2008-02-23 08:58:20 +00:00
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/*
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* linux/arch/i386/kernel/head32.c -- prepare to run common code
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*
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* Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
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* Copyright (C) 2007 Eric Biederman <ebiederm@xmission.com>
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*/
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#include <linux/init.h>
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#include <linux/start_kernel.h>
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x86: Make sure free_init_pages() frees pages on page boundary
When CONFIG_NO_BOOTMEM=y, it could use memory more effiently, or
in a more compact fashion.
Example:
Allocated new RAMDISK: 00ec2000 - 0248ce57
Move RAMDISK from 000000002ea04000 - 000000002ffcee56 to 00ec2000 - 0248ce56
The new RAMDISK's end is not page aligned.
Last page could be shared with other users.
When free_init_pages are called for initrd or .init, the page
could be freed and we could corrupt other data.
code segment in free_init_pages():
| for (; addr < end; addr += PAGE_SIZE) {
| ClearPageReserved(virt_to_page(addr));
| init_page_count(virt_to_page(addr));
| memset((void *)(addr & ~(PAGE_SIZE-1)),
| POISON_FREE_INITMEM, PAGE_SIZE);
| free_page(addr);
| totalram_pages++;
| }
last half page could be used as one whole free page.
So page align the boundaries.
-v2: make the original initramdisk to be aligned, according to
Johannes, otherwise we have the chance to lose one page.
we still need to keep initrd_end not aligned, otherwise it could
confuse decompressor.
-v3: change to WARN_ON instead, suggested by Johannes.
-v4: use PAGE_ALIGN, suggested by Johannes.
We may fix that macro name later to PAGE_ALIGN_UP, and PAGE_ALIGN_DOWN
Add comments about assuming ramdisk start is aligned
in relocate_initrd(), change to re get ramdisk_image instead of save it
to make diff smaller. Add warning for wrong range, suggested by Johannes.
-v6: remove one WARN()
We need to align beginning in free_init_pages()
do not copy more than ramdisk_size, noticed by Johannes
Reported-by: Stanislaw Gruszka <sgruszka@redhat.com>
Tested-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: David Miller <davem@davemloft.net>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <1269830604-26214-3-git-send-email-yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-03-29 02:42:55 +00:00
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#include <linux/mm.h>
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2010-08-25 20:39:17 +00:00
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#include <linux/memblock.h>
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2008-02-23 08:58:20 +00:00
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2008-05-18 08:18:57 +00:00
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#include <asm/setup.h>
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#include <asm/sections.h>
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#include <asm/e820.h>
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2009-08-19 12:36:27 +00:00
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#include <asm/page.h>
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2009-08-20 07:27:29 +00:00
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#include <asm/apic.h>
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#include <asm/io_apic.h>
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2009-08-29 13:03:59 +00:00
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#include <asm/bios_ebda.h>
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2010-08-28 13:58:33 +00:00
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#include <asm/tlbflush.h>
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2013-01-29 09:05:24 +00:00
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#include <asm/bootparam_utils.h>
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2009-08-29 13:03:59 +00:00
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static void __init i386_default_early_setup(void)
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{
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2010-06-11 10:17:00 +00:00
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/* Initialize 32bit specific setup functions */
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2009-08-29 13:03:59 +00:00
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x86_init.resources.reserve_resources = i386_reserve_resources;
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x86_init.mpparse.setup_ioapic_ids = setup_ioapic_ids_from_mpc;
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x86/boot: Reorganize and clean up the BIOS area reservation code
So the reserve_ebda_region() code has accumulated a number of
problems over the years that make it really difficult to read
and understand:
- The calculation of 'lowmem' and 'ebda_addr' is an unnecessarily
interleaved mess of first lowmem, then ebda_addr, then lowmem tweaks...
- 'lowmem' here means 'super low mem' - i.e. 16-bit addressable memory. In other
parts of the x86 code 'lowmem' means 32-bit addressable memory... This makes it
super confusing to read.
- It does not help at all that we have various memory range markers, half of which
are 'start of range', half of which are 'end of range' - but this crucial
property is not obvious in the naming at all ... gave me a headache trying to
understand all this.
- Also, the 'ebda_addr' name sucks: it highlights that it's an address (which is
obvious, all values here are addresses!), while it does not highlight that it's
the _start_ of the EBDA region ...
- 'BIOS_LOWMEM_KILOBYTES' says a lot of things, except that this is the only value
that is a pointer to a value, not a memory range address!
- The function name itself is a misnomer: it says 'reserve_ebda_region()' while
its main purpose is to reserve all the firmware ROM typically between 640K and
1MB, while the 'EBDA' part is only a small part of that ...
- Likewise, the paravirt quirk flag name 'ebda_search' is misleading as well: this
too should be about whether to reserve firmware areas in the paravirt case.
- In fact thinking about this as 'end of RAM' is confusing: what this function
*really* wants to reserve is firmware data and code areas! Once the thinking is
inverted from a mixed 'ram' and 'reserved firmware area' notion to a pure
'reserved area' notion everything becomes a lot clearer.
To improve all this rewrite the whole code (without changing the logic):
- Firstly invert the naming from 'lowmem end' to 'BIOS reserved area start'
and propagate this concept through all the variable names and constants.
BIOS_RAM_SIZE_KB_PTR // was: BIOS_LOWMEM_KILOBYTES
BIOS_START_MIN // was: INSANE_CUTOFF
ebda_start // was: ebda_addr
bios_start // was: lowmem
BIOS_START_MAX // was: LOWMEM_CAP
- Then clean up the name of the function itself by renaming it
to reserve_bios_regions() and renaming the ::ebda_search paravirt
flag to ::reserve_bios_regions.
- Fix up all the comments (fix typos), harmonize and simplify their
formulation and remove comments that become unnecessary due to
the much better naming all around.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-21 07:53:52 +00:00
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reserve_bios_regions();
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2009-08-29 13:03:59 +00:00
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}
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2008-05-18 08:18:57 +00:00
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2014-05-01 22:44:37 +00:00
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asmlinkage __visible void __init i386_start_kernel(void)
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2008-02-23 08:58:20 +00:00
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{
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2014-10-24 22:58:08 +00:00
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cr4_init_shadow();
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2013-01-29 09:05:24 +00:00
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sanitize_boot_params(&boot_params);
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2016-04-14 00:04:34 +00:00
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x86_early_init_platform_quirks();
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2009-08-29 13:03:59 +00:00
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/* Call the subarch specific early setup function */
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switch (boot_params.hdr.hardware_subarch) {
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2013-10-17 22:35:29 +00:00
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case X86_SUBARCH_INTEL_MID:
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x86_intel_mid_early_setup();
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2009-08-29 12:54:20 +00:00
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break;
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2010-11-09 20:08:04 +00:00
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case X86_SUBARCH_CE4100:
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x86_ce4100_early_setup();
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break;
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2009-08-29 13:03:59 +00:00
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default:
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i386_default_early_setup();
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break;
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}
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2008-05-18 08:18:57 +00:00
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2008-02-23 08:58:20 +00:00
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start_kernel();
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}
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