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authorAtish Patra <atish.patra@wdc.com>2021-01-11 15:45:02 -0800
committerPalmer Dabbelt <palmerdabbelt@google.com>2021-01-15 21:35:47 -0800
commitabb8e86b269604e906a6a4af7a09f04b72dbb862 (patch)
tree88e7655d7a88a88c0160f88d7fee5cd1ac70192a
parent797f0375dd2ef5cdc68ac23450cbae9a5c67a74e (diff)
RISC-V: Set current memblock limit
Currently, linux kernel can not use last 4k bytes of addressable space because IS_ERR_VALUE macro treats those as an error. This will be an issue for RV32 as any memblock allocator potentially allocate chunk of memory from the end of DRAM (2GB) leading bad address error even though the address was technically valid. Fix this issue by limiting the memblock if available memory spans the entire address space. Reviewed-by: Anup Patel <anup@brainfault.org> Signed-off-by: Atish Patra <atish.patra@wdc.com> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
-rw-r--r--arch/riscv/mm/init.c16
1 files changed, 14 insertions, 2 deletions
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index bf5379135e39..7cd4993f4ff2 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -157,9 +157,10 @@ disable:
void __init setup_bootmem(void)
{
phys_addr_t mem_start = 0;
- phys_addr_t start, end = 0;
+ phys_addr_t start, dram_end, end = 0;
phys_addr_t vmlinux_end = __pa_symbol(&_end);
phys_addr_t vmlinux_start = __pa_symbol(&_start);
+ phys_addr_t max_mapped_addr = __pa(~(ulong)0);
u64 i;
/* Find the memory region containing the kernel */
@@ -181,7 +182,18 @@ void __init setup_bootmem(void)
/* Reserve from the start of the kernel to the end of the kernel */
memblock_reserve(vmlinux_start, vmlinux_end - vmlinux_start);
- max_pfn = PFN_DOWN(memblock_end_of_DRAM());
+ dram_end = memblock_end_of_DRAM();
+
+ /*
+ * memblock allocator is not aware of the fact that last 4K bytes of
+ * the addressable memory can not be mapped because of IS_ERR_VALUE
+ * macro. Make sure that last 4k bytes are not usable by memblock
+ * if end of dram is equal to maximum addressable memory.
+ */
+ if (max_mapped_addr == (dram_end - 1))
+ memblock_set_current_limit(max_mapped_addr - 4096);
+
+ max_pfn = PFN_DOWN(dram_end);
max_low_pfn = max_pfn;
dma32_phys_limit = min(4UL * SZ_1G, (unsigned long)PFN_PHYS(max_low_pfn));
set_max_mapnr(max_low_pfn);