kernel_optimize_test/arch/arm64/kernel/vmlinux.lds.S
Mark Rutland bd00cd5f8c arm64: place initial page tables above the kernel
Currently we place swapper_pg_dir and idmap_pg_dir below the kernel
image, between PHYS_OFFSET and (PHYS_OFFSET + TEXT_OFFSET). However,
bootloaders may use portions of this memory below the kernel and we do
not parse the memory reservation list until after the MMU has been
enabled. As such we may clobber some memory a bootloader wishes to have
preserved.

To enable the use of all of this memory by bootloaders (when the
required memory reservations are communicated to the kernel) it is
necessary to move our initial page tables elsewhere. As we currently
have an effectively unbound requirement for memory at the end of the
kernel image for .bss, we can place the page tables here.

This patch moves the initial page table to the end of the kernel image,
after the BSS. As they do not consist of any initialised data they will
be stripped from the kernel Image as with the BSS. The BSS clearing
routine is updated to stop at __bss_stop rather than _end so as to not
clobber the page tables, and memory reservations made redundant by the
new organisation are removed.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Laura Abbott <lauraa@codeaurora.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2014-07-10 12:36:12 +01:00

124 lines
2.3 KiB
ArmAsm

/*
* ld script to make ARM Linux kernel
* taken from the i386 version by Russell King
* Written by Martin Mares <mj@atrey.karlin.mff.cuni.cz>
*/
#include <asm-generic/vmlinux.lds.h>
#include <asm/thread_info.h>
#include <asm/memory.h>
#include <asm/page.h>
#define ARM_EXIT_KEEP(x)
#define ARM_EXIT_DISCARD(x) x
OUTPUT_ARCH(aarch64)
ENTRY(_text)
jiffies = jiffies_64;
#define HYPERVISOR_TEXT \
/* \
* Force the alignment to be compatible with \
* the vectors requirements \
*/ \
. = ALIGN(2048); \
VMLINUX_SYMBOL(__hyp_idmap_text_start) = .; \
*(.hyp.idmap.text) \
VMLINUX_SYMBOL(__hyp_idmap_text_end) = .; \
VMLINUX_SYMBOL(__hyp_text_start) = .; \
*(.hyp.text) \
VMLINUX_SYMBOL(__hyp_text_end) = .;
SECTIONS
{
/*
* XXX: The linker does not define how output sections are
* assigned to input sections when there are multiple statements
* matching the same input section name. There is no documented
* order of matching.
*/
/DISCARD/ : {
ARM_EXIT_DISCARD(EXIT_TEXT)
ARM_EXIT_DISCARD(EXIT_DATA)
EXIT_CALL
*(.discard)
*(.discard.*)
}
. = PAGE_OFFSET + TEXT_OFFSET;
.head.text : {
_text = .;
HEAD_TEXT
}
.text : { /* Real text segment */
_stext = .; /* Text and read-only data */
__exception_text_start = .;
*(.exception.text)
__exception_text_end = .;
IRQENTRY_TEXT
TEXT_TEXT
SCHED_TEXT
LOCK_TEXT
HYPERVISOR_TEXT
*(.fixup)
*(.gnu.warning)
. = ALIGN(16);
*(.got) /* Global offset table */
}
RO_DATA(PAGE_SIZE)
EXCEPTION_TABLE(8)
NOTES
_etext = .; /* End of text and rodata section */
. = ALIGN(PAGE_SIZE);
__init_begin = .;
INIT_TEXT_SECTION(8)
.exit.text : {
ARM_EXIT_KEEP(EXIT_TEXT)
}
. = ALIGN(16);
.init.data : {
INIT_DATA
INIT_SETUP(16)
INIT_CALLS
CON_INITCALL
SECURITY_INITCALL
INIT_RAM_FS
}
.exit.data : {
ARM_EXIT_KEEP(EXIT_DATA)
}
PERCPU_SECTION(64)
__init_end = .;
. = ALIGN(PAGE_SIZE);
_data = .;
_sdata = .;
RW_DATA_SECTION(64, PAGE_SIZE, THREAD_SIZE)
_edata = .;
BSS_SECTION(0, 0, 0)
. = ALIGN(PAGE_SIZE);
idmap_pg_dir = .;
. += IDMAP_DIR_SIZE;
swapper_pg_dir = .;
. += SWAPPER_DIR_SIZE;
_end = .;
STABS_DEBUG
}
/*
* The HYP init code can't be more than a page long.
*/
ASSERT(((__hyp_idmap_text_start + PAGE_SIZE) > __hyp_idmap_text_end),
"HYP init code too big")