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/edac/ecs.c | 207 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 207 insertions(+) create mode 100644 drivers/edac/ecs.c (limited to 'drivers/edac/ecs.c') diff --git a/drivers/edac/ecs.c b/drivers/edac/ecs.c new file mode 100644 index 000000000..51c451c7f --- /dev/null +++ b/drivers/edac/ecs.c @@ -0,0 +1,207 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * The generic ECS driver is designed to support control of on-die error + * check scrub (e.g., DDR5 ECS). The common sysfs ECS interface abstracts + * the control of various ECS functionalities into a unified set of functions. + * + * Copyright (c) 2024-2025 HiSilicon Limited. + */ + +#include + +#define EDAC_ECS_FRU_NAME "ecs_fru" + +enum edac_ecs_attributes { + ECS_LOG_ENTRY_TYPE, + ECS_MODE, + ECS_RESET, + ECS_THRESHOLD, + ECS_MAX_ATTRS +}; + +struct edac_ecs_dev_attr { + struct device_attribute dev_attr; + int fru_id; +}; + +struct edac_ecs_fru_context { + char name[EDAC_FEAT_NAME_LEN]; + struct edac_ecs_dev_attr dev_attr[ECS_MAX_ATTRS]; + struct attribute *ecs_attrs[ECS_MAX_ATTRS + 1]; + struct attribute_group group; +}; + +struct edac_ecs_context { + u16 num_media_frus; + struct edac_ecs_fru_context *fru_ctxs; +}; + +#define TO_ECS_DEV_ATTR(_dev_attr) \ + container_of(_dev_attr, struct edac_ecs_dev_attr, dev_attr) + +#define EDAC_ECS_ATTR_SHOW(attrib, cb, type, format) \ +static ssize_t attrib##_show(struct device *ras_feat_dev, \ + struct device_attribute *attr, char *buf) \ +{ \ + struct edac_ecs_dev_attr *dev_attr = TO_ECS_DEV_ATTR(attr); \ + struct edac_dev_feat_ctx *ctx = dev_get_drvdata(ras_feat_dev); \ + const struct edac_ecs_ops *ops = ctx->ecs.ecs_ops; \ + type data; \ + int ret; \ + \ + ret = ops->cb(ras_feat_dev->parent, ctx->ecs.private, \ + dev_attr->fru_id, &data); \ + if (ret) \ + return ret; \ + \ + return sysfs_emit(buf, format, data); \ +} + +EDAC_ECS_ATTR_SHOW(log_entry_type, get_log_entry_type, u32, "%u\n") +EDAC_ECS_ATTR_SHOW(mode, get_mode, u32, "%u\n") +EDAC_ECS_ATTR_SHOW(threshold, get_threshold, u32, "%u\n") + +#define EDAC_ECS_ATTR_STORE(attrib, cb, type, conv_func) \ +static ssize_t attrib##_store(struct device *ras_feat_dev, \ + struct device_attribute *attr, \ + const char *buf, size_t len) \ +{ \ + struct edac_ecs_dev_attr *dev_attr = TO_ECS_DEV_ATTR(attr); \ + struct edac_dev_feat_ctx *ctx = dev_get_drvdata(ras_feat_dev); \ + const struct edac_ecs_ops *ops = ctx->ecs.ecs_ops; \ + type data; \ + int ret; \ + \ + ret = conv_func(buf, 0, &data); \ + if (ret < 0) \ + return ret; \ + \ + ret = ops->cb(ras_feat_dev->parent, ctx->ecs.private, \ + dev_attr->fru_id, data); \ + if (ret) \ + return ret; \ + \ + return len; \ +} + +EDAC_ECS_ATTR_STORE(log_entry_type, set_log_entry_type, unsigned long, kstrtoul) +EDAC_ECS_ATTR_STORE(mode, set_mode, unsigned long, kstrtoul) +EDAC_ECS_ATTR_STORE(reset, reset, unsigned long, kstrtoul) +EDAC_ECS_ATTR_STORE(threshold, set_threshold, unsigned long, kstrtoul) + +static umode_t ecs_attr_visible(struct kobject *kobj, struct attribute *a, int attr_id) +{ + struct device *ras_feat_dev = kobj_to_dev(kobj); + struct edac_dev_feat_ctx *ctx = dev_get_drvdata(ras_feat_dev); + const struct edac_ecs_ops *ops = ctx->ecs.ecs_ops; + + switch (attr_id) { + case ECS_LOG_ENTRY_TYPE: + if (ops->get_log_entry_type) { + if (ops->set_log_entry_type) + return a->mode; + else + return 0444; + } + break; + case ECS_MODE: + if (ops->get_mode) { + if (ops->set_mode) + return a->mode; + else + return 0444; + } + break; + case ECS_RESET: + if (ops->reset) + return a->mode; + break; + case ECS_THRESHOLD: + if (ops->get_threshold) { + if (ops->set_threshold) + return a->mode; + else + return 0444; + } + break; + default: + break; + } + + return 0; +} + +#define EDAC_ECS_ATTR_RO(_name, _fru_id) \ + ((struct edac_ecs_dev_attr) { .dev_attr = __ATTR_RO(_name), \ + .fru_id = _fru_id }) + +#define EDAC_ECS_ATTR_WO(_name, _fru_id) \ + ((struct edac_ecs_dev_attr) { .dev_attr = __ATTR_WO(_name), \ + .fru_id = _fru_id }) + +#define EDAC_ECS_ATTR_RW(_name, _fru_id) \ + ((struct edac_ecs_dev_attr) { .dev_attr = __ATTR_RW(_name), \ + .fru_id = _fru_id }) + +static int ecs_create_desc(struct device *ecs_dev, const struct attribute_group **attr_groups, + u16 num_media_frus) +{ + struct edac_ecs_context *ecs_ctx; + u32 fru; + + ecs_ctx = devm_kzalloc(ecs_dev, sizeof(*ecs_ctx), GFP_KERNEL); + if (!ecs_ctx) + return -ENOMEM; + + ecs_ctx->num_media_frus = num_media_frus; + ecs_ctx->fru_ctxs = devm_kcalloc(ecs_dev, num_media_frus, + sizeof(*ecs_ctx->fru_ctxs), + GFP_KERNEL); + if (!ecs_ctx->fru_ctxs) + return -ENOMEM; + + for (fru = 0; fru < num_media_frus; fru++) { + struct edac_ecs_fru_context *fru_ctx = &ecs_ctx->fru_ctxs[fru]; + struct attribute_group *group = &fru_ctx->group; + int i; + + fru_ctx->dev_attr[ECS_LOG_ENTRY_TYPE] = EDAC_ECS_ATTR_RW(log_entry_type, fru); + fru_ctx->dev_attr[ECS_MODE] = EDAC_ECS_ATTR_RW(mode, fru); + fru_ctx->dev_attr[ECS_RESET] = EDAC_ECS_ATTR_WO(reset, fru); + fru_ctx->dev_attr[ECS_THRESHOLD] = EDAC_ECS_ATTR_RW(threshold, fru); + + for (i = 0; i < ECS_MAX_ATTRS; i++) { + sysfs_attr_init(&fru_ctx->dev_attr[i].dev_attr.attr); + fru_ctx->ecs_attrs[i] = &fru_ctx->dev_attr[i].dev_attr.attr; + } + + sprintf(fru_ctx->name, "%s%d", EDAC_ECS_FRU_NAME, fru); + group->name = fru_ctx->name; + group->attrs = fru_ctx->ecs_attrs; + group->is_visible = ecs_attr_visible; + + attr_groups[fru] = group; + } + + return 0; +} + +/** + * edac_ecs_get_desc - get EDAC ECS descriptors + * @ecs_dev: client device, supports ECS feature + * @attr_groups: pointer to attribute group container + * @num_media_frus: number of media FRUs in the device + * + * Return: + * * %0 - Success. + * * %-EINVAL - Invalid parameters passed. + * * %-ENOMEM - Dynamic memory allocation failed. + */ +int edac_ecs_get_desc(struct device *ecs_dev, + const struct attribute_group **attr_groups, u16 num_media_frus) +{ + if (!ecs_dev || !attr_groups || !num_media_frus) + return -EINVAL; + + return ecs_create_desc(ecs_dev, attr_groups, num_media_frus); +} -- cgit v1.3.1