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x86/boot/e820: Rename e820_table_saved to e820_table_firmware and improve the description

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So the 'e820_table_saved' is a bit of a misnomer that hides its real purpose.

At first sight the name suggests that it's some sort save/restore mechanism,
as this is how we typically name such facilities in the kernel.

But that is not so, e820_table_saved is the original firmware version of the
e820 table, not modified by the kernel. This table is displayed in the
/sys/firmware/memmap file, and it's also used by the hibernation code to
calculate a physical memory layout MD5 fingerprint checksum which is
invariant of the kernel.

So rename it to 'e820_table_firmware' and update all the comments to better
describe the main e820 data strutures.

Also rename:

  'initial_e820_table_saved'  =>  'e820_table_firmware_init'
  'e820_update_range_saved'   =>  'e820_update_range_firmware'

... to better match the new nomenclature.

No change in functionality.

Cc: Alex Thorlton <athorlton@sgi.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Jackson <pj@sgi.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Ingo Molnar 2017-01-28 10:07:49 +01:00
parent 103e206309
commit 544a0f47e7
5 changed files with 56 additions and 37 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
arch/x86/include/asm/e820/api.h
View File

@ -3,9 +3,8 @@
#include <asm/e820/types.h>
/* see comment in arch/x86/kernel/e820.c */
extern struct e820_table *e820_table;
extern struct e820_table *e820_table_saved;
extern struct e820_table *e820_table_firmware;
extern unsigned long pci_mem_start;

74
arch/x86/kernel/e820.c
View File

@ -27,23 +27,43 @@
#include <asm/cpufeature.h>
/*
* The e820 table is the array that gets modified e.g. with command line parameters
* and that is also registered with modifications in the kernel resource tree
* with the iomem_resource as parent.
* The firmware and bootloader passes us an E820 table that is the primary
* physical memory layout description available about x86 systems.
*
* The e820_table_saved is directly saved after the BIOS-provided memory map is
* copied. It doesn't get modified afterwards. It's registered for the
* /sys/firmware/memmap interface.
* The kernel takes the e820 memory layout and optionally modifies it with
* quirks and other tweaks, and feeds that into the generic Linux memory
* allocation code routines via a platform independent interface (memblock, etc.).
*
* That memory map is not modified and is used as base for kexec. The kexec'd
* kernel should get the same memory map as the firmware provides. Then the
* user can e.g. boot the original kernel with mem=1G while still booting the
* next kernel with full memory.
* We organize the E820 table into two main data structures:
*
* - 'e820_table_firmware': the original firmware version passed to us by the
* bootloader - not modified by the kernel. We use this to:
*
* - inform the user about the firmware's notion of memory layout
* via /sys/firmware/memmap
*
* - the hibernation code uses it to generate a kernel-independent MD5
* fingerprint of the physical memory layout of a system.
*
* - kexec, which is a bootloader in disguise, uses the original e820
* layout to pass to the kexec-ed kernel. This way the original kernel
* can have a restricted e820 map while the kexec()-ed kexec-kernel
* can have access to full memory - etc.
*
* - 'e820_table': this is the main e820 table that is massaged by the
* low level x86 platform code, or modified by boot parameters, before
* passed on to higher level MM layers.
*
* Once the e820 map has been converted to the standard Linux memory layout
* information its role stops - modifying it has no effect and does not get
* re-propagated. So itsmain role is a temporary bootstrap storage of firmware
* specific memory layout data during early bootup.
*/
static struct e820_table e820_table_init __initdata;
static struct e820_table initial_e820_table_saved __initdata;
static struct e820_table e820_table_firmware_init __initdata;
struct e820_table *e820_table __refdata = &e820_table_init;
struct e820_table *e820_table_saved __refdata = &initial_e820_table_saved;
struct e820_table *e820_table_firmware __refdata = &e820_table_firmware_init;
/* For PCI or other memory-mapped resources */
unsigned long pci_mem_start = 0xaeedbabe;
@ -497,10 +517,10 @@ u64 __init e820_update_range(u64 start, u64 size, unsigned old_type,
return __e820_update_range(e820_table, start, size, old_type, new_type);
}
static u64 __init e820_update_range_saved(u64 start, u64 size,
static u64 __init e820_update_range_firmware(u64 start, u64 size,
unsigned old_type, unsigned new_type)
{
return __e820_update_range(e820_table_saved, start, size, old_type,
return __e820_update_range(e820_table_firmware, start, size, old_type,
new_type);
}
@ -572,9 +592,9 @@ void __init update_e820(void)
printk(KERN_INFO "e820: modified physical RAM map:\n");
e820_print_map("modified");
}
static void __init update_e820_table_saved(void)
static void __init update_e820_table_firmware(void)
{
sanitize_e820_table(e820_table_saved->entries, ARRAY_SIZE(e820_table_saved->entries), &e820_table_saved->nr_entries);
sanitize_e820_table(e820_table_firmware->entries, ARRAY_SIZE(e820_table_firmware->entries), &e820_table_firmware->nr_entries);
}
#define MAX_GAP_END 0x100000000ull
/*
@ -648,7 +668,7 @@ __init void e820_setup_gap(void)
/*
* Called late during init, in free_initmem().
*
* Initial e820 and e820_table_saved are largish __initdata arrays.
* Initial e820 and e820_table_firmware are largish __initdata arrays.
* Copy them to (usually much smaller) dynamically allocated area.
* This is done after all tweaks we ever do to them:
* all functions which modify them are __init functions,
@ -665,11 +685,11 @@ __init void e820_reallocate_tables(void)
memcpy(n, e820_table, size);
e820_table = n;
size = offsetof(struct e820_table, entries) + sizeof(struct e820_entry) * e820_table_saved->nr_entries;
size = offsetof(struct e820_table, entries) + sizeof(struct e820_entry) * e820_table_firmware->nr_entries;
n = kmalloc(size, GFP_KERNEL);
BUG_ON(!n);
memcpy(n, e820_table_saved, size);
e820_table_saved = n;
memcpy(n, e820_table_firmware, size);
e820_table_firmware = n;
}
/**
@ -745,7 +765,7 @@ core_initcall(e820_mark_nvs_memory);
#endif
/*
* pre allocated 4k and reserved it in memblock and e820_table_saved
* pre allocated 4k and reserved it in memblock and e820_table_firmware
*/
u64 __init early_reserve_e820(u64 size, u64 align)
{
@ -753,9 +773,9 @@ u64 __init early_reserve_e820(u64 size, u64 align)
addr = __memblock_alloc_base(size, align, MEMBLOCK_ALLOC_ACCESSIBLE);
if (addr) {
e820_update_range_saved(addr, size, E820_RAM, E820_RESERVED);
printk(KERN_INFO "e820: update e820_table_saved for early_reserve_e820\n");
update_e820_table_saved();
e820_update_range_firmware(addr, size, E820_RAM, E820_RESERVED);
printk(KERN_INFO "e820: update e820_table_firmware for early_reserve_e820\n");
update_e820_table_firmware();
}
return addr;
@ -1034,8 +1054,8 @@ void __init e820_reserve_resources(void)
res++;
}
for (i = 0; i < e820_table_saved->nr_entries; i++) {
struct e820_entry *entry = &e820_table_saved->entries[i];
for (i = 0; i < e820_table_firmware->nr_entries; i++) {
struct e820_entry *entry = &e820_table_firmware->entries[i];
firmware_map_add_early(entry->addr,
entry->addr + entry->size,
e820_type_to_string(entry->type));
@ -1145,7 +1165,7 @@ void __init e820__memory_setup(void)
char *who;
who = x86_init.resources.memory_setup();
memcpy(e820_table_saved, e820_table, sizeof(struct e820_table));
memcpy(e820_table_firmware, e820_table, sizeof(struct e820_table));
printk(KERN_INFO "e820: BIOS-provided physical RAM map:\n");
e820_print_map(who);
}

