From 51b26ada79b605ed709ddcedbb6012e8f8e0ebed Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Sun, 26 Apr 2009 10:12:47 -0700
Subject: x86: unify arch/x86/boot/compressed/vmlinux_*.lds

Look at the:

	diff -u arch/x86/boot/compressed/vmlinux_*.lds

output and realize that they're basially exactly the same except for
trivial naming differences, and the fact that the 64-bit version has a
"pgtable" thing.

So unify them.

There's some trivial cleanup there (make the output format a Kconfig thing
rather than doing #ifdef's for it, and unify both 32-bit and 64-bit BSS
end to "_ebss", where 32-bit used to use the traditional "_end"), but
other than that it's really very mindless and straigt conversion.

For example, I think we should aim to remove "startup_32" vs "startup_64",
and just call it "startup", and get rid of one more difference. I didn't
do that.

Also, notice the comment in the unified vmlinux.lds.S talks about
"head_64" and "startup_32" which is an odd and incorrect mix, but that was
actually what the old 64-bit only lds file had, so the confusion isn't
new, and now that mixing is arguably more accurate thanks to the
vmlinux.lds.S file being shared between the two cases ;)

[ Impact: cleanup, unification ]

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 arch/x86/boot/compressed/head_32.S | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

(limited to 'arch/x86/boot/compressed/head_32.S')

diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S
index 3a8a866fb2e..85bd3285706 100644
--- a/arch/x86/boot/compressed/head_32.S
+++ b/arch/x86/boot/compressed/head_32.S
@@ -88,9 +88,9 @@ ENTRY(startup_32)
  * where decompression in place becomes safe.
  */
 	pushl %esi
-	leal _end(%ebp), %esi
-	leal _end(%ebx), %edi
-	movl $(_end - startup_32), %ecx
+	leal _ebss(%ebp), %esi
+	leal _ebss(%ebx), %edi
+	movl $(_ebss - startup_32), %ecx
 	std
 	rep
 	movsb
@@ -121,7 +121,7 @@ relocated:
  */
 	xorl %eax,%eax
 	leal _edata(%ebx),%edi
-	leal _end(%ebx), %ecx
+	leal _ebss(%ebx), %ecx
 	subl %edi,%ecx
 	cld
 	rep
-- 
cgit v1.2.3-70-g09d2


From bd2a36984c50bb546a7d04cb395fddcf98a1092c Mon Sep 17 00:00:00 2001
From: "H. Peter Anvin" <hpa@zytor.com>
Date: Tue, 5 May 2009 23:24:50 -0700
Subject: x86, boot: use BP_scratch in arch/x86/boot/compressed/head_*.S

Use the BP_scratch symbol from asm-offsets.h instead of hard-coding
the location.

[ Impact: cleanup ]

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---
 arch/x86/boot/compressed/head_32.S | 2 +-
 arch/x86/boot/compressed/head_64.S | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

(limited to 'arch/x86/boot/compressed/head_32.S')

diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S
index 85bd3285706..e3398f3d1b3 100644
--- a/arch/x86/boot/compressed/head_32.S
+++ b/arch/x86/boot/compressed/head_32.S
@@ -53,7 +53,7 @@ ENTRY(startup_32)
  * data at 0x1e4 (defined as a scratch field) are used as the stack
  * for this calculation. Only 4 bytes are needed.
  */
-	leal (0x1e4+4)(%esi), %esp
+	leal (BP_scratch+4)(%esi), %esp
 	call 1f
 1:	popl %ebp
 	subl $1b, %ebp
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index ed4a8294800..06cc7e59352 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -56,7 +56,7 @@ ENTRY(startup_32)
  * data at 0x1e4 (defined as a scratch field) are used as the stack
  * for this calculation. Only 4 bytes are needed.
  */
-	leal	(0x1e4+4)(%esi), %esp
+	leal	(BP_scratch+4)(%esi), %esp
 	call	1f
 1:	popl	%ebp
 	subl	$1b, %ebp
-- 
cgit v1.2.3-70-g09d2


From 5f64ec64e7f9b246c0a94f34cdf7782f98a6e55d Mon Sep 17 00:00:00 2001
From: "H. Peter Anvin" <hpa@zytor.com>
Date: Fri, 8 May 2009 15:45:17 -0700
Subject: x86, boot: stylistic cleanups for boot/compressed/head_32.S

Reformat arch/x86/boot/compressed/head_32.S to be closer to currently
preferred kernel assembly style, that is:

- opcode and operand separated by tab
- operands separated by ", "
- C-style comments

This also makes it more similar to head_64.S.

[ Impact: cleanup, no object code change ]

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---
 arch/x86/boot/compressed/head_32.S | 170 +++++++++++++++++++------------------
 1 file changed, 89 insertions(+), 81 deletions(-)

(limited to 'arch/x86/boot/compressed/head_32.S')

diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S
index e3398f3d1b3..7bd7766ffab 100644
--- a/arch/x86/boot/compressed/head_32.S
+++ b/arch/x86/boot/compressed/head_32.S
@@ -12,16 +12,16 @@
  * the page directory. [According to comments etc elsewhere on a compressed
  * kernel it will end up at 0x1000 + 1Mb I hope so as I assume this. - AC]
  *
- * Page 0 is deliberately kept safe, since System Management Mode code in 
+ * Page 0 is deliberately kept safe, since System Management Mode code in
  * laptops may need to access the BIOS data stored there.  This is also
- * useful for future device drivers that either access the BIOS via VM86 
+ * useful for future device drivers that either access the BIOS via VM86
  * mode.
  */
 
