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, 135 insertions, 0 deletions

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 <linux/delay.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+#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 <Eugeniy.Paltsev@synopsys.com>");
+MODULE_DESCRIPTION("Synopsys HSDK SDP reset driver");
+MODULE_LICENSE("GPL v2");