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authorRoland McGrath <roland@redhat.com>2008-01-30 07:30:41 -0500
committerIngo Molnar <mingo@elte.hu>2008-01-30 07:30:41 -0500
commitf6b46ebf904f69a73907a5e6b1ed2228e3f03d9e (patch)
tree4f939fa0f6624a2a42fb0f14de2c7f72a6773fa7
parent2b9c97e16101e8dc2b0810d6f932d475a051d785 (diff)
x86 vDSO: new layout
This revamps the vDSO linker script to lay things out with the best packing of the data and good, separate alignment of the code. The rigid layout using VDSO_TEXT_OFFSET no longer matters to the kernel. I've moved the layout parts of the linker script into a new include file, vdso-layout.lds.S; this is in preparation for sharing the script for the 32-bit vDSO builds too. Signed-off-by: Roland McGrath <roland@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat
-rw-r--r--arch/x86/vdso/vdso-layout.lds.S64
-rw-r--r--arch/x86/vdso/vdso.lds.S102
-rw-r--r--arch/x86/vdso/voffset.h1
3 files changed, 89 insertions, 78 deletions
diff --git a/arch/x86/vdso/vdso-layout.lds.S b/arch/x86/vdso/vdso-layout.lds.S
new file mode 100644
index 000000000000..634a2cf62046
--- /dev/null
+++ b/arch/x86/vdso/vdso-layout.lds.S
@@ -0,0 +1,64 @@
1/*
2 * Linker script for vDSO. This is an ELF shared object prelinked to
3 * its virtual address, and with only one read-only segment.
4 * This script controls its layout.
5 */
6
7SECTIONS
8{
9 . = VDSO_PRELINK + SIZEOF_HEADERS;
10
11 .hash : { *(.hash) } :text
12 .gnu.hash : { *(.gnu.hash) }
13 .dynsym : { *(.dynsym) }
14 .dynstr : { *(.dynstr) }
15 .gnu.version : { *(.gnu.version) }
16 .gnu.version_d : { *(.gnu.version_d) }
17 .gnu.version_r : { *(.gnu.version_r) }
18
19 .note : { *(.note.*) } :text :note
20
21 .eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr
22 .eh_frame : { KEEP (*(.eh_frame)) } :text
23
24 .dynamic : { *(.dynamic) } :text :dynamic
25
26 .rodata : { *(.rodata*) } :text
27 .data : {
28 *(.data*)
29 *(.sdata*)
30 *(.got.plt) *(.got)
31 *(.gnu.linkonce.d.*)
32 *(.bss*)
33 *(.dynbss*)
34 *(.gnu.linkonce.b.*)
35 }
36
37 .altinstructions : { *(.altinstructions) }
38 .altinstr_replacement : { *(.altinstr_replacement) }
39
40 /*
41 * Align the actual code well away from the non-instruction data.
42 * This is the best thing for the I-cache.
43 */
44 . = ALIGN(0x100);
45
46 .text : { *(.text*) } :text =0x90909090
47}
48
49/*
50 * Very old versions of ld do not recognize this name token; use the constant.
51 */
52#define PT_GNU_EH_FRAME 0x6474e550
53
54/*
55 * We must supply the ELF program headers explicitly to get just one
56 * PT_LOAD segment, and set the flags explicitly to make segments read-only.
57 */
58PHDRS
59{
60 text PT_LOAD FLAGS(5) FILEHDR PHDRS; /* PF_R|PF_X */
61 dynamic PT_DYNAMIC FLAGS(4); /* PF_R */
62 note PT_NOTE FLAGS(4); /* PF_R */
63 eh_frame_hdr PT_GNU_EH_FRAME;
64}
diff --git a/arch/x86/vdso/vdso.lds.S b/arch/x86/vdso/vdso.lds.S
index d40d0e906190..4e5dd3b4de7f 100644
--- a/arch/x86/vdso/vdso.lds.S
+++ b/arch/x86/vdso/vdso.lds.S
@@ -1,89 +1,37 @@
1/* 1/*
2 * Linker script for vsyscall DSO. The vsyscall page is an ELF shared 2 * Linker script for 64-bit vDSO.
3 * object prelinked to its virtual address, and with only one read-only 3 * We #include the file to define the layout details.
4 * segment (that fits in one page). This script controls its layout. 4 * Here we only choose the prelinked virtual address.
