From: HATAYAMA Daisuke Date: Wed, 19 Jun 2013 00:06:09 +0000 (+1000) Subject: vmcore: disable mmap_vmcore() if CONFIG_MMU is not defined X-Git-Tag: next-20130619~2^2~502 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=b5f7bd4a3ed1710c053d206fb4de0622c415fb37;p=karo-tx-linux.git vmcore: disable mmap_vmcore() if CONFIG_MMU is not defined From Arnd's report of a link-time build error in vmcore.c, it turned out that mmap_vmcore() work overlooked no-MMU configuraiton. In the current design, it's impossible to implement mmap_vmcore() for no-MMU configuration since MMU is essential in order to map physically non-contiguous objects (ELF header, ELF note segment and memory regions in the 1st kernel pointed to by PT_LOAD entries) into virtually contiguous user-space in ELF layout. Hence, this patch disables mmap_vmcore() if CONFIG_MMU is not defined, returning -ENOSYS. Another change is to fix the build error by using vmalloc_user() instead of calling vzalloc() and find_vm_area() in order, by which we no longer need to call find_vm_area() in vmcore.c that has no counterpart on non-MMU configuration. Also, on no-MMU configuration, because we don't export buffer for ELF note segment to user-space, we use vzalloc() to allocate the buffer. Therefore, we use differnet functions to allocate the buffer for ELF note segment. To avoid code duplication, introduce a helper alloc_elfnotes_buf(). Signed-off-by: HATAYAMA Daisuke Reported-by: Arnd Bergmann Cc: Atsushi Kumagai Cc: HATAYAMA Daisuke Cc: KOSAKI Motohiro Cc: Lisa Mitchell Cc: Vivek Goyal Cc: Zhang Yanfei Signed-off-by: Andrew Morton --- diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c index 0f6db5269d38..28503172f2e4 100644 --- a/fs/proc/vmcore.c +++ b/fs/proc/vmcore.c @@ -195,6 +195,35 @@ static ssize_t read_vmcore(struct file *file, char __user *buffer, return acc; } +/** + * alloc_elfnotes_buf - allocate buffer for ELF note segment in + * vmalloc memory + * + * @notes_sz: size of buffer + * + * If CONFIG_MMU is defined, use vmalloc_user() to allow users to mmap + * the buffer to user-space by means of remap_vmalloc_range(). + * + * If CONFIG_MMU is not defined, use vzalloc() since mmap_vmcore() is + * disabled and there's no need to allow users to mmap the buffer. + */ +static inline char *alloc_elfnotes_buf(size_t notes_sz) +{ +#ifdef CONFIG_MMU + return vmalloc_user(notes_sz); +#else + return vzalloc(notes_sz); +#endif +} + +/* + * Disable mmap_vmcore() if CONFIG_MMU is not defined. MMU is + * essential for mmap_vmcore() in order to map physically + * non-contiguous objects (ELF header, ELF note segment and memory + * regions in the 1st kernel pointed to by PT_LOAD entries) into + * virtually contiguous user-space in ELF layout. + */ +#ifdef CONFIG_MMU static int mmap_vmcore(struct file *file, struct vm_area_struct *vma) { size_t size = vma->vm_end - vma->vm_start; @@ -271,6 +300,12 @@ fail: do_munmap(vma->vm_mm, vma->vm_start, len); return -EAGAIN; } +#else +static int mmap_vmcore(struct file *file, struct vm_area_struct *vma) +{ + return -ENOSYS; +} +#endif static const struct file_operations proc_vmcore_operations = { .read = read_vmcore, @@ -427,7 +462,6 @@ static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz, Elf64_Ehdr *ehdr_ptr; Elf64_Phdr phdr; u64 phdr_sz = 0, note_off; - struct vm_struct *vm; ehdr_ptr = (Elf64_Ehdr *)elfptr; @@ -440,18 +474,10 @@ static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz, return rc; *notes_sz = roundup(phdr_sz, PAGE_SIZE); - *notes_buf = vzalloc(*notes_sz); + *notes_buf = alloc_elfnotes_buf(*notes_sz); if (!*notes_buf) return -ENOMEM; - /* - * Allow users to remap ELF note segment buffer on vmalloc memory using - * remap_vmalloc_range.() - */ - vm = find_vm_area(*notes_buf); - BUG_ON(!vm); - vm->flags |= VM_USERMAP; - rc = copy_notes_elf64(ehdr_ptr, *notes_buf); if (rc < 0) return rc; @@ -615,7 +641,6 @@ static int __init merge_note_headers_elf32(char *elfptr, size_t *elfsz, Elf32_Ehdr *ehdr_ptr; Elf32_Phdr phdr; u64 phdr_sz = 0, note_off; - struct vm_struct *vm; ehdr_ptr = (Elf32_Ehdr *)elfptr; @@ -628,18 +653,10 @@ static int __init merge_note_headers_elf32(char *elfptr, size_t *elfsz, return rc; *notes_sz = roundup(phdr_sz, PAGE_SIZE); - *notes_buf = vzalloc(*notes_sz); + *notes_buf = alloc_elfnotes_buf(*notes_sz); if (!*notes_buf) return -ENOMEM; - /* - * Allow users to remap ELF note segment buffer on vmalloc memory using - * remap_vmalloc_range() - */ - vm = find_vm_area(*notes_buf); - BUG_ON(!vm); - vm->flags |= VM_USERMAP; - rc = copy_notes_elf32(ehdr_ptr, *notes_buf); if (rc < 0) return rc;