x86 boot: setup data

This patch add a field of 64-bit physical pointer to NULL terminated single linked list of struct setup_data to real-mode kernel header. This is used as a more extensible boot parameters passing mechanism.

Signed-off-by Huang Ying <[email protected]>

---

 arch/x86/boot/header.S      |    6 +++++-
 arch/x86/kernel/e820_64.c   |    6 +++---
 arch/x86/kernel/head64.c    |   26 ++++++++++++++++++++++++++
 arch/x86/kernel/head_32.S   |   37 ++++++++++++++++++++++++++++++++++++-
 arch/x86/kernel/setup_32.c  |   25 +++++++++++++++++++++++--
 arch/x86/kernel/setup_64.c  |   22 ++++++++++++++++++++--
 arch/x86/mm/discontig_32.c  |    3 ++-
 include/asm-x86/bootparam.h |   12 ++++++++++++
 include/asm-x86/e820_64.h   |    1 +
 include/asm-x86/setup_32.h  |    7 +++++++
 include/asm-x86/setup_64.h  |    2 ++
 11 files changed, 137 insertions(+), 10 deletions(-)

Index: linux-2.6/include/asm-x86/bootparam.h
===================================================================

include/asm-x86/bootparam.h +1 -0

@@ -9,6 +9,17 @@
 #include <asm/ist.h>
 #include <video/edid.h>
 
+/* setup data types */

include/asm-x86/bootparam.h +1 -0

+
 struct setup_header {
 	u8	setup_sects;

include/asm-x86/bootparam.h +1 -0

 	u16	root_flags;

@@ -46,6 +57,7 @@
 	u32	cmdline_size;
 	u32	hardware_subarch;
 	u64	hardware_subarch_data;
+	u64	setup_data;
 } __attribute__((packed));
 
 struct sys_desc_table {

Index: linux-2.6/arch/x86/boot/header.S
===================================================================

arch/x86/boot/header.S +5 -1

@@ -119,7 +119,7 @@
 	# Part 2 of the header, from the old setup.S
 
 		.ascii	"HdrS"		# header signature
-		.word	0x0207		# header version number (>= 0x0105)
+		.word	0x0208		# header version number (>= 0x0105)
 					# or else old loadlin-1.5 will fail)
 		.globl realmode_swtch
 realmode_swtch:	.word	0, 0		# default_switch, SETUPSEG

@@ -219,6 +219,10 @@
 
 hardware_subarch_data:	.quad 0
 
+setup_data:		.quad 0			# 64-bit physical pointer to
+						# single linked list of
+						# struct setup_data
+
 # End of setup header #####################################################
 
 	.section ".inittext", "ax"

Index: linux-2.6/arch/x86/kernel/setup_64.c
===================================================================

arch/x86/kernel/setup_64.c +20 -2

@@ -247,6 +247,22 @@
 		ebda_size = 64*1024;
 }
 
+static void __init parse_setup_data(void)
+{
+	struct setup_data *data;
+
+	if (boot_params.hdr.version < 0x0207)
+		return;
+	for (data = __va(boot_params.hdr.setup_data);
+	     data != __va(0);
+	     data = __va(data->next)) {
+		switch (data->type) {
+		default:
+			break;
+		}
+	}
+}
+
 void __init setup_arch(char **cmdline_p)
 {
 	printk(KERN_INFO "Command line: %s\n", boot_command_line);

@@ -282,6 +298,8 @@
 	strlcpy(command_line, boot_command_line, COMMAND_LINE_SIZE);
 	*cmdline_p = command_line;
 
+	parse_setup_data();
+
 	parse_early_param();
 
 	finish_e820_parsing();

@@ -340,9 +358,9 @@
 	reserve_bootmem_generic(table_start << PAGE_SHIFT, 
 				(table_end - table_start) << PAGE_SHIFT);
 
-	/* reserve kernel */
+	/* reserve kernel and setup data */
 	reserve_bootmem_generic(__pa_symbol(&_text),
-				__pa_symbol(&_end) - __pa_symbol(&_text));
+				setup_data_end - __pa_symbol(&_text));
 
 	/*
 	 * reserve physical page 0 - it's a special BIOS page on many boxes,

Index: linux-2.6/arch/x86/kernel/setup_32.c
===================================================================

arch/x86/kernel/setup_32.c +9 -1

@@ -66,6 +66,8 @@
    address, and must not be in the .bss segment! */
 unsigned long init_pg_tables_end __initdata = ~0UL;
 
