Objects exported from ELF note segments are in fact located apart from each other on old memory. But on /proc/vmcore they are exported as a single ELF note segment. To satisfy mmap()'s page-size boundary requirement, copy them in a page-size aligned buffer allocated by __get_free_pages() on 2nd kernel and remap the buffer to user-space.
The buffer for ELF note segments is added to vmcore_list as the object of VMCORE_2ND_KERNEL type. Copy of ELF note segments is done in two pass: first pass tries to calculate real total size of ELF note segments, and then 2nd pass copies the segment data into the buffer of the real total size. Signed-off-by: HATAYAMA Daisuke <[email protected]> --- fs/proc/vmcore.c | 78 +++++++++++++++++++++++++++++++++++++++++------------- 1 files changed, 59 insertions(+), 19 deletions(-) diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c index 3aedb52..ccf0dc5 100644 --- a/fs/proc/vmcore.c +++ b/fs/proc/vmcore.c @@ -230,27 +230,25 @@ static u64 __init get_vmcore_size_elf32(char *elfptr) return size; } -/* Merges all the PT_NOTE headers into one. */ -static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz, - struct list_head *vc_list) +static int __init parse_note_segments_elf64(char *elfptr, int *nr_ptnote, + u64 *phdr_sz, char *notebuf) { - int i, nr_ptnote=0, rc=0; - char *tmp; + int i, rc=0; + loff_t notebuf_off = 0; Elf64_Ehdr *ehdr_ptr; - Elf64_Phdr phdr, *phdr_ptr; Elf64_Nhdr *nhdr_ptr; - u64 phdr_sz = 0, note_off; + Elf64_Phdr *phdr_ptr; ehdr_ptr = (Elf64_Ehdr *)elfptr; phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr)); for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) { int j; void *notes_section; - struct vmcore *new; u64 offset, max_sz, sz, real_sz = 0; if (phdr_ptr->p_type != PT_NOTE) continue; - nr_ptnote++; + if (nr_ptnote) + *nr_ptnote = *nr_ptnote + 1; max_sz = phdr_ptr->p_memsz; offset = phdr_ptr->p_offset; notes_section = kmalloc(max_sz, GFP_KERNEL); @@ -271,20 +269,51 @@ static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz, real_sz += sz; nhdr_ptr = (Elf64_Nhdr*)((char*)nhdr_ptr + sz); } - - /* Add this contiguous chunk of notes section to vmcore list.*/ - new = get_new_element(); - if (!new) { - kfree(notes_section); - return -ENOMEM; + if (phdr_sz) + *phdr_sz += real_sz; + if (notebuf) { + memcpy(notebuf + notebuf_off, notes_section, real_sz); + notebuf_off += real_sz; } - new->paddr = phdr_ptr->p_offset; - new->size = real_sz; - list_add_tail(&new->list, vc_list); - phdr_sz += real_sz; kfree(notes_section); } + return 0; +} + +/* Merges all the PT_NOTE headers into one. */ +static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz, + struct list_head *vc_list) +{ + int i, nr_ptnote, rc=0; + char *tmp, *notebuf; + Elf64_Ehdr *ehdr_ptr; + Elf64_Phdr phdr; + u64 phdr_sz, note_off, notebuf_sz; + struct vmcore *new; + + ehdr_ptr = (Elf64_Ehdr *)elfptr; + + /* The 1st pass calculates real size of ELF note segments. */ + nr_ptnote = 0; + phdr_sz = 0; + rc = parse_note_segments_elf64(elfptr, &nr_ptnote, &phdr_sz, NULL); + if (rc < 0) + return rc; + + /* The 2nd pass copies the ELF note segments into the buffer + * of the exact size. */ + notebuf_sz = roundup(phdr_sz, PAGE_SIZE); + notebuf = (char *) __get_free_pages(GFP_KERNEL | __GFP_ZERO, + get_order(notebuf_sz)); + if (!notebuf) + return -ENOMEM; + rc = parse_note_segments_elf64(elfptr, NULL, NULL, notebuf); + if (rc < 0) { + free_pages((unsigned long)notebuf, get_order(notebuf_sz)); + return rc; + } + /* Prepare merged PT_NOTE program header. */ phdr.p_type = PT_NOTE; phdr.p_flags = 0; @@ -315,6 +344,17 @@ static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz, *elfsz = roundup(*elfsz, PAGE_SIZE); + /* Add the merged unique ELF note segments in vmcore_list. */ + new = get_new_element(); + if (!new) { + free_pages((unsigned long)notebuf, get_order(notebuf_sz)); + return -ENOMEM; + } + new->type = VMCORE_2ND_KERNEL; + new->buf = notebuf; + new->size = notebuf_sz; + list_add_tail(&new->list, vc_list); + return 0; } -- 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/
