Commit d9dedc13 authored Apr 27, 2008 by Roland McGrath Committed by Linus Torvalds Apr 28, 2008

x86_64 vDSO: use initdata



The 64-bit vDSO image is in a special ".vdso" section for no reason
I can determine.  Furthermore, the location of the vdso_end symbol
includes some wrongly-calculated padding space in the image, which
is then (correctly) rounded to page size, resulting in an extra page
of zeros in the image mapped in to user processes.

This changes it to put the vdso.so image into normal initdata as we
have always done for the 32-bit vDSO images.  The extra padding is
gone, so the user VMA is one page instead of two.  The image that
was already copied around at boot time is now in initdata, so we
recover that wasted space after boot.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 7f6c69dc

arch/x86/kernel/vmlinux_64.lds.S

+0 −6

Original line number	Diff line number	Diff line
		@@ -209,12 +209,6 @@ SECTIONS
		EXIT_DATA
		}

		/* vdso blob that is mapped into user space */
		vdso_start = . ;
		.vdso : AT(ADDR(.vdso) - LOAD_OFFSET) { *(.vdso) }
		. = ALIGN(PAGE_SIZE);
		vdso_end = .;

		#ifdef CONFIG_BLK_DEV_INITRD
		. = ALIGN(PAGE_SIZE);
		__initramfs_start = .;

arch/x86/vdso/vdso.S

+9 −1

Original line number	Diff line number	Diff line
		.section ".vdso","a"
		#include <linux/init.h>

		__INITDATA

		.globl vdso_start, vdso_end
		vdso_start:
		.incbin "arch/x86/vdso/vdso.so"
		vdso_end:

		__FINIT

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