4
arch/x86/kernel/kexec-bzimage64.c
View File

@ -100,14 +100,14 @@ static int setup_e820_entries(struct boot_params *params)
{
unsigned int nr_e820_entries;
nr_e820_entries = e820_table_saved->nr_entries;
nr_e820_entries = e820_table_firmware->nr_entries;
/* TODO: Pass entries more than E820MAX in bootparams setup data */
if (nr_e820_entries > E820MAX)
nr_e820_entries = E820MAX;
params->e820_entries = nr_e820_entries;
memcpy(&params->e820_table, &e820_table_saved->entries, nr_e820_entries*sizeof(struct e820_entry));
memcpy(&params->e820_table, &e820_table_firmware->entries, nr_e820_entries*sizeof(struct e820_entry));
return 0;
}

4
arch/x86/kernel/setup.c
View File

@ -459,7 +459,7 @@ static void __init e820_reserve_setup_data(void)
}
sanitize_e820_table(e820_table->entries, ARRAY_SIZE(e820_table->entries), &e820_table->nr_entries);
memcpy(e820_table_saved, e820_table, sizeof(struct e820_table));
memcpy(e820_table_firmware, e820_table, sizeof(struct e820_table));
printk(KERN_INFO "extended physical RAM map:\n");
e820_print_map("reserve setup_data");
}
@ -1026,7 +1026,7 @@ void __init setup_arch(char **cmdline_p)
early_dump_pci_devices();
#endif
/* update the e820_table_saved too */
/* update the e820_table_firmware too */
e820_reserve_setup_data();
finish_e820_parsing();

4
arch/x86/power/hibernate_64.c
View File

@ -231,7 +231,7 @@ static int get_e820_md5(struct e820_table *table, void *buf)
static void hibernation_e820_save(void *buf)
{
get_e820_md5(e820_table_saved, buf);
get_e820_md5(e820_table_firmware, buf);
}
static bool hibernation_e820_mismatch(void *buf)
@ -244,7 +244,7 @@ static bool hibernation_e820_mismatch(void *buf)
if (!memcmp(result, buf, MD5_DIGEST_SIZE))
return false;
ret = get_e820_md5(e820_table_saved, result);
ret = get_e820_md5(e820_table_firmware, result);
if (ret)
return true;