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Re: [PATCH v2 0/9] kexec_file_load implementation for PowerPC

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Am Donnerstag, 16 Juni 2016, 15:48:30 schrieb Michael Ellerman:
> On Tue, 2016-06-14 at 11:59 -0300, Thiago Jung Bauermann wrote:
> > Hello,
> > 
> > This patch series implements the kexec_file_load system call on PowerPC.
> 
> Can you tell me what this syscall does and why I would want it?

Sorry, should have provided the motivation when I posted the patches.

This system call moves the reading of the kernel, initrd and the device tree 
from the userspace kexec tool to the kernel. This is needed if you want to 
do one or both of the following:

1. only allow loading of signed kernels.
2. "measure" (i.e., record the hashes of) the kernel, initrd, kernel command 
line and other boot inputs for the  Integrity Measurement Architecture 
subsystem.

The above are the functions kexec already has built into kexec_file_load. I 
will soon post a set of patches which will allow a third feature:

3. have IMA pass-on its event log (where integrity measurements are 
registered) accross kexec to the second kernel, so that the event history is 
preserved.

Because OpenPower uses an intermediary Linux instance as a boot loader 
(skiroot), feature 1 is needed to implement secure boot for the platform, 
while features 2 and 3 are needed to implement trusted boot.

There's an LWN article giving more context on the origins of the system 
call, if you are interested:

https://lwn.net/Articles/603116/

-- 
[]'s
Thiago Jung Bauermann
IBM Linux Technology Center

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[PATCH v2 0/9] kexec_file_load implementation for PowerPC Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> - 2016-06-14 17:00 +0200
  [PATCH v2 9/9] powerpc: Add purgatory for kexec_file_load implementation. Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> - 2016-06-14 17:10 +0200
  [PATCH v2 2/9] kexec_file: Generalize kexec_add_buffer. Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> - 2016-06-14 17:10 +0200
    Re: [PATCH v2 2/9] kexec_file: Generalize kexec_add_buffer. Dave Young <dyoung@redhat.com> - 2016-06-15 09:40 +0200
      Re: [PATCH v2 2/9] kexec_file: Generalize kexec_add_buffer. Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> - 2016-06-15 18:30 +0200
        Re: [PATCH v2 2/9] kexec_file: Generalize kexec_add_buffer. Dave Young <dyoung@redhat.com> - 2016-06-16 04:00 +0200
          Re: [PATCH v2 2/9] kexec_file: Generalize kexec_add_buffer. Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> - 2016-06-16 22:40 +0200
            Re: [PATCH v2 2/9] kexec_file: Generalize kexec_add_buffer. Dave Young <dyoung@redhat.com> - 2016-06-17 09:40 +0200
              Re: [PATCH v2 2/9] kexec_file: Generalize kexec_add_buffer. Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> - 2016-06-17 23:00 +0200
                Re: [PATCH v2 2/9] kexec_file: Generalize kexec_add_buffer. Dave Young <dyoung@redhat.com> - 2016-06-20 04:30 +0200
                Re: [PATCH v2 2/9] kexec_file: Generalize kexec_add_buffer. Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> - 2016-06-20 19:50 +0200
  [PATCH v2 8/9] powerpc: Add support for loading ELF kernels with kexec_file_load. Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> - 2016-06-14 17:10 +0200
  [PATCH v2 6/9] powerpc: Add functions to read ELF files of any endianness. Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> - 2016-06-14 17:10 +0200
  [PATCH v2 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer. Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> - 2016-06-14 17:10 +0200
  [PATCH v2 7/9] powerpc: Implement kexec_file_load. Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> - 2016-06-14 17:10 +0200
  [PATCH v2 5/9] powerpc: Generalize elf64_apply_relocate_add. Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> - 2016-06-14 17:10 +0200
  [PATCH v2 4/9] powerpc: Factor out relocation code from module_64.c to elf_util_64.c. Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> - 2016-06-14 17:10 +0200
  Re: [PATCH v2 0/9] kexec_file_load implementation for PowerPC Michael Ellerman <mpe@ellerman.id.au> - 2016-06-16 07:50 +0200
    Re: [PATCH v2 0/9] kexec_file_load implementation for PowerPC Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> - 2016-06-16 22:00 +0200

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