arm64: support initrd outside kernel linear map

The use of mem= could leave part or all of the initrd outside of the
kernel linear map.  This will lead to an error when unpacking the initrd
and a probable failure to boot.  This patch catches that situation and
relocates the initrd to be fully within the linear map.

Signed-off-by: Mark Salter <msalter@redhat.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 62 insertions, 0 deletions

diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 888478881243..6bab21f84a9f 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -339,6 +339,67 @@ static void __init request_standard_resources(void)
         }
 }
 
+#ifdef CONFIG_BLK_DEV_INITRD
+/*
+ * Relocate initrd if it is not completely within the linear mapping.
+ * This would be the case if mem= cuts out all or part of it.
+ */
+static void __init relocate_initrd(void)
+{
+        phys_addr_t orig_start = __virt_to_phys(initrd_start);
+        phys_addr_t orig_end = __virt_to_phys(initrd_end);
+        phys_addr_t ram_end = memblock_end_of_DRAM();
+        phys_addr_t new_start;
+        unsigned long size, to_free = 0;
+        void *dest;
+
+        if (orig_end <= ram_end)
+                return;
+
+        /*
+         * Any of the original initrd which overlaps the linear map should
+         * be freed after relocating.
+         */
+        if (orig_start < ram_end)
+                to_free = ram_end - orig_start;
+
+        size = orig_end - orig_start;
+
+        /* initrd needs to be relocated completely inside linear mapping */
+        new_start = memblock_find_in_range(0, PFN_PHYS(max_pfn),
+                                           size, PAGE_SIZE);
+        if (!new_start)
+                panic("Cannot relocate initrd of size %ld\n", size);
+        memblock_reserve(new_start, size);
+
+        initrd_start = __phys_to_virt(new_start);
+        initrd_end   = initrd_start + size;
+
+        pr_info("Moving initrd from [%llx-%llx] to [%llx-%llx]\n",
+                orig_start, orig_start + size - 1,
+                new_start, new_start + size - 1);
+
+        dest = (void *)initrd_start;
+
+        if (to_free) {
+                memcpy(dest, (void *)__phys_to_virt(orig_start), to_free);
+                dest += to_free;
+        }
+
+        copy_from_early_mem(dest, orig_start + to_free, size - to_free);
+
+        if (to_free) {
+                pr_info("Freeing original RAMDISK from [%llx-%llx]\n",
+                        orig_start, orig_start + to_free - 1);
+                memblock_free(orig_start, to_free);
+        }
+}
+#else
+static inline void __init relocate_initrd(void)
+{
+}
+#endif
+
 u64 __cpu_logical_map[NR_CPUS] = { [0 ... NR_CPUS-1] = INVALID_HWID };
 
 void __init setup_arch(char **cmdline_p)
@@ -372,6 +433,7 @@ void __init setup_arch(char **cmdline_p)
         acpi_boot_table_init();
 
         paging_init();
+        relocate_initrd();
         request_standard_resources();
 
         early_ioremap_reset();