x86-32: use brk segment for allocating initial kernel pagetable
Impact: use new interface instead of previous ad hoc implementation Rather than having special purpose init_pg_table_start/end variables to delimit the kernel pagetable built by head_32.S, just use the brk mechanism to extend the bss for the new pagetable. This patch removes init_pg_table_start/end and pg0, defines __brk_base (which is page-aligned and immediately follows _end), initializes the brk region to start there, and uses it for the 32-bit pagetable. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This commit is contained in:
Jeremy Fitzhardinge
H. Peter Anvin
parent
5368a2be34
commit
ccf3fe02e3
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@ -42,9 +42,6 @@ extern void set_pmd_pfn(unsigned long, unsigned long, pgprot_t);
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*/
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#undef TEST_ACCESS_OK
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/* The boot page tables (all created as a single array) */
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extern unsigned long pg0[];
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#ifdef CONFIG_X86_PAE
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# include <asm/pgtable-3level.h>
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#else
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@ -109,9 +109,6 @@ void *extend_brk(size_t size, size_t align);
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void __init i386_start_kernel(void);
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extern void probe_roms(void);
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extern unsigned long init_pg_tables_start;
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extern unsigned long init_pg_tables_end;
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#else
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void __init x86_64_start_kernel(char *real_mode);
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void __init x86_64_start_reservations(char *real_mode_data);
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@ -29,9 +29,6 @@ void __init i386_start_kernel(void)
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reserve_early(ramdisk_image, ramdisk_end, "RAMDISK");
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}
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#endif
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reserve_early(init_pg_tables_start, init_pg_tables_end,
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"INIT_PG_TABLE");
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reserve_ebda_region();
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/*
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@ -167,7 +167,7 @@ num_subarch_entries = (. - subarch_entries) / 4
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/*
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* Initialize page tables. This creates a PDE and a set of page
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* tables, which are located immediately beyond _end. The variable
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* init_pg_tables_end is set up to point to the first "safe" location.
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* _brk_end is set up to point to the first "safe" location.
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* Mappings are created both at virtual address 0 (identity mapping)
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* and PAGE_OFFSET for up to _end+sizeof(page tables)+INIT_MAP_BEYOND_END.
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*
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@ -190,8 +190,7 @@ default_entry:
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xorl %ebx,%ebx /* %ebx is kept at zero */
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movl $pa(pg0), %edi
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movl %edi, pa(init_pg_tables_start)
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movl $pa(__brk_base), %edi
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movl $pa(swapper_pg_pmd), %edx
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movl $PTE_IDENT_ATTR, %eax
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10:
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@ -216,7 +215,8 @@ default_entry:
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cmpl %ebp,%eax
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jb 10b
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1:
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movl %edi,pa(init_pg_tables_end)
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addl $__PAGE_OFFSET, %edi
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movl %edi, pa(_brk_end)
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shrl $12, %eax
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movl %eax, pa(max_pfn_mapped)
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@ -227,8 +227,7 @@ default_entry:
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page_pde_offset = (__PAGE_OFFSET >> 20);
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movl $pa(pg0), %edi
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movl %edi, pa(init_pg_tables_start)
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movl $pa(__brk_base), %edi
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movl $pa(swapper_pg_dir), %edx
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movl $PTE_IDENT_ATTR, %eax
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10:
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@ -249,7 +248,8 @@ page_pde_offset = (__PAGE_OFFSET >> 20);
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leal (INIT_MAP_BEYOND_END+PTE_IDENT_ATTR)(%edi),%ebp
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cmpl %ebp,%eax
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jb 10b
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movl %edi,pa(init_pg_tables_end)
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addl $__PAGE_OFFSET, %edi
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movl %edi, pa(_brk_end)
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shrl $12, %eax
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movl %eax, pa(max_pfn_mapped)
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@ -161,12 +161,6 @@ static struct resource bss_resource = {
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#ifdef CONFIG_X86_32
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/* This value is set up by the early boot code to point to the value
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immediately after the boot time page tables. It contains a *physical*
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address, and must not be in the .bss segment! */
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unsigned long init_pg_tables_start __initdata = ~0UL;
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unsigned long init_pg_tables_end __initdata = ~0UL;
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static struct resource video_ram_resource = {
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.name = "Video RAM area",
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.start = 0xa0000,
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@ -196,10 +196,6 @@ SECTIONS
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__brk_limit = . ;
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_end = . ;
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/* This is where the kernel creates the early boot page tables */
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. = ALIGN(PAGE_SIZE);
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pg0 = . ;
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}
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/* Sections to be discarded */
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@ -1058,14 +1058,6 @@ __init void lguest_init(void)
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* lguest_init() where the rest of the fairly chaotic boot setup
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* occurs. */
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/* The native boot code sets up initial page tables immediately after
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* the kernel itself, and sets init_pg_tables_end so they're not
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* clobbered. The Launcher places our initial pagetables somewhere at
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* the top of our physical memory, so we don't need extra space: set
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* init_pg_tables_end to the end of the kernel. */
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init_pg_tables_start = __pa(pg0);
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init_pg_tables_end = __pa(pg0);
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/* As described in head_32.S, we map the first 128M of memory. */
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max_pfn_mapped = (128*1024*1024) >> PAGE_SHIFT;
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