Messages in this thread | | | From | Arvind Sankar <> | Date | Tue, 18 Feb 2020 13:03:54 -0500 | Subject | Re: [PATCH 1/2] x86/boot/compressed/64: Remove .bss/.pgtable from bzImage |
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On Wed, Feb 05, 2020 at 11:29:21AM -0500, Arvind Sankar wrote: > On Thu, Jan 09, 2020 at 10:02:17AM -0500, Arvind Sankar wrote: > > Commit 5b11f1cee579 ("x86, boot: straighten out ranges to copy/zero in > > compressed/head*.S") introduced a separate .pgtable section, splitting > > it out from the rest of .bss. This section was added without the > > writeable flag, marking it as read-only. This results in the linker > > putting the .rela.dyn section (containing bogus dynamic relocations from > > head_64.o) after the .bss and .pgtable sections. > > > > When we use objcopy to convert compressed/vmlinux into a binary for the > > bzImage, the .bss and .pgtable sections get materialized as ~176KiB of > > zero bytes in the binary in order to place .rela.dyn at the correct > > location. > > > > Fix this by marking .pgtable as writeable. This moves the .rela.dyn > > section earlier so that .bss and .pgtable are the last allocated > > sections and so don't appear in bzImage. > > > > Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> > > --- > > arch/x86/boot/compressed/head_64.S | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S > > index 58a512e33d8d..6eb30f8a3ce7 100644 > > --- a/arch/x86/boot/compressed/head_64.S > > +++ b/arch/x86/boot/compressed/head_64.S > > @@ -709,7 +709,7 @@ SYM_DATA_END_LABEL(boot_stack, SYM_L_LOCAL, boot_stack_end) > > /* > > * Space for page tables (not in .bss so not zeroed) > > */ > > - .section ".pgtable","a",@nobits > > + .section ".pgtable","aw",@nobits > > .balign 4096 > > SYM_DATA_LOCAL(pgtable, .fill BOOT_PGT_SIZE, 1, 0) > > > > -- > > 2.24.1 > > > > Gentle reminder. > > https://lore.kernel.org/lkml/20200109150218.16544-1-nivedita@alum.mit.edu
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