Advertise the location of bootable RAM to kexec-tools.  kexec needs to
know where it can place the kernel in RAM, and so be executable when
the system needs to jump into it.

Advertise these areas in /proc/iomem with a "System RAM (boot alias)"
tag.

Signed-off-by: Russell King <rmk+ker...@arm.linux.org.uk>
---
 arch/arm/kernel/setup.c | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 19b25ad61385..7cf1c0d4f773 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -847,10 +847,29 @@ static void __init request_standard_resources(const 
struct machine_desc *mdesc)
        kernel_data.end     = virt_to_phys(_end - 1);
 
        for_each_memblock(memory, region) {
+               phys_addr_t start = 
__pfn_to_phys(memblock_region_memory_base_pfn(region));
+               phys_addr_t end = 
__pfn_to_phys(memblock_region_memory_end_pfn(region)) - 1;
+               unsigned long boot_alias_start;
+
+               /*
+                * Some systems have a special memory alias which is only
+                * used for booting.  We need to advertise this region to
+                * kexec-tools so they know where bootable RAM is located.
+                */
+               boot_alias_start = phys_to_idmap(start);
+               if (arm_has_idmap_alias() && boot_alias_start != 
INVALID_IDMAP_ADDR) {
+                       res = memblock_virt_alloc(sizeof(*res), 0);
+                       res->name = "System RAM (boot alias)";
+                       res->start = boot_alias_start;
+                       res->end = phys_to_idmap(end);
+                       res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
+                       request_resource(&iomem_resource, res);
+               }
+
                res = memblock_virt_alloc(sizeof(*res), 0);
                res->name  = "System RAM";
-               res->start = 
__pfn_to_phys(memblock_region_memory_base_pfn(region));
-               res->end = 
__pfn_to_phys(memblock_region_memory_end_pfn(region)) - 1;
+               res->start = start;
+               res->end = end;
                res->flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
 
                request_resource(&iomem_resource, res);
-- 
2.1.0

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