 /*
  * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
  */
-.text
+	.text
 
 #include <linux/linkage.h>
 #include <asm/segment.h>
@@ -29,75 +29,80 @@
 #include <asm/boot.h>
 #include <asm/asm-offsets.h>
 
-.section ".text.head","ax",@progbits
+	.section ".text.head","ax",@progbits
 ENTRY(startup_32)
 	cld
-	/* test KEEP_SEGMENTS flag to see if the bootloader is asking
-	 * us to not reload segments */
-	testb $(1<<6), BP_loadflags(%esi)
-	jnz 1f
+	/*
+	 * Test KEEP_SEGMENTS flag to see if the bootloader is asking
+	 * us to not reload segments
+	 */
+	testb	$(1<<6), BP_loadflags(%esi)
+	jnz	1f
 
 	cli
-	movl $(__BOOT_DS),%eax
-	movl %eax,%ds
-	movl %eax,%es
-	movl %eax,%fs
-	movl %eax,%gs
-	movl %eax,%ss
+	movl	$__BOOT_DS, %eax
+	movl	%eax, %ds
+	movl	%eax, %es
+	movl	%eax, %fs
+	movl	%eax, %gs
+	movl	%eax, %ss
 1:
 
-/* Calculate the delta between where we were compiled to run
+/*
+ * Calculate the delta between where we were compiled to run
  * at and where we were actually loaded at.  This can only be done
  * with a short local call on x86.  Nothing  else will tell us what
  * address we are running at.  The reserved chunk of the real-mode
  * data at 0x1e4 (defined as a scratch field) are used as the stack
  * for this calculation. Only 4 bytes are needed.
  */
-	leal (BP_scratch+4)(%esi), %esp
-	call 1f
-1:	popl %ebp
-	subl $1b, %ebp
+	leal	(BP_scratch+4)(%esi), %esp
+	call	1f
+1:	popl	%ebp
+	subl	$1b, %ebp
 
-/* %ebp contains the address we are loaded at by the boot loader and %ebx
+/*
+ * %ebp contains the address we are loaded at by the boot loader and %ebx
  * contains the address where we should move the kernel image temporarily
  * for safe in-place decompression.
  */
 
 #ifdef CONFIG_RELOCATABLE
-	movl 	%ebp, %ebx
+	movl	%ebp, %ebx
 	addl    $(CONFIG_PHYSICAL_ALIGN - 1), %ebx
 	andl    $(~(CONFIG_PHYSICAL_ALIGN - 1)), %ebx
 #else
-	movl $LOAD_PHYSICAL_ADDR, %ebx
+	movl	$LOAD_PHYSICAL_ADDR, %ebx
 #endif
 
 	/* Replace the compressed data size with the uncompressed size */
-	subl input_len(%ebp), %ebx
-	movl output_len(%ebp), %eax
-	addl %eax, %ebx
+	subl	input_len(%ebp), %ebx
+	movl	output_len(%ebp), %eax
+	addl	%eax, %ebx
 	/* Add 8 bytes for every 32K input block */
-	shrl $12, %eax
-	addl %eax, %ebx
+	shrl	$12, %eax
+	addl	%eax, %ebx
 	/* Add 32K + 18 bytes of extra slack */
-	addl $(32768 + 18), %ebx
+	addl	$(32768 + 18), %ebx
 	/* Align on a 4K boundary */
-	addl $4095, %ebx
-	andl $~4095, %ebx
+	addl	$4095, %ebx
+	andl	$~4095, %ebx
 
-/* Copy the compressed kernel to the end of our buffer
+/*
+ * Copy the compressed kernel to the end of our buffer
  * where decompression in place becomes safe.
  */
-	pushl %esi
-	leal _ebss(%ebp), %esi
-	leal _ebss(%ebx), %edi
-	movl $(_ebss - startup_32), %ecx
+	pushl	%esi
+	leal	_ebss(%ebp), %esi
+	leal	_ebss(%ebx), %edi
+	movl	$(_ebss - startup_32), %ecx
 	std
-	rep
-	movsb
+	rep	movsb
 	cld
-	popl %esi
+	popl	%esi
 
-/* Compute the kernel start address.
+/*
+ * Compute the kernel start address.
  */
 #ifdef CONFIG_RELOCATABLE
 	addl    $(CONFIG_PHYSICAL_ALIGN - 1), %ebp
@@ -109,81 +114,84 @@ ENTRY(startup_32)
 /*
  * Jump to the relocated address.
  */
-	leal relocated(%ebx), %eax
-	jmp *%eax
+	leal	relocated(%ebx), %eax
+	jmp	*%eax
 ENDPROC(startup_32)
 
-.section ".text"
+	.text
 relocated:
 
 /*
  * Clear BSS
  */
-	xorl %eax,%eax
-	leal _edata(%ebx),%edi
-	leal _ebss(%ebx), %ecx
-	subl %edi,%ecx
+	xorl	%eax, %eax
+	leal	_edata(%ebx), %edi
+	leal	_ebss(%ebx), %ecx
+	subl	%edi, %ecx
 	cld
-	rep
-	stosb
+	rep	stosb
 
 /*
  * Setup the stack for the decompressor
  */
-	leal boot_stack_end(%ebx), %esp
+	leal	boot_stack_end(%ebx), %esp
 
