From 6b0f68e32ea8749ff7d4a66cd5761e915e48e59d Mon Sep 17 00:00:00 2001 From: Mark Salter Date: Tue, 8 Sep 2015 15:03:01 -0700 Subject: mm: add utility for early copy from unmapped ram When booting an arm64 kernel w/initrd using UEFI/grub, use of mem= will likely cut off part or all of the initrd. This leaves it outside the kernel linear map which leads to failure when unpacking. The x86 code has a similar need to relocate an initrd outside of mapped memory in some cases. The current x86 code uses early_memremap() to copy the original initrd from unmapped to mapped RAM. This patchset creates a generic copy_from_early_mem() utility based on that x86 code and has arm64 and x86 share it in their respective initrd relocation code. This patch (of 3): In some early boot circumstances, it may be necessary to copy from RAM outside the kernel linear mapping to mapped RAM. The need to relocate an initrd is one example in the x86 code. This patch creates a helper function based on current x86 code. Signed-off-by: Mark Salter Cc: Catalin Marinas Cc: Will Deacon Cc: Arnd Bergmann Cc: Ard Biesheuvel Cc: Mark Rutland Cc: Russell King Cc: Ingo Molnar Cc: Thomas Gleixner Cc: "H. Peter Anvin" Cc: Yinghai Lu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/early_ioremap.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) (limited to 'mm/early_ioremap.c') diff --git a/mm/early_ioremap.c b/mm/early_ioremap.c index e10ccd299d66..a0baeb4be934 100644 --- a/mm/early_ioremap.c +++ b/mm/early_ioremap.c @@ -217,6 +217,28 @@ early_memremap(resource_size_t phys_addr, unsigned long size) return (__force void *)__early_ioremap(phys_addr, size, FIXMAP_PAGE_NORMAL); } + +#define MAX_MAP_CHUNK (NR_FIX_BTMAPS << PAGE_SHIFT) + +void __init copy_from_early_mem(void *dest, phys_addr_t src, unsigned long size) +{ + unsigned long slop, clen; + char *p; + + while (size) { + slop = src & ~PAGE_MASK; + clen = size; + if (clen > MAX_MAP_CHUNK - slop) + clen = MAX_MAP_CHUNK - slop; + p = early_memremap(src & PAGE_MASK, clen + slop); + memcpy(dest, p + slop, clen); + early_memunmap(p, clen + slop); + dest += clen; + src += clen; + size -= clen; + } +} + #else /* CONFIG_MMU */ void __init __iomem * -- cgit v1.2.1