linux/arch/i386/kernel/vmlinux.lds.S

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/* ld script to make i386 Linux kernel
* Written by Martin Mares <mj@atrey.karlin.mff.cuni.cz>;
[PATCH] i386: Distinguish absolute symbols Ld knows about 2 kinds of symbols, absolute and section relative. Section relative symbols symbols change value when a section is moved and absolute symbols do not. Currently in the linker script we have several labels marking the beginning and ending of sections that are outside of sections, making them absolute symbols. Having a mixture of absolute and section relative symbols refereing to the same data is currently harmless but it is confusing. This must be done carefully as newer revs of ld do not place symbols that appear in sections without data and instead ld makes those symbols global :( My ultimate goal is to build a relocatable kernel. The safest and least intrusive technique is to generate relocation entries so the kernel can be relocated at load time. The only penalty would be an increase in the size of the kernel binary. The problem is that if absolute and relocatable symbols are not properly specified absolute symbols will be relocated or section relative symbols won't be, which is fatal. The practical motivation is that when generating kernels that will run from a reserved area for analyzing what caused a kernel panic, it is simpler if you don't need to hard code the physical memory location they will run at, especially for the distributions. [AK: and merged:] o Also put a message so that in future people can be aware of it and avoid introducing absolute symbols. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07 01:14:03 +00:00
*
* Don't define absolute symbols until and unless you know that symbol
* value is should remain constant even if kernel image is relocated
* at run time. Absolute symbols are not relocated. If symbol value should
* change if kernel is relocated, make the symbol section relative and
* put it inside the section definition.
*/
/* Don't define absolute symbols until and unless you know that symbol
* value is should remain constant even if kernel image is relocated
* at run time. Absolute symbols are not relocated. If symbol value should
* change if kernel is relocated, make the symbol section relative and
* put it inside the section definition.
*/
#define LOAD_OFFSET __PAGE_OFFSET
#include <asm-generic/vmlinux.lds.h>
#include <asm/thread_info.h>
#include <asm/page.h>
#include <asm/cache.h>
#include <asm/boot.h>
OUTPUT_FORMAT("elf32-i386", "elf32-i386", "elf32-i386")
OUTPUT_ARCH(i386)
ENTRY(phys_startup_32)
jiffies = jiffies_64;
PHDRS {
text PT_LOAD FLAGS(5); /* R_E */
data PT_LOAD FLAGS(7); /* RWE */
note PT_NOTE FLAGS(0); /* ___ */
}
SECTIONS
{
. = LOAD_OFFSET + LOAD_PHYSICAL_ADDR;
phys_startup_32 = startup_32 - LOAD_OFFSET;
.text.head : AT(ADDR(.text.head) - LOAD_OFFSET) {
_text = .; /* Text and read-only data */
*(.text.head)
} :text = 0x9090
/* read-only */
.text : AT(ADDR(.text) - LOAD_OFFSET) {
TEXT_TEXT
SCHED_TEXT
LOCK_TEXT
KPROBES_TEXT
*(.fixup)
*(.gnu.warning)
[PATCH] i386: Distinguish absolute symbols Ld knows about 2 kinds of symbols, absolute and section relative. Section relative symbols symbols change value when a section is moved and absolute symbols do not. Currently in the linker script we have several labels marking the beginning and ending of sections that are outside of sections, making them absolute symbols. Having a mixture of absolute and section relative symbols refereing to the same data is currently harmless but it is confusing. This must be done carefully as newer revs of ld do not place symbols that appear in sections without data and instead ld makes those symbols global :( My ultimate goal is to build a relocatable kernel. The safest and least intrusive technique is to generate relocation entries so the kernel can be relocated at load time. The only penalty would be an increase in the size of the kernel binary. The problem is that if absolute and relocatable symbols are not properly specified absolute symbols will be relocated or section relative symbols won't be, which is fatal. The practical motivation is that when generating kernels that will run from a reserved area for analyzing what caused a kernel panic, it is simpler if you don't need to hard code the physical memory location they will run at, especially for the distributions. [AK: and merged:] o Also put a message so that in future people can be aware of it and avoid introducing absolute symbols. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07 01:14:03 +00:00
_etext = .; /* End of text section */
} :text = 0x9090
. = ALIGN(16); /* Exception table */
[PATCH] i386: Distinguish absolute symbols Ld knows about 2 kinds of symbols, absolute and section relative. Section relative symbols symbols change value when a section is moved and absolute symbols do not. Currently in the linker script we have several labels marking the beginning and ending of sections that are outside of sections, making them absolute symbols. Having a mixture of absolute and section relative symbols refereing to the same data is currently harmless but it is confusing. This must be done carefully as newer revs of ld do not place symbols that appear in sections without data and instead ld makes those symbols global :( My ultimate goal is to build a relocatable kernel. The safest and least intrusive technique is to generate relocation entries so the kernel can be relocated at load time. The only penalty would be an increase in the size of the kernel binary. The problem is that if absolute and relocatable symbols are not properly specified absolute symbols will be relocated or section relative symbols won't be, which is fatal. The practical motivation is that when generating kernels that will run from a reserved area for analyzing what caused a kernel panic, it is simpler if you don't need to hard code the physical memory location they will run at, especially for the distributions. [AK: and merged:] o Also put a message so that in future people can be aware of it and avoid introducing absolute symbols. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07 01:14:03 +00:00
__ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) {
__start___ex_table = .;
*(__ex_table)
__stop___ex_table = .;
}
NOTES :text :note
BUG_TABLE :text
. = ALIGN(4);
