Revision ec3937107ab43f3e8b2bc9dad95710043c462ff7 authored by Baoquan He on 04 April 2019, 02:03:13 UTC, committed by Borislav Petkov on 18 April 2019, 08:42:58 UTC
kernel_randomize_memory() uses __PHYSICAL_MASK_SHIFT to calculate the maximum amount of system RAM supported. The size of the direct mapping section is obtained from the smaller one of the below two values: (actual system RAM size + padding size) vs (max system RAM size supported) This calculation is wrong since commit b83ce5ee9147 ("x86/mm/64: Make __PHYSICAL_MASK_SHIFT always 52"). In it, __PHYSICAL_MASK_SHIFT was changed to be 52, regardless of whether the kernel is using 4-level or 5-level page tables. Thus, it will always use 4 PB as the maximum amount of system RAM, even in 4-level paging mode where it should actually be 64 TB. Thus, the size of the direct mapping section will always be the sum of the actual system RAM size plus the padding size. Even when the amount of system RAM is 64 TB, the following layout will still be used. Obviously KALSR will be weakened significantly. |____|_______actual RAM_______|_padding_|______the rest_______| 0 64TB ~120TB Instead, it should be like this: |____|_______actual RAM_______|_________the rest______________| 0 64TB ~120TB The size of padding region is controlled by CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING, which is 10 TB by default. The above issue only exists when CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING is set to a non-zero value, which is the case when CONFIG_MEMORY_HOTPLUG is enabled. Otherwise, using __PHYSICAL_MASK_SHIFT doesn't affect KASLR. Fix it by replacing __PHYSICAL_MASK_SHIFT with MAX_PHYSMEM_BITS. [ bp: Massage commit message. ] Fixes: b83ce5ee9147 ("x86/mm/64: Make __PHYSICAL_MASK_SHIFT always 52") Signed-off-by: Baoquan He <bhe@redhat.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Thomas Garnier <thgarnie@google.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kees Cook <keescook@chromium.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: frank.ramsay@hpe.com Cc: herbert@gondor.apana.org.au Cc: kirill@shutemov.name Cc: mike.travis@hpe.com Cc: thgarnie@google.com Cc: x86-ml <x86@kernel.org> Cc: yamada.masahiro@socionext.com Link: https://lkml.kernel.org/r/20190417083536.GE7065@MiWiFi-R3L-srv
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percpu-stats.c
/*
* mm/percpu-debug.c
*
* Copyright (C) 2017 Facebook Inc.
* Copyright (C) 2017 Dennis Zhou <dennisz@fb.com>
*
* This file is released under the GPLv2.
*
* Prints statistics about the percpu allocator and backing chunks.
*/
#include <linux/debugfs.h>
#include <linux/list.h>
#include <linux/percpu.h>
#include <linux/seq_file.h>
#include <linux/sort.h>
#include <linux/vmalloc.h>
#include "percpu-internal.h"
#define P(X, Y) \
seq_printf(m, " %-20s: %12lld\n", X, (long long int)Y)
struct percpu_stats pcpu_stats;
struct pcpu_alloc_info pcpu_stats_ai;
static int cmpint(const void *a, const void *b)
{
return *(int *)a - *(int *)b;
}
/*
* Iterates over all chunks to find the max nr_alloc entries.
*/
static int find_max_nr_alloc(void)
{
struct pcpu_chunk *chunk;
int slot, max_nr_alloc;
max_nr_alloc = 0;
for (slot = 0; slot < pcpu_nr_slots; slot++)
list_for_each_entry(chunk, &pcpu_slot[slot], list)
max_nr_alloc = max(max_nr_alloc, chunk->nr_alloc);
return max_nr_alloc;
}
/*
* Prints out chunk state. Fragmentation is considered between
* the beginning of the chunk to the last allocation.
*
* All statistics are in bytes unless stated otherwise.
*/
static void chunk_map_stats(struct seq_file *m, struct pcpu_chunk *chunk,
int *buffer)
{
int i, last_alloc, as_len, start, end;
int *alloc_sizes, *p;
/* statistics */
int sum_frag = 0, max_frag = 0;
int cur_min_alloc = 0, cur_med_alloc = 0, cur_max_alloc = 0;
alloc_sizes = buffer;
/*
* find_last_bit returns the start value if nothing found.
* Therefore, we must determine if it is a failure of find_last_bit
* and set the appropriate value.
*/
last_alloc = find_last_bit(chunk->alloc_map,
pcpu_chunk_map_bits(chunk) -
chunk->end_offset / PCPU_MIN_ALLOC_SIZE - 1);
last_alloc = test_bit(last_alloc, chunk->alloc_map) ?
last_alloc + 1 : 0;
as_len = 0;
start = chunk->start_offset / PCPU_MIN_ALLOC_SIZE;
/*
* If a bit is set in the allocation map, the bound_map identifies
* where the allocation ends. If the allocation is not set, the
* bound_map does not identify free areas as it is only kept accurate
* on allocation, not free.
