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    Subject[PATCH 2/2] x86_64: Remove CONFIG_PHYSICAL_START and CONFIG_RELOCATABLE
    Date

    Now that the vmlinux is marked as relocatable there is no reason to
    retain the CONFIG_PHYSICAL_START option, as we can put the binary we
    have at any 2MB aligned address in memory.

    With CONFIG_PHYSICAL_START gone the handful of code lines that depend
    on CONFIG_RELOCATABLE no longer make sense to be conditional and can
    be removed.

    The big win of this patch (besides Kconfig simplicity) is that the
    nasty BUILD_BUG_ON test for people misaligning their kernel when using
    CONFIG_PHYSICAL_START can be removed as this case can only happen with
    CONFIG_PHYSICAL_START selected.

    Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
    ---
    arch/x86_64/Kconfig | 55 +-----------------------------------
    arch/x86_64/Makefile | 2 -
    arch/x86_64/boot/compressed/head.S | 13 +--------
    arch/x86_64/boot/setup.S | 4 --
    arch/x86_64/defconfig | 2 -
    arch/x86_64/kernel/head64.c | 7 ----
    include/asm-x86_64/page.h | 2 +-
    7 files changed, 3 insertions(+), 82 deletions(-)

    diff --git a/arch/x86_64/Kconfig b/arch/x86_64/Kconfig
    index 773b487..713c1ad 100644
    --- a/arch/x86_64/Kconfig
    +++ b/arch/x86_64/Kconfig
    @@ -565,62 +565,9 @@ config CRASH_DUMP
    which are loaded in the main kernel with kexec-tools into
    a specially reserved region and then later executed after
    a crash by kdump/kexec. The crash dump kernel must be compiled
    - to a memory address not used by the main kernel or BIOS using
    - PHYSICAL_START.
    + to a memory address not used by the main kernel or BIOS
    For more details see Documentation/kdump/kdump.txt

    -config RELOCATABLE
    - bool "Build a relocatable kernel(EXPERIMENTAL)"
    - depends on EXPERIMENTAL
    - help
    - Builds a relocatable kernel. This enables loading and running
    - a kernel binary from a different physical address than it has
    - been compiled for.
    -
    - One use is for the kexec on panic case where the recovery kernel
    - must live at a different physical address than the primary
    - kernel.
    -
    - Note: If CONFIG_RELOCATABLE=y, then kernel run from the address
    - it has been loaded at and compile time physical address
    - (CONFIG_PHYSICAL_START) is ignored.
    -
    -config PHYSICAL_START
    - hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
    - default "0x200000"
    - help
    - This gives the physical address where the kernel is loaded. It
    - should be aligned to 2MB boundary.
    -
    - If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
    - bzImage will decompress itself to above physical address and
    - run from there. Otherwise, bzImage will run from the address where
    - it has been loaded by the boot loader and will ignore above physical
    - address.
    -
    - In normal kdump cases one does not have to set/change this option
    - as now bzImage can be compiled as a completely relocatable image
    - (CONFIG_RELOCATABLE=y) and be used to load and run from a different
    - address. This option is mainly useful for the folks who don't want
    - to use a bzImage for capturing the crash dump and want to use a
    - vmlinux instead.
    -
    - So if you are using bzImage for capturing the crash dump, leave
    - the value here unchanged to 0x200000 and set CONFIG_RELOCATABLE=y.
    - Otherwise if you plan to use vmlinux for capturing the crash dump
    - change this value to start of the reserved region (Typically 16MB
    - 0x1000000). In other words, it can be set based on the "X" value as
    - specified in the "crashkernel=YM@XM" command line boot parameter
    - passed to the panic-ed kernel. Typically this parameter is set as
    - crashkernel=64M@16M. Please take a look at
    - Documentation/kdump/kdump.txt for more details about crash dumps.
    -
    - Usage of bzImage for capturing the crash dump is advantageous as
    - one does not have to build two kernels. Same kernel can be used
    - as production kernel and capture kernel.
    -
    - Don't change this unless you know what you are doing.
    -
    config SECCOMP
    bool "Enable seccomp to safely compute untrusted bytecode"
    depends on PROC_FS
    diff --git a/arch/x86_64/Makefile b/arch/x86_64/Makefile
    index 5ae79ab..5d96f4f 100644
    --- a/arch/x86_64/Makefile
    +++ b/arch/x86_64/Makefile
    @@ -124,7 +124,6 @@ define archhelp
    echo ' isoimage - Create a boot CD-ROM image'
    endef

    -ifeq ($(CONFIG_RELOCATABLE),y)
    define cmd_vmlinux__
    $(LD) $(LDFLAGS) $(LDFLAGS_vmlinux) -o $@ \
    -T $(vmlinux-lds) $(vmlinux-init) \
    @@ -132,7 +131,6 @@ define cmd_vmlinux__
    $(filter-out $(vmlinux-lds) $(vmlinux-init) $(vmlinux-main) FORCE ,$^) \
    && scripts/mketrel $@
    endef
    -endif

