[PATCH] Clean up empty_zero_page abuse
From: Brian Gerst (bgerst_at_didntduck.org)
Date: 03/02/04
- Previous message: viro_at_parcelfarce.linux.theplanet.co.uk: "Re: modules registering as sysctl handlers"
- In reply to: H. Peter Anvin: "Re: [CFT][PATCH] 2.6.4-rc1 remove x86 boot page tables"
- Next in thread: Eric W. Biederman: "Re: [CFT][PATCH] 2.6.4-rc1 remove x86 boot page tables"
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
Date: Tue, 02 Mar 2004 07:53:35 -0500 To: "H. Peter Anvin" <hpa@zytor.com>
H. Peter Anvin wrote:
> Oh yes, with this change you should probably just move swapper_pg_dir
> (and empty_zero_page?) into .bss like anything else that should be
> zero after boot.
This patch (against EWB's boot segment patch) fixes the abuse of
empty_zero_page for storing boot parameters. This usage is an artifact
from before we had discardable init sections.
- Move some constants to setup.h
- Copy the command line directly to saved_command_line
- Add boot_params as temporary storage of the parameters block
- Move empty_zero_page to .bss
-- Brian Gerst
diff -urN linux-bootseg/arch/i386/boot/setup.S linux/arch/i386/boot/setup.S
--- linux-bootseg/arch/i386/boot/setup.S 2004-02-28 23:35:03.000000000 -0500
+++ linux/arch/i386/boot/setup.S 2004-03-01 16:09:04.000000000 -0500
@@ -605,7 +605,7 @@
# int 13h ah=48h "Get Device Parameters"
#
# A buffer of size EDDMAXNR*(EDDEXTSIZE+EDDPARMSIZE) is reserved for our use
-# in the empty_zero_page at EDDBUF. The first four bytes of which are
+# in boot_params at EDDBUF. The first four bytes of which are
# used to store the device number, interface support map and version
# results from fn41. The following 74 bytes are used to store
# the results from fn48. Starting from device 80h, fn41, then fn48
@@ -617,9 +617,9 @@
# the structure, and the fn41 results are stored at offsets
# from there. This removes the need to increment the pointer for
# every store, and leaves it ready for the fn48 call.
-# A second one-byte buffer, EDDNR, in the empty_zero_page stores
+# A second one-byte buffer, EDDNR, in boot_params stores
# the number of BIOS devices which exist, up to EDDMAXNR.
-# In setup.c, copy_edd() stores both empty_zero_page buffers away
+# In setup.c, copy_edd() stores both boot_params buffers away
# for later use, as they would get overwritten otherwise.
# This code is sensitive to the size of the structs in edd.h
edd_start:
diff -urN linux-bootseg/arch/i386/kernel/head.S linux/arch/i386/kernel/head.S
--- linux-bootseg/arch/i386/kernel/head.S 2004-03-01 16:12:47.000000000 -0500
+++ linux/arch/i386/kernel/head.S 2004-03-01 16:12:18.000000000 -0500
@@ -17,13 +17,7 @@
#include <asm/desc.h>
#include <asm/cache.h>
#include <asm/thread_info.h>
-
-
-#define OLD_CL_MAGIC_ADDR 0x90020
-#define OLD_CL_MAGIC 0xA33F
-#define OLD_CL_BASE_ADDR 0x90000
-#define OLD_CL_OFFSET 0x90022
-#define NEW_CL_POINTER 0x228 /* Relative to real mode data */
+#include <asm/setup.h>
/*
* References to members of the new_cpu_data structure.
@@ -93,23 +87,16 @@
*/
call setup_idt
/*
- * Copy bootup parameters out of the way. First 2kB of
- * _empty_zero_page is for boot parameters, second 2kB
- * is for the command line.
- *
+ * Copy bootup parameters out of the way.
* Note: %esi still has the pointer to the real-mode data.
* No need to cld as DF is already clear from above...
*/
addl $__PAGE_OFFSET, %esi /* Make %esi virtual */
- movl $empty_zero_page,%edi
- movl $512,%ecx
+ movl $boot_params,%edi
+ movl $(PARAM_SIZE/4),%ecx
rep
movsl
- xorl %eax,%eax
- movl $512,%ecx
- rep
- stosl
- movl empty_zero_page+NEW_CL_POINTER,%esi
+ movl boot_params+NEW_CL_POINTER,%esi
andl %esi,%esi
jnz 2f # New command line protocol
cmpw $(OLD_CL_MAGIC),OLD_CL_MAGIC_ADDR+__PAGE_OFFSET
@@ -118,8 +105,8 @@
addl $(OLD_CL_BASE_ADDR),%esi
2:
addl $__PAGE_OFFSET, %esi /* Make %esi virtual */
- movl $empty_zero_page+2048,%edi
- movl $512,%ecx
+ movl $saved_command_line,%edi
+ movl $(COMMAND_LINE_SIZE/4),%ecx
rep
movsl
1:
@@ -399,10 +386,6 @@
ENTRY(swapper_pg_dir)
.fill 1024,4,0
-.balign 4096
-ENTRY(empty_zero_page)
- .fill 4096,1,0
-
/*
* Real beginning of normal "text" segment
*/
diff -urN linux-bootseg/arch/i386/kernel/setup.c linux/arch/i386/kernel/setup.c
--- linux-bootseg/arch/i386/kernel/setup.c 2004-02-28 23:35:03.000000000 -0500
+++ linux/arch/i386/kernel/setup.c 2004-03-01 16:15:48.000000000 -0500
@@ -126,6 +126,8 @@
static char command_line[COMMAND_LINE_SIZE];
char saved_command_line[COMMAND_LINE_SIZE];
+unsigned char __initdata boot_params[PARAM_SIZE] = { 0, };
+
static struct resource code_resource = { "Kernel code", 0x100000, 0 };
static struct resource data_resource = { "Kernel data", 0, 0 };
@@ -452,7 +454,7 @@
#endif
/**
* copy_edd() - Copy the BIOS EDD information
- * from empty_zero_page into a safe place.