*
* Positive values are allocations and negative values are free
* fragments.
*/
while (start < last_alloc) {
if (test_bit(start, chunk->alloc_map)) {
end = find_next_bit(chunk->bound_map, last_alloc,
start + 1);
alloc_sizes[as_len] = 1;
} else {
end = find_next_bit(chunk->alloc_map, last_alloc,
start + 1);
alloc_sizes[as_len] = -1;
}
alloc_sizes[as_len++] *= (end - start) * PCPU_MIN_ALLOC_SIZE;
start = end;
}
/*
* The negative values are free fragments and thus sorting gives the
* free fragments at the beginning in largest first order.
*/
if (as_len > 0) {
sort(alloc_sizes, as_len, sizeof(int), cmpint, NULL);
/* iterate through the unallocated fragments */
for (i = 0, p = alloc_sizes; *p < 0 && i < as_len; i++, p++) {
sum_frag -= *p;
max_frag = max(max_frag, -1 * (*p));
}
cur_min_alloc = alloc_sizes[i];
cur_med_alloc = alloc_sizes[(i + as_len - 1) / 2];
cur_max_alloc = alloc_sizes[as_len - 1];
}
P("nr_alloc", chunk->nr_alloc);
P("max_alloc_size", chunk->max_alloc_size);
P("empty_pop_pages", chunk->nr_empty_pop_pages);
P("first_bit", chunk->first_bit);
P("free_bytes", chunk->free_bytes);
P("contig_bytes", chunk->contig_bits * PCPU_MIN_ALLOC_SIZE);
P("sum_frag", sum_frag);
P("max_frag", max_frag);
P("cur_min_alloc", cur_min_alloc);
P("cur_med_alloc", cur_med_alloc);
P("cur_max_alloc", cur_max_alloc);
seq_putc(m, '\n');
}
static int percpu_stats_show(struct seq_file *m, void *v)
{
struct pcpu_chunk *chunk;
int slot, max_nr_alloc;
int *buffer;
alloc_buffer:
spin_lock_irq(&pcpu_lock);
max_nr_alloc = find_max_nr_alloc();
spin_unlock_irq(&pcpu_lock);
/* there can be at most this many free and allocated fragments */
buffer = vmalloc(array_size(sizeof(int), (2 * max_nr_alloc + 1)));
if (!buffer)
return -ENOMEM;
spin_lock_irq(&pcpu_lock);
/* if the buffer allocated earlier is too small */
if (max_nr_alloc < find_max_nr_alloc()) {
spin_unlock_irq(&pcpu_lock);
vfree(buffer);
goto alloc_buffer;
}
#define PL(X) \
seq_printf(m, " %-20s: %12lld\n", #X, (long long int)pcpu_stats_ai.X)
seq_printf(m,
"Percpu Memory Statistics\n"
"Allocation Info:\n"
"----------------------------------------\n");
PL(unit_size);
PL(static_size);
PL(reserved_size);
PL(dyn_size);
PL(atom_size);
PL(alloc_size);
seq_putc(m, '\n');
#undef PL
#define PU(X) \
seq_printf(m, " %-20s: %12llu\n", #X, (unsigned long long)pcpu_stats.X)
seq_printf(m,
"Global Stats:\n"
"----------------------------------------\n");
PU(nr_alloc);
PU(nr_dealloc);
PU(nr_cur_alloc);
PU(nr_max_alloc);
PU(nr_chunks);
PU(nr_max_chunks);
PU(min_alloc_size);
PU(max_alloc_size);
P("empty_pop_pages", pcpu_nr_empty_pop_pages);
seq_putc(m, '\n');
#undef PU
seq_printf(m,
"Per Chunk Stats:\n"
"----------------------------------------\n");
if (pcpu_reserved_chunk) {
seq_puts(m, "Chunk: <- Reserved Chunk\n");
chunk_map_stats(m, pcpu_reserved_chunk, buffer);
}
for (slot = 0; slot < pcpu_nr_slots; slot++) {
list_for_each_entry(chunk, &pcpu_slot[slot], list) {
if (chunk == pcpu_first_chunk) {
seq_puts(m, "Chunk: <- First Chunk\n");
chunk_map_stats(m, chunk, buffer);
} else {
seq_puts(m, "Chunk:\n");
chunk_map_stats(m, chunk, buffer);
}
}
}
spin_unlock_irq(&pcpu_lock);
vfree(buffer);
return 0;
}
DEFINE_SHOW_ATTRIBUTE(percpu_stats);
static int __init init_percpu_stats_debugfs(void)
{
debugfs_create_file("percpu_stats", 0444, NULL, NULL,
&percpu_stats_fops);
return 0;
}
late_initcall(init_percpu_stats_debugfs);
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