.tracedata : AT(ADDR(.tracedata) - LOAD_OFFSET) {
[PATCH] i386: Distinguish absolute symbols Ld knows about 2 kinds of symbols, absolute and section relative. Section relative symbols symbols change value when a section is moved and absolute symbols do not. Currently in the linker script we have several labels marking the beginning and ending of sections that are outside of sections, making them absolute symbols. Having a mixture of absolute and section relative symbols refereing to the same data is currently harmless but it is confusing. This must be done carefully as newer revs of ld do not place symbols that appear in sections without data and instead ld makes those symbols global :( My ultimate goal is to build a relocatable kernel. The safest and least intrusive technique is to generate relocation entries so the kernel can be relocated at load time. The only penalty would be an increase in the size of the kernel binary. The problem is that if absolute and relocatable symbols are not properly specified absolute symbols will be relocated or section relative symbols won't be, which is fatal. The practical motivation is that when generating kernels that will run from a reserved area for analyzing what caused a kernel panic, it is simpler if you don't need to hard code the physical memory location they will run at, especially for the distributions. [AK: and merged:] o Also put a message so that in future people can be aware of it and avoid introducing absolute symbols. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07 01:14:03 +00:00
__tracedata_start = .;
*(.tracedata)
[PATCH] i386: Distinguish absolute symbols Ld knows about 2 kinds of symbols, absolute and section relative. Section relative symbols symbols change value when a section is moved and absolute symbols do not. Currently in the linker script we have several labels marking the beginning and ending of sections that are outside of sections, making them absolute symbols. Having a mixture of absolute and section relative symbols refereing to the same data is currently harmless but it is confusing. This must be done carefully as newer revs of ld do not place symbols that appear in sections without data and instead ld makes those symbols global :( My ultimate goal is to build a relocatable kernel. The safest and least intrusive technique is to generate relocation entries so the kernel can be relocated at load time. The only penalty would be an increase in the size of the kernel binary. The problem is that if absolute and relocatable symbols are not properly specified absolute symbols will be relocated or section relative symbols won't be, which is fatal. The practical motivation is that when generating kernels that will run from a reserved area for analyzing what caused a kernel panic, it is simpler if you don't need to hard code the physical memory location they will run at, especially for the distributions. [AK: and merged:] o Also put a message so that in future people can be aware of it and avoid introducing absolute symbols. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07 01:14:03 +00:00
__tracedata_end = .;
}
RODATA
/* writeable */
. = ALIGN(4096);
.data : AT(ADDR(.data) - LOAD_OFFSET) { /* Data */
DATA_DATA
CONSTRUCTORS
} :data
. = ALIGN(4096);
[PATCH] i386: Distinguish absolute symbols Ld knows about 2 kinds of symbols, absolute and section relative. Section relative symbols symbols change value when a section is moved and absolute symbols do not. Currently in the linker script we have several labels marking the beginning and ending of sections that are outside of sections, making them absolute symbols. Having a mixture of absolute and section relative symbols refereing to the same data is currently harmless but it is confusing. This must be done carefully as newer revs of ld do not place symbols that appear in sections without data and instead ld makes those symbols global :( My ultimate goal is to build a relocatable kernel. The safest and least intrusive technique is to generate relocation entries so the kernel can be relocated at load time. The only penalty would be an increase in the size of the kernel binary. The problem is that if absolute and relocatable symbols are not properly specified absolute symbols will be relocated or section relative symbols won't be, which is fatal. The practical motivation is that when generating kernels that will run from a reserved area for analyzing what caused a kernel panic, it is simpler if you don't need to hard code the physical memory location they will run at, especially for the distributions. [AK: and merged:] o Also put a message so that in future people can be aware of it and avoid introducing absolute symbols. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07 01:14:03 +00:00
.data_nosave : AT(ADDR(.data_nosave) - LOAD_OFFSET) {
__nosave_begin = .;
*(.data.nosave)
. = ALIGN(4096);
__nosave_end = .;
}
. = ALIGN(4096);
.data.page_aligned : AT(ADDR(.data.page_aligned) - LOAD_OFFSET) {
xen: Core Xen implementation This patch is a rollup of all the core pieces of the Xen implementation, including: - booting and setup - pagetable setup - privileged instructions - segmentation - interrupt flags - upcalls - multicall batching BOOTING AND SETUP The vmlinux image is decorated with ELF notes which tell the Xen domain builder what the kernel's requirements are; the domain builder then constructs the address space accordingly and starts the kernel. Xen has its own entrypoint for the kernel (contained in an ELF note). The ELF notes are set up by xen-head.S, which is included into head.S. In principle it could be linked separately, but it seems to provoke lots of binutils bugs. Because the domain builder starts the kernel in a fairly sane state (32-bit protected mode, paging enabled, flat segments set up), there's not a lot of setup needed before starting the kernel proper. The main steps are: 1. Install the Xen paravirt_ops, which is simply a matter of a structure assignment. 2. Set init_mm to use the Xen-supplied pagetables (analogous to the head.S generated pagetables in a native boot). 