[PATCH] arm: Support initrd with address in boot alias region

If bootloader passes address of initrd in boot alias region, initrd
will fail on memblock_is_region_memory as memblock with such address
doesn't exist.

Issue was observed with kexec which passed initrd address in boot alias
region, while bootloader will typically pass physical address. Commit
fe7db7570379 ("of/fdt: Populate phys_initrd_start/phys_initrd_size from FDT")
uncovered problem by removing virt_to_phys on the initrd physical
address. __virt_to_phys on our platform coincidentally fixed address.

Fix by trying to correct address in case of invalid physical address.

Signed-off-by: Matija Glavinic Pecotic <redacted>
---
 arch/arm/mm/init.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index 000c1b48e973..6cbf64383cfc 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c

@@ -164,6 +164,17 @@ static void __init arm_initrd_init(void)
 	if (!phys_initrd_size)
 		return;
 
+	/*
+	 * In case initrd is not valid physical address, try with boot
+	 * memory region alias as bootloader may have passed address
+	 * within.
+	 */
+	if (!pfn_valid(__phys_to_pfn(phys_initrd_start))) {
+		pr_info("initrd at invalid address, trying with boot alias\n");
+		if (arm_has_idmap_alias())
+			phys_initrd_start = idmap_to_phys(phys_initrd_start);
+	}
+
 	/*
 	 * Round the memory region to page boundaries as per free_initrd_mem()
 	 * This allows us to detect whether the pages overlapping the initrd

-- 
2.28.0

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