5 *
6 * This file defines the version script giving the user-exported symbols in
7 * the DSO. We can define local symbols here called VDSO* to make their
8 * values visible using the asm-x86/vdso.h macros from the kernel proper.
5 */ 9 */
6#include <asm/asm-offsets.h>
7#include "voffset.h"
8 10
9#define VDSO_PRELINK 0xffffffffff700000 11#define VDSO_PRELINK 0xffffffffff700000
12#include "vdso-layout.lds.S"
10 13
11/* 14/*
12 * Symbols we define here called VDSO* get their values into vdso-syms.lds 15 * This controls what userland symbols we export from the vDSO.
13 * and become visible to the kernel itself.
14 */ 16 */
15VDSO64_PRELINK = VDSO_PRELINK; 17VERSION {
16 18 LINUX_2.6 {
17#define VEXTERN(x) VDSO64_ ## x = vdso_ ## x; 19 global:
18#include "vextern.h" 20 clock_gettime;
19#undef VEXTERN 21 __vdso_clock_gettime;
20 22 gettimeofday;
21SECTIONS 23 __vdso_gettimeofday;
22{ 24 getcpu;
23 . = VDSO_PRELINK + SIZEOF_HEADERS; 25 __vdso_getcpu;
24 26 local: *;
25 .hash : { *(.hash) } :text 27 };
26 .gnu.hash : { *(.gnu.hash) }
27 .dynsym : { *(.dynsym) }
28 .dynstr : { *(.dynstr) }
29 .gnu.version : { *(.gnu.version) }
30 .gnu.version_d : { *(.gnu.version_d) }
31 .gnu.version_r : { *(.gnu.version_r) }
32
33 /* This linker script is used both with -r and with -shared.
34 For the layouts to match, we need to skip more than enough
35 space for the dynamic symbol table et al. If this amount
36 is insufficient, ld -shared will barf. Just increase it here. */
37 . = VDSO_PRELINK + VDSO_TEXT_OFFSET;
38
39 .text : { *(.text*) } :text
40 .rodata : { *(.rodata*) } :text
41 .data : {
42 *(.data*)
43 *(.sdata*)
44 *(.bss*)
45 *(.dynbss*)
46 } :text
47
48 .altinstructions : { *(.altinstructions) } :text
49 .altinstr_replacement : { *(.altinstr_replacement) } :text
50
51 .note : { *(.note.*) } :text :note
52 .eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr
53 .eh_frame : { KEEP (*(.eh_frame)) } :text
54 .dynamic : { *(.dynamic) } :text :dynamic
55 .useless : {
56 *(.got.plt) *(.got)
57 *(.gnu.linkonce.d.*)
58 *(.gnu.linkonce.b.*)
59 } :text
60} 28}
61 29
62/* 30VDSO64_PRELINK = VDSO_PRELINK;
63 * We must supply the ELF program headers explicitly to get just one
64 * PT_LOAD segment, and set the flags explicitly to make segments read-only.
65 */
66PHDRS
67{
68 text PT_LOAD FILEHDR PHDRS FLAGS(5); /* PF_R|PF_X */
69 dynamic PT_DYNAMIC FLAGS(4); /* PF_R */
70 note PT_NOTE FLAGS(4); /* PF_R */
71 eh_frame_hdr 0x6474e550; /* PT_GNU_EH_FRAME, but ld doesn't match the name */
72}
73 31
74/* 32/*
75 * This controls what symbols we export from the DSO. 33 * Define VDSO64_x for each VEXTERN(x), for use via VDSO64_SYMBOL.
76 */ 34 */
77VERSION 35#define VEXTERN(x) VDSO64_ ## x = vdso_ ## x;
78{ 36#include "vextern.h"
79 LINUX_2.6 { 37#undef VEXTERN
80 global:
81 clock_gettime;
82 __vdso_clock_gettime;
83 gettimeofday;
84 __vdso_gettimeofday;
85 getcpu;
86 __vdso_getcpu;
87 local: *;
88 };
89}
diff --git a/arch/x86/vdso/voffset.h b/arch/x86/vdso/voffset.h
deleted file mode 100644
index 4af67c79085f..000000000000
--- a/arch/x86/vdso/voffset.h
+++ /dev/null
@@ -1 +0,0 @@
1#define VDSO_TEXT_OFFSET 0x600
generated by cgit v1.2.2 (git 2.25.0) at 2024-11-08 07:00:47 -0500