On Mon, Jul 01, 2013 at 09:32:35PM +0200, Michael Holzheu wrote: > Currently for s390 we create the ELF core header in the 2nd kernel > with a small trick. We relocate the addresses in the ELF header in > a way that for the /proc/vmcore code it seems to be in the 1st kernel > (old) memory and the read_from_oldmem() returns the correct data. > This allows the /proc/vmcore code to use the ELF header in the > 2nd kernel. > > This patch now exchanges the old mechanism with the new and much > cleaner function call override feature that now offcially allows to > create the ELF core header in the 2nd kernel. > > To use the new feature the following function have to be defined > by the architecture backend code to read from new memory: > > * elfcorehdr_alloc: Allocate ELF header > * elfcorehdr_free: Free the memory of the ELF header > * elfcorehdr_read: Read from ELF header > * elfcorehdr_read_notes: Read from ELF notes > > Signed-off-by: Michael Holzheu <[email protected]>
Looks good to me. Acked-by: Vivek Goyal <[email protected]> Vivek > --- > fs/proc/vmcore.c | 61 > ++++++++++++++++++++++++++++++++++++++-------- > include/linux/crash_dump.h | 6 +++++ > 2 files changed, 57 insertions(+), 10 deletions(-) > > diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c > index 0f6db52..c28189c 100644 > --- a/fs/proc/vmcore.c > +++ b/fs/proc/vmcore.c > @@ -123,6 +123,36 @@ static ssize_t read_from_oldmem(char *buf, size_t count, > return read; > } > > +/* > + * Architectures may override this function to allocate ELF header in 2nd > kernel > + */ > +int __weak elfcorehdr_alloc(unsigned long long *addr, unsigned long long > *size) > +{ > + return 0; > +} > + > +/* > + * Architectures may override this function to free header > + */ > +void __weak elfcorehdr_free(unsigned long long addr) > +{} > + > +/* > + * Architectures may override this function to read from ELF header > + */ > +ssize_t __weak elfcorehdr_read(char *buf, size_t count, u64 *ppos) > +{ > + return read_from_oldmem(buf, count, ppos, 0); > +} > + > +/* > + * Architectures may override this function to read from notes sections > + */ > +ssize_t __weak elfcorehdr_read_notes(char *buf, size_t count, u64 *ppos) > +{ > + return read_from_oldmem(buf, count, ppos, 0); > +} > + > /* Read from the ELF header and then the crash dump. On error, negative > value is > * returned otherwise number of bytes read are returned. > */ > @@ -322,7 +352,7 @@ static int __init update_note_header_size_elf64(const > Elf64_Ehdr *ehdr_ptr) > notes_section = kmalloc(max_sz, GFP_KERNEL); > if (!notes_section) > return -ENOMEM; > - rc = read_from_oldmem(notes_section, max_sz, &offset, 0); > + rc = elfcorehdr_read_notes(notes_section, max_sz, &offset); > if (rc < 0) { > kfree(notes_section); > return rc; > @@ -409,7 +439,8 @@ static int __init copy_notes_elf64(const Elf64_Ehdr > *ehdr_ptr, char *notes_buf) > if (phdr_ptr->p_type != PT_NOTE) > continue; > offset = phdr_ptr->p_offset; > - rc = read_from_oldmem(notes_buf, phdr_ptr->p_memsz, &offset, 0); > + rc = elfcorehdr_read_notes(notes_buf, phdr_ptr->p_memsz, > + &offset); > if (rc < 0) > return rc; > notes_buf += phdr_ptr->p_memsz; > @@ -510,7 +541,7 @@ static int __init update_note_header_size_elf32(const > Elf32_Ehdr *ehdr_ptr) > notes_section = kmalloc(max_sz, GFP_KERNEL); > if (!notes_section) > return -ENOMEM; > - rc = read_from_oldmem(notes_section, max_sz, &offset, 0); > + rc = elfcorehdr_read_notes(notes_section, max_sz, &offset); > if (rc < 0) { > kfree(notes_section); > return rc; > @@ -597,7 +628,8 @@ static int __init copy_notes_elf32(const Elf32_Ehdr > *ehdr_ptr, char *notes_buf) > if (phdr_ptr->p_type != PT_NOTE) > continue; > offset = phdr_ptr->p_offset; > - rc = read_from_oldmem(notes_buf, phdr_ptr->p_memsz, &offset, 0); > + rc = elfcorehdr_read_notes(notes_buf, phdr_ptr->p_memsz, > + &offset); > if (rc < 0) > return rc; > notes_buf += phdr_ptr->p_memsz; > @@ -793,7 +825,7 @@ static int __init parse_crash_elf64_headers(void) > addr = elfcorehdr_addr; > > /* Read Elf header */ > - rc = read_from_oldmem((char*)&ehdr, sizeof(Elf64_Ehdr), &addr, 0); > + rc = elfcorehdr_read((char *)&ehdr, sizeof(Elf64_Ehdr), &addr); > if (rc < 0) > return rc; > > @@ -820,7 +852,7 @@ static int __init parse_crash_elf64_headers(void) > if (!elfcorebuf) > return -ENOMEM; > addr = elfcorehdr_addr; > - rc = read_from_oldmem(elfcorebuf, elfcorebuf_sz_orig, &addr, 0); > + rc = elfcorehdr_read(elfcorebuf, elfcorebuf_sz_orig, &addr); > if (rc < 0) > goto fail; > > @@ -849,7 +881,7 @@ static int __init parse_crash_elf32_headers(void) > addr = elfcorehdr_addr; > > /* Read Elf header */ > - rc = read_from_oldmem((char*)&ehdr, sizeof(Elf32_Ehdr), &addr, 0); > + rc = elfcorehdr_read((char *)&ehdr, sizeof(Elf32_Ehdr), &addr); > if (rc < 0) > return rc; > > @@ -875,7 +907,7 @@ static int __init parse_crash_elf32_headers(void) > if (!elfcorebuf) > return -ENOMEM; > addr = elfcorehdr_addr; > - rc = read_from_oldmem(elfcorebuf, elfcorebuf_sz_orig, &addr, 0); > + rc = elfcorehdr_read(elfcorebuf, elfcorebuf_sz_orig, &addr); > if (rc < 0) > goto fail; > > @@ -902,7 +934,7 @@ static int __init parse_crash_elf_headers(void) > int rc=0; > > addr = elfcorehdr_addr; > - rc = read_from_oldmem(e_ident, EI_NIDENT, &addr, 0); > + rc = elfcorehdr_read(e_ident, EI_NIDENT, &addr); > if (rc < 0) > return rc; > if (memcmp(e_ident, ELFMAG, SELFMAG) != 0) { > @@ -935,7 +967,14 @@ static int __init vmcore_init(void) > { > int rc = 0; > > - /* If elfcorehdr= has been passed in cmdline, then capture the dump.*/ > + /* Allow architectures to allocate ELF header in 2nd kernel */ > + rc = elfcorehdr_alloc(&elfcorehdr_addr, &elfcorehdr_size); > + if (rc) > + return rc; > + /* > + * If elfcorehdr= has been passed in cmdline or created in 2nd kernel, > + * then capture the dump. > + */ > if (!(is_vmcore_usable())) > return rc; > rc = parse_crash_elf_headers(); > @@ -943,6 +982,8 @@ static int __init vmcore_init(void) > pr_warn("Kdump: vmcore not initialized\n"); > return rc; > } > + elfcorehdr_free(elfcorehdr_addr); > + elfcorehdr_addr = ELFCORE_ADDR_ERR; > > proc_vmcore = proc_create("vmcore", S_IRUSR, NULL, > &proc_vmcore_operations); > if (proc_vmcore) > diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h > index 37e4f8d..6571f82 100644 > --- a/include/linux/crash_dump.h > +++ b/include/linux/crash_dump.h > @@ -12,6 +12,12 @@ > extern unsigned long long elfcorehdr_addr; > extern unsigned long long elfcorehdr_size; > > +extern int __weak elfcorehdr_alloc(unsigned long long *addr, > + unsigned long long *size); > +extern void __weak elfcorehdr_free(unsigned long long addr); > +extern ssize_t __weak elfcorehdr_read(char *buf, size_t count, u64 *ppos); > +extern ssize_t __weak elfcorehdr_read_notes(char *buf, size_t count, u64 > *ppos); > + > extern ssize_t copy_oldmem_page(unsigned long, char *, size_t, > unsigned long, int); > > -- > 1.8.2.2 -- 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/
