While _text is currently aligned to PAGE_SIZE in the vmlinux linker script because it's based on CONFIG_PHYSICAL_ALIGN, it's always better to be explicit about these things to be sure no alignment bugs are lurking. There's no analogous enforcement for _end.
Dave provided an example of why the 'npages' calculation is wrong, "Just for fun, imagine that _end=0xfff and _text=0x1001. npages would be 0." Use PFN_ALIGN() to be sure the calculation is correctly aligned to PAGE_SIZE. Reported-by: Dave Hansen <[email protected]> Reported-by: Thomas Gleixner <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Sai Praneeth Prakhya <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: <[email protected]> Signed-off-by: Matt Fleming <[email protected]> --- arch/x86/platform/efi/efi_64.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c index a0ac0f9c307f..3a90eb72d153 100644 --- a/arch/x86/platform/efi/efi_64.c +++ b/arch/x86/platform/efi/efi_64.c @@ -183,7 +183,7 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages) efi_scratch.phys_stack = virt_to_phys(page_address(page)); efi_scratch.phys_stack += PAGE_SIZE; /* stack grows down */ - npages = (_end - _text) >> PAGE_SHIFT; + npages = (PFN_ALIGN(_end) - PFN_ALIGN(_text)) >> PAGE_SHIFT; text = __pa(_text); if (kernel_map_pages_in_pgd(pgd, text >> PAGE_SHIFT, text, npages, 0)) { -- 2.6.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
