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Subject[RFC] arm: add relocate initrd support
Date
Add support for initrd on ARM arch, in case
mem= boot option change the memory size or the initrd are
not placed in low memory region, we need copy the initrd
to low memory region.

Signed-off-by: yalin wang <yalin.wang2010@gmail.com>
---
arch/arm/include/asm/fixmap.h | 1 +
arch/arm/kernel/setup.c | 72 +++++++++++++++++++++++++++++++++++++++++++
2 files changed, 73 insertions(+)

diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
index 58cfe9f..18ad90f 100644
--- a/arch/arm/include/asm/fixmap.h
+++ b/arch/arm/include/asm/fixmap.h
@@ -10,6 +10,7 @@

enum fixed_addresses {
FIX_EARLYCON_MEM_BASE,
+ FIX_RELOCATE_INITRD,
__end_of_permanent_fixed_addresses,

FIX_KMAP_BEGIN = __end_of_permanent_fixed_addresses,
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 20edd34..4260d59 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -811,6 +811,77 @@ static void __init request_standard_resources(const struct machine_desc *mdesc)
request_resource(&ioport_resource, &lp2);
}

+#if defined(CONFIG_BLK_DEV_INITRD) && defined(CONFIG_MMU)
+/*
+ * Relocate initrd if it is not completely within the linear mapping.
+ * This would be the case if mem= cuts out all or part of it
+ * or the initrd are not in low mem region place.
+ */
+static void __init relocate_initrd(void)
+{
+ phys_addr_t orig_start = __virt_to_phys(initrd_start);
+ phys_addr_t orig_end = __virt_to_phys(initrd_end);
+ phys_addr_t ram_end = memblock_end_of_DRAM();
+ phys_addr_t new_start;
+ phys_addr_t src;
+ unsigned long size, to_free = 0;
+ unsigned long slop, clen, p;
+ void *dest;
+
+ if (orig_end <= memblock_get_current_limit())
+ return;
+
+ /*
+ * Any of the original initrd which overlaps the linear map should
+ * be freed after relocating.
+ */
+ if (orig_start < ram_end)
+ to_free = min(ram_end, orig_end) - orig_start;
+
+ size = orig_end - orig_start;
+
+ /* initrd needs to be relocated completely inside linear mapping */
+ new_start = memblock_find_in_range(0, 0, size, PAGE_SIZE);
+ if (!new_start)
+ panic("Cannot relocate initrd of size %ld\n", size);
+ memblock_reserve(new_start, size);
+
+ initrd_start = __phys_to_virt(new_start);
+ initrd_end = initrd_start + size;
+
+ pr_info("Moving initrd from [%llx-%llx] to [%llx-%llx]\n",
+ (unsigned long long)orig_start,
+ (unsigned long long)(orig_start + size - 1),
+ (unsigned long long)new_start,
+ (unsigned long long)(new_start + size - 1));
+
+ dest = (void *)initrd_start;
+
+ src = orig_start;
+ while (size) {
+ slop = src & ~PAGE_MASK;
+ clen = min(PAGE_SIZE - slop, size);
+ p = set_fixmap_offset(FIX_RELOCATE_INITRD, src);
+ memcpy(dest, (void *)p, clen);
+ clear_fixmap(FIX_RELOCATE_INITRD);
+ dest += clen;
+ src += clen;
+ size -= clen;
+ }
+
+ if (to_free) {
+ pr_info("Freeing original RAMDISK from [%llx-%llx]\n",
+ (unsigned long long)orig_start,
+ (unsigned long long)(orig_start + to_free - 1));
+ memblock_free(orig_start, to_free);
+ }
+}
+#else
+static inline void __init relocate_initrd(void)
+{
+}
+#endif
+
#if defined(CONFIG_VGA_CONSOLE) || defined(CONFIG_DUMMY_CONSOLE)
struct screen_info screen_info = {
.orig_video_lines = 30,
@@ -969,6 +1040,7 @@ void __init setup_arch(char **cmdline_p)
arm_memblock_init(mdesc);

paging_init(mdesc);
+ relocate_initrd();
request_standard_resources(mdesc);

if (mdesc->restart)
--
1.9.1


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