 /*
  * Do the decompression, and jump to the new kernel..
  */
-	movl output_len(%ebx), %eax
-	pushl %eax
-			# push arguments for decompress_kernel:
-	pushl %ebp	# output address
-	movl input_len(%ebx), %eax
-	pushl %eax	# input_len
-	leal input_data(%ebx), %eax
-	pushl %eax	# input_data
-	leal boot_heap(%ebx), %eax
-	pushl %eax	# heap area
-	pushl %esi	# real mode pointer
-	call decompress_kernel
-	addl $20, %esp
-	popl %ecx
+	movl	output_len(%ebx), %eax
+	pushl	%eax
+				/* push arguments for decompress_kernel: */
+	pushl	%ebp		/* output address */
+	movl	input_len(%ebx), %eax
+	pushl	%eax		/* input_len */
+	leal	input_data(%ebx), %eax
+	pushl	%eax		/* input_data */
+	leal	boot_heap(%ebx), %eax
+	pushl	%eax		/* heap area */
+	pushl	%esi		/* real mode pointer */
+	call	decompress_kernel
+	addl	$20, %esp
+	popl	%ecx
 
 #if CONFIG_RELOCATABLE
-/* Find the address of the relocations.
+/*
+ * Find the address of the relocations.
  */
-	movl %ebp, %edi
-	addl %ecx, %edi
+	movl	%ebp, %edi
+	addl	%ecx, %edi
 
-/* Calculate the delta between where vmlinux was compiled to run
+/*
+ * Calculate the delta between where vmlinux was compiled to run
  * and where it was actually loaded.
  */
-	movl %ebp, %ebx
-	subl $LOAD_PHYSICAL_ADDR, %ebx
-	jz   2f		/* Nothing to be done if loaded at compiled addr. */
+	movl	%ebp, %ebx
+	subl	$LOAD_PHYSICAL_ADDR, %ebx
+	jz	2f	/* Nothing to be done if loaded at compiled addr. */
 /*
  * Process relocations.
  */
 
-1:	subl $4, %edi
-	movl 0(%edi), %ecx
-	testl %ecx, %ecx
-	jz 2f
-	addl %ebx, -__PAGE_OFFSET(%ebx, %ecx)
-	jmp 1b
+1:	subl	$4, %edi
+	movl	(%edi), %ecx
+	testl	%ecx, %ecx
+	jz	2f
+	addl	%ebx, -__PAGE_OFFSET(%ebx, %ecx)
+	jmp	1b
 2:
 #endif
 
 /*
  * Jump to the decompressed kernel.
  */
-	xorl %ebx,%ebx
-	jmp *%ebp
+	xorl	%ebx, %ebx
+	jmp	*%ebp
 
-.bss
-/* Stack and heap for uncompression */
-.balign 4
+/*
+ * Stack and heap for uncompression
+ */
+	.bss
+	.balign 4
 boot_heap:
 	.fill BOOT_HEAP_SIZE, 1, 0
 boot_stack:
-- 
cgit v1.2.3-70-g09d2


From 5b11f1cee5797b38d16b94d8745b12b6727a8373 Mon Sep 17 00:00:00 2001
From: "H. Peter Anvin" <hpa@zytor.com>
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 <hpa@zytor.com>
---
 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/head_32.S')

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 <asm/page_types.h>
+
 #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 v1.2.3-70-g09d2


From 0a137736704ef9af719409933b3c33e138461786 Mon Sep 17 00:00:00 2001
From: "H. Peter Anvin" <hpa@zytor.com>
Date: Fri, 8 May 2009 16:27:41 -0700
Subject: x86, boot: set up the decompression stack as early as possible

Set up the decompression stack as soon as we know where it needs to
go.  That way we have a full-service stack as soon as possible, rather
than relying on the BP_scratch field.

Note that the stack does need to be empty during bss zeroing (or
else the stack needs to be moved out of the bss segment, which is also
an option.)

[ Impact: cleanup, minor paranoia ]

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---
 arch/x86/boot/compressed/head_32.S | 10 ++++------
 arch/x86/boot/compressed/head_64.S | 16 ++++++++--------
 2 files changed, 12 insertions(+), 14 deletions(-)

(limited to 'arch/x86/boot/compressed/head_32.S')

diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S
index 59425e157df..d7245cf8026 100644
--- a/arch/x86/boot/compressed/head_32.S
+++ b/arch/x86/boot/compressed/head_32.S
@@ -88,6 +88,9 @@ ENTRY(startup_32)
 	addl	$4095, %ebx
 	andl	$~4095, %ebx
 
+	/* Set up the stack */
+	leal	boot_stack_end(%ebx), %esp
+
 /*
  * Copy the compressed kernel to the end of our buffer
  * where decompression in place becomes safe.
@@ -122,7 +125,7 @@ ENDPROC(startup_32)
 relocated:
 
 /*
- * Clear BSS
+ * Clear BSS (stack is currently empty)
  */
 	xorl	%eax, %eax
 	leal	_bss(%ebx), %edi
@@ -131,11 +134,6 @@ relocated:
 	cld
 	rep	stosb
 
-/*
- * Setup the stack for the decompressor
- */
-	leal	boot_stack_end(%ebx), %esp
-
 /*
  * Do the decompression, and jump to the new kernel..
  */
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index 5bc9052615b..a0b18426069 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -249,6 +249,13 @@ ENTRY(startup_64)
 	addq	$(32768 + 18 + 4095), %rbx
 	andq	$~4095, %rbx
 
+	/* Set up the stack */
+	leaq	boot_stack_end(%rbx), %rsp
+
+	/* Zero EFLAGS */
+	pushq	$0
+	popfq
+
 /*
  * Copy the compressed kernel to the end of our buffer
  * where decompression in place becomes safe.
@@ -273,7 +280,7 @@ ENTRY(startup_64)
 relocated:
 
