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Commit f8657e1b authored by Vivek Goyal's avatar Vivek Goyal Committed by Andi Kleen
Browse files

[PATCH] i386: move startup_32() in text.head section 



o Entry startup_32 was in .text section but it was accessing some init
  data too and it prompts MODPOST to generate compilation warnings.

WARNING: vmlinux - Section mismatch: reference to .init.data:boot_params from
.text between '_text' (at offset 0xc0100029) and 'startup_32_smp'
WARNING: vmlinux - Section mismatch: reference to .init.data:boot_params from
.text between '_text' (at offset 0xc0100037) and 'startup_32_smp'
WARNING: vmlinux - Section mismatch: reference to
.init.data:init_pg_tables_end from .text between '_text' (at offset
0xc0100099) and 'startup_32_smp'

o Can't move startup_32 to .init.text as this entry point has to be at the
  start of bzImage. Hence moved startup_32 to a new section .text.head and
  instructed MODPOST to not to generate warnings if init data is being
  accessed from .text.head section. This code has been audited.

o SMP boot up code (startup_32_smp) can go into .init.text if CPU hotplug
  is not supported. Otherwise it generates more warnings

WARNING: vmlinux - Section mismatch: reference to .init.data:new_cpu_data from
.text between 'checkCPUtype' (at offset 0xc0100126) and 'is486'
WARNING: vmlinux - Section mismatch: reference to .init.data:new_cpu_data from
.text between 'checkCPUtype' (at offset 0xc0100130) and 'is486'

Signed-off-by: default avatarVivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarAndi Kleen <ak@suse.de>
parent 7c0b49f9

arch/i386/kernel/head.S

+14 −3
Original line number Diff line number Diff line
@@ -53,6 +53,7 @@ 
 * any particular GDT layout, because we load our own as soon as we

 * can.

 */

.section .text.head,"ax",@progbits

ENTRY(startup_32)



#ifdef CONFIG_PARAVIRT
@@ -141,16 +142,25 @@ page_pde_offset = (__PAGE_OFFSET >> 20); 
	jb 10b

	movl %edi,(init_pg_tables_end - __PAGE_OFFSET)



#ifdef CONFIG_SMP

	xorl %ebx,%ebx				/* This is the boot CPU (BSP) */

	jmp 3f



/*

 * Non-boot CPU entry point; entered from trampoline.S

 * We can't lgdt here, because lgdt itself uses a data segment, but

 * we know the trampoline has already loaded the boot_gdt_table GDT

 * for us.

 *

 * If cpu hotplug is not supported then this code can go in init section

 * which will be freed later

 */



#ifdef CONFIG_HOTPLUG_CPU

.section .text,"ax",@progbits

#else

.section .init.text,"ax",@progbits

#endif



#ifdef CONFIG_SMP

ENTRY(startup_32_smp)

	cld

	movl $(__BOOT_DS),%eax
@@ -208,8 +218,8 @@ ENTRY(startup_32_smp) 
	xorl %ebx,%ebx

	incl %ebx



3:

#endif /* CONFIG_SMP */

3:



/*

 * Enable paging
@@ -492,6 +502,7 @@ ignore_int: 
#endif

	iret



.section .text

#ifdef CONFIG_PARAVIRT

startup_paravirt:

	cld

arch/i386/kernel/vmlinux.lds.S

+6 −1
Original line number Diff line number Diff line
@@ -37,9 +37,14 @@ SECTIONS 
{

  . = LOAD_OFFSET + LOAD_PHYSICAL_ADDR;

  phys_startup_32 = startup_32 - LOAD_OFFSET;



  .text.head : AT(ADDR(.text.head) - LOAD_OFFSET) {

  	_text = .;			/* Text and read-only data */

	*(.text.head)

  } :text = 0x9090



  /* read-only */

  .text : AT(ADDR(.text) - LOAD_OFFSET) {

  	_text = .;			/* Text and read-only data */

	*(.text)

	SCHED_TEXT

	LOCK_TEXT

scripts/mod/modpost.c

+9 −1
Original line number Diff line number Diff line
@@ -641,12 +641,20 @@ static int secref_whitelist(const char *modname, const char *tosec, 
	if (f1 && f2)

		return 1;



	/* Whitelist all references from .pci_fixup section if vmlinux */

	/* Whitelist all references from .pci_fixup section if vmlinux

	 * Whitelist all refereces from .text.head to .init.data if vmlinux

	 * Whitelist all refereces from .text.head to .init.text if vmlinux

	 */

	if (is_vmlinux(modname)) {

		if ((strcmp(fromsec, ".pci_fixup") == 0) &&

		    (strcmp(tosec, ".init.text") == 0))

		return 1;



		if ((strcmp(fromsec, ".text.head") == 0) &&

			((strcmp(tosec, ".init.data") == 0) ||

			(strcmp(tosec, ".init.text") == 0)))

		return 1;



		/* Check for pattern 3 */

		for (s = pat3refsym; *s; s++)

			if (strcmp(refsymname, *s) == 0)