3. Reserve address space for Xen, since it takes a chunk at the top of the address space for its own use. 4. Call start_kernel() PAGETABLE SETUP Once we hit the main kernel boot sequence, it will end up calling back via paravirt_ops to set up various pieces of Xen specific state. One of the critical things which requires a bit of extra care is the construction of the initial init_mm pagetable. Because Xen places tight constraints on pagetables (an active pagetable must always be valid, and must always be mapped read-only to the guest domain), we need to be careful when constructing the new pagetable to keep these constraints in mind. It turns out that the easiest way to do this is use the initial Xen-provided pagetable as a template, and then just insert new mappings for memory where a mapping doesn't already exist. This means that during pagetable setup, it uses a special version of xen_set_pte which ignores any attempt to remap a read-only page as read-write (since Xen will map its own initial pagetable as RO), but lets other changes to the ptes happen, so that things like NX are set properly. PRIVILEGED INSTRUCTIONS AND SEGMENTATION When the kernel runs under Xen, it runs in ring 1 rather than ring 0. This means that it is more privileged than user-mode in ring 3, but it still can't run privileged instructions directly. Non-performance critical instructions are dealt with by taking a privilege exception and trapping into the hypervisor and emulating the instruction, but more performance-critical instructions have their own specific paravirt_ops. In many cases we can avoid having to do any hypercalls for these instructions, or the Xen implementation is quite different from the normal native version. The privileged instructions fall into the broad classes of: Segmentation: setting up the GDT and the GDT entries, LDT, TLS and so on. Xen doesn't allow the GDT to be directly modified; all GDT updates are done via hypercalls where the new entries can be validated. This is important because Xen uses segment limits to prevent the guest kernel from damaging the hypervisor itself. Traps and exceptions: Xen uses a special format for trap entrypoints, so when the kernel wants to set an IDT entry, it needs to be converted to the form Xen expects. Xen sets int 0x80 up specially so that the trap goes straight from userspace into the guest kernel without going via the hypervisor. sysenter isn't supported. Kernel stack: The esp0 entry is extracted from the tss and provided to Xen. TLB operations: the various TLB calls are mapped into corresponding Xen hypercalls. Control registers: all the control registers are privileged. The most important is cr3, which points to the base of the current pagetable, and we handle it specially. Another instruction we treat specially is CPUID, even though its not privileged. We want to control what CPU features are visible to the rest of the kernel, and so CPUID ends up going into a paravirt_op. Xen implements this mainly to disable the ACPI and APIC subsystems. INTERRUPT FLAGS Xen maintains its own separate flag for masking events, which is contained within the per-cpu vcpu_info structure. Because the guest kernel runs in ring 1 and not 0, the IF flag in EFLAGS is completely ignored (and must be, because even if a guest domain disables interrupts for itself, it can't disable them overall). (A note on terminology: "events" and interrupts are effectively synonymous. However, rather than using an "enable flag", Xen uses a "mask flag", which blocks event delivery when it is non-zero.) There are paravirt_ops for each of cli/sti/save_fl/restore_fl, which are implemented to manage the Xen event mask state. The only thing worth noting is that when events are unmasked, we need to explicitly see if there's a pending event and call into the hypervisor to make sure it gets delivered. UPCALLS Xen needs a couple of upcall (or callback) functions to be implemented by each guest. One is the event upcalls, which is how events (interrupts, effectively) are delivered to the guests. The other is the failsafe callback, which is used to report errors in either reloading a segment register, or caused by iret. These are implemented in i386/kernel/entry.S so they can jump into the normal iret_exc path when necessary. MULTICALL BATCHING Xen provides a multicall mechanism, which allows multiple hypercalls to be issued at once in order to mitigate the cost of trapping into the hypervisor. This is particularly useful for context switches, since the 4-5 hypercalls they would normally need (reload cr3, update TLS, maybe update LDT) can be reduced to one. This patch implements a generic batching mechanism for hypercalls, which gets used in many places in the Xen code. Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: Chris Wright <chrisw@sous-sol.org> Cc: Ian Pratt <ian.pratt@xensource.com> Cc: Christian Limpach <Christian.Limpach@cl.cam.ac.uk> Cc: Adrian Bunk <bunk@stusta.de>
2007-07-18 01:37:04 +00:00
*(.data.page_aligned)
*(.data.idt)
}
. = ALIGN(32);
.data.cacheline_aligned : AT(ADDR(.data.cacheline_aligned) - LOAD_OFFSET) {
*(.data.cacheline_aligned)
}
/* rarely changed data like cpu maps */
. = ALIGN(32);
[PATCH] i386: Distinguish absolute symbols Ld knows about 2 kinds of symbols, absolute and section relative. Section relative symbols symbols change value when a section is moved and absolute symbols do not. Currently in the linker script we have several labels marking the beginning and ending of sections that are outside of sections, making them absolute symbols. Having a mixture of absolute and section relative symbols refereing to the same data is currently harmless but it is confusing. This must be done carefully as newer revs of ld do not place symbols that appear in sections without data and instead ld makes those symbols global :( My ultimate goal is to build a relocatable kernel. The safest and least intrusive technique is to generate relocation entries so the kernel can be relocated at load time. The only penalty would be an increase in the size of the kernel binary. The problem is that if absolute and relocatable symbols are not properly specified absolute symbols will be relocated or section relative symbols won't be, which is fatal. The practical motivation is that when generating kernels that will run from a reserved area for analyzing what caused a kernel panic, it is simpler if you don't need to hard code the physical memory location they will run at, especially for the distributions. [AK: and merged:] o Also put a message so that in future people can be aware of it and avoid introducing absolute symbols. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07 01:14:03 +00:00