 /*
- * Clear BSS
+ * Clear BSS (stack is currently empty)
  */
 	xorq	%rax, %rax
 	leaq    _bss(%rbx), %rdi
@@ -282,13 +289,6 @@ relocated:
 	cld
 	rep	stosb
 
-	/* Setup the stack */
-	leaq	boot_stack_end(%rip), %rsp
-
-	/* zero EFLAGS after setting rsp */
-	pushq	$0
-	popfq
-
 /*
  * Do the decompression, and jump to the new kernel..
  */
-- 
cgit v1.2.3-70-g09d2


From 97541912785369925723b6255438ad9fce2ddf04 Mon Sep 17 00:00:00 2001
From: "H. Peter Anvin" <hpa@zytor.com>
Date: Wed, 6 May 2009 17:56:51 -0700
Subject: x86, boot: zero EFLAGS on 32 bits

The 64-bit code already clears EFLAGS as soon as it has a stack.  This
seems like a reasonable precaution, so do it on 32 bits as well.

[ Impact: extra paranoia ]

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---
 arch/x86/boot/compressed/head_32.S | 4 ++++
 1 file changed, 4 insertions(+)

(limited to 'arch/x86/boot/compressed/head_32.S')

diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S
index d7245cf8026..d02a4f02be1 100644
--- a/arch/x86/boot/compressed/head_32.S
+++ b/arch/x86/boot/compressed/head_32.S
@@ -91,6 +91,10 @@ ENTRY(startup_32)
 	/* Set up the stack */
 	leal	boot_stack_end(%ebx), %esp
 
+	/* Zero EFLAGS */
+	pushl	$0
+	popfl
+
 /*
  * Copy the compressed kernel to the end of our buffer
  * where decompression in place becomes safe.
-- 
cgit v1.2.3-70-g09d2


From 36d3793c947f1ef7ba3d24eeeddc1be41adc5ab4 Mon Sep 17 00:00:00 2001
From: "H. Peter Anvin" <hpa@zytor.com>
Date: Fri, 8 May 2009 16:45:15 -0700
Subject: x86, boot: use appropriate rep string for move and clear

In the pre-decompression code, use the appropriate largest possible
rep movs and rep stos to move code and clear bss, respectively.  For
reverse copy, do note that the initial values are supposed to be the
address of the first (highest) copy datum, not one byte beyond the end
of the buffer.

rep strings are not necessarily the fastest way to perform these
operations on all current processors, but are likely to be in the
future, and perhaps more importantly, we want to encourage the
architecturally right thing to do here.

This also fixes a couple of trivial inefficiencies on 64 bits.

[ Impact: trivial performance enhancement, increase code similarity ]

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---
 arch/x86/boot/compressed/head_32.S | 11 ++++++-----
 arch/x86/boot/compressed/head_64.S | 26 +++++++++++++-------------
 2 files changed, 19 insertions(+), 18 deletions(-)

(limited to 'arch/x86/boot/compressed/head_32.S')

diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S
index d02a4f02be1..6710dc78ac5 100644
--- a/arch/x86/boot/compressed/head_32.S
+++ b/arch/x86/boot/compressed/head_32.S
@@ -100,11 +100,12 @@ ENTRY(startup_32)
  * where decompression in place becomes safe.
  */
 	pushl	%esi
-	leal	_bss(%ebp), %esi
-	leal	_bss(%ebx), %edi
+	leal	(_bss-4)(%ebp), %esi
+	leal	(_bss-4)(%ebx), %edi
 	movl	$(_bss - startup_32), %ecx
+	shrl	$2, %ecx
 	std
-	rep	movsb
+	rep	movsl
 	cld
 	popl	%esi
 
@@ -135,8 +136,8 @@ relocated:
 	leal	_bss(%ebx), %edi
 	leal	_ebss(%ebx), %ecx
 	subl	%edi, %ecx
-	cld
-	rep	stosb
+	shrl	$2, %ecx
+	rep	stosl
 
 /*
  * Do the decompression, and jump to the new kernel..
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index a0b18426069..723c72dfd7b 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -260,15 +260,15 @@ ENTRY(startup_64)
  * Copy the compressed kernel to the end of our buffer
  * where decompression in place becomes safe.
  */
-	leaq	_bss(%rip), %r8
-	leaq	_bss(%rbx), %r9
+	pushq	%rsi
+	leaq	(_bss-8)(%rip), %rsi
+	leaq	(_bss-8)(%rbx), %rdi
 	movq	$_bss /* - $startup_32 */, %rcx
-1:	subq	$8, %r8
-	subq	$8, %r9
-	movq	0(%r8), %rax
-	movq	%rax, 0(%r9)
-	subq	$8, %rcx
-	jnz	1b
+	shrq	$3, %rcx
+	std
+	rep	movsq
+	cld
+	popq	%rsi
 
 /*
  * Jump to the relocated address.
@@ -282,12 +282,12 @@ relocated:
 /*
  * Clear BSS (stack is currently empty)
  */
-	xorq	%rax, %rax
-	leaq    _bss(%rbx), %rdi
-	leaq    _ebss(%rbx), %rcx
+	xorl	%eax, %eax
+	leaq    _bss(%rip), %rdi
+	leaq    _ebss(%rip), %rcx
 	subq	%rdi, %rcx
-	cld
-	rep	stosb
+	shrq	$3, %rcx
+	rep	stosq
 
 /*
  * Do the decompression, and jump to the new kernel..
-- 
cgit v1.2.3-70-g09d2


From 02a884c0fe7ec8459d00d34b7d4101af21fc4a86 Mon Sep 17 00:00:00 2001
From: "H. Peter Anvin" <hpa@zytor.com>
Date: Fri, 8 May 2009 17:42:16 -0700
Subject: x86, boot: determine compressed code offset at compile time

Determine the compressed code offset (from the kernel runtime address)
at compile time.  This allows some minor optimizations in
arch/x86/boot/compressed/head_*.S, but more importantly it makes this
value available to the build process, which will enable a future patch
to export the necessary linear memory footprint into the bzImage
header.

