[PATCH 1/7] iommu/io-pgtable: Introduce dynamic io-pgtable format registration

["Isaac J. Manjarres" <isaacm@codeaurora.org>]

The io-pgtable code constructs an array of init functions for each
page table format at compile time. This is not ideal, as it prevents
io-pgtable formats from being built as kernel modules.

In preparation for modularizing the io-pgtable formats, switch to a
dynamic registration scheme, where each io-pgtable format can register
their init functions with the io-pgtable code at boot or module
insertion time.

Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>
---
 drivers/iommu/io-pgtable-arm-v7s.c | 33 ++++++++++++-
 drivers/iommu/io-pgtable-arm.c     | 97 ++++++++++++++++++++++++++++----------
 drivers/iommu/io-pgtable.c         | 44 +++++++++++------
 include/linux/io-pgtable.h         | 50 ++++++++++++--------
 4 files changed, 164 insertions(+), 60 deletions(-)

diff --git a/drivers/iommu/io-pgtable-arm-v7s.c b/drivers/iommu/io-pgtable-arm-v7s.c
index 1d92ac9..080881b 100644
--- a/drivers/iommu/io-pgtable-arm-v7s.c
+++ b/drivers/iommu/io-pgtable-arm-v7s.c
@@ -28,6 +28,7 @@
 #include <linux/iommu.h>
 #include <linux/kernel.h>
 #include <linux/kmemleak.h>
+#include <linux/module.h>
 #include <linux/sizes.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
@@ -835,7 +836,7 @@ static struct io_pgtable *arm_v7s_alloc_pgtable(struct io_pgtable_cfg *cfg,
 	return NULL;
 }
 
-struct io_pgtable_init_fns io_pgtable_arm_v7s_init_fns = {
+static struct io_pgtable_init_fns io_pgtable_arm_v7s_init_fns = {
 	.alloc	= arm_v7s_alloc_pgtable,
 	.free	= arm_v7s_free_pgtable,
 };
@@ -982,5 +983,33 @@ static int __init arm_v7s_do_selftests(void)
 	pr_info("self test ok\n");
 	return 0;
 }
-subsys_initcall(arm_v7s_do_selftests);
+#else
+static int arm_v7s_do_selftests(void)
+{
+	return 0;
+}
 #endif
+
+static int __init arm_v7s_init(void)
+{
+	int ret;
+
+	ret = io_pgtable_ops_register(ARM_V7S, &io_pgtable_arm_v7s_init_fns);
+	if (ret < 0) {
+		pr_err("Failed to register ARM v7s fmt ret = %d\n", ret);
+		return ret;
+	}
+
+	ret = arm_v7s_do_selftests();
+	if (ret < 0)
+		io_pgtable_ops_unregister(ARM_V7S);
+
+	return ret;
+}
+core_initcall(arm_v7s_init);
+
+static void __exit arm_v7s_exit(void)
+{
+	io_pgtable_ops_unregister(ARM_V7S);
+}
+module_exit(arm_v7s_exit);
diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index 87def58..e1f8d54 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -13,6 +13,7 @@
 #include <linux/bitops.h>
 #include <linux/io-pgtable.h>
 #include <linux/kernel.h>
+#include <linux/module.h>
 #include <linux/sizes.h>
 #include <linux/slab.h>
 #include <linux/types.h>
@@ -145,6 +146,11 @@ struct arm_lpae_io_pgtable {
 	void			*pgd;
 };
 
+struct arm_lpae_io_pgtable_init_fns {
+	enum io_pgtable_fmt fmt;
+	struct io_pgtable_init_fns init_fns;
+};
+
 typedef u64 arm_lpae_iopte;
 
 static inline bool iopte_leaf(arm_lpae_iopte pte, int lvl,
@@ -1043,29 +1049,32 @@ arm_mali_lpae_alloc_pgtable(struct io_pgtable_cfg *cfg, void *cookie)
 	return NULL;
 }
 