.data.read_mostly : AT(ADDR(.data.read_mostly) - LOAD_OFFSET) {
*(.data.read_mostly)
_edata = .; /* End of data section */
}
. = ALIGN(THREAD_SIZE); /* init_task */
.data.init_task : AT(ADDR(.data.init_task) - LOAD_OFFSET) {
*(.data.init_task)
}
[PATCH] x86: SMP alternatives Implement SMP alternatives, i.e. switching at runtime between different code versions for UP and SMP. The code can patch both SMP->UP and UP->SMP. The UP->SMP case is useful for CPU hotplug. With CONFIG_CPU_HOTPLUG enabled the code switches to UP at boot time and when the number of CPUs goes down to 1, and switches to SMP when the number of CPUs goes up to 2. Without CONFIG_CPU_HOTPLUG or on non-SMP-capable systems the code is patched once at boot time (if needed) and the tables are released afterwards. The changes in detail: * The current alternatives bits are moved to a separate file, the SMP alternatives code is added there. * The patch adds some new elf sections to the kernel: .smp_altinstructions like .altinstructions, also contains a list of alt_instr structs. .smp_altinstr_replacement like .altinstr_replacement, but also has some space to save original instruction before replaving it. .smp_locks list of pointers to lock prefixes which can be nop'ed out on UP. The first two are used to replace more complex instruction sequences such as spinlocks and semaphores. It would be possible to deal with the lock prefixes with that as well, but by handling them as special case the table sizes become much smaller. * The sections are page-aligned and padded up to page size, so they can be free if they are not needed. * Splitted the code to release init pages to a separate function and use it to release the elf sections if they are unused. Signed-off-by: Gerd Hoffmann <kraxel@suse.de> Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-23 10:59:32 +00:00
/* might get freed after init */
. = ALIGN(4096);
.smp_locks : AT(ADDR(.smp_locks) - LOAD_OFFSET) {
[PATCH] i386: Distinguish absolute symbols Ld knows about 2 kinds of symbols, absolute and section relative. Section relative symbols symbols change value when a section is moved and absolute symbols do not. Currently in the linker script we have several labels marking the beginning and ending of sections that are outside of sections, making them absolute symbols. Having a mixture of absolute and section relative symbols refereing to the same data is currently harmless but it is confusing. This must be done carefully as newer revs of ld do not place symbols that appear in sections without data and instead ld makes those symbols global :( My ultimate goal is to build a relocatable kernel. The safest and least intrusive technique is to generate relocation entries so the kernel can be relocated at load time. The only penalty would be an increase in the size of the kernel binary. The problem is that if absolute and relocatable symbols are not properly specified absolute symbols will be relocated or section relative symbols won't be, which is fatal. The practical motivation is that when generating kernels that will run from a reserved area for analyzing what caused a kernel panic, it is simpler if you don't need to hard code the physical memory location they will run at, especially for the distributions. [AK: and merged:] o Also put a message so that in future people can be aware of it and avoid introducing absolute symbols. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07 01:14:03 +00:00
__smp_locks = .;
[PATCH] x86: SMP alternatives Implement SMP alternatives, i.e. switching at runtime between different code versions for UP and SMP. The code can patch both SMP->UP and UP->SMP. The UP->SMP case is useful for CPU hotplug. With CONFIG_CPU_HOTPLUG enabled the code switches to UP at boot time and when the number of CPUs goes down to 1, and switches to SMP when the number of CPUs goes up to 2. Without CONFIG_CPU_HOTPLUG or on non-SMP-capable systems the code is patched once at boot time (if needed) and the tables are released afterwards. The changes in detail: * The current alternatives bits are moved to a separate file, the SMP alternatives code is added there. * The patch adds some new elf sections to the kernel: .smp_altinstructions like .altinstructions, also contains a list of alt_instr structs. .smp_altinstr_replacement like .altinstr_replacement, but also has some space to save original instruction before replaving it. .smp_locks list of pointers to lock prefixes which can be nop'ed out on UP. The first two are used to replace more complex instruction sequences such as spinlocks and semaphores. It would be possible to deal with the lock prefixes with that as well, but by handling them as special case the table sizes become much smaller. * The sections are page-aligned and padded up to page size, so they can be free if they are not needed. * Splitted the code to release init pages to a separate function and use it to release the elf sections if they are unused. Signed-off-by: Gerd Hoffmann <kraxel@suse.de> Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-23 10:59:32 +00:00
*(.smp_locks)
[PATCH] i386: Distinguish absolute symbols Ld knows about 2 kinds of symbols, absolute and section relative. Section relative symbols symbols change value when a section is moved and absolute symbols do not. Currently in the linker script we have several labels marking the beginning and ending of sections that are outside of sections, making them absolute symbols. Having a mixture of absolute and section relative symbols refereing to the same data is currently harmless but it is confusing. This must be done carefully as newer revs of ld do not place symbols that appear in sections without data and instead ld makes those symbols global :( My ultimate goal is to build a relocatable kernel. The safest and least intrusive technique is to generate relocation entries so the kernel can be relocated at load time. The only penalty would be an increase in the size of the kernel binary. The problem is that if absolute and relocatable symbols are not properly specified absolute symbols will be relocated or section relative symbols won't be, which is fatal. The practical motivation is that when generating kernels that will run from a reserved area for analyzing what caused a kernel panic, it is simpler if you don't need to hard code the physical memory location they will run at, especially for the distributions. [AK: and merged:] o Also put a message so that in future people can be aware of it and avoid introducing absolute symbols. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07 01:14:03 +00:00
