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, 302 insertions, 0 deletions

diff --git a/drivers/nvmem/rockchip-efuse.c b/drivers/nvmem/rockchip-efuse.c
new file mode 100644
index 000000000..013e67136
--- /dev/null
+++ b/drivers/nvmem/rockchip-efuse.c
@@ -0,0 +1,302 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Rockchip eFuse Driver
+ *
+ * Copyright (c) 2015 Rockchip Electronics Co. Ltd.
+ * Author: Caesar Wang <wxt@rock-chips.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/nvmem-provider.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+
+#define RK3288_A_SHIFT		6
+#define RK3288_A_MASK		0x3ff
+#define RK3288_PGENB		BIT(3)
+#define RK3288_LOAD		BIT(2)
+#define RK3288_STROBE		BIT(1)
+#define RK3288_CSB		BIT(0)
+
+#define RK3328_SECURE_SIZES	96
+#define RK3328_INT_STATUS	0x0018
+#define RK3328_DOUT		0x0020
+#define RK3328_AUTO_CTRL	0x0024
+#define RK3328_INT_FINISH	BIT(0)
+#define RK3328_AUTO_ENB		BIT(0)
+#define RK3328_AUTO_RD		BIT(1)
+
+#define RK3399_A_SHIFT		16
+#define RK3399_A_MASK		0x3ff
+#define RK3399_NBYTES		4
+#define RK3399_STROBSFTSEL	BIT(9)
+#define RK3399_RSB		BIT(7)
+#define RK3399_PD		BIT(5)
+#define RK3399_PGENB		BIT(3)
+#define RK3399_LOAD		BIT(2)
+#define RK3399_STROBE		BIT(1)
+#define RK3399_CSB		BIT(0)
+
+#define REG_EFUSE_CTRL		0x0000
+#define REG_EFUSE_DOUT		0x0004
+
+struct rockchip_efuse_chip {
+	struct device *dev;
+	void __iomem *base;
+	struct clk *clk;
+};
+
+static int rockchip_rk3288_efuse_read(void *context, unsigned int offset,
+				      void *val, size_t bytes)
+{
+	struct rockchip_efuse_chip *efuse = context;
+	u8 *buf = val;
+	int ret;
+
+	ret = clk_prepare_enable(efuse->clk);
+	if (ret < 0) {
+		dev_err(efuse->dev, "failed to prepare/enable efuse clk\n");
+		return ret;
+	}
+
+	writel(RK3288_LOAD | RK3288_PGENB, efuse->base + REG_EFUSE_CTRL);
+	udelay(1);
+	while (bytes--) {
+		writel(readl(efuse->base + REG_EFUSE_CTRL) &
+			     (~(RK3288_A_MASK << RK3288_A_SHIFT)),
+			     efuse->base + REG_EFUSE_CTRL);
+		writel(readl(efuse->base + REG_EFUSE_CTRL) |
+			     ((offset++ & RK3288_A_MASK) << RK3288_A_SHIFT),
+			     efuse->base + REG_EFUSE_CTRL);
+		udelay(1);
+		writel(readl(efuse->base + REG_EFUSE_CTRL) |
+			     RK3288_STROBE, efuse->base + REG_EFUSE_CTRL);
+		udelay(1);
+		*buf++ = readb(efuse->base + REG_EFUSE_DOUT);
+		writel(readl(efuse->base + REG_EFUSE_CTRL) &
+		       (~RK3288_STROBE), efuse->base + REG_EFUSE_CTRL);
+		udelay(1);
+	}
+
+	/* Switch to standby mode */
+	writel(RK3288_PGENB | RK3288_CSB, efuse->base + REG_EFUSE_CTRL);
+
+	clk_disable_unprepare(efuse->clk);
+
+	return 0;
+}
+
+static int rockchip_rk3328_efuse_read(void *context, unsigned int offset,
+				      void *val, size_t bytes)
+{
