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authorJan Beulich <jbeulich@novell.com>2009-03-12 13:07:23 +0000
committerIngo Molnar <mingo@elte.hu>2009-03-13 02:37:19 +0100
commit5c0e6f035df983210e4d22213aed624ced502d3d (patch)
tree6986ed92d5f62f421d3b3be776132994c8c05d6b /arch/x86/kernel/e820.c
parent82034d6f59b4772f4233bbb61c670290803a9960 (diff)
x86: fix code paths used by update_mptable
Impact: fix crashes under Xen due to unrobust e820 code find_e820_area_size() must return a properly distinguishable and out-of-bounds value when it fails, and -1UL does not meet that criteria on i386/PAE. Additionally, callers of the function must check against that value. early_reserve_e820() should be prepared for the region found to be outside of the addressable range on 32-bits. e820_update_range_map() should not blindly update e820, but should do all it work on the map it got a pointer passed for (which in 50% of the cases is &e820_saved). It must also not call e820_add_region(), as that again acts on e820 unconditionally. The issues were found when trying to make this option work in our Xen kernel (i.e. where some of the silent assumptions made in the code would not hold). Signed-off-by: Jan Beulich <jbeulich@novell.com> LKML-Reference: <49B9171B.76E4.0078.0@novell.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel/e820.c')
-rw-r--r--arch/x86/kernel/e820.c32
1 files changed, 25 insertions, 7 deletions
diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index 508bec1cee2..3cf6681ac80 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -421,7 +421,7 @@ static u64 __init e820_update_range_map(struct e820map *e820x, u64 start,
u64 size, unsigned old_type,
unsigned new_type)
{
- int i;
+ unsigned int i, x;
u64 real_updated_size = 0;
BUG_ON(old_type == new_type);
@@ -429,7 +429,7 @@ static u64 __init e820_update_range_map(struct e820map *e820x, u64 start,
if (size > (ULLONG_MAX - start))
size = ULLONG_MAX - start;
- for (i = 0; i < e820.nr_map; i++) {
+ for (i = 0; i < e820x->nr_map; i++) {
struct e820entry *ei = &e820x->map[i];
u64 final_start, final_end;
if (ei->type != old_type)
@@ -446,14 +446,23 @@ static u64 __init e820_update_range_map(struct e820map *e820x, u64 start,
final_end = min(start + size, ei->addr + ei->size);
if (final_start >= final_end)
continue;
- e820_add_region(final_start, final_end - final_start,
- new_type);
+
+ x = e820x->nr_map;
+ if (x == ARRAY_SIZE(e820x->map)) {
+ printk(KERN_ERR "Too many memory map entries!\n");
+ break;
+ }
+ e820x->map[x].addr = final_start;
+ e820x->map[x].size = final_end - final_start;
+ e820x->map[x].type = new_type;
+ e820x->nr_map++;
+
real_updated_size += final_end - final_start;
- ei->size -= final_end - final_start;
if (ei->addr < final_start)
continue;
ei->addr = final_end;
+ ei->size -= final_end - final_start;
}
return real_updated_size;
}
@@ -1020,8 +1029,8 @@ u64 __init find_e820_area_size(u64 start, u64 *sizep, u64 align)
continue;
return addr;
}
- return -1UL;
+ return -1ULL;
}
/*
@@ -1034,13 +1043,22 @@ u64 __init early_reserve_e820(u64 startt, u64 sizet, u64 align)
u64 start;
start = startt;
- while (size < sizet)
+ while (size < sizet && (start + 1))
start = find_e820_area_size(start, &size, align);
if (size < sizet)
return 0;
+#ifdef CONFIG_X86_32
+ if (start >= MAXMEM)
+ return 0;
+ if (start + size > MAXMEM)
+ size = MAXMEM - start;
+#endif
+
addr = round_down(start + size - sizet, align);
+ if (addr < start)
+ return 0;
e820_update_range(addr, sizet, E820_RAM, E820_RESERVED);
e820_update_range_saved(addr, sizet, E820_RAM, E820_RESERVED);
printk(KERN_INFO "update e820 for early_reserve_e820\n");