[ Impact: cleanup, future patch enabling ]

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---
 arch/x86/boot/compressed/Makefile    | 11 ++--
 arch/x86/boot/compressed/head_32.S   | 24 ++-------
 arch/x86/boot/compressed/head_64.S   | 41 +++++----------
 arch/x86/boot/compressed/mkpiggy.c   | 97 ++++++++++++++++++++++++++++++++++++
 arch/x86/boot/compressed/vmlinux.scr | 10 ----
 5 files changed, 123 insertions(+), 60 deletions(-)
 create mode 100644 arch/x86/boot/compressed/mkpiggy.c
 delete mode 100644 arch/x86/boot/compressed/vmlinux.scr

(limited to 'arch/x86/boot/compressed/head_32.S')

diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index 7f24fdb584e..49c8a4c37d7 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -19,6 +19,8 @@ KBUILD_AFLAGS  := $(KBUILD_CFLAGS) -D__ASSEMBLY__
 LDFLAGS := -m elf_$(UTS_MACHINE)
 LDFLAGS_vmlinux := -T
 
+hostprogs-y	:= mkpiggy
+
 $(obj)/vmlinux: $(obj)/vmlinux.lds $(obj)/head_$(BITS).o $(obj)/misc.o $(obj)/piggy.o FORCE
 	$(call if_changed,ld)
 	@:
@@ -50,6 +52,9 @@ suffix-$(CONFIG_KERNEL_GZIP)	:= gz
 suffix-$(CONFIG_KERNEL_BZIP2)	:= bz2
 suffix-$(CONFIG_KERNEL_LZMA)	:= lzma
 
-LDFLAGS_piggy.o := -r --format binary --oformat $(CONFIG_OUTPUT_FORMAT) -T
-$(obj)/piggy.o: $(obj)/vmlinux.scr $(obj)/vmlinux.bin.$(suffix-y) FORCE
-	$(call if_changed,ld)
+quiet_cmd_mkpiggy = MKPIGGY $@
+      cmd_mkpiggy = $(obj)/mkpiggy $< > $@ || ( rm -f $@ ; false )
+
+targets += piggy.S
+$(obj)/piggy.S: $(obj)/vmlinux.bin.$(suffix-y) $(obj)/mkpiggy FORCE
+	$(call if_changed,mkpiggy)
diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S
index 6710dc78ac5..470474bafc4 100644
--- a/arch/x86/boot/compressed/head_32.S
+++ b/arch/x86/boot/compressed/head_32.S
@@ -75,18 +75,8 @@ ENTRY(startup_32)
 	movl	$LOAD_PHYSICAL_ADDR, %ebx
 #endif
 
-	/* Replace the compressed data size with the uncompressed size */
-	subl	input_len(%ebp), %ebx
-	movl	output_len(%ebp), %eax
-	addl	%eax, %ebx
-	/* Add 8 bytes for every 32K input block */
-	shrl	$12, %eax
-	addl	%eax, %ebx
-	/* Add 32K + 18 bytes of extra slack */
-	addl	$(32768 + 18), %ebx
-	/* Align on a 4K boundary */
-	addl	$4095, %ebx
-	andl	$~4095, %ebx
+	/* Target address to relocate to for decompression */
+	addl	$z_extract_offset, %ebx
 
 	/* Set up the stack */
 	leal	boot_stack_end(%ebx), %esp
@@ -142,12 +132,10 @@ relocated:
 /*
  * Do the decompression, and jump to the new kernel..
  */
-	movl	output_len(%ebx), %eax
-	pushl	%eax
+	leal	z_extract_offset_negative(%ebx), %ebp
 				/* push arguments for decompress_kernel: */
 	pushl	%ebp		/* output address */
-	movl	input_len(%ebx), %eax
-	pushl	%eax		/* input_len */
+	pushl	$z_input_len	/* input_len */
 	leal	input_data(%ebx), %eax
 	pushl	%eax		/* input_data */
 	leal	boot_heap(%ebx), %eax
@@ -155,14 +143,12 @@ relocated:
 	pushl	%esi		/* real mode pointer */
 	call	decompress_kernel
 	addl	$20, %esp
-	popl	%ecx
 
 #if CONFIG_RELOCATABLE
 /*
  * Find the address of the relocations.
  */
-	movl	%ebp, %edi
-	addl	%ecx, %edi
+	leal	z_output_len(%ebp), %edi
 
 /*
  * Calculate the delta between where vmlinux was compiled to run
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index 723c72dfd7b..2b9f2510507 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -90,16 +90,8 @@ ENTRY(startup_32)
 	movl	$CONFIG_PHYSICAL_START, %ebx
 #endif
 
-	/* Replace the compressed data size with the uncompressed size */
-	subl	input_len(%ebp), %ebx
-	movl	output_len(%ebp), %eax
-	addl	%eax, %ebx
-	/* Add 8 bytes for every 32K input block */
-	shrl	$12, %eax
-	addl	%eax, %ebx
-	/* Add 32K + 18 bytes of extra slack and align on a 4K boundary */
-	addl	$(32768 + 18 + 4095), %ebx
-	andl	$~4095, %ebx
+	/* Target address to relocate to for decompression */
+	addl	$z_extract_offset, %ebx
 
