Messages in this thread | | | Date | Wed, 4 Mar 2015 21:22:27 +0100 | From | Ingo Molnar <> | Subject | Re: [GIT PULL] x86/alternatives padding |
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* Borislav Petkov <bp@alien8.de> wrote:
> On Wed, Mar 04, 2015 at 12:22:06PM +0100, Borislav Petkov wrote: > > Well, kernel image doesn't change while vmlinux shows only a very small > > .text increase of about 2K. I'm not sure yet why that happens though > > because it shouldn't be the padding. Because we will have to do it > > anyway, this patchset makes it automatic instead of by-hand, so to > > speak. > > > > Let me bisect it and see which patch adds the increase. > > Doh, of course. I've added u8 padlen to the alternative instruction > entry struct. For 2Kish alt sites in total, this explains the almost > exact same increase in text size: > > text data bss dec hex filename > 12290539 1595264 1085440 14971243 e4716b vmlinux > > 338ea55579d1... x86/lib/copy_user_64.S: Remove FIX_ALIGNMENT define > text data bss dec hex filename > 12290539 1595264 1085440 14971243 e4716b vmlinux > > db477a3386de... x86/alternatives: Cleanup DPRINTK macro > text data bss dec hex filename > 12290539 1595264 1085440 14971243 e4716b vmlinux > > 4332195c5615... x86/alternatives: Add instruction padding > text data bss dec hex filename > 12293030 1595264 1085440 14973734 e47b26 vmlinux > ^^^^^^^
So you could have a look at the detailed section dump itself via:
objdump -h vmlinux
there .text will be the raw text and .alt* will be listed separately. The 'size' tool will add up executable sections IIRC, mixing these sections.
.alt* is freed after init, so it's not really a kernel image size increase, right?
Thanks,
Ingo
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