mm/execmem, arch: convert simple overrides of module_alloc to execmem

Several architectures override module_alloc() only to define address
range for code allocations different than VMALLOC address space.

Provide a generic implementation in execmem that uses the parameters for
address space ranges, required alignment and page protections provided
by architectures.

The architectures must fill execmem_info structure and implement
execmem_arch_setup() that returns a pointer to that structure. This way the
execmem initialization won't be called from every architecture, but rather
from a central place, namely a core_initcall() in execmem.

The execmem provides execmem_alloc() API that wraps __vmalloc_node_range()
with the parameters defined by the architectures.  If an architecture does
not implement execmem_arch_setup(), execmem_alloc() will fall back to
module_alloc().
Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

arch/loongarch/kernel/module.c

@@ -18,6 +18,7 @@
 #include <linux/ftrace.h>
 #include <linux/string.h>
 #include <linux/kernel.h>
+#include <linux/execmem.h>
 #include <asm/alternative.h>
 #include <asm/inst.h>
 #include <asm/unwind.h>
@@ -490,10 +491,22 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
 	return 0;
 }
 
-void *module_alloc(unsigned long size)
+static struct execmem_info execmem_info __ro_after_init;
+
+struct execmem_info __init *execmem_arch_setup(void)
 {
-	return __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END,
-			GFP_KERNEL, PAGE_KERNEL, 0, NUMA_NO_NODE, __builtin_return_address(0));
+	execmem_info = (struct execmem_info){
+		.ranges = {
+			[EXECMEM_DEFAULT] = {
+				.start	= MODULES_VADDR,
+				.end	= MODULES_END,
+				.pgprot	= PAGE_KERNEL,
+				.alignment = 1,
+			},
+		},
+	};
+
+	return &execmem_info;
 }
 
 static void module_init_ftrace_plt(const Elf_Ehdr *hdr,

arch/mips/kernel/module.c

@@ -20,6 +20,7 @@
 #include <linux/kernel.h>
 #include <linux/spinlock.h>
 #include <linux/jump_label.h>
+#include <linux/execmem.h>
 #include <asm/jump_label.h>
 
 struct mips_hi16 {
@@ -32,11 +33,22 @@ static LIST_HEAD(dbe_list);
 static DEFINE_SPINLOCK(dbe_lock);
 
 #ifdef MODULES_VADDR
-void *module_alloc(unsigned long size)
+static struct execmem_info execmem_info __ro_after_init;
+
+struct execmem_info __init *execmem_arch_setup(void)
 {
-	return __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END,
-				GFP_KERNEL, PAGE_KERNEL, 0, NUMA_NO_NODE,
-				__builtin_return_address(0));
+	execmem_info = (struct execmem_info){
+		.ranges = {
+			[EXECMEM_DEFAULT] = {
+				.start	= MODULES_VADDR,
+				.end	= MODULES_END,
+				.pgprot	= PAGE_KERNEL,
+				.alignment = 1,
+			},
+		},
+	};
+
+	return &execmem_info;
 }
 #endif
 

arch/nios2/kernel/module.c

@@ -18,15 +18,26 @@
 #include <linux/fs.h>
 #include <linux/string.h>
 #include <linux/kernel.h>
+#include <linux/execmem.h>
 
 #include <asm/cacheflush.h>
 
-void *module_alloc(unsigned long size)
+static struct execmem_info execmem_info __ro_after_init;
+
+struct execmem_info __init *execmem_arch_setup(void)
 {
-	return __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END,
-				    GFP_KERNEL, PAGE_KERNEL_EXEC,
-				    VM_FLUSH_RESET_PERMS, NUMA_NO_NODE,
-				    __builtin_return_address(0));
+	execmem_info = (struct execmem_info){
+		.ranges = {
+			[EXECMEM_DEFAULT] = {
+				.start	= MODULES_VADDR,
+				.end	= MODULES_END,
+				.pgprot	= PAGE_KERNEL_EXEC,
+				.alignment = 1,
+			},
+		},
+	};
+
+	return &execmem_info;
 }
 
 int apply_relocate_add(Elf32_Shdr *sechdrs, const char *strtab,

arch/parisc/kernel/module.c

@@ -49,6 +49,7 @@
 #include <linux/bug.h>
 #include <linux/mm.h>
 #include <linux/slab.h>
+#include <linux/execmem.h>
 
