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[PATCH] i386 vDSO: add PT_NOTE segment

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This patch adds an ELF note to the vDSO giving the LINUX_VERSION_CODE
value.  Having this in the vDSO lets the dynamic linker avoid the `uname'
syscall it now always does at startup to ascertain the kernel ABI
available.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Roland McGrath 2005-04-16 15:24:48 -07:00 committed by Linus Torvalds
parent ecd02dddd1
commit c97db4a0a7
3 changed files with 31 additions and 3 deletions
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6
arch/i386/kernel/Makefile
View File

@ -56,7 +56,8 @@ SYSCFLAGS_vsyscall-sysenter.so = $(vsyscall-flags)
SYSCFLAGS_vsyscall-int80.so = $(vsyscall-flags)
$(obj)/vsyscall-int80.so $(obj)/vsyscall-sysenter.so: \
$(obj)/vsyscall-%.so: $(src)/vsyscall.lds $(obj)/vsyscall-%.o FORCE
$(obj)/vsyscall-%.so: $(src)/vsyscall.lds \
$(obj)/vsyscall-%.o $(obj)/vsyscall-note.o FORCE
$(call if_changed,syscall)
# We also create a special relocatable object that should mirror the symbol
@ -67,5 +68,6 @@ $(obj)/built-in.o: $(obj)/vsyscall-syms.o
$(obj)/built-in.o: ld_flags += -R $(obj)/vsyscall-syms.o
SYSCFLAGS_vsyscall-syms.o = -r
$(obj)/vsyscall-syms.o: $(src)/vsyscall.lds $(obj)/vsyscall-sysenter.o FORCE
$(obj)/vsyscall-syms.o: $(src)/vsyscall.lds \
$(obj)/vsyscall-sysenter.o $(obj)/vsyscall-note.o FORCE
$(call if_changed,syscall)

25
arch/i386/kernel/vsyscall-note.S Normal file
View File

@ -0,0 +1,25 @@
/*
* This supplies .note.* sections to go into the PT_NOTE inside the vDSO text.
* Here we can supply some information useful to userland.
*/
#include <linux/uts.h>
#include <linux/version.h>
#define ASM_ELF_NOTE_BEGIN(name, flags, vendor, type) \
.section name, flags; \
.balign 4; \
.long 1f - 0f; /* name length */ \
.long 3f - 2f; /* data length */ \
.long type; /* note type */ \
0: .asciz vendor; /* vendor name */ \
1: .balign 4; \
2:
#define ASM_ELF_NOTE_END \
3: .balign 4; /* pad out section */ \
.previous
ASM_ELF_NOTE_BEGIN(".note.kernel-version", "a", UTS_SYSNAME, 0)
.long LINUX_VERSION_CODE
ASM_ELF_NOTE_END

3
arch/i386/kernel/vsyscall.lds.S
View File

@ -23,7 +23,7 @@ SECTIONS
. = VSYSCALL_BASE + 0x400;
.text : { *(.text) } :text =0x90909090
.note : { *(.note.*) } :text :note
.eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr
.eh_frame : { KEEP (*(.eh_frame)) } :text
.dynamic : { *(.dynamic) } :text :dynamic
@ -43,6 +43,7 @@ PHDRS
{
text PT_LOAD FILEHDR PHDRS FLAGS(5); /* PF_R|PF_X */
dynamic PT_DYNAMIC FLAGS(4); /* PF_R */
note PT_NOTE FLAGS(4); /* PF_R */
eh_frame_hdr 0x6474e550; /* PT_GNU_EH_FRAME, but ld doesn't match the name */
}