From: Brian Gerst <bgerst@didntduck.org>
- Move empty_zero_page and swapper_pg_dir to BSS. This requires that BSS
is cleared earlier, but reclaims over 3k that was lost due to page
alignment.
- Move stack_start, ready, and int_msg, boot_gdt_descr, idt_descr, and
cpu_gdt_descr to .data. They were interfering with disassembly while in
.text.
---
25-akpm/arch/i386/kernel/head.S | 94 ++++++++++++++-------------------
25-akpm/arch/i386/kernel/vmlinux.lds.S | 5 +
2 files changed, 46 insertions(+), 53 deletions(-)
diff -puN arch/i386/kernel/head.S~i386-head_S-cleanups arch/i386/kernel/head.S
--- 25/arch/i386/kernel/head.S~i386-head_S-cleanups 2004-04-04 17:01:44.972795344 -0700
+++ 25-akpm/arch/i386/kernel/head.S 2004-04-04 17:01:44.978794432 -0700
@@ -70,9 +70,22 @@ ENTRY(startup_32)
movl %eax,%gs
/*
+ * Clear BSS first so that there are no surprises...
+ * No need to cld as DF is already clear from cld above...
+ */
+ xorl %eax,%eax
+ movl $__bss_start - __PAGE_OFFSET,%edi
+ movl $__bss_stop - __PAGE_OFFSET,%ecx
+ subl %edi,%ecx
+ shrl $2,%ecx
+ rep ; stosl
+
+/*
* Initialize page tables. This creates a PDE and a set of page
* tables, which are located immediately beyond _end. The variable
* init_pg_tables_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.
*
* Warning: don't use %esi or the stack in this code. However, %esp
* can be used as a GPR if you really need it...
@@ -174,17 +187,6 @@ ENTRY(startup_32_smp)
#endif /* CONFIG_SMP */
/*
- * Clear BSS first so that there are no surprises...
- * No need to cld as DF is already clear from cld above...
- */
- xorl %eax,%eax
- movl $__bss_start,%edi
- movl $__bss_stop,%ecx
- subl %edi,%ecx
- shrl $2,%ecx
- rep ; stosl
-
-/*
* start system 32-bit setup. We need to re-do some of the things done
* in 16-bit mode for the "real" operations.
*/
@@ -305,8 +307,6 @@ L6:
jmp L6 # main should never return here, but
# just in case, we know what happens.
-ready: .byte 0
-
/*
* We depend on ET to be correct. This checks for 287/387.
*/
@@ -354,13 +354,7 @@ rp_sidt:
jne rp_sidt
ret
-ENTRY(stack_start)
- .long init_thread_union+THREAD_SIZE
- .long __BOOT_DS
-
/* This is the default interrupt "handler" :-) */
-int_msg:
- .asciz "Unknown interrupt or fault at EIP %p %p %p\n"
ALIGN
ignore_int:
cld
@@ -387,6 +381,35 @@ ignore_int:
iret
/*
+ * Real beginning of normal "text" segment
+ */
+ENTRY(stext)
+ENTRY(_stext)
+
+/*
+ * BSS section
+ */
+.section ".bss.page_aligned","w"
+ENTRY(swapper_pg_dir)
+ .fill 1024,4,0
+ENTRY(empty_zero_page)
+ .fill 4096,1,0
+
+/*
+ * This starts the data section.
+ */
+.data
+
+ENTRY(stack_start)
+ .long init_thread_union+THREAD_SIZE
+ .long __BOOT_DS
+
+ready: .byte 0
+
+int_msg:
+ .asciz "Unknown interrupt or fault at EIP %p %p %p\n"
+
+/*
* The IDT and GDT 'descriptors' are a strange 48-bit object
* only used by the lidt and lgdt instructions. They are not
* like usual segment descriptors - they consist of a 16-bit
@@ -418,39 +441,6 @@ cpu_gdt_descr:
.fill NR_CPUS-1,8,0 # space for the other GDT descriptors
/*
- * swapper_pg_dir is the main page directory, address 0x00101000
- *
- * This is initialized to create an identity-mapping at 0 (for bootup
- * purposes) and another mapping at virtual address PAGE_OFFSET. The
- * values put here should be all invalid (zero); the valid
- * entries are created dynamically at boot time.
- *
- * The code creates enough page tables to map 0-_end, the page tables
- * themselves, plus INIT_MAP_BEYOND_END bytes; see comment at beginning.
- */
-.org 0x1000
-ENTRY(swapper_pg_dir)
- .fill 1024,4,0
-
-.org 0x2000
-ENTRY(empty_zero_page)
- .fill 4096,1,0
-
-.org 0x3000
-/*
- * Real beginning of normal "text" segment
- */
-ENTRY(stext)
-ENTRY(_stext)
-
-/*
- * This starts the data section. Note that the above is all
- * in the text section because it has alignment requirements
- * that we cannot fulfill any other way.
- */
-.data
-
-/*
* The boot_gdt_table must mirror the equivalent in setup.S and is
* used only for booting.
*/
diff -puN arch/i386/kernel/vmlinux.lds.S~i386-head_S-cleanups arch/i386/kernel/vmlinux.lds.S
--- 25/arch/i386/kernel/vmlinux.lds.S~i386-head_S-cleanups 2004-04-04 17:01:44.973795192 -0700
+++ 25-akpm/arch/i386/kernel/vmlinux.lds.S 2004-04-04 17:01:44.978794432 -0700
@@ -106,7 +106,10 @@ SECTIONS
/* freed after init ends here */
__bss_start = .; /* BSS */
- .bss : { *(.bss) }
+ .bss : {
+ *(.bss.page_aligned)
+ *(.bss)
+ }
. = ALIGN(4);
__bss_stop = .;
_