 #include <asm/unwind.h>
 #include <asm/sections.h>
@@ -173,15 +174,22 @@ static inline int reassemble_22(int as22)
 		((as22 & 0x0003ff) << 3));
 }
 
-void *module_alloc(unsigned long size)
+static struct execmem_info execmem_info __ro_after_init;
+
+struct execmem_info __init *execmem_arch_setup(void)
 {
-	/* using RWX means less protection for modules, but it's
-	 * easier than trying to map the text, data, init_text and
-	 * init_data correctly */
-	return __vmalloc_node_range(size, 1, VMALLOC_START, VMALLOC_END,
-				    GFP_KERNEL,
-				    PAGE_KERNEL_RWX, 0, NUMA_NO_NODE,
-				    __builtin_return_address(0));
+	execmem_info = (struct execmem_info){
+		.ranges = {
+			[EXECMEM_DEFAULT] = {
+				.start	= VMALLOC_START,
+				.end	= VMALLOC_END,
+				.pgprot	= PAGE_KERNEL_RWX,
+				.alignment = 1,
+			},
+		},
+	};
+
+	return &execmem_info;
 }
 
 #ifndef CONFIG_64BIT

arch/riscv/kernel/module.c

@@ -14,6 +14,7 @@
 #include <linux/vmalloc.h>
 #include <linux/sizes.h>
 #include <linux/pgtable.h>
+#include <linux/execmem.h>
 #include <asm/alternative.h>
 #include <asm/sections.h>
 
@@ -906,13 +907,22 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
 }
 
 #if defined(CONFIG_MMU) && defined(CONFIG_64BIT)
-void *module_alloc(unsigned long size)
-{
-	return __vmalloc_node_range(size, 1, MODULES_VADDR,
-				    MODULES_END, GFP_KERNEL,
-				    PAGE_KERNEL, VM_FLUSH_RESET_PERMS,
-				    NUMA_NO_NODE,
-				    __builtin_return_address(0));
+static struct execmem_info execmem_info __ro_after_init;
+
+struct execmem_info __init *execmem_arch_setup(void)
+{
+	execmem_info = (struct execmem_info){
+		.ranges = {
+			[EXECMEM_DEFAULT] = {
+				.start	= MODULES_VADDR,
+				.end	= MODULES_END,
+				.pgprot	= PAGE_KERNEL,
+				.alignment = 1,
+			},
+		},
+	};
+
+	return &execmem_info;
 }
 #endif
 

arch/sparc/kernel/module.c

@@ -14,6 +14,7 @@
 #include <linux/string.h>
 #include <linux/ctype.h>
 #include <linux/mm.h>
+#include <linux/execmem.h>
 
 #include <asm/processor.h>
 #include <asm/spitfire.h>
@@ -21,11 +22,22 @@
 
 #include "entry.h"
 
-void *module_alloc(unsigned long size)
+static struct execmem_info execmem_info __ro_after_init;
+
+struct execmem_info __init *execmem_arch_setup(void)
 {
-	return __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END,
-				GFP_KERNEL, PAGE_KERNEL, 0, NUMA_NO_NODE,
-				__builtin_return_address(0));
+	execmem_info = (struct execmem_info){
+		.ranges = {
+			[EXECMEM_DEFAULT] = {
+				.start	= MODULES_VADDR,
+				.end	= MODULES_END,
+				.pgprot	= PAGE_KERNEL,
+				.alignment = 1,
+			},
+		},
+	};
+
+	return &execmem_info;
 }
 
 /* Make generic code ignore STT_REGISTER dummy undefined symbols.  */

include/linux/execmem.h

@@ -33,6 +33,47 @@ enum execmem_type {
 	EXECMEM_TYPE_MAX,
 };
 
