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bpf: Move stack_map_get_build_id into lib
Moving stack_map_get_build_id into lib with declaration in linux/buildid.h header: int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id); This function returns build id for given struct vm_area_struct. There is no functional change to stack_map_get_build_id function. Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20210114134044.1418404-2-jolsa@kernel.org
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Jiri Olsa
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Alexei Starovoitov
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Jan 15, 2021
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,11 @@ | ||
| /* SPDX-License-Identifier: GPL-2.0 */ | ||
| #ifndef _LINUX_BUILDID_H | ||
| #define _LINUX_BUILDID_H | ||
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| #include <linux/mm_types.h> | ||
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| #define BUILD_ID_SIZE_MAX 20 | ||
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| int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id); | ||
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| #endif |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,136 @@ | ||
| // SPDX-License-Identifier: GPL-2.0 | ||
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| #include <linux/buildid.h> | ||
| #include <linux/elf.h> | ||
| #include <linux/pagemap.h> | ||
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| #define BUILD_ID 3 | ||
| /* | ||
| * Parse build id from the note segment. This logic can be shared between | ||
| * 32-bit and 64-bit system, because Elf32_Nhdr and Elf64_Nhdr are | ||
| * identical. | ||
| */ | ||
| static inline int parse_build_id(void *page_addr, | ||
| unsigned char *build_id, | ||
| void *note_start, | ||
| Elf32_Word note_size) | ||
| { | ||
| Elf32_Word note_offs = 0, new_offs; | ||
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| /* check for overflow */ | ||
| if (note_start < page_addr || note_start + note_size < note_start) | ||
| return -EINVAL; | ||
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| /* only supports note that fits in the first page */ | ||
| if (note_start + note_size > page_addr + PAGE_SIZE) | ||
| return -EINVAL; | ||
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| while (note_offs + sizeof(Elf32_Nhdr) < note_size) { | ||
| Elf32_Nhdr *nhdr = (Elf32_Nhdr *)(note_start + note_offs); | ||
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| if (nhdr->n_type == BUILD_ID && | ||
| nhdr->n_namesz == sizeof("GNU") && | ||
| nhdr->n_descsz > 0 && | ||
| nhdr->n_descsz <= BUILD_ID_SIZE_MAX) { | ||
| memcpy(build_id, | ||
| note_start + note_offs + | ||
| ALIGN(sizeof("GNU"), 4) + sizeof(Elf32_Nhdr), | ||
| nhdr->n_descsz); | ||
| memset(build_id + nhdr->n_descsz, 0, | ||
| BUILD_ID_SIZE_MAX - nhdr->n_descsz); | ||
| return 0; | ||
| } | ||
| new_offs = note_offs + sizeof(Elf32_Nhdr) + | ||
| ALIGN(nhdr->n_namesz, 4) + ALIGN(nhdr->n_descsz, 4); | ||
| if (new_offs <= note_offs) /* overflow */ | ||
| break; | ||
| note_offs = new_offs; | ||
| } | ||
| return -EINVAL; | ||
| } | ||
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| /* Parse build ID from 32-bit ELF */ | ||
| static int get_build_id_32(void *page_addr, unsigned char *build_id) | ||
| { | ||
| Elf32_Ehdr *ehdr = (Elf32_Ehdr *)page_addr; | ||
| Elf32_Phdr *phdr; | ||
| int i; | ||
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| /* only supports phdr that fits in one page */ | ||
| if (ehdr->e_phnum > | ||
| (PAGE_SIZE - sizeof(Elf32_Ehdr)) / sizeof(Elf32_Phdr)) | ||
| return -EINVAL; | ||
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| phdr = (Elf32_Phdr *)(page_addr + sizeof(Elf32_Ehdr)); | ||
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| for (i = 0; i < ehdr->e_phnum; ++i) { | ||
| if (phdr[i].p_type == PT_NOTE && | ||
| !parse_build_id(page_addr, build_id, | ||
| page_addr + phdr[i].p_offset, | ||
| phdr[i].p_filesz)) | ||
| return 0; | ||
| } | ||
| return -EINVAL; | ||
| } | ||
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| /* Parse build ID from 64-bit ELF */ | ||
| static int get_build_id_64(void *page_addr, unsigned char *build_id) | ||
| { | ||
| Elf64_Ehdr *ehdr = (Elf64_Ehdr *)page_addr; | ||
| Elf64_Phdr *phdr; | ||
| int i; | ||
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| /* only supports phdr that fits in one page */ | ||
| if (ehdr->e_phnum > | ||
| (PAGE_SIZE - sizeof(Elf64_Ehdr)) / sizeof(Elf64_Phdr)) | ||
| return -EINVAL; | ||
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| phdr = (Elf64_Phdr *)(page_addr + sizeof(Elf64_Ehdr)); | ||
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| for (i = 0; i < ehdr->e_phnum; ++i) { | ||
| if (phdr[i].p_type == PT_NOTE && | ||
| !parse_build_id(page_addr, build_id, | ||
| page_addr + phdr[i].p_offset, | ||
| phdr[i].p_filesz)) | ||
| return 0; | ||
| } | ||
| return -EINVAL; | ||
| } | ||
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| /* Parse build ID of ELF file mapped to vma */ | ||
| int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id) | ||
| { | ||
| Elf32_Ehdr *ehdr; | ||
| struct page *page; | ||
| void *page_addr; | ||
| int ret; | ||
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| /* only works for page backed storage */ | ||
| if (!vma->vm_file) | ||
| return -EINVAL; | ||
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| page = find_get_page(vma->vm_file->f_mapping, 0); | ||
| if (!page) | ||
| return -EFAULT; /* page not mapped */ | ||
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| ret = -EINVAL; | ||
| page_addr = kmap_atomic(page); | ||
| ehdr = (Elf32_Ehdr *)page_addr; | ||
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| /* compare magic x7f "ELF" */ | ||
| if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG) != 0) | ||
| goto out; | ||
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| /* only support executable file and shared object file */ | ||
| if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN) | ||
| goto out; | ||
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| if (ehdr->e_ident[EI_CLASS] == ELFCLASS32) | ||
| ret = get_build_id_32(page_addr, build_id); | ||
| else if (ehdr->e_ident[EI_CLASS] == ELFCLASS64) | ||
| ret = get_build_id_64(page_addr, build_id); | ||
| out: | ||
| kunmap_atomic(page_addr); | ||
| put_page(page); | ||
| return ret; | ||
| } |