Messages in this thread | | | Date | Fri, 10 Mar 2017 09:24:18 -0500 | From | Vivek Goyal <> | Subject | Re: kexec, x86/purgatory: Cleanup the unholy mess |
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On Fri, Mar 10, 2017 at 02:57:38PM +0100, Thomas Gleixner wrote: > On Fri, 10 Mar 2017, Mike Galbraith wrote: > > On Fri, 2017-03-10 at 13:17 +0100, Thomas Gleixner wrote: > > > The purgatory code defines global variables which are referenced via a > > > symbol lookup in the kexec code (core and arch). > > > > > > A recent commit addressing sparse warning made these static and thereby > > > broke kexec file. > > > > > > Why did this happen? Simply because the whole machinery is undocumented and > > > lacks any form of forward declarations. The variable names are unspecific > > > and lack a prefix, so adding forward declarations creates shadow variables > > > in the core code. Aside of that the code relies on magic constants and > > > duplicate struct definitions with no way to ensure that these things stay > > > in sync. > > > > > > Unbreak kexec and cleanup the mess by: > > > > > > - Adding proper forward declarations and document the usage > > > - Use the proper common defines instead of magic constants > > > - Add a purgatory_ prefix to have a proper name space > > > - Use ARRAY_SIZE() instead of a homebrewn reimplementation > > > > > > Fixes: 72042a8c7b01 ("x86/purgatory: Make functions and variables static") > > > > Well, almost fixes. > > > > [ 15.118820] kexec: symbol 'purgatory_sha_regions' in common section > > [ 15.119187] kexec-bzImage64: Loading purgatory failed > > Bah. /me goes to investigate.
I think we probably will have to initialize these global variables in purgatory itself and that puts them in .data section and relocation works.
That's how the code was intially. I initialized value of purgatory_sha256_digest in the code and then did "readelf -a purgatory.o" and symbol section index changed from COM to 3.
13: 0000000000000000 32 OBJECT GLOBAL DEFAULT 3 purgatory_sha256_digest
[ 3] .data PROGBITS 0000000000000000 00000120 0000000000000020 0000000000000000 WA 0 0 32
Thanks Vivek
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