+	struct rockchip_efuse_chip *efuse = context;
+	unsigned int addr_start, addr_end, addr_offset, addr_len;
+	u32 out_value, status;
+	u8 *buf;
+	int ret, i = 0;
+
+	ret = clk_prepare_enable(efuse->clk);
+	if (ret < 0) {
+		dev_err(efuse->dev, "failed to prepare/enable efuse clk\n");
+		return ret;
+	}
+
+	/* 128 Byte efuse, 96 Byte for secure, 32 Byte for non-secure */
+	offset += RK3328_SECURE_SIZES;
+	addr_start = rounddown(offset, RK3399_NBYTES) / RK3399_NBYTES;
+	addr_end = roundup(offset + bytes, RK3399_NBYTES) / RK3399_NBYTES;
+	addr_offset = offset % RK3399_NBYTES;
+	addr_len = addr_end - addr_start;
+
+	buf = kzalloc(array3_size(addr_len, RK3399_NBYTES, sizeof(*buf)),
+		      GFP_KERNEL);
+	if (!buf) {
+		ret = -ENOMEM;
+		goto nomem;
+	}
+
+	while (addr_len--) {
+		writel(RK3328_AUTO_RD | RK3328_AUTO_ENB |
+		       ((addr_start++ & RK3399_A_MASK) << RK3399_A_SHIFT),
+		       efuse->base + RK3328_AUTO_CTRL);
+		udelay(4);
+		status = readl(efuse->base + RK3328_INT_STATUS);
+		if (!(status & RK3328_INT_FINISH)) {
+			ret = -EIO;
+			goto err;
+		}
+		out_value = readl(efuse->base + RK3328_DOUT);
+		writel(RK3328_INT_FINISH, efuse->base + RK3328_INT_STATUS);
+
+		memcpy(&buf[i], &out_value, RK3399_NBYTES);
+		i += RK3399_NBYTES;
+	}
+
+	memcpy(val, buf + addr_offset, bytes);
+err:
+	kfree(buf);
+nomem:
+	clk_disable_unprepare(efuse->clk);
+
+	return ret;
+}
+
+static int rockchip_rk3399_efuse_read(void *context, unsigned int offset,
+				      void *val, size_t bytes)
+{
+	struct rockchip_efuse_chip *efuse = context;
+	unsigned int addr_start, addr_end, addr_offset, addr_len;
+	u32 out_value;
+	u8 *buf;
+	int ret, i = 0;
+
+	ret = clk_prepare_enable(efuse->clk);
+	if (ret < 0) {
+		dev_err(efuse->dev, "failed to prepare/enable efuse clk\n");
+		return ret;
+	}
+
+	addr_start = rounddown(offset, RK3399_NBYTES) / RK3399_NBYTES;
+	addr_end = roundup(offset + bytes, RK3399_NBYTES) / RK3399_NBYTES;
+	addr_offset = offset % RK3399_NBYTES;
+	addr_len = addr_end - addr_start;
+
+	buf = kzalloc(array3_size(addr_len, RK3399_NBYTES, sizeof(*buf)),
+		      GFP_KERNEL);
+	if (!buf) {
+		clk_disable_unprepare(efuse->clk);
+		return -ENOMEM;
+	}
+
+	writel(RK3399_LOAD | RK3399_PGENB | RK3399_STROBSFTSEL | RK3399_RSB,
+	       efuse->base + REG_EFUSE_CTRL);
+	udelay(1);
+	while (addr_len--) {
+		writel(readl(efuse->base + REG_EFUSE_CTRL) | RK3399_STROBE |
+		       ((addr_start++ & RK3399_A_MASK) << RK3399_A_SHIFT),
+		       efuse->base + REG_EFUSE_CTRL);
+		udelay(1);
+		out_value = readl(efuse->base + REG_EFUSE_DOUT);
+		writel(readl(efuse->base + REG_EFUSE_CTRL) & (~RK3399_STROBE),
+		       efuse->base + REG_EFUSE_CTRL);
+		udelay(1);
+
+		memcpy(&buf[i], &out_value, RK3399_NBYTES);
