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Re: [PATCH v5 07/21] x86, boot: Fix run_size calculation

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* Kees Cook <keescook@chromium.org> wrote:

> From: Yinghai Lu <yinghai@kernel.org>
> 
> Currently, the kernel run_size (size of code plus brk and bss) is
> calculated via the shell script arch/x86/tools/calc_run_size.sh.
> It gets the file offset and mem size of for the .bss and .brk sections in 
> vmlinux, and adds them as follows:

'of for'?

> So, from this we can see that the existing run_size calculation is
> 0x400000 too high. 

Btw., why is it too high? Were some sections discarded?

> [...] And, as it turns out, the correct run_size is
> actually equal to VO_end - VO_text, which is certainly easier to calculate.
> _end: 0xffffffff8205f000
> _text:0xffffffff81000000
> 
> 0xffffffff8205f000 - 0xffffffff81000000 = 0x105f000
> 
> As a result, run_size is a simple constant, so we don't need to pass it
> around; we already have voffset.h such things.

(Typo.)

> [...] We can share voffset.h
> between misc.c and header.S instead of getting run_size in other ways.
> This patch moves voffset.h creation code to boot/compressed/Makefile,
> and switches misc.c to use the VO_end - VO_text calculation.

Btw., 'run_size' is a pretty meaningless name, it doesn't really tell us the most 
important thing: that this is the complete size of the uncompressed kernel, the 
total physically continuous size we need to allocate to it so it can execute?

So can we rename it to something more expressive, such as kernel_total_size or so?

