From 202f9d0a41809e3424af5f61489b48b622824aed Mon Sep 17 00:00:00 2001 From: Matthew Garrett Date: Thu, 5 May 2011 15:19:44 -0400 Subject: [PATCH] x86, efi: Merge contiguous memory regions of the same type and attribute Some firmware implementations assume that physically contiguous regions will be contiguous in virtual address space. This assumption is, obviously, entirely unjustifiable. Said firmware implementations lack the good grace to handle their failings in a measured and reasonable manner, instead tending to shit all over address space and oopsing the kernel. In an ideal universe these firmware implementations would simultaneously catch fire and cease to be a problem, but since some of them are present in attractively thin and shiny metal devices vanity wins out and some poor developer spends an extended period of time surrounded by a growing array of empty bottles until the underlying reason becomes apparent. Said developer presents this patch, which simply merges adjacent regions if they happen to be contiguous and have the same EFI memory type and caching attributes. Signed-off-by: Matthew Garrett Link: http://lkml.kernel.org/r/1304623186-18261-3-git-send-email-mjg@redhat.com Signed-off-by: H. Peter Anvin --- arch/x86/platform/efi/efi.c | 30 +++++++++++++++++++++++++++++- 1 file changed, 29 insertions(+), 1 deletion(-) diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c index 7daae27..a46a73e 100644 --- a/arch/x86/platform/efi/efi.c +++ b/arch/x86/platform/efi/efi.c @@ -498,13 +498,41 @@ static void __init runtime_code_page_mkexec(void) */ void __init efi_enter_virtual_mode(void) { - efi_memory_desc_t *md; + efi_memory_desc_t *md, *prev_md = NULL; efi_status_t status; unsigned long size; u64 end, systab, addr, npages, end_pfn; void *p, *va; efi.systab = NULL; + + /* Merge contiguous regions of the same type and attribute */ + for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) { + u64 prev_size; + md = p; + + if (!prev_md) { + prev_md = md; + continue; + } + + if (prev_md->type != md->type || + prev_md->attribute != md->attribute) { + prev_md = md; + continue; + } + + prev_size = prev_md->num_pages << EFI_PAGE_SHIFT; + + if (md->phys_addr == (prev_md->phys_addr + prev_size)) { + prev_md->num_pages += md->num_pages; + md->type = EFI_RESERVED_TYPE; + md->attribute = 0; + continue; + } + prev_md = md; + } + for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) { md = p; if (!(md->attribute & EFI_MEMORY_RUNTIME)) -- 2.7.4