kbuild: rust: keep Rust objects out of Clang LTO with inline helpersgrafted

Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit
`objtool` errors such as:

    vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a:
    can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd

The reason is that in such builds, the Clang invocation that compiles
the combined Rust plus helpers bitcode emits LLVM bitcode (again) --
the final code generation happens in the linker's LTO step, which the
`-mllvm` trap options passed to Clang do not reach.

This, in turn, means that unreachable traps are missing, and the
impossible paths do not merely fallthrough to the next symbol, but past
the end of their own section, since LTO builds place each function in
its own section.

Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always
emits machine code directly, with the traps in place.

Assisted-by: LLM
Cc: Gary Guo <gary@garyguo.net>
Cc: Boqun Feng <boqun@kernel.org>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust")
Acked-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

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);
+}