-struct io_pgtable_init_fns io_pgtable_arm_64_lpae_s1_init_fns = {
-	.alloc	= arm_64_lpae_alloc_pgtable_s1,
-	.free	= arm_lpae_free_pgtable,
-};
-
-struct io_pgtable_init_fns io_pgtable_arm_64_lpae_s2_init_fns = {
-	.alloc	= arm_64_lpae_alloc_pgtable_s2,
-	.free	= arm_lpae_free_pgtable,
-};
-
-struct io_pgtable_init_fns io_pgtable_arm_32_lpae_s1_init_fns = {
-	.alloc	= arm_32_lpae_alloc_pgtable_s1,
-	.free	= arm_lpae_free_pgtable,
-};
-
-struct io_pgtable_init_fns io_pgtable_arm_32_lpae_s2_init_fns = {
-	.alloc	= arm_32_lpae_alloc_pgtable_s2,
-	.free	= arm_lpae_free_pgtable,
-};
-
-struct io_pgtable_init_fns io_pgtable_arm_mali_lpae_init_fns = {
-	.alloc	= arm_mali_lpae_alloc_pgtable,
-	.free	= arm_lpae_free_pgtable,
+static struct arm_lpae_io_pgtable_init_fns arm_lpae_init_fns_table[] = {
+	{
+		.fmt		= ARM_32_LPAE_S1,
+		.init_fns.alloc	= arm_32_lpae_alloc_pgtable_s1,
+		.init_fns.free	= arm_lpae_free_pgtable,
+	},
+	{
+		.fmt		= ARM_32_LPAE_S2,
+		.init_fns.alloc	= arm_32_lpae_alloc_pgtable_s2,
+		.init_fns.free	= arm_lpae_free_pgtable,
+	},
+	{
+		.fmt		= ARM_64_LPAE_S1,
+		.init_fns.alloc	= arm_64_lpae_alloc_pgtable_s1,
+		.init_fns.free	= arm_lpae_free_pgtable,
+	},
+	{
+		.fmt		= ARM_64_LPAE_S2,
+		.init_fns.alloc	= arm_64_lpae_alloc_pgtable_s2,
+		.init_fns.free	= arm_lpae_free_pgtable,
+	},
+	{
+		.fmt		= ARM_MALI_LPAE,
+		.init_fns.alloc	= arm_mali_lpae_alloc_pgtable,
+		.init_fns.free	= arm_lpae_free_pgtable,
+	},
 };
 
 #ifdef CONFIG_IOMMU_IO_PGTABLE_LPAE_SELFTEST
@@ -1250,5 +1259,45 @@ static int __init arm_lpae_do_selftests(void)
 	pr_info("selftest: completed with %d PASS %d FAIL\n", pass, fail);
 	return fail ? -EFAULT : 0;
 }
-subsys_initcall(arm_lpae_do_selftests);
+#else
+static int __init arm_lpae_do_selftests(void)
+{
+	return 0;
+}
 #endif
+
+static int __init arm_lpae_init(void)
+{
+	int ret, i;
+
+	for (i = 0; i < ARRAY_SIZE(arm_lpae_init_fns_table); i++) {
+		ret = io_pgtable_ops_register(arm_lpae_init_fns_table[i].fmt,
+					      &arm_lpae_init_fns_table[i].init_fns);
+		if (ret < 0) {
+			pr_err("Failed to register ARM LPAE fmt: %d ret: %d\n",
+			       arm_lpae_init_fns_table[i].fmt, ret);
+			goto err_io_pgtable_register;
+		}
+	}
+
+	ret = arm_lpae_do_selftests();
+	if (ret < 0)
+		goto err_io_pgtable_register;
+
+	return 0;
+
+err_io_pgtable_register:
+	while (i--)
+		io_pgtable_ops_unregister(arm_lpae_init_fns_table[i].fmt);
+	return ret;
+}
+core_initcall(arm_lpae_init);
+
+static void __exit arm_lpae_exit(void)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(arm_lpae_init_fns_table); i++)
+		io_pgtable_ops_unregister(arm_lpae_init_fns_table[i].fmt);
+}
+module_exit(arm_lpae_exit);
diff --git a/drivers/iommu/io-pgtable.c b/drivers/iommu/io-pgtable.c
index 94394c8..95e872d 100644
--- a/drivers/iommu/io-pgtable.c
+++ b/drivers/iommu/io-pgtable.c
@@ -12,26 +12,14 @@
 #include <linux/kernel.h>
 #include <linux/types.h>
 
-static const struct io_pgtable_init_fns *
-io_pgtable_init_table[IO_PGTABLE_NUM_FMTS] = {
-#ifdef CONFIG_IOMMU_IO_PGTABLE_LPAE
-	[ARM_32_LPAE_S1] = &io_pgtable_arm_32_lpae_s1_init_fns,
-	[ARM_32_LPAE_S2] = &io_pgtable_arm_32_lpae_s2_init_fns,
-	[ARM_64_LPAE_S1] = &io_pgtable_arm_64_lpae_s1_init_fns,
-	[ARM_64_LPAE_S2] = &io_pgtable_arm_64_lpae_s2_init_fns,
-	[ARM_MALI_LPAE] = &io_pgtable_arm_mali_lpae_init_fns,
-#endif
-#ifdef CONFIG_IOMMU_IO_PGTABLE_ARMV7S
-	[ARM_V7S] = &io_pgtable_arm_v7s_init_fns,
-#endif
-};
+static struct io_pgtable_init_fns *io_pgtable_init_table[IO_PGTABLE_NUM_FMTS];
 