+		i += RK3399_NBYTES;
+	}
+
+	/* Switch to standby mode */
+	writel(RK3399_PD | RK3399_CSB, efuse->base + REG_EFUSE_CTRL);
+
+	memcpy(val, buf + addr_offset, bytes);
+
+	kfree(buf);
+
+	clk_disable_unprepare(efuse->clk);
+
+	return 0;
+}
+
+static struct nvmem_config econfig = {
+	.name = "rockchip-efuse",
+	.add_legacy_fixed_of_cells = true,
+	.type = NVMEM_TYPE_OTP,
+	.stride = 1,
+	.word_size = 1,
+	.read_only = true,
+};
+
+static const struct of_device_id rockchip_efuse_match[] = {
+	/* deprecated but kept around for dts binding compatibility */
+	{
+		.compatible = "rockchip,rockchip-efuse",
+		.data = (void *)&rockchip_rk3288_efuse_read,
+	},
+	{
+		.compatible = "rockchip,rk3066a-efuse",
+		.data = (void *)&rockchip_rk3288_efuse_read,
+	},
+	{
+		.compatible = "rockchip,rk3188-efuse",
+		.data = (void *)&rockchip_rk3288_efuse_read,
+	},
+	{
+		.compatible = "rockchip,rk3228-efuse",
+		.data = (void *)&rockchip_rk3288_efuse_read,
+	},
+	{
+		.compatible = "rockchip,rk3288-efuse",
+		.data = (void *)&rockchip_rk3288_efuse_read,
+	},
+	{
+		.compatible = "rockchip,rk3368-efuse",
+		.data = (void *)&rockchip_rk3288_efuse_read,
+	},
+	{
+		.compatible = "rockchip,rk3328-efuse",
+		.data = (void *)&rockchip_rk3328_efuse_read,
+	},
+	{
+		.compatible = "rockchip,rk3399-efuse",
+		.data = (void *)&rockchip_rk3399_efuse_read,
+	},
+	{ /* sentinel */},
+};
+MODULE_DEVICE_TABLE(of, rockchip_efuse_match);
+
+static int rockchip_efuse_probe(struct platform_device *pdev)
+{
+	struct resource *res;
+	struct nvmem_device *nvmem;
+	struct rockchip_efuse_chip *efuse;
+	const void *data;
+	struct device *dev = &pdev->dev;
+
+	data = of_device_get_match_data(dev);
+	if (!data) {
+		dev_err(dev, "failed to get match data\n");
+		return -EINVAL;
+	}
+
+	efuse = devm_kzalloc(dev, sizeof(struct rockchip_efuse_chip),
+			     GFP_KERNEL);
+	if (!efuse)
+		return -ENOMEM;
+
+	efuse->base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
+	if (IS_ERR(efuse->base))
+		return PTR_ERR(efuse->base);
+
+	efuse->clk = devm_clk_get(dev, "pclk_efuse");
+	if (IS_ERR(efuse->clk))
+		return PTR_ERR(efuse->clk);
+
+	efuse->dev = dev;
+	if (of_property_read_u32(dev->of_node, "rockchip,efuse-size",
+				 &econfig.size))
+		econfig.size = resource_size(res);
+	econfig.reg_read = data;
+	econfig.priv = efuse;
+	econfig.dev = efuse->dev;
+	nvmem = devm_nvmem_register(dev, &econfig);
+
+	return PTR_ERR_OR_ZERO(nvmem);
+}
+
+static struct platform_driver rockchip_efuse_driver = {
+	.probe = rockchip_efuse_probe,
+	.driver = {
+		.name = "rockchip-efuse",
+		.of_match_table = rockchip_efuse_match,
+	},
+};
+
+module_platform_driver(rockchip_efuse_driver);
+MODULE_DESCRIPTION("rockchip_efuse driver");
+MODULE_LICENSE("GPL v2");