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-rw-r--r--arch/x86/kernel/head_32.S43
-rw-r--r--arch/x86/kernel/vmlinux_32.lds.S6
2 files changed, 20 insertions, 29 deletions
diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
index 9e89f2a14b9..c79741cfb07 100644
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -41,41 +41,28 @@
* This is how much memory *in addition to the memory covered up to
* and including _end* we need mapped initially.
* We need:
- * - one bit for each possible page, but only in low memory, which means
- * 2^32/4096/8 = 128K worst case (4G/4G split.)
- * - enough space to map all low memory, which means
- * (2^32/4096) / 1024 pages (worst case, non PAE)
- * (2^32/4096) / 512 + 4 pages (worst case for PAE)
- * - a few pages for allocator use before the kernel pagetable has
- * been set up
+ * (KERNEL_IMAGE_SIZE/4096) / 1024 pages (worst case, non PAE)
+ * (KERNEL_IMAGE_SIZE/4096) / 512 + 4 pages (worst case for PAE)
*
* Modulo rounding, each megabyte assigned here requires a kilobyte of
* memory, which is currently unreclaimed.
*
* This should be a multiple of a page.
+ *
+ * KERNEL_IMAGE_SIZE should be greater than pa(_end)
+ * and small than max_low_pfn, otherwise will waste some page table entries
*/
LOW_PAGES = (KERNEL_IMAGE_SIZE + PAGE_SIZE_asm - 1)>>PAGE_SHIFT
-/*
- * To preserve the DMA pool in PAGEALLOC kernels, we'll allocate
- * pagetables from above the 16MB DMA limit, so we'll have to set
- * up pagetables 16MB more (worst-case):
- */
-#ifdef CONFIG_DEBUG_PAGEALLOC
-LOW_PAGES = LOW_PAGES + 0x1000000
-#endif
-
#if PTRS_PER_PMD > 1
PAGE_TABLE_SIZE = (LOW_PAGES / PTRS_PER_PMD) + PTRS_PER_PGD
#else
PAGE_TABLE_SIZE = (LOW_PAGES / PTRS_PER_PGD)
#endif
-BOOTBITMAP_SIZE = LOW_PAGES / 8
ALLOCATOR_SLOP = 4
-INIT_MAP_BEYOND_END = BOOTBITMAP_SIZE + (PAGE_TABLE_SIZE + ALLOCATOR_SLOP)*PAGE_SIZE_asm
-
-RESERVE_BRK(pagetables, PAGE_TABLE_SIZE * PAGE_SIZE)
+INIT_MAP_SIZE = (PAGE_TABLE_SIZE + ALLOCATOR_SLOP) * PAGE_SIZE_asm
+RESERVE_BRK(pagetables, INIT_MAP_SIZE)
/*
* 32-bit kernel entrypoint; only used by the boot CPU. On entry,
@@ -168,10 +155,10 @@ num_subarch_entries = (. - subarch_entries) / 4
/*
* Initialize page tables. This creates a PDE and a set of page
- * tables, which are located immediately beyond _end. The variable
+ * tables, which are located immediately beyond __brk_base. The variable
* _brk_end is set up to point to the first "safe" location.
* Mappings are created both at virtual address 0 (identity mapping)
- * and PAGE_OFFSET for up to _end+sizeof(page tables)+INIT_MAP_BEYOND_END.
+ * and PAGE_OFFSET for up to _end.
*
* Note that the stack is not yet set up!
*/
@@ -210,10 +197,9 @@ default_entry:
loop 11b
/*
- * End condition: we must map up to and including INIT_MAP_BEYOND_END
- * bytes beyond the end of our own page tables.
+ * End condition: we must map up to the end.
*/
- leal (INIT_MAP_BEYOND_END+PTE_IDENT_ATTR)(%edi),%ebp
+ movl $pa(_end) + PTE_IDENT_ATTR, %ebp
cmpl %ebp,%eax
jb 10b
1:
@@ -243,11 +229,9 @@ page_pde_offset = (__PAGE_OFFSET >> 20);
addl $0x1000,%eax
loop 11b
/*
- * End condition: we must map up to and including INIT_MAP_BEYOND_END
- * bytes beyond the end of our own page tables; the +0x007 is
- * the attribute bits
+ * End condition: we must map up to end
*/
- leal (INIT_MAP_BEYOND_END+PTE_IDENT_ATTR)(%edi),%ebp
+ movl $pa(_end) + PTE_IDENT_ATTR, %ebp
cmpl %ebp,%eax
jb 10b
addl $__PAGE_OFFSET, %edi
@@ -638,6 +622,7 @@ swapper_pg_fixmap:
.fill 1024,4,0
ENTRY(empty_zero_page)
.fill 4096,1,0
+
/*
* This starts the data section.
*/
diff --git a/arch/x86/kernel/vmlinux_32.lds.S b/arch/x86/kernel/vmlinux_32.lds.S
index a1f28b85fb3..98424f33e07 100644
--- a/arch/x86/kernel/vmlinux_32.lds.S
+++ b/arch/x86/kernel/vmlinux_32.lds.S
@@ -210,6 +210,12 @@ SECTIONS
DWARF_DEBUG
}
+/*
+ * Build-time check on the image size:
+ */
+ASSERT((_end - LOAD_OFFSET <= KERNEL_IMAGE_SIZE),
+ "kernel image bigger than KERNEL_IMAGE_SIZE")
+
#ifdef CONFIG_KEXEC
/* Link time checks */
#include <asm/kexec.h>