1 files changed, 215 insertions, 0 deletions
diff --git a/include/linux/execmem.h b/include/linux/execmem.h
new file mode 100644
index 000000000000..3be35680a54f
--- /dev/null
+++ b/include/linux/execmem.h
@@ -0,0 +1,215 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_EXECMEM_ALLOC_H
+#define _LINUX_EXECMEM_ALLOC_H
+
+#include <linux/types.h>
+#include <linux/moduleloader.h>
+#include <linux/cleanup.h>
+
+#if (defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)) && \
+		!defined(CONFIG_KASAN_VMALLOC)
+#include <linux/kasan.h>
+#define MODULE_ALIGN (PAGE_SIZE << KASAN_SHADOW_SCALE_SHIFT)
+#else
+#define MODULE_ALIGN PAGE_SIZE
+#endif
+
+/**
+ * enum execmem_type - types of executable memory ranges
+ *
+ * There are several subsystems that allocate executable memory.
+ * Architectures define different restrictions on placement,
+ * permissions, alignment and other parameters for memory that can be used
+ * by these subsystems.
+ * Types in this enum identify subsystems that allocate executable memory
+ * and let architectures define parameters for ranges suitable for
+ * allocations by each subsystem.
+ *
+ * @EXECMEM_DEFAULT: default parameters that would be used for types that
+ * are not explicitly defined.
+ * @EXECMEM_MODULE_TEXT: parameters for module text sections
+ * @EXECMEM_KPROBES: parameters for kprobes
+ * @EXECMEM_FTRACE: parameters for ftrace
+ * @EXECMEM_BPF: parameters for BPF
+ * @EXECMEM_MODULE_DATA: parameters for module data sections
+ * @EXECMEM_TYPE_MAX:
+ */
+enum execmem_type {
+	EXECMEM_DEFAULT,
+	EXECMEM_MODULE_TEXT = EXECMEM_DEFAULT,
+	EXECMEM_KPROBES,
+	EXECMEM_FTRACE,
+	EXECMEM_BPF,
+	EXECMEM_MODULE_DATA,
+	EXECMEM_TYPE_MAX,
+};
+
+/**
+ * enum execmem_range_flags - options for executable memory allocations
+ * @EXECMEM_KASAN_SHADOW:	allocate kasan shadow
+ * @EXECMEM_ROX_CACHE:		allocations should use ROX cache of huge pages
+ */
+enum execmem_range_flags {
+	EXECMEM_KASAN_SHADOW	= (1 << 0),
+	EXECMEM_ROX_CACHE	= (1 << 1),
+};
+
+#ifdef CONFIG_ARCH_HAS_EXECMEM_ROX
+/**
+ * execmem_fill_trapping_insns - set memory to contain instructions that
+ *				 will trap
+ * @ptr:	pointer to memory to fill
+ * @size:	size of the range to fill
+ * @writable:	is the memory poited by @ptr is writable or ROX
+ *
+ * A hook for architecures to fill execmem ranges with invalid instructions.
+ * Architectures that use EXECMEM_ROX_CACHE must implement this.
+ */
+void execmem_fill_trapping_insns(void *ptr, size_t size, bool writable);
+
+/**
+ * execmem_make_temp_rw - temporarily remap region with read-write
+ *			  permissions
+ * @ptr:	address of the region to remap
+ * @size:	size of the region to remap
+ *
+ * Remaps a part of the cached large page in the ROX cache in the range
+ * [@ptr, @ptr + @size) as writable and not executable. The caller must
+ * have exclusive ownership of this range and ensure nothing will try to
+ * execute code in this range.
+ *
+ * Return: 0 on success or negative error code on failure.
+ */
+int execmem_make_temp_rw(void *ptr, size_t size);
+
+/**
+ * execmem_restore_rox - restore read-only-execute permissions
+ * @ptr:	address of the region to remap
+ * @size:	size of the region to remap
+ *
+ * Restores read-only-execute permissions on a range [@ptr, @ptr + @size)
+ * after it was temporarily remapped as writable. Relies on architecture
+ * implementation of set_memory_rox() to restore mapping using large pages.
+ *
+ * Return: 0 on success or negative error code on failure.
