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author | Marcel Ziswiler <marcel.ziswiler@toradex.com> | 2017-06-17 17:01:11 +0200 |
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committer | Marcel Ziswiler <marcel.ziswiler@toradex.com> | 2017-06-17 17:01:11 +0200 |
commit | c1d5fe2d54551b95b812143d94d8168da2220dd8 (patch) | |
tree | fdde4472ab2b19fcadaae22d68a0c9b008f74373 /arch/x86/mm/init.c | |
parent | 0068a1b36d309f22698f7de7478b72e672360129 (diff) | |
parent | 1bd30958ec55d80ca72d2ca4e7e5c3d9fbf3173e (diff) |
Merge tag 'v4.4.73' into toradex_vf_4.4-nextColibri-VF_LXDE-Image_2.7b3-20170630
This is the 4.4.73 stable release
Diffstat (limited to 'arch/x86/mm/init.c')
-rw-r--r-- | arch/x86/mm/init.c | 41 |
1 files changed, 30 insertions, 11 deletions
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index 493f54172b4a..3aebbd6c6f5f 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -628,21 +628,40 @@ void __init init_mem_mapping(void) * devmem_is_allowed() checks to see if /dev/mem access to a certain address * is valid. The argument is a physical page number. * - * - * On x86, access has to be given to the first megabyte of ram because that area - * contains BIOS code and data regions used by X and dosemu and similar apps. - * Access has to be given to non-kernel-ram areas as well, these contain the PCI - * mmio resources as well as potential bios/acpi data regions. + * On x86, access has to be given to the first megabyte of RAM because that + * area traditionally contains BIOS code and data regions used by X, dosemu, + * and similar apps. Since they map the entire memory range, the whole range + * must be allowed (for mapping), but any areas that would otherwise be + * disallowed are flagged as being "zero filled" instead of rejected. + * Access has to be given to non-kernel-ram areas as well, these contain the + * PCI mmio resources as well as potential bios/acpi data regions. */ int devmem_is_allowed(unsigned long pagenr) { - if (pagenr < 256) - return 1; - if (iomem_is_exclusive(pagenr << PAGE_SHIFT)) + if (page_is_ram(pagenr)) { + /* + * For disallowed memory regions in the low 1MB range, + * request that the page be shown as all zeros. + */ + if (pagenr < 256) + return 2; + + return 0; + } + + /* + * This must follow RAM test, since System RAM is considered a + * restricted resource under CONFIG_STRICT_IOMEM. + */ + if (iomem_is_exclusive(pagenr << PAGE_SHIFT)) { + /* Low 1MB bypasses iomem restrictions. */ + if (pagenr < 256) + return 1; + return 0; - if (!page_is_ram(pagenr)) - return 1; - return 0; + } + + return 1; } void free_init_pages(char *what, unsigned long begin, unsigned long end) |