+unsigned long setup_data_len __initdata;
+
 int disable_pse __devinitdata = 0;
 
 /*

@@ -327,7 +329,7 @@
 	 * partially used pages are not usable - thus
 	 * we are rounding upwards:
 	 */
-	min_low_pfn = PFN_UP(init_pg_tables_end);
+	min_low_pfn = PFN_UP(init_pg_tables_end+setup_data_len);
 
 	find_max_pfn();
 

@@ -532,6 +534,22 @@
 	return machine_specific_memory_setup();
 }
 
+static void __init parse_setup_data(void)
+{
+	struct setup_data *data;
+
+	if (boot_params.hdr.version < 0x0207)
+		return;

arch/x86/kernel/setup_32.c +1 -0

+
 /*
  * Determine if we were loaded by an EFI loader.  If so, then we have also been

* passed the efi memmap, systab, etc., so we should use these data structures

arch/x86/kernel/setup_32.c +4 -1

@@ -579,6 +597,9 @@
 	rd_prompt = ((boot_params.hdr.ram_size & RAMDISK_PROMPT_FLAG) != 0);
 	rd_doload = ((boot_params.hdr.ram_size & RAMDISK_LOAD_FLAG) != 0);
 #endif
+
+	parse_setup_data();
+
 	ARCH_SETUP
 	if (efi_enabled)
 		efi_init();

@@ -594,7 +615,7 @@
 	init_mm.start_code = (unsigned long) _text;
 	init_mm.end_code = (unsigned long) _etext;
 	init_mm.end_data = (unsigned long) _edata;
-	init_mm.brk = init_pg_tables_end + PAGE_OFFSET;
+	init_mm.brk = init_pg_tables_end + setup_data_len + PAGE_OFFSET;
 
 	code_resource.start = virt_to_phys(_text);
 	code_resource.end = virt_to_phys(_etext)-1;

Index: linux-2.6/arch/x86/kernel/e820_64.c
===================================================================

arch/x86/kernel/e820_64.c +3 -3

@@ -79,9 +79,9 @@
 		}
 	} 
 #endif
-	/* kernel code */
-	if (last >= __pa_symbol(&_text) && addr < __pa_symbol(&_end)) {
-		*addrp = PAGE_ALIGN(__pa_symbol(&_end));
+	/* kernel code and setup data */
+	if (last >= __pa_symbol(&_text) && addr < setup_data_end) {
+		*addrp = PAGE_ALIGN(setup_data_end);
 		return 1;
 	}
 

Index: linux-2.6/arch/x86/kernel/head64.c
===================================================================

arch/x86/kernel/head64.c +26 -0

@@ -19,6 +19,9 @@
 #include <asm/pgtable.h>
 #include <asm/tlbflush.h>
 #include <asm/sections.h>
+#include <asm/io.h>
+
+unsigned long __initdata setup_data_end;
 
 static void __init zap_identity_mappings(void)
 {

@@ -38,12 +41,35 @@
 static void __init copy_bootdata(char *real_mode_data)
 {
 	char * command_line;
+	void *sdata_dst;
+	struct setup_data *sdata;
+	u64 *ppa_next;
+	unsigned long sdata_len;
 
 	memcpy(&boot_params, real_mode_data, sizeof boot_params);
 	if (boot_params.hdr.cmd_line_ptr) {
 		command_line = __va(boot_params.hdr.cmd_line_ptr);
 		memcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
 	}
+
+#define SETUP_DATA_ALIGN(addr) \
+	(((unsigned long)(addr)+(SETUP_DATA_ALIGN_SIZE-1))& \
+	 ~(SETUP_DATA_ALIGN_SIZE-1))
+
+	sdata_dst = __va(SETUP_DATA_ALIGN(__pa_symbol(&_end)));
+	ppa_next = &boot_params.hdr.setup_data;
+	while (*ppa_next) {
+		sdata = early_ioremap(*ppa_next, sizeof(*sdata));
+		sdata_len = sizeof(*sdata) + sdata->len;
+		early_iounmap(sdata, sizeof(*sdata));
+		sdata = early_ioremap(*ppa_next, sdata_len);
+		memcpy(sdata_dst, sdata, sdata_len);
+		early_iounmap(sdata, sdata_len);
+		*ppa_next = __pa(sdata_dst);
+		ppa_next = &((struct setup_data *)sdata_dst)->next;
+		sdata_dst = (void *)SETUP_DATA_ALIGN(sdata_dst+sdata_len);
+	}
+	setup_data_end = __pa(sdata_dst);
 }
 
 void __init x86_64_start_kernel(char * real_mode_data)

