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, 326 insertions, 0 deletions

diff --git a/drivers/crypto/ccp/ccp-debugfs.c b/drivers/crypto/ccp/ccp-debugfs.c
new file mode 100644
index 000000000..dc26bc22c
--- /dev/null
+++ b/drivers/crypto/ccp/ccp-debugfs.c
@@ -0,0 +1,326 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * AMD Cryptographic Coprocessor (CCP) driver
+ *
+ * Copyright (C) 2017 Advanced Micro Devices, Inc.
+ *
+ * Author: Gary R Hook <gary.hook@amd.com>
+ */
+
+#include <linux/debugfs.h>
+#include <linux/ccp.h>
+
+#include "ccp-dev.h"
+
+/* DebugFS helpers */
+#define	OBUFP		(obuf + oboff)
+#define	OBUFLEN		512
+#define	OBUFSPC		(OBUFLEN - oboff)
+#define	OSCNPRINTF(fmt, ...) \
+		scnprintf(OBUFP, OBUFSPC, fmt, ## __VA_ARGS__)
+
+#define BUFLEN	63
+
+#define	RI_VERSION_NUM	0x0000003F
+#define	RI_AES_PRESENT	0x00000040
+#define	RI_3DES_PRESENT	0x00000080
+#define	RI_SHA_PRESENT	0x00000100
+#define	RI_RSA_PRESENT	0x00000200
+#define	RI_ECC_PRESENT	0x00000400
+#define	RI_ZDE_PRESENT	0x00000800
+#define	RI_ZCE_PRESENT	0x00001000
+#define	RI_TRNG_PRESENT	0x00002000
+#define	RI_ELFC_PRESENT	0x00004000
+#define	RI_ELFC_SHIFT	14
+#define	RI_NUM_VQM	0x00078000
+#define	RI_NVQM_SHIFT	15
+#define	RI_NVQM(r)	(((r) * RI_NUM_VQM) >> RI_NVQM_SHIFT)
+#define	RI_LSB_ENTRIES	0x0FF80000
+#define	RI_NLSB_SHIFT	19
+#define	RI_NLSB(r)	(((r) * RI_LSB_ENTRIES) >> RI_NLSB_SHIFT)
+
+static ssize_t ccp5_debugfs_info_read(struct file *filp, char __user *ubuf,
+				      size_t count, loff_t *offp)
+{
+	struct ccp_device *ccp = filp->private_data;
+	unsigned int oboff = 0;
+	unsigned int regval;
+	ssize_t ret;
+	char *obuf;
+
+	if (!ccp)
+		return 0;
+
+	obuf = kmalloc(OBUFLEN, GFP_KERNEL);
+	if (!obuf)
+		return -ENOMEM;
+
+	oboff += OSCNPRINTF("Device name: %s\n", ccp->name);
+	oboff += OSCNPRINTF("   RNG name: %s\n", ccp->rngname);
+	oboff += OSCNPRINTF("   # Queues: %d\n", ccp->cmd_q_count);
+	oboff += OSCNPRINTF("     # Cmds: %d\n", ccp->cmd_count);
+
+	regval = ioread32(ccp->io_regs + CMD5_PSP_CCP_VERSION);
+	oboff += OSCNPRINTF("    Version: %d\n", regval & RI_VERSION_NUM);
+	oboff += OSCNPRINTF("    Engines:");
+	if (regval & RI_AES_PRESENT)
+		oboff += OSCNPRINTF(" AES");
+	if (regval & RI_3DES_PRESENT)
+		oboff += OSCNPRINTF(" 3DES");
+	if (regval & RI_SHA_PRESENT)
+		oboff += OSCNPRINTF(" SHA");
+	if (regval & RI_RSA_PRESENT)
+		oboff += OSCNPRINTF(" RSA");
+	if (regval & RI_ECC_PRESENT)
+		oboff += OSCNPRINTF(" ECC");
+	if (regval & RI_ZDE_PRESENT)
+		oboff += OSCNPRINTF(" ZDE");
+	if (regval & RI_ZCE_PRESENT)
+		oboff += OSCNPRINTF(" ZCE");
+	if (regval & RI_TRNG_PRESENT)
+		oboff += OSCNPRINTF(" TRNG");
+	oboff += OSCNPRINTF("\n");
+	oboff += OSCNPRINTF("     Queues: %d\n",
+		   (regval & RI_NUM_VQM) >> RI_NVQM_SHIFT);
+	oboff += OSCNPRINTF("LSB Entries: %d\n",
+		   (regval & RI_LSB_ENTRIES) >> RI_NLSB_SHIFT);
+
+	ret = simple_read_from_buffer(ubuf, count, offp, obuf, oboff);
+	kfree(obuf);
+
+	return ret;
+}
+
+/* Return a formatted buffer containing the current
+ * statistics across all queues for a CCP.