__smp_locks_end = .;
[PATCH] x86: SMP alternatives Implement SMP alternatives, i.e. switching at runtime between different code versions for UP and SMP. The code can patch both SMP->UP and UP->SMP. The UP->SMP case is useful for CPU hotplug. With CONFIG_CPU_HOTPLUG enabled the code switches to UP at boot time and when the number of CPUs goes down to 1, and switches to SMP when the number of CPUs goes up to 2. Without CONFIG_CPU_HOTPLUG or on non-SMP-capable systems the code is patched once at boot time (if needed) and the tables are released afterwards. The changes in detail: * The current alternatives bits are moved to a separate file, the SMP alternatives code is added there. * The patch adds some new elf sections to the kernel: .smp_altinstructions like .altinstructions, also contains a list of alt_instr structs. .smp_altinstr_replacement like .altinstr_replacement, but also has some space to save original instruction before replaving it. .smp_locks list of pointers to lock prefixes which can be nop'ed out on UP. The first two are used to replace more complex instruction sequences such as spinlocks and semaphores. It would be possible to deal with the lock prefixes with that as well, but by handling them as special case the table sizes become much smaller. * The sections are page-aligned and padded up to page size, so they can be free if they are not needed. * Splitted the code to release init pages to a separate function and use it to release the elf sections if they are unused. Signed-off-by: Gerd Hoffmann <kraxel@suse.de> Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-23 10:59:32 +00:00
}
/* will be freed after init
* Following ALIGN() is required to make sure no other data falls on the
* same page where __smp_alt_end is pointing as that page might be freed
* after boot. Always make sure that ALIGN() directive is present after
* the section which contains __smp_alt_end.
*/
[PATCH] x86: SMP alternatives Implement SMP alternatives, i.e. switching at runtime between different code versions for UP and SMP. The code can patch both SMP->UP and UP->SMP. The UP->SMP case is useful for CPU hotplug. With CONFIG_CPU_HOTPLUG enabled the code switches to UP at boot time and when the number of CPUs goes down to 1, and switches to SMP when the number of CPUs goes up to 2. Without CONFIG_CPU_HOTPLUG or on non-SMP-capable systems the code is patched once at boot time (if needed) and the tables are released afterwards. The changes in detail: * The current alternatives bits are moved to a separate file, the SMP alternatives code is added there. * The patch adds some new elf sections to the kernel: .smp_altinstructions like .altinstructions, also contains a list of alt_instr structs. .smp_altinstr_replacement like .altinstr_replacement, but also has some space to save original instruction before replaving it. .smp_locks list of pointers to lock prefixes which can be nop'ed out on UP. The first two are used to replace more complex instruction sequences such as spinlocks and semaphores. It would be possible to deal with the lock prefixes with that as well, but by handling them as special case the table sizes become much smaller. * The sections are page-aligned and padded up to page size, so they can be free if they are not needed. * Splitted the code to release init pages to a separate function and use it to release the elf sections if they are unused. Signed-off-by: Gerd Hoffmann <kraxel@suse.de> Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-23 10:59:32 +00:00
. = ALIGN(4096);
/* will be freed after init */
. = ALIGN(4096); /* Init code and data */
.init.text : AT(ADDR(.init.text) - LOAD_OFFSET) {
[PATCH] i386: Distinguish absolute symbols Ld knows about 2 kinds of symbols, absolute and section relative. Section relative symbols symbols change value when a section is moved and absolute symbols do not. Currently in the linker script we have several labels marking the beginning and ending of sections that are outside of sections, making them absolute symbols. Having a mixture of absolute and section relative symbols refereing to the same data is currently harmless but it is confusing. This must be done carefully as newer revs of ld do not place symbols that appear in sections without data and instead ld makes those symbols global :( My ultimate goal is to build a relocatable kernel. The safest and least intrusive technique is to generate relocation entries so the kernel can be relocated at load time. The only penalty would be an increase in the size of the kernel binary. The problem is that if absolute and relocatable symbols are not properly specified absolute symbols will be relocated or section relative symbols won't be, which is fatal. The practical motivation is that when generating kernels that will run from a reserved area for analyzing what caused a kernel panic, it is simpler if you don't need to hard code the physical memory location they will run at, especially for the distributions. [AK: and merged:] o Also put a message so that in future people can be aware of it and avoid introducing absolute symbols. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07 01:14:03 +00:00
__init_begin = .;
_sinittext = .;
*(.init.text)
_einittext = .;
}
.init.data : AT(ADDR(.init.data) - LOAD_OFFSET) { *(.init.data) }
. = ALIGN(16);
[PATCH] i386: Distinguish absolute symbols Ld knows about 2 kinds of symbols, absolute and section relative. Section relative symbols symbols change value when a section is moved and absolute symbols do not. Currently in the linker script we have several labels marking the beginning and ending of sections that are outside of sections, making them absolute symbols. Having a mixture of absolute and section relative symbols refereing to the same data is currently harmless but it is confusing. This must be done carefully as newer revs of ld do not place symbols that appear in sections without data and instead ld makes those symbols global :( My ultimate goal is to build a relocatable kernel. The safest and least intrusive technique is to generate relocation entries so the kernel can be relocated at load time. The only penalty would be an increase in the size of the kernel binary. The problem is that if absolute and relocatable symbols are not properly specified absolute symbols will be relocated or section relative symbols won't be, which is fatal. The practical motivation is that when generating kernels that will run from a reserved area for analyzing what caused a kernel panic, it is simpler if you don't need to hard code the physical memory location they will run at, especially for the distributions. [AK: and merged:] o Also put a message so that in future people can be aware of it and avoid introducing absolute symbols. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07 01:14:03 +00:00