Thanks,

	Ingo

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[PATCH v5 00/21] x86, boot: KASLR cleanup and 64-bit improvements Kees Cook <keescook@chromium.org> - 2016-04-15 00:30 +0200
  [PATCH v5 05/21] x86, boot: Calculate decompression size during boot not build Kees Cook <keescook@chromium.org> - 2016-04-15 00:30 +0200
    Re: [PATCH v5 05/21] x86, boot: Calculate decompression size during  boot not build Ingo Molnar <mingo@kernel.org> - 2016-04-15 10:20 +0200
      Re: [PATCH v5 05/21] x86, boot: Calculate decompression size during  boot not build Kees Cook <keescook@chromium.org> - 2016-04-15 21:20 +0200
  [PATCH v5 21/21] x86, KASLR: Allow randomization below load address Kees Cook <keescook@chromium.org> - 2016-04-15 00:30 +0200
  [PATCH v5 09/21] x86, KASLR: Correctly bounds-check relocations Kees Cook <keescook@chromium.org> - 2016-04-15 00:40 +0200
  [PATCH v5 20/21] x86, KASLR: Remove unused slot tracking code Kees Cook <keescook@chromium.org> - 2016-04-15 00:40 +0200
  [PATCH v5 01/21] x86, KASLR: Remove unneeded boot_params argument Kees Cook <keescook@chromium.org> - 2016-04-15 00:40 +0200
    Re: [PATCH v5 01/21] x86, KASLR: Remove unneeded boot_params argument Ingo Molnar <mingo@kernel.org> - 2016-04-15 09:30 +0200
      Re: [PATCH v5 01/21] x86, KASLR: Remove unneeded boot_params argument Kees Cook <keescook@chromium.org> - 2016-04-15 21:00 +0200
  [PATCH v5 19/21] x86, KASLR: Add physical address randomization >4G Kees Cook <keescook@chromium.org> - 2016-04-15 00:40 +0200
  [PATCH v5 13/21] x86, boot: Report overlap failures in memcpy Kees Cook <keescook@chromium.org> - 2016-04-15 00:40 +0200
    Re: [PATCH v5 13/21] x86, boot: Report overlap failures in memcpy Lasse Collin <lasse.collin@tukaani.org> - 2016-04-15 17:00 +0200
      Re: [PATCH v5 13/21] x86, boot: Report overlap failures in memcpy Kees Cook <keescook@chromium.org> - 2016-04-15 21:30 +0200
  [PATCH v5 02/21] x86, KASLR: Handle kernel relocation above 2G Kees Cook <keescook@chromium.org> - 2016-04-15 00:40 +0200
    Re: [PATCH v5 02/21] x86, KASLR: Handle kernel relocation above 2G Ingo Molnar <mingo@kernel.org> - 2016-04-15 09:50 +0200
      Re: [PATCH v5 02/21] x86, KASLR: Handle kernel relocation above 2G Kees Cook <keescook@chromium.org> - 2016-04-15 21:10 +0200
  [PATCH v5 16/21] x86, KASLR: Add virtual address choosing function Kees Cook <keescook@chromium.org> - 2016-04-15 00:40 +0200
  [PATCH v5 15/21] x86, KASLR: Add slot_area support functions Kees Cook <keescook@chromium.org> - 2016-04-15 00:40 +0200
  [PATCH v5 04/21] x86, boot: Move compressed kernel to end of decompression buffer Kees Cook <keescook@chromium.org> - 2016-04-15 00:40 +0200
    Re: [PATCH v5 04/21] x86, boot: Move compressed kernel to end of  decompression buffer Ingo Molnar <mingo@kernel.org> - 2016-04-15 10:20 +0200
      Re: [PATCH v5 04/21] x86, boot: Move compressed kernel to end of  decompression buffer Kees Cook <keescook@chromium.org> - 2016-04-18 19:00 +0200
    Re: [PATCH v5 04/21] x86, boot: Move compressed kernel to end of  decompression buffer Ingo Molnar <mingo@kernel.org> - 2016-04-15 11:10 +0200
  [PATCH v5 12/21] x86, 64bit: Set ident_mapping for KASLR Kees Cook <keescook@chromium.org> - 2016-04-15 00:40 +0200
  [PATCH v5 08/21] x86, KASLR: Clean up unused code from old run_size Kees Cook <keescook@chromium.org> - 2016-04-15 00:40 +0200
  [PATCH v5 14/21] x86, KASLR: Add slot_area to manage random slots Kees Cook <keescook@chromium.org> - 2016-04-15 00:40 +0200
  [PATCH v5 17/21] x86, KASLR: Clarify purpose of each get_random_long Kees Cook <keescook@chromium.org> - 2016-04-15 00:40 +0200
  [PATCH v5 11/21] x86, boot: Split out kernel_ident_mapping_init Kees Cook <keescook@chromium.org> - 2016-04-15 00:40 +0200
  [PATCH v5 10/21] x86, KASLR: Consolidate mem_avoid entries Kees Cook <keescook@chromium.org> - 2016-04-15 00:40 +0200
  [PATCH v5 03/21] x86, KASLR: Drop CONFIG_RANDOMIZE_BASE_MAX_OFFSET Kees Cook <keescook@chromium.org> - 2016-04-15 00:40 +0200
    Re: [PATCH v5 03/21] x86, KASLR: Drop  CONFIG_RANDOMIZE_BASE_MAX_OFFSET Ingo Molnar <mingo@kernel.org> - 2016-04-15 10:10 +0200
      Re: [PATCH v5 03/21] x86, KASLR: Drop CONFIG_RANDOMIZE_BASE_MAX_OFFSET Kees Cook <keescook@chromium.org> - 2016-04-15 21:20 +0200
        Re: [PATCH v5 03/21] x86, KASLR: Drop  CONFIG_RANDOMIZE_BASE_MAX_OFFSET Ingo Molnar <mingo@kernel.org> - 2016-04-16 10:50 +0200
  [PATCH v5 06/21] x86, KASLR: Update description for decompressor worst case size Kees Cook <keescook@chromium.org> - 2016-04-15 00:40 +0200
    Re: [PATCH v5 06/21] x86, KASLR: Update description for  decompressor worst case size Lasse Collin <lasse.collin@tukaani.org> - 2016-04-15 18:20 +0200
  [PATCH v5 07/21] x86, boot: Fix run_size calculation Kees Cook <keescook@chromium.org> - 2016-04-15 00:40 +0200
    Re: [PATCH v5 07/21] x86, boot: Fix run_size calculation Ingo Molnar <mingo@kernel.org> - 2016-04-15 10:40 +0200
      Re: [PATCH v5 07/21] x86, boot: Fix run_size calculation Kees Cook <keescook@chromium.org> - 2016-04-15 21:30 +0200
        Re: [PATCH v5 07/21] x86, boot: Fix run_size calculation Ingo Molnar <mingo@kernel.org> - 2016-04-16 11:10 +0200

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