 struct io_pgtable_ops *alloc_io_pgtable_ops(enum io_pgtable_fmt fmt,
 					    struct io_pgtable_cfg *cfg,
 					    void *cookie)
 {
 	struct io_pgtable *iop;
-	const struct io_pgtable_init_fns *fns;
+	struct io_pgtable_init_fns *fns;
 
 	if (fmt >= IO_PGTABLE_NUM_FMTS)
 		return NULL;
@@ -59,12 +47,38 @@ EXPORT_SYMBOL_GPL(alloc_io_pgtable_ops);
 void free_io_pgtable_ops(struct io_pgtable_ops *ops)
 {
 	struct io_pgtable *iop;
+	struct io_pgtable_init_fns *fns;
 
 	if (!ops)
 		return;
 
 	iop = io_pgtable_ops_to_pgtable(ops);
 	io_pgtable_tlb_flush_all(iop);
-	io_pgtable_init_table[iop->fmt]->free(iop);
+	fns = io_pgtable_init_table[iop->fmt];
+	if (fns)
+		fns->free(iop);
 }
 EXPORT_SYMBOL_GPL(free_io_pgtable_ops);
+
+int io_pgtable_ops_register(enum io_pgtable_fmt fmt,
+			    struct io_pgtable_init_fns *init_fns)
+{
+	if (fmt >= IO_PGTABLE_NUM_FMTS || !init_fns || !init_fns->alloc ||
+	    !init_fns->free)
+		return -EINVAL;
+	else if (io_pgtable_init_table[fmt])
+		return -EEXIST;
+
+	io_pgtable_init_table[fmt] = init_fns;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(io_pgtable_ops_register);
+
+void io_pgtable_ops_unregister(enum io_pgtable_fmt fmt)
+{
+	if (fmt >= IO_PGTABLE_NUM_FMTS)
+		return;
+
+	io_pgtable_init_table[fmt] = NULL;
+}
+EXPORT_SYMBOL_GPL(io_pgtable_ops_unregister);
diff --git a/include/linux/io-pgtable.h b/include/linux/io-pgtable.h
index ea727eb..a460ae1 100644
--- a/include/linux/io-pgtable.h
+++ b/include/linux/io-pgtable.h
@@ -163,6 +163,37 @@ struct io_pgtable_ops {
 };
 
 /**
+ * struct io_pgtable_init_fns - Alloc/free a set of page tables for a
+ *                              particular format.
+ *
+ * @alloc: Allocate a set of page tables described by cfg.
+ * @free:  Free the page tables associated with iop.
+ */
+struct io_pgtable_init_fns {
+	struct io_pgtable *(*alloc)(struct io_pgtable_cfg *cfg, void *cookie);
+	void (*free)(struct io_pgtable *iop);
+};
+
+/**
+ * io_pgtable_ops_register() - Register the page table routines for a page table
+ *                             format.
+ *
+ * @fmt:      The page table format for which we are registering ops for.
+ * @init_fns: The functions for allocating and freeing the page tables of
+ *            a particular format.
+ */
+int io_pgtable_ops_register(enum io_pgtable_fmt fmt,
+			    struct io_pgtable_init_fns *init_fns);
+
+/**
+ * io_pgtable_ops_unregister() - Unregister the page table routines for a page
+ *                               table format.
+ *
+ * @fmt: The format for which we are unregistering ops for.
+ */
+void io_pgtable_ops_unregister(enum io_pgtable_fmt fmt);
+
+/**
  * alloc_io_pgtable_ops() - Allocate a page table allocator for use by an IOMMU.
  *
  * @fmt:    The page table format.
@@ -233,23 +264,4 @@ io_pgtable_tlb_add_page(struct io_pgtable *iop,
 		iop->cfg.tlb->tlb_add_page(gather, iova, granule, iop->cookie);
 }
 
-/**
- * struct io_pgtable_init_fns - Alloc/free a set of page tables for a
- *                              particular format.
- *
- * @alloc: Allocate a set of page tables described by cfg.
- * @free:  Free the page tables associated with iop.
- */
-struct io_pgtable_init_fns {
-	struct io_pgtable *(*alloc)(struct io_pgtable_cfg *cfg, void *cookie);
-	void (*free)(struct io_pgtable *iop);
-};
-
-extern struct io_pgtable_init_fns io_pgtable_arm_32_lpae_s1_init_fns;
-extern struct io_pgtable_init_fns io_pgtable_arm_32_lpae_s2_init_fns;
-extern struct io_pgtable_init_fns io_pgtable_arm_64_lpae_s1_init_fns;
-extern struct io_pgtable_init_fns io_pgtable_arm_64_lpae_s2_init_fns;
-extern struct io_pgtable_init_fns io_pgtable_arm_v7s_init_fns;
-extern struct io_pgtable_init_fns io_pgtable_arm_mali_lpae_init_fns;
-
 #endif /* __IO_PGTABLE_H */
-- 
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a Linux Foundation Collaborative Project

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