arm64: add the initrd region to the linear mapping explicitly

[cascardo/linux.git] / arch / arm64 / mm / init.c

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index ea989d8..82ced5f 100644 (file)
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -190,8 +190,12 @@ void __init arm64_memblock_init(void)
         */
        memblock_remove(max_t(u64, memstart_addr + linear_region_size, __pa(_end)),
                        ULLONG_MAX);
-       if (memblock_end_of_DRAM() > linear_region_size)
-               memblock_remove(0, memblock_end_of_DRAM() - linear_region_size);
+       if (memstart_addr + linear_region_size < memblock_end_of_DRAM()) {
+               /* ensure that memstart_addr remains sufficiently aligned */
+               memstart_addr = round_up(memblock_end_of_DRAM() - linear_region_size,
+                                        ARM64_MEMSTART_ALIGN);
+               memblock_remove(0, memstart_addr);
+       }
 
        /*
         * Apply the memory limit if it was set. Since the kernel may be loaded
@@ -203,6 +207,35 @@ void __init arm64_memblock_init(void)
                memblock_add(__pa(_text), (u64)(_end - _text));
        }
 
+       if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && initrd_start) {
+               /*
+                * Add back the memory we just removed if it results in the
+                * initrd to become inaccessible via the linear mapping.
+                * Otherwise, this is a no-op
+                */
+               u64 base = initrd_start & PAGE_MASK;
+               u64 size = PAGE_ALIGN(initrd_end) - base;
+
+               /*
+                * We can only add back the initrd memory if we don't end up
+                * with more memory than we can address via the linear mapping.
+                * It is up to the bootloader to position the kernel and the
+                * initrd reasonably close to each other (i.e., within 32 GB of
+                * each other) so that all granule/#levels combinations can
+                * always access both.
+                */
+               if (WARN(base < memblock_start_of_DRAM() ||
+                        base + size > memblock_start_of_DRAM() +
+                                      linear_region_size,
+                       "initrd not fully accessible via the linear mapping -- please check your bootloader ...\n")) {
+                       initrd_start = 0;
+               } else {
+                       memblock_remove(base, size); /* clear MEMBLOCK_ flags */
+                       memblock_add(base, size);
+                       memblock_reserve(base, size);
+               }
+       }
+
        if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
                extern u16 memstart_offset_seed;
                u64 range = linear_region_size -