 /*
  * Prepare for entering 64 bit mode
@@ -224,6 +216,9 @@ ENTRY(startup_64)
 	 * If it is a relocatable kernel then decompress and run the kernel
 	 * from load address aligned to 2MB addr, otherwise decompress and
 	 * run the kernel from CONFIG_PHYSICAL_START
+	 *
+	 * We cannot rely on the calculation done in 32-bit mode, since we
+	 * may have been invoked via the 64-bit entry point.
 	 */
 
 	/* Start with the delta to where the kernel will run at. */
@@ -237,17 +232,8 @@ ENTRY(startup_64)
 	movq	%rbp, %rbx
 #endif
 
-	/* Replace the compressed data size with the uncompressed size */
-	movl	input_len(%rip), %eax
-	subq	%rax, %rbx
-	movl	output_len(%rip), %eax
-	addq	%rax, %rbx
-	/* Add 8 bytes for every 32K input block */
-	shrq	$12, %rax
-	addq	%rax, %rbx
-	/* Add 32K + 18 bytes of extra slack and align on a 4K boundary */
-	addq	$(32768 + 18 + 4095), %rbx
-	andq	$~4095, %rbx
+	/* Target address to relocate to for decompression */
+	leaq	z_extract_offset(%rbp), %rbx
 
 	/* Set up the stack */
 	leaq	boot_stack_end(%rbx), %rsp
@@ -292,13 +278,12 @@ relocated:
 /*
  * Do the decompression, and jump to the new kernel..
  */
-	pushq	%rsi			# Save the real mode argument
-	movq	%rsi, %rdi		# real mode address
-	leaq	boot_heap(%rip), %rsi	# malloc area for uncompression
-	leaq	input_data(%rip), %rdx  # input_data
-	movl	input_len(%rip), %eax
-	movq	%rax, %rcx		# input_len
-	movq	%rbp, %r8		# output
+	pushq	%rsi			/* Save the real mode argument */
+	movq	%rsi, %rdi		/* real mode address */
+	leaq	boot_heap(%rip), %rsi	/* malloc area for uncompression */
+	leaq	input_data(%rip), %rdx  /* input_data */
+	movl	$z_input_len, %ecx	/* input_len */
+	movq	%rbp, %r8		/* output target address */
 	call	decompress_kernel
 	popq	%rsi
 
diff --git a/arch/x86/boot/compressed/mkpiggy.c b/arch/x86/boot/compressed/mkpiggy.c
new file mode 100644
index 00000000000..bcbd36c4143
--- /dev/null
+++ b/arch/x86/boot/compressed/mkpiggy.c
@@ -0,0 +1,97 @@
+/* ----------------------------------------------------------------------- *
+ *
+ *  Copyright (C) 2009 Intel Corporation. All rights reserved.
+ *
+ *  This program is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU General Public License version
+ *  2 as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ *  02110-1301, USA.
+ *
+ *  H. Peter Anvin <hpa@linux.intel.com>
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * Compute the desired load offset from a compressed program; outputs
+ * a small assembly wrapper with the appropriate symbols defined.
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <inttypes.h>
+
+static uint32_t getle32(const void *p)
+{
+	const uint8_t *cp = p;
+
+	return (uint32_t)cp[0] + ((uint32_t)cp[1] << 8) +
+		((uint32_t)cp[2] << 16) + ((uint32_t)cp[3] << 24);
+}
+
+int main(int argc, char *argv[])
+{
+	uint32_t olen;
+	long ilen;
+	unsigned long offs;
+	FILE *f;
+
+	if (argc < 2) {
+		fprintf(stderr, "Usage: %s compressed_file\n", argv[0]);
+		return 1;
+	}
+
+	/* Get the information for the compressed kernel image first */
+
+	f = fopen(argv[1], "r");
+	if (!f) {
+		perror(argv[1]);
+		return 1;
+	}
+
+
+	if (fseek(f, -4L, SEEK_END)) {
+		perror(argv[1]);
+	}
+	fread(&olen, sizeof olen, 1, f);
+	ilen = ftell(f);
+	olen = getle32(&olen);
+	fclose(f);
+
+	/*
+	 * Now we have the input (compressed) and output (uncompressed)
+	 * sizes, compute the necessary decompression offset...
+	 */
+
+	offs = (olen > ilen) ? olen - ilen : 0;
+	offs += olen >> 12;	/* Add 8 bytes for each 32K block */
+	offs += 32*1024 + 18;	/* Add 32K + 18 bytes slack */
+	offs = (offs+4095) & ~4095; /* Round to a 4K boundary */
+
+	printf(".section \".rodata.compressed\",\"a\",@progbits\n");
+	printf(".globl z_input_len\n");
+	printf("z_input_len = %lu\n", ilen);
+	printf(".globl z_output_len\n");
+	printf("z_output_len = %lu\n", (unsigned long)olen);
+	printf(".globl z_extract_offset\n");
+	printf("z_extract_offset = 0x%lx\n", offs);
+	/* z_extract_offset_negative allows simplification of head_32.S */
+	printf(".globl z_extract_offset_negative\n");
+	printf("z_extract_offset_negative = -0x%lx\n", offs);
+
+	printf(".globl input_data, input_data_end\n");
+	printf("input_data:\n");
+	printf(".incbin \"%s\"\n", argv[1]);
+	printf("input_data_end:\n");
+
+	return 0;
+}
diff --git a/arch/x86/boot/compressed/vmlinux.scr b/arch/x86/boot/compressed/vmlinux.scr
deleted file mode 100644
index f02382ae5c4..00000000000
--- a/arch/x86/boot/compressed/vmlinux.scr
+++ /dev/null
@@ -1,10 +0,0 @@
-SECTIONS
-{
-  .rodata.compressed : {
-	input_len = .;
-	LONG(input_data_end - input_data) input_data = .;
-	*(.data)
-	output_len = . - 4;
-	input_data_end = .;
-	}
-}
-- 
cgit v1.2.3-70-g09d2


