RISC-V: Remove any memblock representing unusable memory area

RISC-V limits the physical memory size by -PAGE_OFFSET. Any memory beyond
that size from DRAM start is unusable. Just remove any memblock pointing
to those memory region without worrying about computing the maximum size.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index ea933b789a882f29bec8b1f81892747764b7de3e..42c14eb6bc433a250331ba47213fdf0009b09f01 100644 (file)
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -154,9 +154,8 @@ disable:
 
 void __init setup_bootmem(void)
 {
-       phys_addr_t mem_size = 0;
-       phys_addr_t total_mem = 0;
-       phys_addr_t mem_start, start, end = 0;
+       phys_addr_t mem_start = 0;
+       phys_addr_t start, end = 0;
        phys_addr_t vmlinux_end = __pa_symbol(&_end);
        phys_addr_t vmlinux_start = __pa_symbol(&_start);
        u64 i;
@@ -164,21 +163,18 @@ void __init setup_bootmem(void)
        /* Find the memory region containing the kernel */
        for_each_mem_range(i, &start, &end) {
                phys_addr_t size = end - start;
-               if (!total_mem)
+               if (!mem_start)
                        mem_start = start;
                if (start <= vmlinux_start && vmlinux_end <= end)
                        BUG_ON(size == 0);
-               total_mem = total_mem + size;
        }
 
        /*
-        * Remove memblock from the end of usable area to the
-        * end of region
+        * The maximal physical memory size is -PAGE_OFFSET.
+        * Make sure that any memory beyond mem_start + (-PAGE_OFFSET) is removed
+        * as it is unusable by kernel.
         */
-       mem_size = min(total_mem, (phys_addr_t)-PAGE_OFFSET);
-       if (mem_start + mem_size < end)
-               memblock_remove(mem_start + mem_size,
-                               end - mem_start - mem_size);
+       memblock_enforce_memory_limit(mem_start - PAGE_OFFSET);
 
        /* Reserve from the start of the kernel to the end of the kernel */
        memblock_reserve(vmlinux_start, vmlinux_end - vmlinux_start);