kernel: fix crashlog regression on x86

Check memblock regions for sufficient size before attempting to use
them. Allow checks for multiple memblock regions until a suitable one is
found.

Signed-off-by: Felix Fietkau <nbd@nbd.name>

target/linux/generic/patches-4.4/930-crashlog.patch

@@ -43,7 +43,7 @@
  
 --- /dev/null
 +++ b/kernel/crashlog.c
-@@ -0,0 +1,193 @@
+@@ -0,0 +1,196 @@
 +/*
 + * Crash information logger
 + * Copyright (C) 2010 Felix Fietkau <nbd@nbd.name>
@@ -127,6 +127,9 @@
 +	if (crashlog_addr)
 +		return;
 +
++	if (size <= CRASHLOG_OFFSET + CRASHLOG_SIZE)
++		return;
++
 +	addr += size - CRASHLOG_OFFSET;
 +	if (memblock_reserve(addr, CRASHLOG_SIZE)) {
 +		printk("Crashlog failed to allocate RAM at address 0x%lx\n", (unsigned long) addr);
@@ -237,24 +240,6 @@
 +	return 0;
 +}
 +module_init(crashlog_init_fs);
---- a/mm/bootmem.c
-+++ b/mm/bootmem.c
-@@ -15,6 +15,7 @@
- #include <linux/export.h>
- #include <linux/kmemleak.h>
- #include <linux/range.h>
-+#include <linux/crashlog.h>
- #include <linux/memblock.h>
- #include <linux/bug.h>
- #include <linux/io.h>
-@@ -177,6 +178,7 @@ static unsigned long __init free_all_boo
- 	if (!bdata->node_bootmem_map)
- 		return 0;
- 
-+	crashlog_init_bootmem(bdata);
- 	map = bdata->node_bootmem_map;
- 	start = bdata->node_min_pfn;
- 	end = bdata->node_low_pfn;
 --- a/kernel/module.c
 +++ b/kernel/module.c
 @@ -275,6 +275,9 @@ static void mod_update_bounds(struct mod
@@ -277,7 +262,16 @@
  
  #include <asm-generic/sections.h>
  #include <linux/io.h>
-@@ -541,6 +542,8 @@ int __init_memblock memblock_add_range(s
+@@ -503,6 +504,8 @@ static void __init_memblock memblock_ins
+ 	memblock_set_region_node(rgn, nid);
+ 	type->cnt++;
+ 	type->total_size += size;
++	if (type == &memblock.memory)
++		crashlog_init_memblock(base, size);
+ }
+ 
+ /**
+@@ -541,6 +544,8 @@ int __init_memblock memblock_add_range(s
  		type->regions[0].flags = flags;
  		memblock_set_region_node(&type->regions[0], nid);
  		type->total_size = size;
@@ -286,3 +280,21 @@
  		return 0;
  	}
  repeat:
+--- a/mm/bootmem.c
++++ b/mm/bootmem.c
+@@ -15,6 +15,7 @@
+ #include <linux/export.h>
+ #include <linux/kmemleak.h>
+ #include <linux/range.h>
++#include <linux/crashlog.h>
+ #include <linux/memblock.h>
+ #include <linux/bug.h>
+ #include <linux/io.h>
+@@ -177,6 +178,7 @@ static unsigned long __init free_all_boo
+ 	if (!bdata->node_bootmem_map)
+ 		return 0;
+ 
++	crashlog_init_bootmem(bdata);
+ 	map = bdata->node_bootmem_map;
+ 	start = bdata->node_min_pfn;
+ 	end = bdata->node_low_pfn;