[PATCH v3 2/4] initramfs: Provide a common initrd reserve function

Kefeng Wang
2021-01-15T05:41:31Z

Some architectures(eg, ARM and riscv) have similar logic to
check and reserve the memory of initrd, let's provide a common
function reserve_initrd_mem() to reduce duplicated code.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
include/linux/initrd.h | 6 ++++++
init/initramfs.c | 45 ++++++++++++++++++++++++++++++++++++++++++
2 files changed, 51 insertions(+)

diff --git a/include/linux/initrd.h b/include/linux/initrd.h
index fc30ac30e10e..85c15717af34 100644
--- a/include/linux/initrd.h
+++ b/include/linux/initrd.h
@@ -18,6 +18,12 @@ extern int initrd_below_start_ok;
extern unsigned long initrd_start, initrd_end;
extern void free_initrd_mem(unsigned long, unsigned long);

+#ifdef CONFIG_BLK_DEV_INITRD
+extern void __init reserve_initrd_mem(void);
+#else
+static inline void __init reserve_initrd_mem(void) {}
+#endif
+
extern phys_addr_t phys_initrd_start;
extern unsigned long phys_initrd_size;

diff --git a/init/initramfs.c b/init/initramfs.c
index 55b74d7e5260..f75c89e9d602 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -535,6 +535,51 @@ extern unsigned long __initramfs_size;
#include <linux/initrd.h>
#include <linux/kexec.h>

+void __init reserve_initrd_mem(void)
+{
+ phys_addr_t start;
+ unsigned long size;
+
+ /* Ignore the virtul address computed during device tree parsing */
+ initrd_start = initrd_end = 0;
+
+ if (!phys_initrd_size)
+ return;
+ /*
+ * Round the memory region to page boundaries as per free_initrd_mem()
+ * This allows us to detect whether the pages overlapping the initrd
+ * are in use, but more importantly, reserves the entire set of pages
+ * as we don't want these pages allocated for other purposes.
+ */
+ start = round_down(phys_initrd_start, PAGE_SIZE);
+ size = phys_initrd_size + (phys_initrd_start - start);
+ size = round_up(size, PAGE_SIZE);
+
+ if (!memblock_is_region_memory(start, size)) {
+ pr_err("INITRD: 0x%08llx+0x%08lx is not a memory region",
+ (u64)start, size);
+ goto disable;
+ }
+
+ if (memblock_is_region_reserved(start, size)) {
+ pr_err("INITRD: 0x%08llx+0x%08lx overlaps in-use memory region\n",
+ (u64)start, size);
+ goto disable;
+ }
+
+ memblock_reserve(start, size);
+ /* Now convert initrd to virtual addresses */
+ initrd_start = (unsigned long)__va(phys_initrd_start);
+ initrd_end = initrd_start + phys_initrd_size;
+ initrd_below_start_ok = 1;
+
+ return;
+disable:
+ pr_cont(" - disabling initrd\n");
+ initrd_start = 0;
+ initrd_end = 0;
+}
+
void __weak __init free_initrd_mem(unsigned long start, unsigned long end)
{
#ifdef CONFIG_ARCH_KEEP_MEMBLOCK
--
2.26.2