.init.setup : AT(ADDR(.init.setup) - LOAD_OFFSET) {
__setup_start = .;
*(.init.setup)
__setup_end = .;
}
.initcall.init : AT(ADDR(.initcall.init) - LOAD_OFFSET) {
[PATCH] i386: Distinguish absolute symbols Ld knows about 2 kinds of symbols, absolute and section relative. Section relative symbols symbols change value when a section is moved and absolute symbols do not. Currently in the linker script we have several labels marking the beginning and ending of sections that are outside of sections, making them absolute symbols. Having a mixture of absolute and section relative symbols refereing to the same data is currently harmless but it is confusing. This must be done carefully as newer revs of ld do not place symbols that appear in sections without data and instead ld makes those symbols global :( My ultimate goal is to build a relocatable kernel. The safest and least intrusive technique is to generate relocation entries so the kernel can be relocated at load time. The only penalty would be an increase in the size of the kernel binary. The problem is that if absolute and relocatable symbols are not properly specified absolute symbols will be relocated or section relative symbols won't be, which is fatal. The practical motivation is that when generating kernels that will run from a reserved area for analyzing what caused a kernel panic, it is simpler if you don't need to hard code the physical memory location they will run at, especially for the distributions. [AK: and merged:] o Also put a message so that in future people can be aware of it and avoid introducing absolute symbols. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07 01:14:03 +00:00
__initcall_start = .;
INITCALLS
[PATCH] i386: Distinguish absolute symbols Ld knows about 2 kinds of symbols, absolute and section relative. Section relative symbols symbols change value when a section is moved and absolute symbols do not. Currently in the linker script we have several labels marking the beginning and ending of sections that are outside of sections, making them absolute symbols. Having a mixture of absolute and section relative symbols refereing to the same data is currently harmless but it is confusing. This must be done carefully as newer revs of ld do not place symbols that appear in sections without data and instead ld makes those symbols global :( My ultimate goal is to build a relocatable kernel. The safest and least intrusive technique is to generate relocation entries so the kernel can be relocated at load time. The only penalty would be an increase in the size of the kernel binary. The problem is that if absolute and relocatable symbols are not properly specified absolute symbols will be relocated or section relative symbols won't be, which is fatal. The practical motivation is that when generating kernels that will run from a reserved area for analyzing what caused a kernel panic, it is simpler if you don't need to hard code the physical memory location they will run at, especially for the distributions. [AK: and merged:] o Also put a message so that in future people can be aware of it and avoid introducing absolute symbols. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07 01:14:03 +00:00
__initcall_end = .;
}
.con_initcall.init : AT(ADDR(.con_initcall.init) - LOAD_OFFSET) {
[PATCH] i386: Distinguish absolute symbols Ld knows about 2 kinds of symbols, absolute and section relative. Section relative symbols symbols change value when a section is moved and absolute symbols do not. Currently in the linker script we have several labels marking the beginning and ending of sections that are outside of sections, making them absolute symbols. Having a mixture of absolute and section relative symbols refereing to the same data is currently harmless but it is confusing. This must be done carefully as newer revs of ld do not place symbols that appear in sections without data and instead ld makes those symbols global :( My ultimate goal is to build a relocatable kernel. The safest and least intrusive technique is to generate relocation entries so the kernel can be relocated at load time. The only penalty would be an increase in the size of the kernel binary. The problem is that if absolute and relocatable symbols are not properly specified absolute symbols will be relocated or section relative symbols won't be, which is fatal. The practical motivation is that when generating kernels that will run from a reserved area for analyzing what caused a kernel panic, it is simpler if you don't need to hard code the physical memory location they will run at, especially for the distributions. [AK: and merged:] o Also put a message so that in future people can be aware of it and avoid introducing absolute symbols. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07 01:14:03 +00:00
__con_initcall_start = .;
*(.con_initcall.init)
[PATCH] i386: Distinguish absolute symbols Ld knows about 2 kinds of symbols, absolute and section relative. Section relative symbols symbols change value when a section is moved and absolute symbols do not. Currently in the linker script we have several labels marking the beginning and ending of sections that are outside of sections, making them absolute symbols. Having a mixture of absolute and section relative symbols refereing to the same data is currently harmless but it is confusing. This must be done carefully as newer revs of ld do not place symbols that appear in sections without data and instead ld makes those symbols global :( My ultimate goal is to build a relocatable kernel. The safest and least intrusive technique is to generate relocation entries so the kernel can be relocated at load time. The only penalty would be an increase in the size of the kernel binary. The problem is that if absolute and relocatable symbols are not properly specified absolute symbols will be relocated or section relative symbols won't be, which is fatal. The practical motivation is that when generating kernels that will run from a reserved area for analyzing what caused a kernel panic, it is simpler if you don't need to hard code the physical memory location they will run at, especially for the distributions. [AK: and merged:] o Also put a message so that in future people can be aware of it and avoid introducing absolute symbols. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07 01:14:03 +00:00