+ */
+static ssize_t ccp5_debugfs_stats_read(struct file *filp, char __user *ubuf,
+				       size_t count, loff_t *offp)
+{
+	struct ccp_device *ccp = filp->private_data;
+	unsigned long total_xts_aes_ops = 0;
+	unsigned long total_3des_ops = 0;
+	unsigned long total_aes_ops = 0;
+	unsigned long total_sha_ops = 0;
+	unsigned long total_rsa_ops = 0;
+	unsigned long total_ecc_ops = 0;
+	unsigned long total_pt_ops = 0;
+	unsigned long total_ops = 0;
+	unsigned int oboff = 0;
+	ssize_t ret = 0;
+	unsigned int i;
+	char *obuf;
+
+	for (i = 0; i < ccp->cmd_q_count; i++) {
+		struct ccp_cmd_queue *cmd_q = &ccp->cmd_q[i];
+
+		total_ops += cmd_q->total_ops;
+		total_aes_ops += cmd_q->total_aes_ops;
+		total_xts_aes_ops += cmd_q->total_xts_aes_ops;
+		total_3des_ops += cmd_q->total_3des_ops;
+		total_sha_ops += cmd_q->total_sha_ops;
+		total_rsa_ops += cmd_q->total_rsa_ops;
+		total_pt_ops += cmd_q->total_pt_ops;
+		total_ecc_ops += cmd_q->total_ecc_ops;
+	}
+
+	obuf = kmalloc(OBUFLEN, GFP_KERNEL);
+	if (!obuf)
+		return -ENOMEM;
+
+	oboff += OSCNPRINTF("Total Interrupts Handled: %ld\n",
+			    ccp->total_interrupts);
+	oboff += OSCNPRINTF("        Total Operations: %ld\n",
+			    total_ops);
+	oboff += OSCNPRINTF("                     AES: %ld\n",
+			    total_aes_ops);
+	oboff += OSCNPRINTF("                 XTS AES: %ld\n",
+			    total_xts_aes_ops);
+	oboff += OSCNPRINTF("                     SHA: %ld\n",
+			    total_3des_ops);
+	oboff += OSCNPRINTF("                     SHA: %ld\n",
+			    total_sha_ops);
+	oboff += OSCNPRINTF("                     RSA: %ld\n",
+			    total_rsa_ops);
+	oboff += OSCNPRINTF("               Pass-Thru: %ld\n",
+			    total_pt_ops);
+	oboff += OSCNPRINTF("                     ECC: %ld\n",
+			    total_ecc_ops);
+
+	ret = simple_read_from_buffer(ubuf, count, offp, obuf, oboff);
+	kfree(obuf);
+
+	return ret;
+}
+
+/* Reset the counters in a queue
+ */
+static void ccp5_debugfs_reset_queue_stats(struct ccp_cmd_queue *cmd_q)
+{
+	cmd_q->total_ops = 0L;
+	cmd_q->total_aes_ops = 0L;
+	cmd_q->total_xts_aes_ops = 0L;
+	cmd_q->total_3des_ops = 0L;
+	cmd_q->total_sha_ops = 0L;
+	cmd_q->total_rsa_ops = 0L;
+	cmd_q->total_pt_ops = 0L;
+	cmd_q->total_ecc_ops = 0L;
+}
+
+/* A value was written to the stats variable, which
+ * should be used to reset the queue counters across
+ * that device.