+ * from boot_param into a safe place.
*
*/
static inline void copy_edd(void)
@@ -481,12 +483,11 @@
static void __init parse_cmdline_early (char ** cmdline_p)
{
- char c = ' ', *to = command_line, *from = COMMAND_LINE;
+ char c = ' ', *to = command_line, *from = saved_command_line;
int len = 0;
int userdef = 0;
/* Save unparsed command line copy for /proc/cmdline */
- memcpy(saved_command_line, COMMAND_LINE, COMMAND_LINE_SIZE);
saved_command_line[COMMAND_LINE_SIZE-1] = '\0';
for (;;) {
diff -urN linux-bootseg/arch/i386/kernel/vmlinux.lds.S linux/arch/i386/kernel/vmlinux.lds.S
--- linux-bootseg/arch/i386/kernel/vmlinux.lds.S 2003-12-17 21:58:18.000000000 -0500
+++ linux/arch/i386/kernel/vmlinux.lds.S 2004-03-01 16:09:04.000000000 -0500
@@ -104,7 +104,12 @@
/* freed after init ends here */
__bss_start = .; /* BSS */
- .bss : { *(.bss) }
+ .bss : {
+ . = ALIGN(4096);
+ empty_zero_page = .;
+ . = . + 4096;
+ *(.bss)
+ }
__bss_stop = .;
_end = . ;
diff -urN linux-bootseg/arch/i386/mm/init.c linux/arch/i386/mm/init.c
--- linux-bootseg/arch/i386/mm/init.c 2004-03-01 16:12:47.000000000 -0500
+++ linux/arch/i386/mm/init.c 2004-03-01 16:09:04.000000000 -0500
@@ -476,9 +476,6 @@
high_memory = (void *) __va(max_low_pfn * PAGE_SIZE);
#endif
- /* clear the zero-page */
- memset(empty_zero_page, 0, PAGE_SIZE);
-
/* this will put all low memory onto the freelists */
totalram_pages += __free_all_bootmem();
diff -urN linux-bootseg/include/asm-i386/setup.h linux/include/asm-i386/setup.h
--- linux-bootseg/include/asm-i386/setup.h 2004-02-18 01:37:26.000000000 -0500
+++ linux/include/asm-i386/setup.h 2004-03-01 16:09:04.000000000 -0500
@@ -16,10 +16,22 @@
#define MAXMEM_PFN PFN_DOWN(MAXMEM)
#define MAX_NONPAE_PFN (1 << 20)
+#define PARAM_SIZE 2048
+#define COMMAND_LINE_SIZE 256
+
+#define OLD_CL_MAGIC_ADDR 0x90020
+#define OLD_CL_MAGIC 0xA33F
+#define OLD_CL_BASE_ADDR 0x90000
+#define OLD_CL_OFFSET 0x90022
+#define NEW_CL_POINTER 0x228 /* Relative to real mode data */
+
+#ifndef __ASSEMBLY__
/*
* This is set up by the setup-routine at boot-time
*/
-#define PARAM ((unsigned char *)empty_zero_page)
+extern unsigned char boot_params[PARAM_SIZE];
+
+#define PARAM (boot_params)
#define SCREEN_INFO (*(struct screen_info *) (PARAM+0))
#define EXT_MEM_K (*(unsigned short *) (PARAM+2))
#define ALT_MEM_K (*(unsigned long *) (PARAM+0x1e0))
@@ -47,7 +59,7 @@
#define DISK80_SIGNATURE (*(unsigned int*) (PARAM+DISK80_SIG_BUFFER))
#define EDD_NR (*(unsigned char *) (PARAM+EDDNR))
#define EDD_BUF ((struct edd_info *) (PARAM+EDDBUF))
-#define COMMAND_LINE ((char *) (PARAM+2048))
-#define COMMAND_LINE_SIZE 256
+
+#endif /* __ASSEMBLY__ */
#endif /* _i386_SETUP_H */
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
- Previous message: viro_at_parcelfarce.linux.theplanet.co.uk: "Re: modules registering as sysctl handlers"
- In reply to: H. Peter Anvin: "Re: [CFT][PATCH] 2.6.4-rc1 remove x86 boot page tables"
- Next in thread: Eric W. Biederman: "Re: [CFT][PATCH] 2.6.4-rc1 remove x86 boot page tables"
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
Relevant Pages
|
|
