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authorIan Campbell <Ian.Campbell@XenSource.com>2006-09-26 04:52:38 -0400
committerAndi Kleen <andi@basil.nowhere.org>2006-09-26 04:52:38 -0400
commitf2a9e1dec27189a09ff642f2648e49ad9e76607b (patch)
tree0ff8688e89dcbd47fa2bda2cc418820841fdefde /arch/x86_64/kernel/vmlinux.lds.S
parent26374c7b7dca1ff90607c83d9b82e917119f0456 (diff)
[PATCH] Put .note.* sections into a PT_NOTE segment
This patch updates x86_64 linker script to pack any .note.* sections into a PT_NOTE segment in the output file. To do this, we tell ld that we need a PT_NOTE segment. This requires us to start explicitly mapping sections to segments, so we also need to explicitly create PT_LOAD segments for text and data, and map the sections to them appropriately. Fortunately, each section will default to its previous section's segment, so it doesn't take many changes to vmlinux.lds.S. The corresponding change is already made for i386 in -mm and I'd like this patch to join it. The section to segment mappings do change as do the segment flags so some time in -mm would be good for that reason as well, just in case. In particular .data and .bss move from the text segment to the data segment and .data.cacheline_aligned .data.read_mostly are put in the data segment instead of a separate one. I think that it would be possible to exactly match the existing section to segment mapping and flags but it would be a more intrusive change and I'm not sure there is a reason for the existing layout other than it is what you get by default if you don't explicitly specify something else. If there is a reason for the existing layout then I will of course make the more intrusive change. If there is no reason we could probably drop the executable or writable flags from some segments but I don't know how much attention is paid to them anyway so it might not be worth the effort. The vsyscall related sections need to go in a different segment to the normal data segment and so I invented a "user" segment to contain them. I believe this should appear to be another data segment as far as the kernel is concerned so the flags are setup accordingly. The notes will be used in the Xen paravirt_ops backend to provide additional information to the domain builder. I am in the process of converting the xen-unstable kernels and tools over to this scheme at the moment to support this in the future. It has been suggested to me that the notes segment should have flags 0 (i.e. not readable) since it is only used by the loader and is not used at runtime. For now I went with a readable segment since that is what the i386 patch uses. AK: dropped NOTES addition right now because the needed infrastructure for that is not merged yet Signed-off-by: Ian Campbell <ian.campbell@xensource.com> Signed-off-by: Andi Kleen <ak@suse.de>
Diffstat (limited to 'arch/x86_64/kernel/vmlinux.lds.S')
-rw-r--r--arch/x86_64/kernel/vmlinux.lds.S14
1 files changed, 10 insertions, 4 deletions
diff --git a/arch/x86_64/kernel/vmlinux.lds.S b/arch/x86_64/kernel/vmlinux.lds.S
index 8d5a5149bb3a..2802aa963fa3 100644
--- a/arch/x86_64/kernel/vmlinux.lds.S
+++ b/arch/x86_64/kernel/vmlinux.lds.S
@@ -13,6 +13,12 @@ OUTPUT_FORMAT("elf64-x86-64", "elf64-x86-64", "elf64-x86-64")
13OUTPUT_ARCH(i386:x86-64) 13OUTPUT_ARCH(i386:x86-64)
14ENTRY(phys_startup_64) 14ENTRY(phys_startup_64)
15jiffies_64 = jiffies; 15jiffies_64 = jiffies;
16PHDRS {
17 text PT_LOAD FLAGS(5); /* R_E */
18 data PT_LOAD FLAGS(7); /* RWE */
19 user PT_LOAD FLAGS(7); /* RWE */
20 note PT_NOTE FLAGS(4); /* R__ */
21}
16SECTIONS 22SECTIONS
17{ 23{
18 . = __START_KERNEL; 24 . = __START_KERNEL;
@@ -31,7 +37,7 @@ SECTIONS
31 KPROBES_TEXT 37 KPROBES_TEXT
32 *(.fixup) 38 *(.fixup)
33 *(.gnu.warning) 39 *(.gnu.warning)
34 } = 0x9090 40 } :text = 0x9090
35 /* out-of-line lock text */ 41 /* out-of-line lock text */
36 .text.lock : AT(ADDR(.text.lock) - LOAD_OFFSET) { *(.text.lock) } 42 .text.lock : AT(ADDR(.text.lock) - LOAD_OFFSET) { *(.text.lock) }
37 43
@@ -57,7 +63,7 @@ SECTIONS
57 .data : AT(ADDR(.data) - LOAD_OFFSET) { 63 .data : AT(ADDR(.data) - LOAD_OFFSET) {
58 *(.data) 64 *(.data)
59 CONSTRUCTORS 65 CONSTRUCTORS
60 } 66 } :data
61 67
62 _edata = .; /* End of data section */ 68 _edata = .; /* End of data section */
63 69
@@ -89,7 +95,7 @@ SECTIONS
89#define VVIRT(x) (ADDR(x) - VVIRT_OFFSET) 95#define VVIRT(x) (ADDR(x) - VVIRT_OFFSET)
90 96
91 . = VSYSCALL_ADDR; 97 . = VSYSCALL_ADDR;
92 .vsyscall_0 : AT(VSYSCALL_PHYS_ADDR) { *(.vsyscall_0) } 98 .vsyscall_0 : AT(VSYSCALL_PHYS_ADDR) { *(.vsyscall_0) } :user
93 __vsyscall_0 = VSYSCALL_VIRT_ADDR; 99 __vsyscall_0 = VSYSCALL_VIRT_ADDR;
94 100
95 . = ALIGN(CONFIG_X86_L1_CACHE_BYTES); 101 . = ALIGN(CONFIG_X86_L1_CACHE_BYTES);
@@ -135,7 +141,7 @@ SECTIONS
135 . = ALIGN(8192); /* init_task */ 141 . = ALIGN(8192); /* init_task */
136 .data.init_task : AT(ADDR(.data.init_task) - LOAD_OFFSET) { 142 .data.init_task : AT(ADDR(.data.init_task) - LOAD_OFFSET) {
137 *(.data.init_task) 143 *(.data.init_task)
138 } 144 } :data
139 145
140 . = ALIGN(4096); 146 . = ALIGN(4096);
141 .data.page_aligned : AT(ADDR(.data.page_aligned) - LOAD_OFFSET) { 147 .data.page_aligned : AT(ADDR(.data.page_aligned) - LOAD_OFFSET) {