From 12af2b83d0b17ec8b379b721dd4a8fbcd5d791f3 Mon Sep 17 00:00:00 2001 From: "Mike Rapoport (IBM)" Date: Sun, 5 May 2024 19:06:18 +0300 Subject: mm: introduce execmem_alloc() and execmem_free() module_alloc() is used everywhere as a mean to allocate memory for code. Beside being semantically wrong, this unnecessarily ties all subsystems that need to allocate code, such as ftrace, kprobes and BPF to modules and puts the burden of code allocation to the modules code. Several architectures override module_alloc() because of various constraints where the executable memory can be located and this causes additional obstacles for improvements of code allocation. Start splitting code allocation from modules by introducing execmem_alloc() and execmem_free() APIs. Initially, execmem_alloc() is a wrapper for module_alloc() and execmem_free() is a replacement of module_memfree() to allow updating all call sites to use the new APIs. Since architectures define different restrictions on placement, permissions, alignment and other parameters for memory that can be used by different subsystems that allocate executable memory, execmem_alloc() takes a type argument, that will be used to identify the calling subsystem and to allow architectures define parameters for ranges suitable for that subsystem. No functional changes. Signed-off-by: Mike Rapoport (IBM) Acked-by: Masami Hiramatsu (Google) Acked-by: Song Liu Acked-by: Steven Rostedt (Google) Signed-off-by: Luis Chamberlain --- include/linux/execmem.h | 57 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 57 insertions(+) create mode 100644 include/linux/execmem.h (limited to 'include/linux/execmem.h') diff --git a/include/linux/execmem.h b/include/linux/execmem.h new file mode 100644 index 000000000000..8eebc8ef66e7 --- /dev/null +++ b/include/linux/execmem.h @@ -0,0 +1,57 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_EXECMEM_ALLOC_H +#define _LINUX_EXECMEM_ALLOC_H + +#include +#include + +/** + * 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_TYPE_MAX: + */ +enum execmem_type { + EXECMEM_DEFAULT, + EXECMEM_MODULE_TEXT = EXECMEM_DEFAULT, + EXECMEM_KPROBES, + EXECMEM_FTRACE, + EXECMEM_BPF, + EXECMEM_TYPE_MAX, +}; + +/** + * 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. + * + * 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); + +#endif /* _LINUX_EXECMEM_ALLOC_H */ -- cgit v1.2.3 From f6bec26c0a7364d3506a3e12dab7c228ef32bd65 Mon Sep 17 00:00:00 2001 From: "Mike Rapoport (IBM)" Date: Sun, 5 May 2024 19:06:19 +0300 Subject: 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) Acked-by: Song Liu Reviewed-by: Masami Hiramatsu (Google) Signed-off-by: Luis Chamberlain --- include/linux/execmem.h | 47 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) (limited to 'include/linux/execmem.h') diff --git a/include/linux/execmem.h b/include/linux/execmem.h index 8eebc8ef66e7..96fc59258467 100644 --- a/include/linux/execmem.h +++ b/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 */ -- cgit v1.2.3 From 223b5e57d0d50b0c07b933350dbcde92018d3080 Mon Sep 17 00:00:00 2001 From: "Mike Rapoport (IBM)" Date: Sun, 5 May 2024 19:06:20 +0300 Subject: mm/execmem, arch: convert remaining overrides of module_alloc to execmem Extend execmem parameters to accommodate more complex overrides of module_alloc() by architectures. This includes specification of a fallback range required by arm, arm64 and powerpc, EXECMEM_MODULE_DATA type required by powerpc, support for allocation of KASAN shadow required by s390 and x86 and support for late initialization of execmem required by arm64. The core implementation of execmem_alloc() takes care of suppressing warnings when the initial allocation fails but there is a fallback range defined. Signed-off-by: Mike Rapoport (IBM) Acked-by: Will Deacon Acked-by: Song Liu Tested-by: Liviu Dudau Signed-off-by: Luis Chamberlain --- include/linux/execmem.h | 30 +++++++++++++++++++++++++++++- 1 file changed, 29 insertions(+), 1 deletion(-) (limited to 'include/linux/execmem.h') diff --git a/include/linux/execmem.h b/include/linux/execmem.h index 96fc59258467..32cef1144117 100644 --- a/include/linux/execmem.h +++ b/include/linux/execmem.h @@ -5,6 +5,14 @@ #include #include +#if (defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)) && \ + !defined(CONFIG_KASAN_VMALLOC) +#include +#define MODULE_ALIGN (PAGE_SIZE << KASAN_SHADOW_SCALE_SHIFT) +#else +#define MODULE_ALIGN PAGE_SIZE +#endif + /** * enum execmem_type - types of executable memory ranges * @@ -22,6 +30,7 @@ * @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 { @@ -30,22 +39,38 @@ enum execmem_type { 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 + */ +enum execmem_range_flags { + EXECMEM_KASAN_SHADOW = (1 << 0), +}; + /** * 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; }; /** @@ -82,6 +107,9 @@ struct execmem_info *execmem_arch_setup(void); * 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. * @@ -95,7 +123,7 @@ void *execmem_alloc(enum execmem_type type, size_t size); */ void execmem_free(void *ptr); -#ifdef CONFIG_EXECMEM +#if defined(CONFIG_EXECMEM) && !defined(CONFIG_ARCH_WANTS_EXECMEM_LATE) void execmem_init(void); #else static inline void execmem_init(void) {} -- cgit v1.2.3