+/**
+ * struct execmem_range - definition of an address space suitable for code and
+ *			  related data allocations
+ * @start:	address space start
+ * @end:	address space end (inclusive)
+ * @pgprot:	permissions for memory in this address space
+ * @alignment:	alignment required for text allocations
+ */
+struct execmem_range {
+	unsigned long   start;
+	unsigned long   end;
+	pgprot_t        pgprot;
+	unsigned int	alignment;
+};
+
+/**
+ * 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
@@ -54,4 +95,10 @@ void *execmem_alloc(enum execmem_type type, size_t size);
  */
 void execmem_free(void *ptr);
 
+#ifdef CONFIG_EXECMEM
+void execmem_init(void);
+#else
+static inline void execmem_init(void) {}
+#endif
+
 #endif /* _LINUX_EXECMEM_ALLOC_H */

mm/execmem.c

@@ -11,14 +11,30 @@
 #include <linux/execmem.h>
 #include <linux/moduleloader.h>
 
-static void *__execmem_alloc(size_t size)
+static struct execmem_info *execmem_info __ro_after_init;
+
+static void *__execmem_alloc(struct execmem_range *range, size_t size)
 {
-	return module_alloc(size);
+	unsigned long start = range->start;
+	unsigned long end = range->end;
+	unsigned int align = range->alignment;
+	pgprot_t pgprot = range->pgprot;
+
+	return __vmalloc_node_range(size, align, start, end,
+				    GFP_KERNEL, pgprot, VM_FLUSH_RESET_PERMS,
+				    NUMA_NO_NODE, __builtin_return_address(0));
 }
 
 void *execmem_alloc(enum execmem_type type, size_t size)
 {
-	return __execmem_alloc(size);
+	struct execmem_range *range;
+
+	if (!execmem_info)
+		return module_alloc(size);
+
+	range = &execmem_info->ranges[type];
+
+	return __execmem_alloc(range, size);
 }
 
 void execmem_free(void *ptr)
@@ -30,3 +46,48 @@ void execmem_free(void *ptr)
 	WARN_ON(in_interrupt());
 	vfree(ptr);
 }
+
+static bool execmem_validate(struct execmem_info *info)
+{
+	struct execmem_range *r = &info->ranges[EXECMEM_DEFAULT];
+
+	if (!r->alignment || !r->start || !r->end || !pgprot_val(r->pgprot)) {
+		pr_crit("Invalid parameters for execmem allocator, module loading will fail");
+		return false;
+	}
+
+	return true;
+}
+
+static void execmem_init_missing(struct execmem_info *info)
+{
+	struct execmem_range *default_range = &info->ranges[EXECMEM_DEFAULT];
+
+	for (int i = EXECMEM_DEFAULT + 1; i < EXECMEM_TYPE_MAX; i++) {
+		struct execmem_range *r = &info->ranges[i];
+
+		if (!r->start) {
+			r->pgprot = default_range->pgprot;
+			r->alignment = default_range->alignment;
+			r->start = default_range->start;
+			r->end = default_range->end;
+		}
+	}
+}
+
+struct execmem_info * __weak execmem_arch_setup(void)
+{
+	return NULL;
+}
+
+void __init execmem_init(void)
+{
+	struct execmem_info *info = execmem_arch_setup();
+
+	if (!info || !execmem_validate(info))
+		return;
+
+	execmem_init_missing(info);
+
+	execmem_info = info;
+}

mm/mm_init.c

@@ -27,6 +27,7 @@
 #include <linux/swap.h>
 #include <linux/cma.h>
 #include <linux/crash_dump.h>
+#include <linux/execmem.h>
 #include "internal.h"
 #include "slab.h"
 #include "shuffle.h"
@@ -2793,4 +2794,5 @@ void __init mm_core_init(void)
 	pti_init();
 	kmsan_init_runtime();
 	mm_cache_init();
+	execmem_init();
 }