From 99aa45595f45603526513d5e29fc00f8afbf3913 Mon Sep 17 00:00:00 2001
From: "H. Peter Anvin" <hpa@zytor.com>
Date: Mon, 11 May 2009 16:02:10 -0700
Subject: x86, boot: remove dead code from boot/compressed/head_*.S

Remove a couple of lines of dead code from
arch/x86/boot/compressed/head_*.S; all of these update registers that
are dead in the current code.

[ Impact: cleanup ]

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---
 arch/x86/boot/compressed/head_32.S | 10 ----------
 arch/x86/boot/compressed/head_64.S |  2 --
 2 files changed, 12 deletions(-)

(limited to 'arch/x86/boot/compressed/head_32.S')

diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S
index 470474bafc4..2b8e0dfa4b2 100644
--- a/arch/x86/boot/compressed/head_32.S
+++ b/arch/x86/boot/compressed/head_32.S
@@ -99,16 +99,6 @@ ENTRY(startup_32)
 	cld
 	popl	%esi
 
-/*
- * Compute the kernel start address.
- */
-#ifdef CONFIG_RELOCATABLE
-	addl    $(CONFIG_PHYSICAL_ALIGN - 1), %ebp
-	andl    $(~(CONFIG_PHYSICAL_ALIGN - 1)), %ebp
-#else
-	movl	$LOAD_PHYSICAL_ADDR, %ebp
-#endif
-
 /*
  * Jump to the relocated address.
  */
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index 4135d438b66..2bb500af1bd 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -226,10 +226,8 @@ ENTRY(startup_64)
 	leaq	startup_32(%rip) /* - $startup_32 */, %rbp
 	addq	$(PMD_PAGE_SIZE - 1), %rbp
 	andq	$PMD_PAGE_MASK, %rbp
-	movq	%rbp, %rbx
 #else
 	movq	$LOAD_PHYSICAL_ADDR, %rbp
-	movq	%rbp, %rbx
 #endif
 
 	/* Target address to relocate to for decompression */
-- 
cgit v1.2.3-70-g09d2


From 37ba7ab5e33cebc25c68fffe33e9f21e7c2014e8 Mon Sep 17 00:00:00 2001
From: "H. Peter Anvin" <hpa@zytor.com>
Date: Mon, 11 May 2009 15:56:08 -0700
Subject: x86, boot: make kernel_alignment adjustable; new bzImage fields

Make the kernel_alignment field adjustable; this allows us to set it
to a large value (intended to be 16 MB to avoid ZONE_DMA contention,
memory holes and other weirdness) while a smart bootloader can still
force a loading at a lesser alignment if absolutely necessary.

Also export pref_address (preferred loading address, corresponding to
the link-time address) and init_size, the total amount of linear
memory the kernel will require during initialization.

[ Impact: allows better kernel placement, gives bootloader more info ]

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---
 arch/x86/boot/compressed/head_32.S |  7 +++++--
 arch/x86/boot/compressed/head_64.S | 14 ++++++++++----
 arch/x86/boot/header.S             | 15 +++++++++++++--
 arch/x86/include/asm/boot.h        | 15 +++++++++++++++
 arch/x86/kernel/asm-offsets_32.c   |  1 +
 arch/x86/kernel/asm-offsets_64.c   |  1 +
 6 files changed, 45 insertions(+), 8 deletions(-)

(limited to 'arch/x86/boot/compressed/head_32.S')

diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S
index 2b8e0dfa4b2..75e4f001e70 100644
--- a/arch/x86/boot/compressed/head_32.S
+++ b/arch/x86/boot/compressed/head_32.S
@@ -69,8 +69,11 @@ ENTRY(startup_32)
 
 #ifdef CONFIG_RELOCATABLE
 	movl	%ebp, %ebx
-	addl    $(CONFIG_PHYSICAL_ALIGN - 1), %ebx
-	andl    $(~(CONFIG_PHYSICAL_ALIGN - 1)), %ebx
+	movl	BP_kernel_alignment(%esi), %eax
+	decl	%eax
+	addl    %eax, %ebx
+	notl	%eax
+	andl    %eax, %ebx
 #else
 	movl	$LOAD_PHYSICAL_ADDR, %ebx
 #endif
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index 2bb500af1bd..f62c284db9e 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -84,8 +84,11 @@ ENTRY(startup_32)
 