    CLEAN_FILES += arch/$(ARCH)/boot/fdimage \
    arch/$(ARCH)/boot/image.iso \
    diff --git a/arch/x86_64/boot/compressed/head.S b/arch/x86_64/boot/compressed/head.S
    index f9d5692..493723e 100644
    --- a/arch/x86_64/boot/compressed/head.S
    +++ b/arch/x86_64/boot/compressed/head.S
    @@ -71,13 +71,9 @@ startup_32:
    * for safe in-place decompression.
    */

    -#ifdef CONFIG_RELOCATABLE
    movl %ebp, %ebx
    addl $(LARGE_PAGE_SIZE -1), %ebx
    andl $LARGE_PAGE_MASK, %ebx
    -#else
    - movl $CONFIG_PHYSICAL_START, %ebx
    -#endif

    /* Replace the compressed data size with the uncompressed size */
    subl input_len(%ebp), %ebx
    @@ -200,21 +196,14 @@ ENTRY(startup_64)
    * we were loaded at aligned to a 2M boundary. %rbp contains the
    * decompressed kernel start address.
    *
    - * 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
    + * Decompress and run the kernel from load address aligned to 2MB addr
    */

    /* Start with the delta to where the kernel will run at. */
    -#ifdef CONFIG_RELOCATABLE
    leaq startup_32(%rip) /* - $startup_32 */, %rbp
    addq $(LARGE_PAGE_SIZE - 1), %rbp
    andq $LARGE_PAGE_MASK, %rbp
    movq %rbp, %rbx
    -#else
    - movq $CONFIG_PHYSICAL_START, %rbp
    - movq %rbp, %rbx
    -#endif

    /* Replace the compressed data size with the uncompressed size */
    movl input_len(%rip), %eax
    diff --git a/arch/x86_64/boot/setup.S b/arch/x86_64/boot/setup.S
    index 4f88510..8a70c92 100644
    --- a/arch/x86_64/boot/setup.S
    +++ b/arch/x86_64/boot/setup.S
    @@ -158,11 +158,7 @@ cmd_line_ptr: .long 0 # (Header version 0x0202 or later)
    ramdisk_max: .long 0xffffffff
    kernel_alignment: .long 0x200000 # physical addr alignment required for
    # protected mode relocatable kernel
    -#ifdef CONFIG_RELOCATABLE
    relocatable_kernel: .byte 1
    -#else
    -relocatable_kernel: .byte 0
    -#endif
    pad2: .byte 0
    pad3: .word 0

    diff --git a/arch/x86_64/defconfig b/arch/x86_64/defconfig
    index 90c5a9d..d977bcb 100644
    --- a/arch/x86_64/defconfig
    +++ b/arch/x86_64/defconfig
    @@ -174,8 +174,6 @@ CONFIG_X86_MCE_INTEL=y
    CONFIG_X86_MCE_AMD=y
    # CONFIG_KEXEC is not set
    # CONFIG_CRASH_DUMP is not set
    -# CONFIG_RELOCATABLE is not set
    -CONFIG_PHYSICAL_START=0x200000
    CONFIG_SECCOMP=y
    # CONFIG_CC_STACKPROTECTOR is not set
    # CONFIG_HZ_100 is not set
    diff --git a/arch/x86_64/kernel/head64.c b/arch/x86_64/kernel/head64.c
    index 213d90e..6c34bdd 100644
    --- a/arch/x86_64/kernel/head64.c
    +++ b/arch/x86_64/kernel/head64.c
    @@ -62,13 +62,6 @@ void __init x86_64_start_kernel(char * real_mode_data)
    {
    int i;

    - /*
    - * Make sure kernel is aligned to 2MB address. Catching it at compile
    - * time is better. Change your config file and compile the kernel
    - * for a 2MB aligned address (CONFIG_PHYSICAL_START)
    - */
    - BUILD_BUG_ON(CONFIG_PHYSICAL_START & (__KERNEL_ALIGN - 1));
    -
    /* clear bss before set_intr_gate with early_idt_handler */
    clear_bss();

    diff --git a/include/asm-x86_64/page.h b/include/asm-x86_64/page.h
    index 7bb725f..20662ab 100644
    --- a/include/asm-x86_64/page.h
    +++ b/include/asm-x86_64/page.h
    @@ -78,7 +78,7 @@ extern unsigned long phys_base;

    #endif /* !__ASSEMBLY__ */

    -#define __PHYSICAL_START CONFIG_PHYSICAL_START
    +#define __PHYSICAL_START 0x200000
    #define __KERNEL_ALIGN 0x200000
    #define __START_KERNEL (__START_KERNEL_map + __PHYSICAL_START)
    #define __START_KERNEL_map 0xffffffff80000000
    --
    1.5.1.1.181.g2de0
    -
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