linux-kernel - [PATCH v2 5/5] RISC-V: Fix memory reservation in setup

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Date:   Thu, 21 Mar 2019 09:47:58 +0000
From:   Anup Patel <Anup.Patel@....com>
To:     Palmer Dabbelt <palmer@...ive.com>,
        Albert Ou <aou@...s.berkeley.edu>
CC:     Atish Patra <Atish.Patra@....com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Christoph Hellwig <hch@...radead.org>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        "linux-riscv@...ts.infradead.org" <linux-riscv@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Anup Patel <Anup.Patel@....com>
Subject: [PATCH v2 5/5] RISC-V: Fix memory reservation in setup_bootmem()

Currently, the setup_bootmem() reserves memory from RAM start to the
kernel end. This prevents us from exploring ways to use the RAM below
(or before) the kernel start hence this patch updates setup_bootmem()
to only reserve memory from the kernel start to the kernel end.

Signed-off-by: Mike Rapoport <rppt@...ux.ibm.com>
Signed-off-by: Anup Patel <anup.patel@....com>
---
 arch/riscv/mm/init.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 2e2f2567964c..99b42380d17d 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -18,6 +18,8 @@
 #include <asm/pgtable.h>
 #include <asm/io.h>
 
+extern char _start[];
+
 static void __init zone_sizes_init(void)
 {
 	unsigned long max_zone_pfns[MAX_NR_ZONES] = { 0, };
@@ -93,15 +95,17 @@ void __init setup_bootmem(void)
 
 	/* Find the memory region containing the kernel */
 	for_each_memblock(memory, reg) {
-		phys_addr_t vmlinux_end = __pa(_end);
+		phys_addr_t vmlinux_end = __pa(&_end);
+		phys_addr_t vmlinux_start = __pa(&_start);
 		phys_addr_t end = reg->base + reg->size;
 
 		if (reg->base <= vmlinux_end && vmlinux_end <= end) {
 			/*
-			 * Reserve from the start of the region to the end of
+			 * Reserve from the start of the kernel to the end of
 			 * the kernel
 			 */
-			memblock_reserve(reg->base, vmlinux_end - reg->base);
+			memblock_reserve(vmlinux_start,
+					 vmlinux_end - vmlinux_start);
 			mem_size = min(reg->size, (phys_addr_t)-PAGE_OFFSET);
 		}
 	}
@@ -177,7 +181,6 @@ struct mapping_ops {
 
 static inline void *__load_addr(void *ptr, uintptr_t load_pa)
 {
-	extern char _start;
 	uintptr_t va = (uintptr_t)ptr;
 	uintptr_t sz = (uintptr_t)(&_end) - (uintptr_t)(&_start);
 
-- 
2.17.1