+ */
+int execmem_restore_rox(void *ptr, size_t size);
+#else
+static inline int execmem_make_temp_rw(void *ptr, size_t size) { return 0; }
+static inline int execmem_restore_rox(void *ptr, size_t size) { return 0; }
+#endif
+
+/**
+ * struct execmem_range - definition of an address space suitable for code and
+ *			  related data allocations
+ * @start:	address space start
+ * @end:	address space end (inclusive)
+ * @fallback_start: start of the secondary address space range for fallback
+ *                  allocations on architectures that require it
+ * @fallback_end:   start of the secondary address space (inclusive)
+ * @pgprot:	permissions for memory in this address space
+ * @alignment:	alignment required for text allocations
+ * @flags:	options for memory allocations for this range
+ */
+struct execmem_range {
+	unsigned long   start;
+	unsigned long   end;
+	unsigned long   fallback_start;
+	unsigned long   fallback_end;
+	pgprot_t        pgprot;
+	unsigned int	alignment;
+	enum execmem_range_flags flags;
+};
+
+/**
+ * struct execmem_info - architecture parameters for code allocations
+ * @ranges: array of parameter sets defining architecture specific
+ * parameters for executable memory allocations. The ranges that are not
+ * explicitly initialized by an architecture use parameters defined for
+ * @EXECMEM_DEFAULT.
+ */
+struct execmem_info {
+	struct execmem_range	ranges[EXECMEM_TYPE_MAX];
+};
+
+/**
+ * execmem_arch_setup - define parameters for allocations of executable memory
+ *
+ * A hook for architectures to define parameters for allocations of
+ * executable memory. These parameters should be filled into the
+ * @execmem_info structure.
+ *
+ * For architectures that do not implement this method a default set of
+ * parameters will be used
+ *
+ * Return: a structure defining architecture parameters and restrictions
+ * for allocations of executable memory
+ */
+struct execmem_info *execmem_arch_setup(void);
+
+/**
+ * execmem_alloc - allocate executable memory
+ * @type: type of the allocation
+ * @size: how many bytes of memory are required
+ *
+ * Allocates memory that will contain executable code, either generated or
+ * loaded from kernel modules.
+ *
+ * Allocates memory that will contain data coupled with executable code,
+ * like data sections in kernel modules.
+ *
+ * The memory will have protections defined by architecture for executable
+ * region of the @type.
+ *
+ * Return: a pointer to the allocated memory or %NULL
+ */
+void *execmem_alloc(enum execmem_type type, size_t size);
+
+/**
+ * execmem_free - free executable memory
+ * @ptr: pointer to the memory that should be freed
+ */
+void execmem_free(void *ptr);
+
+DEFINE_FREE(execmem, void *, if (_T) execmem_free(_T));
+
+#ifdef CONFIG_MMU
+/**
+ * execmem_vmap - create virtual mapping for EXECMEM_MODULE_DATA memory
+ * @size: size of the virtual mapping in bytes
+ *
+ * Maps virtually contiguous area in the range suitable for EXECMEM_MODULE_DATA.
+ *
+ * Return: the area descriptor on success or %NULL on failure.
+ */
+struct vm_struct *execmem_vmap(size_t size);
+#endif
+
+/**
+ * execmem_update_copy - copy an update to executable memory
+ * @dst:  destination address to update
+ * @src:  source address containing the data
+ * @size: how many bytes of memory shold be copied
+ *
+ * Copy @size bytes from @src to @dst using text poking if the memory at
+ * @dst is read-only.
+ *
+ * Return: a pointer to @dst or NULL on error
+ */
+void *execmem_update_copy(void *dst, const void *src, size_t size);
+
+/**
+ * execmem_is_rox - check if execmem is read-only
+ * @type - the execmem type to check
+ *
+ * Return: %true if the @type is read-only, %false if it's writable
+ */
+bool execmem_is_rox(enum execmem_type type);
+
+#if defined(CONFIG_EXECMEM) && !defined(CONFIG_ARCH_WANTS_EXECMEM_LATE)
+void execmem_init(void);
+#else
+static inline void execmem_init(void) {}
+#endif
+
+#endif /* _LINUX_EXECMEM_ALLOC_H */