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    Subject[PATCH x86 for review II] [1/39] i386: move startup_32() in text.head section
    Date

    From: Vivek Goyal <vgoyal@in.ibm.com>

    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: Vivek Goyal <vgoyal@in.ibm.com>
    Signed-off-by: Andrew Morton <akpm@osdl.org>
    Signed-off-by: Andi Kleen <ak@suse.de>

    ---

    arch/i386/kernel/head.S | 17 ++++++++++++++---
    arch/i386/kernel/vmlinux.lds.S | 7 ++++++-
    scripts/mod/modpost.c | 10 +++++++++-
    3 files changed, 29 insertions(+), 5 deletions(-)

    Index: linux/arch/i386/kernel/head.S
    ===================================================================
    --- linux.orig/arch/i386/kernel/head.S
    +++ linux/arch/i386/kernel/head.S
    @@ -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
    Index: linux/arch/i386/kernel/vmlinux.lds.S
    ===================================================================
    --- linux.orig/arch/i386/kernel/vmlinux.lds.S
    +++ linux/arch/i386/kernel/vmlinux.lds.S
    @@ -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
    Index: linux/scripts/mod/modpost.c
    ===================================================================
    --- linux.orig/scripts/mod/modpost.c
    +++ linux/scripts/mod/modpost.c
    @@ -641,12 +641,20 @@ static int secref_whitelist(const char *
    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)
    -
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