Messages in this thread | | | Subject | Re: [PATCH v3 01/23] x86/elf: Check in_x32_syscall() in compat_arch_setup_additional_pages() | From | Dmitry Safonov <> | Date | Mon, 21 Jun 2021 21:59:59 +0100 |
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Hi Thomas,
On 6/19/21 9:41 PM, Thomas Gleixner wrote: > On Fri, Jun 11 2021 at 19:02, Dmitry Safonov wrote: >> Partly revert commit 3316ec8ccd34 ("x86/elf: Use e_machine to check for >> x32/ia32 in setup_additional_pages()") and commit 9a29a671902c ("elf: >> Expose ELF header on arch_setup_additional_pages()". >> Both patches did a good thing: removed usage of TIF_X32, but with >> a price of additional macros ARCH_SETUP_ADDITIONAL_PAGES() and ifdeffs. >> >> Instead, use in_x32_syscall() - the first thing load_elf_binary() does >> after parsing and checking new ELF binary. It's done that early after >> exec() that mmap() code already uses it straight away, which is needed >> to know which mmap_base to use (see arch_pick_mmap_layout()). >> Add comments to describe how it works. > > I still have no idea what this is trying to solve. All you describe is > what this does.
Yeah, I still have problems with describing why rather than what sometimes..
How about something like this:
In order to simplify code, new macro ARCH_SETUP_ADDITIONAL_PAGES() can be dropped as well as a new argument in compat_arch_setup_additional_pages(). Resulting in partial revert of the commit 3316ec8ccd34 ("x86/elf: Use e_machine to check for x32/ia32 in setup_additional_pages()") and the commit 9a29a671902c ("elf: Expose ELF header on arch_setup_additional_pages()".
Instead of a new macro and an additional function argument, use in_x32_syscall() which is already valid at the moment of premapping vDSO. Add comments to describe how it works.
Thanks for reviewing, Dmitry
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