On 06/10/2013 04:52 PM, HATAYAMA Daisuke wrote: > Hello, > > This patch fixes the issue reported by Amd on an overlook of no-MMU > configuration. > > This patch is made on top of v3.10-rc4-mmotm-2013-06-06-16-19. > > I tested this on x86_64 and x86 with 1GB and 5GB memory. > > I build this on arm without CONFIG_MMU configuration. > > Thanks. > HATAYAMA, Daisuke > >>From e2f067a497872a9c60002c56ea550e4600072166 Mon Sep 17 00:00:00 2001 > From: HATAYAMA Daisuke <[email protected]> > Date: Sat, 8 Jun 2013 20:46:57 +0900 > Subject: [PATCH] vmcore: disable mmap_vmcore() if CONFIG_MMU is not defined > >>From Amd'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()
Yeah, I think this change makes code more clear by hiding vmcore-irrelevant details. > 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(). > > Reported-by: Amd Bergmann <[email protected]> > Signed-off-by: HATAYAMA Daisuke <[email protected]> > --- > fs/proc/vmcore.c | 57 +++++++++++++++++++++++++++++++++++------------------ > 1 files changed, 37 insertions(+), 20 deletions(-) > > diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c > index 0f6db52..2850317 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; -- Thanks. Zhang Yanfei -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
