| Message ID | 1454373031-24218-1-git-send-email-msalter@redhat.com |
|---|---|
| State | New |
| Headers | show |
On Mon, 2016-02-01 at 19:30 -0500, Mark Salter wrote: > Commit 4dffbfc48d65 ("arm64/efi: mark UEFI reserved regions as > MEMBLOCK_NOMAP") causes a potential problem in arm64 initrd relocation > code. If the kernel uses a pagesize greater than the 4k pagesize used > by UEFI, pagesize rounding may lead to one or both ends of the initrd > image to be marked unmapped. This leads to a panic when the kernel goes > to unpack it. This patch looks for unmapped pages at beginning and end > of the initrd image and if seen, relocated the initrd to a new area > completely covered by the kernel linear map. > > Signed-off-by: Mark Salter <msalter@redhat.com> > Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> > --- The Fedora folks have run into this problem with a certain kernel build. What ever happened to Ard's suggested fix. The MEMBLOCK_NOMAP patch caused a regression which should be fixed. Whether this patch, Ard's patch, or something else. https://bugzilla.redhat.com/show_bug.cgi?id=1309147 > arch/arm64/kernel/setup.c | 46 +++++++++++++++++++++++++++++++++++++--------- > 1 file changed, 37 insertions(+), 9 deletions(-) > > diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c > index d22c5fc..849566e 100644 > --- a/arch/arm64/kernel/setup.c > +++ b/arch/arm64/kernel/setup.c > @@ -235,24 +235,29 @@ static void __init relocate_initrd(void) > phys_addr_t ram_end = memblock_end_of_DRAM(); > phys_addr_t new_start; > unsigned long size, to_free = 0; > + unsigned long unmapped_start = 0, unmapped_end = 0; > void *dest; > > - if (orig_end <= ram_end) > + size = orig_end - orig_start; > + if (!size) > return; > > /* > - * Any of the original initrd which overlaps the linear map should > - * be freed after relocating. > + * If kernel pagesize > 4K, pagesize rounding may have placed > + * part of either end of initrd in an unmapped page. > + * > + * Find any unmapped bytes at start or end of initrd. > */ > - if (orig_start < ram_end) > - to_free = ram_end - orig_start; > + if (!memblock_is_map_memory(orig_start)) > + unmapped_start = PAGE_SIZE - (orig_start & (PAGE_SIZE - 1)); > + if (!memblock_is_map_memory(orig_end - 1)) > + unmapped_end = ((orig_end - 1) & (PAGE_SIZE - 1)) + 1; > > - size = orig_end - orig_start; > - if (!size) > + if (unmapped_start == 0 && unmapped_end == 0 && orig_end <= ram_end) > return; > > /* initrd needs to be relocated completely inside linear mapping */ > - new_start = memblock_find_in_range(0, PFN_PHYS(max_pfn), > + new_start = memblock_find_in_range(0, ram_end, > size, PAGE_SIZE); > if (!new_start) > panic("Cannot relocate initrd of size %ld\n", size); > @@ -267,7 +272,30 @@ static void __init relocate_initrd(void) > > dest = (void *)initrd_start; > > - if (to_free) { > + if (unmapped_end) { > + copy_from_early_mem(dest + size - unmapped_end, > + orig_start + size - unmapped_end, > + unmapped_end); > + size -= unmapped_end; > + if (size == 0) > + return; > + } > + > + if (unmapped_start) { > + copy_from_early_mem(dest, orig_start, unmapped_start); > + dest += unmapped_start; > + orig_start += unmapped_start; > + size -= unmapped_start; > + if (size == 0) > + return; > + } > + > + /* > + * Any of the remaining original initrd which overlaps the linear map > + * should be freed after relocating. > + */ > + if (orig_start < ram_end) { > + to_free = min(size, (unsigned long)(ram_end - orig_start)); > memcpy(dest, (void *)__phys_to_virt(orig_start), to_free); > dest += to_free; > }
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c index d22c5fc..849566e 100644 --- a/arch/arm64/kernel/setup.c +++ b/arch/arm64/kernel/setup.c @@ -235,24 +235,29 @@ static void __init relocate_initrd(void) phys_addr_t ram_end = memblock_end_of_DRAM(); phys_addr_t new_start; unsigned long size, to_free = 0; + unsigned long unmapped_start = 0, unmapped_end = 0; void *dest; - if (orig_end <= ram_end) + size = orig_end - orig_start; + if (!size) return; /* - * Any of the original initrd which overlaps the linear map should - * be freed after relocating. + * If kernel pagesize > 4K, pagesize rounding may have placed + * part of either end of initrd in an unmapped page. + * + * Find any unmapped bytes at start or end of initrd. */ - if (orig_start < ram_end) - to_free = ram_end - orig_start; + if (!memblock_is_map_memory(orig_start)) + unmapped_start = PAGE_SIZE - (orig_start & (PAGE_SIZE - 1)); + if (!memblock_is_map_memory(orig_end - 1)) + unmapped_end = ((orig_end - 1) & (PAGE_SIZE - 1)) + 1; - size = orig_end - orig_start; - if (!size) + if (unmapped_start == 0 && unmapped_end == 0 && orig_end <= ram_end) return; /* initrd needs to be relocated completely inside linear mapping */ - new_start = memblock_find_in_range(0, PFN_PHYS(max_pfn), + new_start = memblock_find_in_range(0, ram_end, size, PAGE_SIZE); if (!new_start) panic("Cannot relocate initrd of size %ld\n", size); @@ -267,7 +272,30 @@ static void __init relocate_initrd(void) dest = (void *)initrd_start; - if (to_free) { + if (unmapped_end) { + copy_from_early_mem(dest + size - unmapped_end, + orig_start + size - unmapped_end, + unmapped_end); + size -= unmapped_end; + if (size == 0) + return; + } + + if (unmapped_start) { + copy_from_early_mem(dest, orig_start, unmapped_start); + dest += unmapped_start; + orig_start += unmapped_start; + size -= unmapped_start; + if (size == 0) + return; + } + + /* + * Any of the remaining original initrd which overlaps the linear map + * should be freed after relocating. + */ + if (orig_start < ram_end) { + to_free = min(size, (unsigned long)(ram_end - orig_start)); memcpy(dest, (void *)__phys_to_virt(orig_start), to_free); dest += to_free; }
Commit 4dffbfc48d65 ("arm64/efi: mark UEFI reserved regions as MEMBLOCK_NOMAP") causes a potential problem in arm64 initrd relocation code. If the kernel uses a pagesize greater than the 4k pagesize used by UEFI, pagesize rounding may lead to one or both ends of the initrd image to be marked unmapped. This leads to a panic when the kernel goes to unpack it. This patch looks for unmapped pages at beginning and end of the initrd image and if seen, relocated the initrd to a new area completely covered by the kernel linear map. Signed-off-by: Mark Salter <msalter@redhat.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> --- arch/arm64/kernel/setup.c | 46 +++++++++++++++++++++++++++++++++++++--------- 1 file changed, 37 insertions(+), 9 deletions(-) -- 1.8.3.1