Re: [PATCH v3 06/13] mm/execmem: introduce execmem_data_alloc()
From: Song Liu <song@kernel.org>
Date: 2023-09-21 22:52:39
Also in:
bpf, linux-arm-kernel, linux-mips, linux-mm, linux-modules, linux-riscv, linux-s390, linux-trace-kernel, linuxppc-dev, lkml, loongarch, sparclinux
On Mon, Sep 18, 2023 at 12:31 AM Mike Rapoport [off-list ref] wrote:
[...]
quoted hunk ↗ jump to hunk
diff --git a/include/linux/execmem.h b/include/linux/execmem.h index 519bdfdca595..09d45ac786e9 100644 --- a/include/linux/execmem.h +++ b/include/linux/execmem.h@@ -29,6 +29,7 @@ * @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 {@@ -37,6 +38,7 @@ enum execmem_type { EXECMEM_KPROBES, EXECMEM_FTRACE,
In longer term, I think we can improve the JITed code and merge kprobe/ftrace/bpf. to use the same ranges. Also, do we need special setting for FTRACE? If not, let's just remove it.
EXECMEM_BPF,
+ EXECMEM_MODULE_DATA,
EXECMEM_TYPE_MAX,
};Overall, it is great that kprobe/ftrace/bpf no longer depend on modules. OTOH, I think we should merge execmem_type and existing mod_mem_type. Otherwise, we still need to handle page permissions in multiple places. What is our plan for that? Thanks, Song
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@@ -107,6 +109,23 @@ struct execmem_params *execmem_arch_params(void); */ void *execmem_text_alloc(enum execmem_type type, size_t size); +/** + * execmem_data_alloc - allocate memory for data coupled to code + * @type: type of the allocation + * @size: how many bytes of memory are required + * + * Allocates memory that will contain data coupled with executable code, + * like data sections in kernel modules. + * + * The memory will have protections defined by architecture. + * + * The allocated memory will reside in an area that does not impose + * restrictions on the addressing modes. + * + * Return: a pointer to the allocated memory or %NULL + */ +void *execmem_data_alloc(enum execmem_type type, size_t size); + /** * execmem_free - free executable memory * @ptr: pointer to the memory that should be freeddiff --git a/kernel/module/main.c b/kernel/module/main.c index c4146bfcd0a7..2ae83a6abf66 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c@@ -1188,25 +1188,16 @@ void __weak module_arch_freeing_init(struct module *mod) { } -static bool mod_mem_use_vmalloc(enum mod_mem_type type) -{ - return IS_ENABLED(CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC) && - mod_mem_type_is_core_data(type); -} - static void *module_memory_alloc(unsigned int size, enum mod_mem_type type) { - if (mod_mem_use_vmalloc(type)) - return vzalloc(size); + if (mod_mem_type_is_data(type)) + return execmem_data_alloc(EXECMEM_MODULE_DATA, size); return execmem_text_alloc(EXECMEM_MODULE_TEXT, size); } static void module_memory_free(void *ptr, enum mod_mem_type type) { - if (mod_mem_use_vmalloc(type)) - vfree(ptr); - else - execmem_free(ptr); + execmem_free(ptr); } static void free_mod_mem(struct module *mod)diff --git a/mm/execmem.c b/mm/execmem.c index abcbd07e05ac..aeff85261360 100644 --- a/mm/execmem.c +++ b/mm/execmem.c@@ -53,11 +53,23 @@ static void *execmem_alloc(size_t size, struct execmem_range *range) return kasan_reset_tag(p); } +static inline bool execmem_range_is_data(enum execmem_type type) +{ + return type == EXECMEM_MODULE_DATA; +} + void *execmem_text_alloc(enum execmem_type type, size_t size) { return execmem_alloc(size, &execmem_params.ranges[type]); } +void *execmem_data_alloc(enum execmem_type type, size_t size) +{ + WARN_ON_ONCE(!execmem_range_is_data(type)); + + return execmem_alloc(size, &execmem_params.ranges[type]); +} + void execmem_free(void *ptr) { /*@@ -93,7 +105,10 @@ static void execmem_init_missing(struct execmem_params *p) struct execmem_range *r = &p->ranges[i]; if (!r->start) { - r->pgprot = default_range->pgprot; + if (execmem_range_is_data(i)) + r->pgprot = PAGE_KERNEL; + else + r->pgprot = default_range->pgprot; r->alignment = default_range->alignment; r->start = default_range->start; r->end = default_range->end; --2.39.2