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authorArd Biesheuvel <ard.biesheuvel@linaro.org>2016-02-16 13:52:42 +0100
committerCatalin Marinas <catalin.marinas@arm.com>2016-02-18 18:16:53 +0000
commita7f8de168ace487fa7b88cb154e413cf40e87fc6 (patch)
tree870a068dba048cdf795c241e97f1e8684fed2208 /arch/arm64/mm/mmu.c
parenta89dea585371a9d5d85499db47c93f129be8e0c4 (diff)
downloadop-kernel-dev-a7f8de168ace487fa7b88cb154e413cf40e87fc6.zip
op-kernel-dev-a7f8de168ace487fa7b88cb154e413cf40e87fc6.tar.gz
arm64: allow kernel Image to be loaded anywhere in physical memory
This relaxes the kernel Image placement requirements, so that it may be placed at any 2 MB aligned offset in physical memory. This is accomplished by ignoring PHYS_OFFSET when installing memblocks, and accounting for the apparent virtual offset of the kernel Image. As a result, virtual address references below PAGE_OFFSET are correctly mapped onto physical references into the kernel Image regardless of where it sits in memory. Special care needs to be taken for dealing with memory limits passed via mem=, since the generic implementation clips memory top down, which may clip the kernel image itself if it is loaded high up in memory. To deal with this case, we simply add back the memory covering the kernel image, which may result in more memory to be retained than was passed as a mem= parameter. Since mem= should not be considered a production feature, a panic notifier handler is installed that dumps the memory limit at panic time if one was set. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/mm/mmu.c')
-rw-r--r--arch/arm64/mm/mmu.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 1d9aea4..32c4a37 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -46,6 +46,9 @@
u64 idmap_t0sz = TCR_T0SZ(VA_BITS);
+u64 kimage_voffset __read_mostly;
+EXPORT_SYMBOL(kimage_voffset);
+
/*
* Empty_zero_page is a special page that is used for zero-initialized data
* and COW.
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