opp_table; + } + return 0; + +out_remove_opp_table: + dev_pm_opp_of_remove_table(dev); + +out_disable_cci_clk: + clk_disable_unprepare(drv->cci_clk); + +out_free_resources: + if (regulator_is_enabled(drv->proc_reg)) + regulator_disable(drv->proc_reg); + if (!IS_ERR_OR_NULL(drv->sram_reg) && + regulator_is_enabled(drv->sram_reg)) + regulator_disable(drv->sram_reg); + + return ret; +} + +static void mtk_ccifreq_remove(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct mtk_ccifreq_drv *drv; + + drv = platform_get_drvdata(pdev); + + dev_pm_opp_unregister_notifier(dev, &drv->opp_nb); + dev_pm_opp_of_remove_table(dev); + clk_disable_unprepare(drv->cci_clk); + regulator_disable(drv->proc_reg); + if (drv->sram_reg) + regulator_disable(drv->sram_reg); +} + +static const struct mtk_ccifreq_platform_data mt8183_platform_data = { + .min_volt_shift = 100000, + .max_volt_shift = 200000, + .proc_max_volt = 1150000, +}; + +static const struct mtk_ccifreq_platform_data mt8186_platform_data = { + .min_volt_shift = 100000, + .max_volt_shift = 250000, + .proc_max_volt = 1118750, + .sram_min_volt = 850000, + .sram_max_volt = 1118750, +}; + +static const struct of_device_id mtk_ccifreq_machines[] = { + { .compatible = "mediatek,mt8183-cci", .data = &mt8183_platform_data }, + { .compatible = "mediatek,mt8186-cci", .data = &mt8186_platform_data }, + { }, +}; +MODULE_DEVICE_TABLE(of, mtk_ccifreq_machines); + +static struct platform_driver mtk_ccifreq_platdrv = { + .probe = mtk_ccifreq_probe, + .remove = mtk_ccifreq_remove, + .driver = { + .name = "mtk-ccifreq", + .of_match_table = mtk_ccifreq_machines, + }, +}; +module_platform_driver(mtk_ccifreq_platdrv); + +MODULE_DESCRIPTION("MediaTek CCI devfreq driver"); +MODULE_AUTHOR("Jia-Wei Chang "); +MODULE_LICENSE("GPL v2"); -- cgit v1.3.1