Index: linux-2.6/include/asm-x86/e820_64.h
===================================================================

include/asm-x86/e820_64.h +1 -0

@@ -56,6 +56,7 @@
 
 extern unsigned ebda_addr, ebda_size;
 extern unsigned long nodemap_addr, nodemap_size;
+extern unsigned long setup_data_end;
 #endif/*!__ASSEMBLY__*/
 
 #endif/*__E820_HEADER*/

Index: linux-2.6/arch/x86/kernel/head_32.S
===================================================================

arch/x86/kernel/head_32.S +14 -0

+	xorl %ecx,%ecx
+2:
+	andl %ebp,%ebp
+	jz 1f
+	movl $(SETUP_DATA_HEADER_LEN+SETUP_DATA_ALIGN_SIZE-1),%eax
+	addl (SETUP_DATA_LEN)(%ebp),%eax
+	andl $~(SETUP_DATA_ALIGN_SIZE-1),%eax
+	addl %eax, %ecx
+	movl SETUP_DATA_NEXT(%ebp),%ebp
+	jmp 2b
+1:
+	addl $(PAGE_SIZE_asm-1),%ecx
+	andl $~(PAGE_SIZE_asm-1),%ecx
+	movl %ecx,(setup_data_len - __PAGE_OFFSET)
 
 #ifdef CONFIG_PARAVIRT

arch/x86/kernel/head_32.S +21 -1

 	cmpw $0x207, (boot_params + BP_version - __PAGE_OFFSET)

@@ -191,13 +206,33 @@
 	stosl
 	addl $0x1000,%eax
 	loop 11b
-	/* End condition: we must map up to and including INIT_MAP_BEYOND_END */
+	/* End condition: we must map up to and including INIT_MAP_BEYOND_END + setup_data_len */
 	/* bytes beyond the end of our own page tables; the +0x007 is the attribute bits */
 	leal (INIT_MAP_BEYOND_END+0x007)(%edi),%ebp
+	addl (setup_data_len - __PAGE_OFFSET),%ebp
 	cmpl %ebp,%eax
 	jb 10b
 	movl %edi,(init_pg_tables_end - __PAGE_OFFSET)
 
+	/* Copy setup data */
+	leal (boot_params - __PAGE_OFFSET + SETUP_DATA_POINTER),%ebx
+2:
+	movl (%ebx),%ebp
+	andl %ebp,%ebp
+	jz 1f
+	movl $SETUP_DATA_HEADER_LEN,%ecx
+	addl SETUP_DATA_LEN(%ebp),%ecx
+	addl $(SETUP_DATA_ALIGN_SIZE-1),%edi
+	andl $~(SETUP_DATA_ALIGN_SIZE-1),%edi
+	movl %edi,(%ebx)
+	movl %ebp,%esi
+	rep
+	movsb
+	movl (%ebx),%ebx
+	leal SETUP_DATA_NEXT(%ebx),%ebx
+	jmp 2b
+1:
+
 	xorl %ebx,%ebx				/* This is the boot CPU (BSP) */
 	jmp 3f
 /*

Index: linux-2.6/arch/x86/mm/discontig_32.c
===================================================================

arch/x86/mm/discontig_32.c +2 -1

@@ -282,7 +282,8 @@
 	kva_pages = calculate_numa_remap_pages();
 
 	/* partially used pages are not usable - thus round upwards */
-	system_start_pfn = min_low_pfn = PFN_UP(init_pg_tables_end);
+	system_start_pfn = min_low_pfn = PFN_UP(init_pg_tables_end +
+						setup_data_len);
 
 	kva_start_pfn = find_max_low_pfn() - kva_pages;
 

