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[PATCH] ppc64: add PT_NOTE section to vDSO

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This patch from Roland adds a PT_NOTE section to both 32 and 64 bits vDSOs
to expose the kernel version to glibc, thus avoiding a uname syscall on
every launch.  This is equivalent to the patches Roland posted already for
x86 and x86-64.

Note: the 64 bits .note is actually using the 32 bits format.  This is
normal.  The ELF spec specifies a different format for 64 bits .note, but
for some reason, this was never properly implemented, the core dumps for
example are all using 32 bits format .note, and binutils cannot even read a
64 bits format .note.  Talking to our toolchain folks, they think we'd
rather stick to 32 bits format .note everywhere and get the spec fixed some
day ...

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Benjamin Herrenschmidt 2005-05-01 08:58:43 -07:00 committed by Linus Torvalds
parent 085e6fc96b
commit 1b29f9d13e
6 changed files with 35 additions and 3 deletions
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2
arch/ppc64/kernel/vdso32/Makefile
View file

@ -1,7 +1,7 @@
# List of files in the vdso, has to be asm only for now
obj-vdso32 = sigtramp.o gettimeofday.o datapage.o cacheflush.o
obj-vdso32 = sigtramp.o gettimeofday.o datapage.o cacheflush.o note.o
# Build rules

25
arch/ppc64/kernel/vdso32/note.S Normal file
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@ -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/ppc64/kernel/vdso32/vdso32.lds.S
View file

@ -20,6 +20,8 @@ SECTIONS
.gnu.version_d : { *(.gnu.version_d) }
.gnu.version_r : { *(.gnu.version_r) }
.note : { *(.note.*) } :text :note
. = ALIGN (16);
.text :
{
@ -87,6 +89,7 @@ SECTIONS
PHDRS
{
text PT_LOAD FILEHDR PHDRS FLAGS(5); /* PF_R|PF_X */
note PT_NOTE FLAGS(4); /* PF_R */
dynamic PT_DYNAMIC FLAGS(4); /* PF_R */
eh_frame_hdr 0x6474e550; /* PT_GNU_EH_FRAME, but ld doesn't match the name */
}

2
arch/ppc64/kernel/vdso64/Makefile
View file

@ -1,6 +1,6 @@
# List of files in the vdso, has to be asm only for now
obj-vdso64 = sigtramp.o gettimeofday.o datapage.o cacheflush.o
obj-vdso64 = sigtramp.o gettimeofday.o datapage.o cacheflush.o note.o
# Build rules

1
arch/ppc64/kernel/vdso64/note.S Normal file
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@ -0,0 +1 @@
#include "../vdso32/note.S"

5
arch/ppc64/kernel/vdso64/vdso64.lds.S
View file

@ -18,12 +18,14 @@ SECTIONS
.gnu.version_d : { *(.gnu.version_d) }
.gnu.version_r : { *(.gnu.version_r) }
.note : { *(.note.*) } :text :note
. = ALIGN (16);
.text :
{
*(.text .stub .text.* .gnu.linkonce.t.*)
*(.sfpr .glink)
}
} :text
PROVIDE (__etext = .);
PROVIDE (_etext = .);
PROVIDE (etext = .);
@ -88,6 +90,7 @@ SECTIONS
PHDRS
{
text PT_LOAD FILEHDR PHDRS FLAGS(5); /* PF_R|PF_X */
note PT_NOTE FLAGS(4); /* PF_R */
dynamic PT_DYNAMIC FLAGS(4); /* PF_R */
eh_frame_hdr 0x6474e550; /* PT_GNU_EH_FRAME, but ld doesn't match the name */
}