Messages in this thread | | | Date | Tue, 15 Dec 2009 16:27:00 +0800 | Subject | Re: [RFC, PATCH 4/4] elf_core_dump(): Add extended numbering support | From | Américo Wang <> |
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On Tue, Dec 15, 2009 at 10:41 AM, Daisuke HATAYAMA <d.hatayama@jp.fujitsu.com> wrote: > The current ELF dumper implementation can produce broken corefiles > if program headers exceed 65535. This number is determined by the > number of vmas which the process have. In particular, some extreme > programs may use more than 65535 vmas. (If you google max_map_count, > you can find some users facing this problem.) This kind of program > never be able to generate correct coredumps. > > This patch implements ``extended numbering'' that uses sh_info > field of the first section header instead of e_phnum field in order > to represent upto 4294967295 vmas. > > This is supported by AMD64-ABI(http://www.x86-64.org/documentation.html) > and Solaris(http://docs.sun.com/app/docs/doc/817-1984/). Of course, > we are preparing patches for gdb and binutils. > > Signed-off-by: Daisuke HATAYAMA <d.hatayama@jp.fujitsu.com>
Some comments below.
> --- > arch/ia64/kernel/elfcore.c | 16 ++++++++ > arch/um/sys-i386/elfcore.c | 18 +++++++++ > fs/binfmt_elf.c | 88 +++++++++++++++++++++++++++++++++++++++----- > include/linux/elf.h | 26 ++++++++++++- > 4 files changed, 137 insertions(+), 11 deletions(-) > > diff --git a/arch/ia64/kernel/elfcore.c b/arch/ia64/kernel/elfcore.c > index 9c0dd8b..a15d8d4 100644 > --- a/arch/ia64/kernel/elfcore.c > +++ b/arch/ia64/kernel/elfcore.c > @@ -73,3 +73,19 @@ int elf_core_write_extra_data(struct file *file, size_t *size, > } > return 1; > } > + > +size_t elf_core_extra_data_size(void) > +{ > + const struct elf_phdr *const gate_phdrs = > + (const struct elf_phdr *) (GATE_ADDR + GATE_EHDR->e_phoff); > + int i; > + size_t size = 0; > + > + for (i = 0; i < GATE_EHDR->e_phnum; ++i) { > + if (gate_phdrs[i].p_type == PT_LOAD) { > + size += PAGE_ALIGN(gate_phdrs[i].p_memsz); > + break; > + } > + } > + return size; > +} > diff --git a/arch/um/sys-i386/elfcore.c b/arch/um/sys-i386/elfcore.c > index 4e320f0..4e34e47 100644 > --- a/arch/um/sys-i386/elfcore.c > +++ b/arch/um/sys-i386/elfcore.c > @@ -76,3 +76,21 @@ int elf_core_write_extra_data(struct file *file, size_t *size, > } > return 1; > } > + > +size_t elf_core_extra_data_size(void) > +{ > + if ( vsyscall_ehdr ) { > + const struct elfhdr *const ehdrp = > + (struct elfhdr *)vsyscall_ehdr; > + const struct elf_phdr *const phdrp = > + (const struct elf_phdr *) (vsyscall_ehdr + ehdrp->e_phoff); > + int i; > + > + for (i = 0; i < ehdrp->e_phnum; ++i) { > + if (phdrp[i].p_type == PT_LOAD) { > + return (size_t) phdrp[i].p_filesz; > + } > + }
Unnecessary braces.
> + } > + return 0; > +} > diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c > index cded1ba..ad2ad5f 100644 > --- a/fs/binfmt_elf.c > +++ b/fs/binfmt_elf.c > @@ -1895,6 +1895,38 @@ static struct vm_area_struct *next_vma(struct vm_area_struct *this_vma, > return gate_vma; > } > > +static void fill_extnum_info(struct elfhdr *elf, struct elf_shdr *shdr4extnum, > + elf_addr_t e_shoff, int segs) > +{ > + elf->e_shoff = e_shoff; > + elf->e_shentsize = sizeof(*shdr4extnum); > + elf->e_shnum = 1; > + elf->e_shstrndx = SHN_UNDEF; > + > + shdr4extnum->sh_name = 0; > + shdr4extnum->sh_addr = 0; > + shdr4extnum->sh_offset = 0; > + shdr4extnum->sh_type = SHT_NULL; > + shdr4extnum->sh_flags = 0; > + shdr4extnum->sh_size = elf->e_shnum; > + shdr4extnum->sh_link = elf->e_shstrndx; > + shdr4extnum->sh_info = segs; > + shdr4extnum->sh_addralign = 0; > + shdr4extnum->sh_entsize = 0;
Why not kzalloc() the struct and just fill the non-zero values?
<snip>
> @@ -2079,11 +2139,19 @@ static int elf_core_dump(long signr, struct pt_regs *regs, struct file *file, un > if (!elf_core_write_extra_data(file, &size, limit)) > goto end_coredump; > > + if (e_phnum == PN_XNUM) { > + size += sizeof(*shdr4extnum); > + if (size > limit > + || !dump_write(file, shdr4extnum, sizeof(*shdr4extnum))) > + goto end_coredump; > + } > + > end_coredump:
Even without the last 'goto', it will also come here finally. So, that is unnecessary. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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