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    SubjectRe: [PATCH v2 02/13] arm64: introduce KIMAGE_VADDR as the virtual base of the kernel region
    On Wed, Dec 30, 2015 at 04:26:01PM +0100, Ard Biesheuvel wrote:
    > This introduces the preprocessor symbol KIMAGE_VADDR which will serve as
    > the symbolic virtual base of the kernel region, i.e., the kernel's virtual
    > offset will be KIMAGE_VADDR + TEXT_OFFSET. For now, we define it as being
    > equal to PAGE_OFFSET, but in the future, it will be moved below it once
    > we move the kernel virtual mapping out of the linear mapping.
    >
    > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
    > ---
    > arch/arm64/include/asm/memory.h | 10 ++++++++--
    > arch/arm64/kernel/head.S | 2 +-
    > arch/arm64/kernel/vmlinux.lds.S | 4 ++--
    > 3 files changed, 11 insertions(+), 5 deletions(-)
    >
    > diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
    > index 853953cd1f08..bea9631b34a8 100644
    > --- a/arch/arm64/include/asm/memory.h
    > +++ b/arch/arm64/include/asm/memory.h
    > @@ -51,7 +51,8 @@
    > #define VA_BITS (CONFIG_ARM64_VA_BITS)
    > #define VA_START (UL(0xffffffffffffffff) << VA_BITS)
    > #define PAGE_OFFSET (UL(0xffffffffffffffff) << (VA_BITS - 1))
    > -#define MODULES_END (PAGE_OFFSET)
    > +#define KIMAGE_VADDR (PAGE_OFFSET)
    > +#define MODULES_END (KIMAGE_VADDR)
    > #define MODULES_VADDR (MODULES_END - SZ_64M)
    > #define PCI_IO_END (MODULES_VADDR - SZ_2M)
    > #define PCI_IO_START (PCI_IO_END - PCI_IO_SIZE)
    > @@ -75,8 +76,13 @@
    > * private definitions which should NOT be used outside memory.h
    > * files. Use virt_to_phys/phys_to_virt/__pa/__va instead.
    > */
    > -#define __virt_to_phys(x) (((phys_addr_t)(x) - PAGE_OFFSET + PHYS_OFFSET))
    > +#define __virt_to_phys(x) ({ \
    > + phys_addr_t __x = (phys_addr_t)(x); \
    > + __x >= PAGE_OFFSET ? (__x - PAGE_OFFSET + PHYS_OFFSET) : \
    > + (__x - KIMAGE_VADDR + PHYS_OFFSET); })

    so __virt_to_phys will now work with a subset of the non-linear namely
    all except vmalloced and ioremapped ones?

    > +
    > #define __phys_to_virt(x) ((unsigned long)((x) - PHYS_OFFSET + PAGE_OFFSET))
    > +#define __phys_to_kimg(x) ((unsigned long)((x) - PHYS_OFFSET + KIMAGE_VADDR))
    >
    > /*
    > * Convert a page to/from a physical address
    > diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
    > index 23cfc08fc8ba..6434c844a0e4 100644
    > --- a/arch/arm64/kernel/head.S
    > +++ b/arch/arm64/kernel/head.S
    > @@ -389,7 +389,7 @@ __create_page_tables:
    > * Map the kernel image (starting with PHYS_OFFSET).
    > */
    > mov x0, x26 // swapper_pg_dir
    > - mov x5, #PAGE_OFFSET
    > + ldr x5, =KIMAGE_VADDR
    > create_pgd_entry x0, x5, x3, x6
    > ldr x6, =KERNEL_END // __va(KERNEL_END)
    > mov x3, x24 // phys offset
    > diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
    > index 7de6c39858a5..ced0dedcabcc 100644
    > --- a/arch/arm64/kernel/vmlinux.lds.S
    > +++ b/arch/arm64/kernel/vmlinux.lds.S
    > @@ -88,7 +88,7 @@ SECTIONS
    > *(.discard.*)
    > }
    >
    > - . = PAGE_OFFSET + TEXT_OFFSET;
    > + . = KIMAGE_VADDR + TEXT_OFFSET;
    >
    > .head.text : {
    > _text = .;
    > @@ -185,4 +185,4 @@ ASSERT(__idmap_text_end - (__idmap_text_start & ~(SZ_4K - 1)) <= SZ_4K,
    > /*
    > * If padding is applied before .head.text, virt<->phys conversions will fail.
    > */
    > -ASSERT(_text == (PAGE_OFFSET + TEXT_OFFSET), "HEAD is misaligned")
    > +ASSERT(_text == (KIMAGE_VADDR + TEXT_OFFSET), "HEAD is misaligned")
    > --
    > 2.5.0
    >


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