x86, boot: add free_early to early reservation machanism

Add free_early to early reservation mechanism - this way early bootup
failure paths can stop wasting memory.

Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

2 files changed, 23 insertions, 0 deletions

diff --git a/arch/x86/kernel/e820_64.c b/arch/x86/kernel/e820_64.c
index cbd42e51cb08..79f0d52fa99a 100644
--- a/arch/x86/kernel/e820_64.c
+++ b/arch/x86/kernel/e820_64.c
@@ -84,6 +84,28 @@ void __init reserve_early(unsigned long start, unsigned long end, char *name)
                 strncpy(r->name, name, sizeof(r->name) - 1);
 }
 
+void __init free_early(unsigned long start, unsigned long end)
+{
+        struct early_res *r;
+        int i, j;
+
+        for (i = 0; i < MAX_EARLY_RES && early_res[i].end; i++) {
+                r = &early_res[i];
+                if (start == r->start && end == r->end)
+                        break;
+        }
+        if (i >= MAX_EARLY_RES || !early_res[i].end)
+                panic("free_early on not reserved area: %lx-%lx!", start, end);
+
+        for (j = i + 1; j < MAX_EARLY_RES && early_res[j].end; j++)
+                ;
+
+        memcpy(&early_res[i], &early_res[i + 1],
+               (j - 1 - i) * sizeof(struct early_res));
+
+        early_res[j - 1].end = 0;
+}
+
 void __init early_res_to_bootmem(void)
 {
         int i;
diff --git a/include/asm-x86/e820_64.h b/include/asm-x86/e820_64.h
index f478c57eb060..b5e02e379af3 100644
--- a/include/asm-x86/e820_64.h
+++ b/include/asm-x86/e820_64.h
@@ -48,6 +48,7 @@ extern struct e820map e820;
 extern void update_e820(void);
 
 extern void reserve_early(unsigned long start, unsigned long end, char *name);
+extern void free_early(unsigned long start, unsigned long end);
 extern void early_res_to_bootmem(void);
 
 #endif/*!__ASSEMBLY__*/