x86/kprobes: Fix crash when probing CS CALL instructionsgrafted

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) <mhiramat@kernel.org>
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000

1 files changed, 203 insertions, 0 deletions

diff --git a/drivers/interconnect/icc-clk.c b/drivers/interconnect/icc-clk.c
new file mode 100644
index 000000000..93c030608
--- /dev/null
+++ b/drivers/interconnect/icc-clk.c
@@ -0,0 +1,203 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2023, Linaro Ltd.
+ */
+
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/interconnect-clk.h>
+#include <linux/interconnect-provider.h>
+
+struct icc_clk_node {
+	struct clk *clk;
+	bool enabled;
+};
+
+struct icc_clk_provider {
+	struct icc_provider provider;
+	int num_clocks;
+	struct icc_clk_node clocks[] __counted_by(num_clocks);
+};
+
+#define to_icc_clk_provider(_provider) \
+	container_of(_provider, struct icc_clk_provider, provider)
+
+static int icc_clk_set(struct icc_node *src, struct icc_node *dst)
+{
+	struct icc_clk_node *qn = src->data;
+	int ret;
+
+	if (!qn || !qn->clk)
+		return 0;
+
+	if (!src->peak_bw) {
+		if (qn->enabled)
+			clk_disable_unprepare(qn->clk);
+		qn->enabled = false;
+
+		return 0;
+	}
+
+	if (!qn->enabled) {
+		ret = clk_prepare_enable(qn->clk);
+		if (ret)
+			return ret;
+		qn->enabled = true;
+	}
+
+	return clk_set_rate(qn->clk, icc_units_to_bps(src->peak_bw));
+}
+
+static int icc_clk_get_bw(struct icc_node *node, u32 *avg, u32 *peak)
+{
+	struct icc_clk_node *qn = node->data;
+
+	if (!qn || !qn->clk)
+		*peak = INT_MAX;
+	else
+		*peak = Bps_to_icc(clk_get_rate(qn->clk));
+
+	return 0;
+}
+
+/**
+ * icc_clk_register() - register a new clk-based interconnect provider
+ * @dev: device supporting this provider
+ * @first_id: an ID of the first provider's node
+ * @num_clocks: number of instances of struct icc_clk_data
+ * @data: data for the provider
+ *
+ * Registers and returns a clk-based interconnect provider. It is a simple
+ * wrapper around COMMON_CLK framework, allowing other devices to vote on the
+ * clock rate.
+ *
+ * Return: 0 on success, or an error code otherwise
+ */
+struct icc_provider *icc_clk_register(struct device *dev,
+				      unsigned int first_id,
+				      unsigned int num_clocks,
+				      const struct icc_clk_data *data)
+{
+	struct icc_clk_provider *qp;
+	struct icc_provider *provider;
+	struct icc_onecell_data *onecell;
+	struct icc_node *node;
+	int ret, i, j;
+
+	onecell = devm_kzalloc(dev, struct_size(onecell, nodes, 2 * num_clocks), GFP_KERNEL);
+	if (!onecell)
+		return ERR_PTR(-ENOMEM);
+	onecell->num_nodes = 2 * num_clocks;
+
+	qp = devm_kzalloc(dev, struct_size(qp, clocks, num_clocks), GFP_KERNEL);
+	if (!qp)
+		return ERR_PTR(-ENOMEM);
+
+	qp->num_clocks = num_clocks;
+
+	provider = &qp->provider;
+	provider->dev = dev;
+	provider->get_bw = icc_clk_get_bw;
+	provider->set = icc_clk_set;
+	provider->aggregate = icc_std_aggregate;
+	provider->xlate = of_icc_xlate_onecell;
+	INIT_LIST_HEAD(&provider->nodes);
+	provider->data = onecell;
+
+	icc_provider_init(provider);
+
+	for (i = 0, j = 0; i < num_clocks; i++) {
+		qp->clocks[i].clk = data[i].clk;
+
+		node = icc_node_create(first_id + data[i].master_id);
+		if (IS_ERR(node)) {
+			ret = PTR_ERR(node);
+			goto err;
+		}
+
+		node->name = devm_kasprintf(dev, GFP_KERNEL, "%s_master", data[i].name);
+		if (!node->name) {
+			icc_node_destroy(node->id);
+			ret = -ENOMEM;
+			goto err;
+		}
+
+		node->data = &qp->clocks[i];
+		icc_node_add(node, provider);
+		/* link to the next node, slave */
+		icc_link_create(node, first_id + data[i].slave_id);
+		onecell->nodes[j++] = node;
+
+		node = icc_node_create(first_id + data[i].slave_id);
+		if (IS_ERR(node)) {
+			ret = PTR_ERR(node);
+			goto err;
+		}
+
+		node->name = devm_kasprintf(dev, GFP_KERNEL, "%s_slave", data[i].name);
+		if (!node->name) {
+			icc_node_destroy(node->id);
+			ret = -ENOMEM;
+			goto err;
+		}
+
+		/* no data for slave node */
+		icc_node_add(node, provider);
+		onecell->nodes[j++] = node;
+	}
+
+	ret = icc_provider_register(provider);
+	if (ret)
+		goto err;
+
+	return provider;
+
+err:
+	icc_nodes_remove(provider);
+
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(icc_clk_register);
+
+static void devm_icc_release(void *res)
+{
+	icc_clk_unregister(res);
+}
+
+int devm_icc_clk_register(struct device *dev, unsigned int first_id,
+			  unsigned int num_clocks, const struct icc_clk_data *data)
+{
+	struct icc_provider *prov;
+
+	prov = icc_clk_register(dev, first_id, num_clocks, data);
+	if (IS_ERR(prov))
+		return PTR_ERR(prov);
+
+	return devm_add_action_or_reset(dev, devm_icc_release, prov);
+}
+EXPORT_SYMBOL_GPL(devm_icc_clk_register);
+
+/**
+ * icc_clk_unregister() - unregister a previously registered clk interconnect provider
+ * @provider: provider returned by icc_clk_register()
+ */
+void icc_clk_unregister(struct icc_provider *provider)
+{
+	struct icc_clk_provider *qp = container_of(provider, struct icc_clk_provider, provider);
+	int i;
+
+	icc_provider_deregister(&qp->provider);
+	icc_nodes_remove(&qp->provider);
+
+	for (i = 0; i < qp->num_clocks; i++) {
+		struct icc_clk_node *qn = &qp->clocks[i];
+
+		if (qn->enabled)
+			clk_disable_unprepare(qn->clk);
+	}
+}
+EXPORT_SYMBOL_GPL(icc_clk_unregister);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Interconnect wrapper for clocks");
+MODULE_AUTHOR("Dmitry Baryshkov <dmitry.baryshkov@linaro.org>");