 #ifdef CONFIG_RELOCATABLE
 	movl	%ebp, %ebx
-	addl	$(PMD_PAGE_SIZE -1), %ebx
-	andl	$PMD_PAGE_MASK, %ebx
+	movl	BP_kernel_alignment(%esi), %eax
+	decl	%eax
+	addl	%eax, %ebx
+	notl	%eax
+	andl	%eax, %ebx
 #else
 	movl	$LOAD_PHYSICAL_ADDR, %ebx
 #endif
@@ -224,8 +227,11 @@ ENTRY(startup_64)
 	/* Start with the delta to where the kernel will run at. */
 #ifdef CONFIG_RELOCATABLE
 	leaq	startup_32(%rip) /* - $startup_32 */, %rbp
-	addq	$(PMD_PAGE_SIZE - 1), %rbp
-	andq	$PMD_PAGE_MASK, %rbp
+	movl	BP_kernel_alignment(%rsi), %eax
+	decl	%eax
+	addq	%rax, %rbp
+	notq	%rax
+	andq	%rax, %rbp
 #else
 	movq	$LOAD_PHYSICAL_ADDR, %rbp
 #endif
diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
index 27285143ade..a0b426978d5 100644
--- a/arch/x86/boot/header.S
+++ b/arch/x86/boot/header.S
@@ -116,7 +116,7 @@ _start:
 	# Part 2 of the header, from the old setup.S
 
 		.ascii	"HdrS"		# header signature
-		.word	0x0209		# header version number (>= 0x0105)
+		.word	0x020a		# header version number (>= 0x0105)
 					# or else old loadlin-1.5 will fail)
 		.globl realmode_swtch
 realmode_swtch:	.word	0, 0		# default_switch, SETUPSEG
@@ -201,7 +201,7 @@ relocatable_kernel:    .byte 1
 #else
 relocatable_kernel:    .byte 0
 #endif
-pad2:			.byte 0
+min_alignment:		.byte MIN_KERNEL_ALIGN_LG2	# minimum alignment
 pad3:			.word 0
 
 cmdline_size:   .long   COMMAND_LINE_SIZE-1     #length of the command line,
@@ -220,6 +220,17 @@ setup_data:		.quad 0			# 64-bit physical pointer to
 						# single linked list of
 						# struct setup_data
 
+pref_address:		.quad LOAD_PHYSICAL_ADDR	# preferred load addr
+
+#define ZO_INIT_SIZE	(ZO__end - ZO_startup_32 + ZO_extract_offset)
+#define VO_INIT_SIZE	(VO__end - VO__text)
+#if ZO_INIT_SIZE > VO_INIT_SIZE
+#define INIT_SIZE ZO_INIT_SIZE
+#else
+#define INIT_SIZE VO_INIT_SIZE
+#endif
+init_size:		.long INIT_SIZE		# kernel initialization size
+
 # End of setup header #####################################################
 
 	.section ".inittext", "ax"
diff --git a/arch/x86/include/asm/boot.h b/arch/x86/include/asm/boot.h
index 6ba23dd9fc9..418e632d4a8 100644
--- a/arch/x86/include/asm/boot.h
+++ b/arch/x86/include/asm/boot.h
@@ -8,11 +8,26 @@
 
 #ifdef __KERNEL__
 
+#include <asm/page_types.h>
+
 /* Physical address where kernel should be loaded. */
 #define LOAD_PHYSICAL_ADDR ((CONFIG_PHYSICAL_START \
 				+ (CONFIG_PHYSICAL_ALIGN - 1)) \
 				& ~(CONFIG_PHYSICAL_ALIGN - 1))
 
+/* Minimum kernel alignment, as a power of two */
+#ifdef CONFIG_x86_64
+#define MIN_KERNEL_ALIGN_LG2	PMD_SHIFT
+#else
+#define MIN_KERNEL_ALIGN_LG2	(PAGE_SHIFT+1)
+#endif
+#define MIN_KERNEL_ALIGN	(_AC(1, UL) << MIN_KERNEL_ALIGN_LG2)
+
+#if (CONFIG_PHYSICAL_ALIGN & (CONFIG_PHYSICAL_ALIGN-1)) || \
+	(CONFIG_PHYSICAL_ALIGN < (_AC(1, UL) << MIN_KERNEL_ALIGN_LG2))
+#error "Invalid value for CONFIG_PHYSICAL_ALIGN"
+#endif
+
 #ifdef CONFIG_KERNEL_BZIP2
 #define BOOT_HEAP_SIZE             0x400000
 #else /* !CONFIG_KERNEL_BZIP2 */
diff --git a/arch/x86/kernel/asm-offsets_32.c b/arch/x86/kernel/asm-offsets_32.c
index 5a6aa1c1162..1a830cbd701 100644
--- a/arch/x86/kernel/asm-offsets_32.c
+++ b/arch/x86/kernel/asm-offsets_32.c
@@ -146,4 +146,5 @@ void foo(void)
 	OFFSET(BP_loadflags, boot_params, hdr.loadflags);
 	OFFSET(BP_hardware_subarch, boot_params, hdr.hardware_subarch);
 	OFFSET(BP_version, boot_params, hdr.version);
+	OFFSET(BP_kernel_alignment, boot_params, hdr.kernel_alignment);
 }
diff --git a/arch/x86/kernel/asm-offsets_64.c b/arch/x86/kernel/asm-offsets_64.c
index e72f062fb4b..898ecc47e12 100644
--- a/arch/x86/kernel/asm-offsets_64.c
+++ b/arch/x86/kernel/asm-offsets_64.c
@@ -125,6 +125,7 @@ int main(void)
 	OFFSET(BP_loadflags, boot_params, hdr.loadflags);
 	OFFSET(BP_hardware_subarch, boot_params, hdr.hardware_subarch);
 	OFFSET(BP_version, boot_params, hdr.version);
+	OFFSET(BP_kernel_alignment, boot_params, hdr.kernel_alignment);
 
 	BLANK();
 	DEFINE(PAGE_SIZE_asm, PAGE_SIZE);
-- 
cgit v1.2.3-70-g09d2