From 5b11f1cee5797b38d16b94d8745b12b6727a8373 Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Fri, 8 May 2009 16:20:34 -0700 Subject: x86, boot: straighten out ranges to copy/zero in compressed/head*.S Both on 32 and 64 bits, we copy all the way up to the end of bss, except that on 64 bits there is a hack to avoid copying on top of the page tables. There is no point in copying bss at all, especially since we are just about to zero it all anyway. To clean up and unify the handling, we now do: - copy from startup_32 to _bss. - zero from _bss to _ebss. - the _ebss symbol is aligned to an 8-byte boundary. - the page tables are moved to a separate section. Use _bss as the copy endpoint since _edata may be misaligned. [ Impact: cleanup, trivial performance improvement ] Signed-off-by: H. Peter Anvin --- arch/x86/boot/compressed/head_32.S | 8 ++++---- arch/x86/boot/compressed/head_64.S | 18 +++++++++++++----- arch/x86/boot/compressed/vmlinux.lds.S | 19 ++++++++++++------- 3 files changed, 29 insertions(+), 16 deletions(-) (limited to 'arch/x86/boot/compressed') diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S index 7bd7766ffab..59425e157df 100644 --- a/arch/x86/boot/compressed/head_32.S +++ b/arch/x86/boot/compressed/head_32.S @@ -93,9 +93,9 @@ ENTRY(startup_32) * where decompression in place becomes safe. */ pushl %esi - leal _ebss(%ebp), %esi - leal _ebss(%ebx), %edi - movl $(_ebss - startup_32), %ecx + leal _bss(%ebp), %esi + leal _bss(%ebx), %edi + movl $(_bss - startup_32), %ecx std rep movsb cld @@ -125,7 +125,7 @@ relocated: * Clear BSS */ xorl %eax, %eax - leal _edata(%ebx), %edi + leal _bss(%ebx), %edi leal _ebss(%ebx), %ecx subl %edi, %ecx cld diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index 26c3def43ac..5bc9052615b 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -253,9 +253,9 @@ ENTRY(startup_64) * Copy the compressed kernel to the end of our buffer * where decompression in place becomes safe. */ - leaq _end_before_pgt(%rip), %r8 - leaq _end_before_pgt(%rbx), %r9 - movq $_end_before_pgt /* - $startup_32 */, %rcx + leaq _bss(%rip), %r8 + leaq _bss(%rbx), %r9 + movq $_bss /* - $startup_32 */, %rcx 1: subq $8, %r8 subq $8, %r9 movq 0(%r8), %rax @@ -276,8 +276,8 @@ relocated: * Clear BSS */ xorq %rax, %rax - leaq _edata(%rbx), %rdi - leaq _end_before_pgt(%rbx), %rcx + leaq _bss(%rbx), %rdi + leaq _ebss(%rbx), %rcx subq %rdi, %rcx cld rep stosb @@ -329,3 +329,11 @@ boot_heap: boot_stack: .fill BOOT_STACK_SIZE, 1, 0 boot_stack_end: + +/* + * Space for page tables (not in .bss so not zeroed) + */ + .section ".pgtable","a",@nobits + .balign 4096 +pgtable: + .fill 6*4096, 1, 0 diff --git a/arch/x86/boot/compressed/vmlinux.lds.S b/arch/x86/boot/compressed/vmlinux.lds.S index dbe515e13fe..cc353e1b3ff 100644 --- a/arch/x86/boot/compressed/vmlinux.lds.S +++ b/arch/x86/boot/compressed/vmlinux.lds.S @@ -2,6 +2,8 @@ OUTPUT_FORMAT(CONFIG_OUTPUT_FORMAT, CONFIG_OUTPUT_FORMAT, CONFIG_OUTPUT_FORMAT) #undef i386 +#include + #ifdef CONFIG_X86_64 OUTPUT_ARCH(i386:x86-64) ENTRY(startup_64) @@ -48,13 +50,16 @@ SECTIONS *(.bss) *(.bss.*) *(COMMON) -#ifdef CONFIG_X86_64 - . = ALIGN(8); - _end_before_pgt = . ; - . = ALIGN(4096); - pgtable = . ; - . = . + 4096 * 6; -#endif + . = ALIGN(8); /* For convenience during zeroing */ _ebss = .; } +#ifdef CONFIG_X86_64 + . = ALIGN(PAGE_SIZE); + .pgtable : { + _pgtable = . ; + *(.pgtable) + _epgtable = . ; + } +#endif + _end = .; } -- cgit