+ */
+static ssize_t ccp5_debugfs_stats_write(struct file *filp,
+					const char __user *ubuf,
+					size_t count, loff_t *offp)
+{
+	struct ccp_device *ccp = filp->private_data;
+	int i;
+
+	for (i = 0; i < ccp->cmd_q_count; i++)
+		ccp5_debugfs_reset_queue_stats(&ccp->cmd_q[i]);
+	ccp->total_interrupts = 0L;
+
+	return count;
+}
+
+/* Return a formatted buffer containing the current information
+ * for that queue
+ */
+static ssize_t ccp5_debugfs_queue_read(struct file *filp, char __user *ubuf,
+				       size_t count, loff_t *offp)
+{
+	struct ccp_cmd_queue *cmd_q = filp->private_data;
+	unsigned int oboff = 0;
+	unsigned int regval;
+	ssize_t ret;
+	char *obuf;
+
+	if (!cmd_q)
+		return 0;
+
+	obuf = kmalloc(OBUFLEN, GFP_KERNEL);
+	if (!obuf)
+		return -ENOMEM;
+
+	oboff += OSCNPRINTF("  Total Queue Operations: %ld\n",
+			    cmd_q->total_ops);
+	oboff += OSCNPRINTF("                     AES: %ld\n",
+			    cmd_q->total_aes_ops);
+	oboff += OSCNPRINTF("                 XTS AES: %ld\n",
+			    cmd_q->total_xts_aes_ops);
+	oboff += OSCNPRINTF("                     SHA: %ld\n",
+			    cmd_q->total_3des_ops);
+	oboff += OSCNPRINTF("                     SHA: %ld\n",
+			    cmd_q->total_sha_ops);
+	oboff += OSCNPRINTF("                     RSA: %ld\n",
+			    cmd_q->total_rsa_ops);
+	oboff += OSCNPRINTF("               Pass-Thru: %ld\n",
+			    cmd_q->total_pt_ops);
+	oboff += OSCNPRINTF("                     ECC: %ld\n",
+			    cmd_q->total_ecc_ops);
+
+	regval = ioread32(cmd_q->reg_int_enable);
+	oboff += OSCNPRINTF("      Enabled Interrupts:");
+	if (regval & INT_EMPTY_QUEUE)
+		oboff += OSCNPRINTF(" EMPTY");
+	if (regval & INT_QUEUE_STOPPED)
+		oboff += OSCNPRINTF(" STOPPED");
+	if (regval & INT_ERROR)
+		oboff += OSCNPRINTF(" ERROR");
+	if (regval & INT_COMPLETION)
+		oboff += OSCNPRINTF(" COMPLETION");
+	oboff += OSCNPRINTF("\n");
+
+	ret = simple_read_from_buffer(ubuf, count, offp, obuf, oboff);
+	kfree(obuf);
+
+	return ret;
+}
+
+/* A value was written to the stats variable for a
+ * queue. Reset the queue counters to this value.
+ */
+static ssize_t ccp5_debugfs_queue_write(struct file *filp,
+					const char __user *ubuf,
+					size_t count, loff_t *offp)
+{
+	struct ccp_cmd_queue *cmd_q = filp->private_data;
+
+	ccp5_debugfs_reset_queue_stats(cmd_q);
+
+	return count;
+}
+
+static const struct file_operations ccp_debugfs_info_ops = {
+	.owner = THIS_MODULE,
+	.open = simple_open,
+	.read = ccp5_debugfs_info_read,
+	.write = NULL,
+};
+
+static const struct file_operations ccp_debugfs_queue_ops = {
+	.owner = THIS_MODULE,
+	.open = simple_open,
+	.read = ccp5_debugfs_queue_read,
+	.write = ccp5_debugfs_queue_write,
+};
+
+static const struct file_operations ccp_debugfs_stats_ops = {
+	.owner = THIS_MODULE,
+	.open = simple_open,
+	.read = ccp5_debugfs_stats_read,
+	.write = ccp5_debugfs_stats_write,
+};
+
+static struct dentry *ccp_debugfs_dir;
+static DEFINE_MUTEX(ccp_debugfs_lock);
+
+#define	MAX_NAME_LEN	20
+
+void ccp5_debugfs_setup(struct ccp_device *ccp)
+{
+	struct ccp_cmd_queue *cmd_q;
+	char name[MAX_NAME_LEN + 1];
+	struct dentry *debugfs_q_instance;
+	int i;
+
+	if (!debugfs_initialized())
+		return;
+
+	mutex_lock(&ccp_debugfs_lock);
+	if (!ccp_debugfs_dir)
+		ccp_debugfs_dir = debugfs_create_dir(KBUILD_MODNAME, NULL);
+	mutex_unlock(&ccp_debugfs_lock);
+
+	ccp->debugfs_instance = debugfs_create_dir(ccp->name, ccp_debugfs_dir);
+
+	debugfs_create_file("info", 0400, ccp->debugfs_instance, ccp,
+			    &ccp_debugfs_info_ops);
+
+	debugfs_create_file("stats", 0600, ccp->debugfs_instance, ccp,
+			    &ccp_debugfs_stats_ops);
+
+	for (i = 0; i < ccp->cmd_q_count; i++) {
+		cmd_q = &ccp->cmd_q[i];
+
+		snprintf(name, MAX_NAME_LEN - 1, "q%d", cmd_q->id);
+
+		debugfs_q_instance =
+			debugfs_create_dir(name, ccp->debugfs_instance);
+
+		debugfs_create_file("stats", 0600, debugfs_q_instance, cmd_q,
+				    &ccp_debugfs_queue_ops);
+	}
+
+	return;
+}
+
+void ccp5_debugfs_destroy(void)
+{
+	mutex_lock(&ccp_debugfs_lock);
+	debugfs_remove_recursive(ccp_debugfs_dir);
+	ccp_debugfs_dir = NULL;
+	mutex_unlock(&ccp_debugfs_lock);
+}