__con_initcall_end = .;
}
SECURITY_INIT
. = ALIGN(4);
.altinstructions : AT(ADDR(.altinstructions) - LOAD_OFFSET) {
[PATCH] i386: Distinguish absolute symbols Ld knows about 2 kinds of symbols, absolute and section relative. Section relative symbols symbols change value when a section is moved and absolute symbols do not. Currently in the linker script we have several labels marking the beginning and ending of sections that are outside of sections, making them absolute symbols. Having a mixture of absolute and section relative symbols refereing to the same data is currently harmless but it is confusing. This must be done carefully as newer revs of ld do not place symbols that appear in sections without data and instead ld makes those symbols global :( My ultimate goal is to build a relocatable kernel. The safest and least intrusive technique is to generate relocation entries so the kernel can be relocated at load time. The only penalty would be an increase in the size of the kernel binary. The problem is that if absolute and relocatable symbols are not properly specified absolute symbols will be relocated or section relative symbols won't be, which is fatal. The practical motivation is that when generating kernels that will run from a reserved area for analyzing what caused a kernel panic, it is simpler if you don't need to hard code the physical memory location they will run at, especially for the distributions. [AK: and merged:] o Also put a message so that in future people can be aware of it and avoid introducing absolute symbols. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07 01:14:03 +00:00
__alt_instructions = .;
*(.altinstructions)
[PATCH] i386: Distinguish absolute symbols Ld knows about 2 kinds of symbols, absolute and section relative. Section relative symbols symbols change value when a section is moved and absolute symbols do not. Currently in the linker script we have several labels marking the beginning and ending of sections that are outside of sections, making them absolute symbols. Having a mixture of absolute and section relative symbols refereing to the same data is currently harmless but it is confusing. This must be done carefully as newer revs of ld do not place symbols that appear in sections without data and instead ld makes those symbols global :( My ultimate goal is to build a relocatable kernel. The safest and least intrusive technique is to generate relocation entries so the kernel can be relocated at load time. The only penalty would be an increase in the size of the kernel binary. The problem is that if absolute and relocatable symbols are not properly specified absolute symbols will be relocated or section relative symbols won't be, which is fatal. The practical motivation is that when generating kernels that will run from a reserved area for analyzing what caused a kernel panic, it is simpler if you don't need to hard code the physical memory location they will run at, especially for the distributions. [AK: and merged:] o Also put a message so that in future people can be aware of it and avoid introducing absolute symbols. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07 01:14:03 +00:00
__alt_instructions_end = .;
}
.altinstr_replacement : AT(ADDR(.altinstr_replacement) - LOAD_OFFSET) {
*(.altinstr_replacement)
}
. = ALIGN(4);
.parainstructions : AT(ADDR(.parainstructions) - LOAD_OFFSET) {
__parainstructions = .;
*(.parainstructions)
__parainstructions_end = .;
}
/* .exit.text is discard at runtime, not link time, to deal with references
from .altinstructions and .eh_frame */
.exit.text : AT(ADDR(.exit.text) - LOAD_OFFSET) { *(.exit.text) }
.exit.data : AT(ADDR(.exit.data) - LOAD_OFFSET) { *(.exit.data) }
#if defined(CONFIG_BLK_DEV_INITRD)
. = ALIGN(4096);
[PATCH] i386: Distinguish absolute symbols Ld knows about 2 kinds of symbols, absolute and section relative. Section relative symbols symbols change value when a section is moved and absolute symbols do not. Currently in the linker script we have several labels marking the beginning and ending of sections that are outside of sections, making them absolute symbols. Having a mixture of absolute and section relative symbols refereing to the same data is currently harmless but it is confusing. This must be done carefully as newer revs of ld do not place symbols that appear in sections without data and instead ld makes those symbols global :( My ultimate goal is to build a relocatable kernel. The safest and least intrusive technique is to generate relocation entries so the kernel can be relocated at load time. The only penalty would be an increase in the size of the kernel binary. The problem is that if absolute and relocatable symbols are not properly specified absolute symbols will be relocated or section relative symbols won't be, which is fatal. The practical motivation is that when generating kernels that will run from a reserved area for analyzing what caused a kernel panic, it is simpler if you don't need to hard code the physical memory location they will run at, especially for the distributions. [AK: and merged:] o Also put a message so that in future people can be aware of it and avoid introducing absolute symbols. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07 01:14:03 +00:00
.init.ramfs : AT(ADDR(.init.ramfs) - LOAD_OFFSET) {
__initramfs_start = .;
*(.init.ramfs)
__initramfs_end = .;
}
#endif
. = ALIGN(4096);