Index: linux-2.6/include/asm-x86/setup_32.h
===================================================================

include/asm-x86/setup_32.h +1 -0

+
 #ifndef __ASSEMBLY__
 

#include <asm/bootparam.h>
Index: linux-2.6/include/asm-x86/setup_64.h
===================================================================

include/asm-x86/setup_64.h +2 -1

@@ -4,7 +4,9 @@
 #define COMMAND_LINE_SIZE	2048
 
 #ifdef __KERNEL__
+#include <linux/const.h>
 
+#define SETUP_DATA_ALIGN_SIZE	__AC(0x8, UL)
 #ifndef __ASSEMBLY__
 #include <asm/bootparam.h>
 
-

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arch/x86/kernel/head_32.S line 138

Quoted 2 lines

1:

arch/x86/kernel/head_32.S +1 -0

+	movl boot_params - __PAGE_OFFSET + SETUP_DATA_POINTER,%ebp

You need to check the boot protocol version before looking at this pointer.

No, he doesn't. The boot protocol version is communication between the boot loader and the kernel (specifically, it is communication FROM the kernel TO the bootloader), not between internal bits of the kernel. Th

Since the pointer is safely inside the setup template, even if the bootloader doesn't understand boot protocol version 2.08 it will have copied it.

Quoted 4 lines · H. Peter Anvin

No, he doesn't. The boot protocol version is communication between the boot loader and the kernel (specifically, it is communication FROM the kernel TO the bootloader), not between internal bits of the kernel. Th

So the bootloader will only fill out fields the kernel claims to understand?

As a general comment, I can't say I'm thrilled about sticking the copied setup data at the end of the initial pagetables. This is already a fairly complex area, and changing it touches a surprisingly large number of places. I wonder if there isn't a better way to deal with this (possibly by fixing up the generation of the initial pagetables in the process).

Or more simply, define a max size for this data, and copy it into an initdata area (which, being initdata, can be quite large without wasting lots of memory).

Quoted 4 lines

include/asm-x86/bootparam.h +4 -0

+
+/* extensible setup data list node */
+struct setup_data {
+	u64 next;

include/asm-x86/bootparam.h line 21

Quoted 5 lines

include/asm-x86/bootparam.h +4 -0

+	u32 type;
+	u32 len;
+	u8 data[0];
+};

What are the alignment rules for this structure? Is it always 64-bit aligned? What about the relationship of len and data?

Furthermore, on looking through the code again, I see a bunch of "init_pg_tables_end + setup_data_len" which really is ugly.

Quoted 3 lines

What are the alignment rules for this structure? Is it always 64-bit aligned? What about the relationship of len and data?

It's x86, so alignment is soft - it presumably *should* be 64-bit aligned, but nothing break if the boot loader doesn't.

Quoted 5 lines · Ying

This patch add a field of 64-bit physical pointer to NULL terminated single linked list of struct setup_data to real-mode kernel header. This is used as a more extensible boot parameters passing mechanism.

As a general comment, I can't say I'm thrilled about sticking the copied setup data at the end of the initial pagetables. This is already a fairly complex area, and changing it touches a surprisingly large number of places. I wonder if there isn't a better way to deal with this (possibly by fixing up the generation of the initial pagetables in the process).

With the early reserve code in ftp://firstfloor.org/pub/ak/x86_64/quilt/patches/early-reserve and
ftp://firstfloor.org/pub/ak/x86_64/quilt/patches/early-alloc
this could be likely done cleaner.

Quoted 7 lines · Andi Kleen

With the early reserve code in ftp://firstfloor.org/pub/ak/x86_64/quilt/patches/early-reserve and ftp://firstfloor.org/pub/ak/x86_64/quilt/patches/early-alloc this could be likely done cleaner.

Indeed it could. For i386, the equivalent code would have another significant benefit: reserving memory and then mapping and accessing it later would (at least eventually) allow accesses > 4 GB on PAE kernels (or with a PSE36 hack, on non-PAE kernels.)

Quoted 7 lines · Andi Kleen

With the early reserve code in ftp://firstfloor.org/pub/ak/x86_64/quilt/patches/early-reserve and ftp://firstfloor.org/pub/ak/x86_64/quilt/patches/early-alloc this could be likely done cleaner.

Indeed it could. For i386, the equivalent code would have another significant benefit: reserving memory and then mapping and accessing it later would (at least eventually) allow accesses > 4 GB on PAE kernels (or with a PSE36 hack, on non-PAE kernels.)