On Mon, Jan 27, 2014 at 01:57:50PM -0500, Vivek Goyal wrote: > This patch provides support for kexec for loading ELF x86_64 images. I have > tested it with loading vmlinux and it worked.
Can you please enlighten me what the use case for ELF kernel images is? bzImage I understand but what produces ELF images? I see that kexec_file_load() can receive ELF segments too but why are we doing that? > Signed-off-by: Vivek Goyal <[email protected]> > --- > arch/x86/include/asm/kexec-elf.h | 11 ++ > arch/x86/kernel/Makefile | 1 + > arch/x86/kernel/kexec-elf.c | 231 > +++++++++++++++++++++++++++++++++++++ > arch/x86/kernel/machine_kexec_64.c | 2 + > 4 files changed, 245 insertions(+) > create mode 100644 arch/x86/include/asm/kexec-elf.h > create mode 100644 arch/x86/kernel/kexec-elf.c > > diff --git a/arch/x86/include/asm/kexec-elf.h > b/arch/x86/include/asm/kexec-elf.h > new file mode 100644 > index 0000000..afef382 > --- /dev/null > +++ b/arch/x86/include/asm/kexec-elf.h > @@ -0,0 +1,11 @@ > +#ifndef _ASM_KEXEC_ELF_H > +#define _ASM_KEXEC_ELF_H > + > +extern int elf_x86_64_probe(const char *buf, unsigned long len); > +extern void *elf_x86_64_load(struct kimage *image, char *kernel, > + unsigned long kernel_len, char *initrd, > + unsigned long initrd_len, char *cmdline, > + unsigned long cmdline_len); > +extern int elf_x86_64_cleanup(struct kimage *image); > + > +#endif /* _ASM_KEXEC_ELF_H */ > diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile > index fa9981d..2d77de7 100644 > --- a/arch/x86/kernel/Makefile > +++ b/arch/x86/kernel/Makefile > @@ -71,6 +71,7 @@ obj-$(CONFIG_KEXEC) += machine_kexec.o > obj-$(CONFIG_KEXEC) += machine_kexec_$(BITS).o > obj-$(CONFIG_KEXEC) += relocate_kernel_$(BITS).o crash.o > obj-$(CONFIG_KEXEC) += kexec-bzimage.o > +obj-$(CONFIG_KEXEC) += kexec-elf.o It looks like kexec could slowly grow its own dir now: arch/x86/kexec/ or so. > obj-$(CONFIG_CRASH_DUMP) += crash_dump_$(BITS).o > obj-y += kprobes/ > obj-$(CONFIG_MODULES) += module.o > diff --git a/arch/x86/kernel/kexec-elf.c b/arch/x86/kernel/kexec-elf.c > new file mode 100644 > index 0000000..ff1017c > --- /dev/null > +++ b/arch/x86/kernel/kexec-elf.c > @@ -0,0 +1,231 @@ > +#include <linux/string.h> > +#include <linux/printk.h> > +#include <linux/errno.h> > +#include <linux/slab.h> > +#include <linux/kexec.h> > +#include <linux/kernel.h> > +#include <linux/mm.h> > + > +#include <asm/bootparam.h> > +#include <asm/setup.h> > + > +#ifdef CONFIG_X86_64 > + > +struct elf_x86_64_data { > + /* > + * Temporary buffer to hold bootparams buffer. This should be > + * freed once the bootparam segment has been loaded. > + */ > + void *bootparams_buf; > +}; > + > +int elf_x86_64_probe(const char *buf, unsigned long len) > +{ > + int ret = -ENOEXEC; > + Elf_Ehdr *ehdr; > + > + if (len < sizeof(Elf_Ehdr)) { > + pr_debug("File is too short to be an ELF executable.\n"); > + return ret; > + } > + > + ehdr = (Elf_Ehdr *)buf; > + > + if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG) != 0 > + || ehdr->e_type != ET_EXEC || !elf_check_arch(ehdr) > + || ehdr->e_phentsize != sizeof(Elf_Phdr)) > + return -ENOEXEC; > + > + if (ehdr->e_phoff >= len > + || (ehdr->e_phnum * sizeof(Elf_Phdr) > len - ehdr->e_phoff)) > + return -ENOEXEC; > + > + /* I've got a bzImage */ > + pr_debug("It's an elf_x86_64 image.\n"); > + ret = 0; > + > + return ret; I think you can drop 'ret' here and return the error vals directly. > +} > + > +static int elf_exec_load(struct kimage *image, char *kernel) > +{ > + Elf_Ehdr *ehdr; > + Elf_Phdr *phdrs; > + int i, ret; > + size_t filesz; > + char *buffer; > + > + ehdr = (Elf_Ehdr *)kernel; > + phdrs = (void *)ehdr + ehdr->e_phoff; > + > + for (i = 0; i < ehdr->e_phnum; i++) { > + if (phdrs[i].p_type != PT_LOAD) > + continue; newline > + filesz = phdrs[i].p_filesz; > + if (filesz > phdrs[i].p_memsz) > + filesz = phdrs[i].p_memsz; > + > + buffer = (char *)ehdr + phdrs[i].p_offset; > + ret = kexec_add_segment(image, buffer, filesz, phdrs[i].p_memsz, > + phdrs[i].p_paddr); > + if (ret) > + break; > + } > + > + return ret; > +} > + > +/* Fill in fields which are usually present in bzImage */ > +static int init_linux_parameters(struct boot_params *params) > +{ > + /* > + * FIXME: It is odd that the information which comes from kernel > + * has to be faked by loading kernel. I guess it is limitation of > + * ELF format. Right now keeping it same as kexec-tools > + * implementation. But this most likely needs fixing. > + */ > + memcpy(¶ms->hdr.header, "HdrS", 4); > + params->hdr.version = 0x0206; > + params->hdr.initrd_addr_max = 0x37FFFFFF; > + params->hdr.cmdline_size = 2048; > + return 0; > +} Why a separate function? Its body is small enough to be merged into elf_x86_64_load. > + > +void *elf_x86_64_load(struct kimage *image, char *kernel, > + unsigned long kernel_len, > + char *initrd, unsigned long initrd_len, > + char *cmdline, unsigned long cmdline_len) > +{ Btw, this functionality below looks very similar to the one in bzImage64_load(). Can we share some of it? -- Regards/Gruss, Boris. Sent from a fat crate under my desk. Formatting is fine. -- _______________________________________________ kexec mailing list [email protected] http://lists.infradead.org/mailman/listinfo/kexec
