early_res: Enhance check_and_double_early_res

... to make it always try to start from low at first.

This makes it less likely for early_memtest to reserve a bad range, in
particular it puts new early_res in a range that is already tested.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <1265793639-15071-24-git-send-email-yinghai@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

1 files changed, 20 insertions, 7 deletions

diff --git a/arch/x86/kernel/early_res.c b/arch/x86/kernel/early_res.c
index 1b99a2619f9f..dbf08bd01252 100644
--- a/arch/x86/kernel/early_res.c
+++ b/arch/x86/kernel/early_res.c
@@ -180,9 +180,9 @@ void __init reserve_early_overlap_ok(u64 start, u64 end, char *name)
         __reserve_early(start, end, name, 1);
 }
 
-static void __init __check_and_double_early_res(u64 start)
+static void __init __check_and_double_early_res(u64 ex_start, u64 ex_end)
 {
-        u64 end, size, mem;
+        u64 start, end, size, mem;
         struct early_res *new;
 
         /* do we have enough slots left ? */
@@ -190,10 +190,23 @@ static void __init __check_and_double_early_res(u64 start)
                 return;
 
         /* double it */
-        end = max_pfn_mapped << PAGE_SHIFT;
+        mem = -1ULL;
         size = sizeof(struct early_res) * max_early_res * 2;
-        mem = find_e820_area(start, end, size, sizeof(struct early_res));
-
+        if (early_res == early_res_x)
+                start = 0;
+        else
+                start = early_res[0].end;
+        end = ex_start;
+        if (start + size < end)
+                mem = find_e820_area(start, end, size,
+                                         sizeof(struct early_res));
+        if (mem == -1ULL) {
+                start = ex_end;
+                end = max_pfn_mapped << PAGE_SHIFT;
+                if (start + size < end)
+                        mem = find_e820_area(start, end, size,
+                                                 sizeof(struct early_res));
+        }
         if (mem == -1ULL)
                 panic("can not find more space for early_res array");
 
@@ -235,7 +248,7 @@ void __init reserve_early(u64 start, u64 end, char *name)
         if (start >= end)
                 return;
 
-        __check_and_double_early_res(end);
+        __check_and_double_early_res(start, end);
 
         drop_overlaps_that_are_ok(start, end);
         __reserve_early(start, end, name, 0);
@@ -248,7 +261,7 @@ void __init reserve_early_without_check(u64 start, u64 end, char *name)
         if (start >= end)
                 return;
 
-        __check_and_double_early_res(end);
+        __check_and_double_early_res(start, end);
 
         r = &early_res[early_res_count];