[PATCH] i386: Distinguish absolute symbols Ld knows about 2 kinds of symbols, absolute and section relative. Section relative symbols symbols change value when a section is moved and absolute symbols do not. Currently in the linker script we have several labels marking the beginning and ending of sections that are outside of sections, making them absolute symbols. Having a mixture of absolute and section relative symbols refereing to the same data is currently harmless but it is confusing. This must be done carefully as newer revs of ld do not place symbols that appear in sections without data and instead ld makes those symbols global :( My ultimate goal is to build a relocatable kernel. The safest and least intrusive technique is to generate relocation entries so the kernel can be relocated at load time. The only penalty would be an increase in the size of the kernel binary. The problem is that if absolute and relocatable symbols are not properly specified absolute symbols will be relocated or section relative symbols won't be, which is fatal. The practical motivation is that when generating kernels that will run from a reserved area for analyzing what caused a kernel panic, it is simpler if you don't need to hard code the physical memory location they will run at, especially for the distributions. [AK: and merged:] o Also put a message so that in future people can be aware of it and avoid introducing absolute symbols. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07 01:14:03 +00:00
.data.percpu : AT(ADDR(.data.percpu) - LOAD_OFFSET) {
__per_cpu_start = .;
*(.data.percpu)
*(.data.percpu.shared_aligned)
[PATCH] i386: Distinguish absolute symbols Ld knows about 2 kinds of symbols, absolute and section relative. Section relative symbols symbols change value when a section is moved and absolute symbols do not. Currently in the linker script we have several labels marking the beginning and ending of sections that are outside of sections, making them absolute symbols. Having a mixture of absolute and section relative symbols refereing to the same data is currently harmless but it is confusing. This must be done carefully as newer revs of ld do not place symbols that appear in sections without data and instead ld makes those symbols global :( My ultimate goal is to build a relocatable kernel. The safest and least intrusive technique is to generate relocation entries so the kernel can be relocated at load time. The only penalty would be an increase in the size of the kernel binary. The problem is that if absolute and relocatable symbols are not properly specified absolute symbols will be relocated or section relative symbols won't be, which is fatal. The practical motivation is that when generating kernels that will run from a reserved area for analyzing what caused a kernel panic, it is simpler if you don't need to hard code the physical memory location they will run at, especially for the distributions. [AK: and merged:] o Also put a message so that in future people can be aware of it and avoid introducing absolute symbols. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07 01:14:03 +00:00
__per_cpu_end = .;
}
. = ALIGN(4096);
/* freed after init ends here */
.bss : AT(ADDR(.bss) - LOAD_OFFSET) {
[PATCH] i386: Distinguish absolute symbols Ld knows about 2 kinds of symbols, absolute and section relative. Section relative symbols symbols change value when a section is moved and absolute symbols do not. Currently in the linker script we have several labels marking the beginning and ending of sections that are outside of sections, making them absolute symbols. Having a mixture of absolute and section relative symbols refereing to the same data is currently harmless but it is confusing. This must be done carefully as newer revs of ld do not place symbols that appear in sections without data and instead ld makes those symbols global :( My ultimate goal is to build a relocatable kernel. The safest and least intrusive technique is to generate relocation entries so the kernel can be relocated at load time. The only penalty would be an increase in the size of the kernel binary. The problem is that if absolute and relocatable symbols are not properly specified absolute symbols will be relocated or section relative symbols won't be, which is fatal. The practical motivation is that when generating kernels that will run from a reserved area for analyzing what caused a kernel panic, it is simpler if you don't need to hard code the physical memory location they will run at, especially for the distributions. [AK: and merged:] o Also put a message so that in future people can be aware of it and avoid introducing absolute symbols. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07 01:14:03 +00:00
__init_end = .;
__bss_start = .; /* BSS */
*(.bss.page_aligned)
*(.bss)
[PATCH] i386: Distinguish absolute symbols Ld knows about 2 kinds of symbols, absolute and section relative. Section relative symbols symbols change value when a section is moved and absolute symbols do not. Currently in the linker script we have several labels marking the beginning and ending of sections that are outside of sections, making them absolute symbols. Having a mixture of absolute and section relative symbols refereing to the same data is currently harmless but it is confusing. This must be done carefully as newer revs of ld do not place symbols that appear in sections without data and instead ld makes those symbols global :( My ultimate goal is to build a relocatable kernel. The safest and least intrusive technique is to generate relocation entries so the kernel can be relocated at load time. The only penalty would be an increase in the size of the kernel binary. The problem is that if absolute and relocatable symbols are not properly specified absolute symbols will be relocated or section relative symbols won't be, which is fatal. The practical motivation is that when generating kernels that will run from a reserved area for analyzing what caused a kernel panic, it is simpler if you don't need to hard code the physical memory location they will run at, especially for the distributions. [AK: and merged:] o Also put a message so that in future people can be aware of it and avoid introducing absolute symbols. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07 01:14:03 +00:00
. = ALIGN(4);
__bss_stop = .;
_end = . ;
/* This is where the kernel creates the early boot page tables */
. = ALIGN(4096);
pg0 = . ;
}
/* Sections to be discarded */
/DISCARD/ : {
*(.exitcall.exit)
}
STABS_DEBUG
DWARF_DEBUG
}