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Commit a23d3bb0 authored by Ard Biesheuvel's avatar Ard Biesheuvel
Browse files

efi: add API to reserve memory persistently across kexec reboot 



Add kernel plumbing to reserve memory regions persistently on a EFI
system by adding entries to the MEMRESERVE linked list.

Tested-by: default avatarJeremy Linton <jeremy.linton@arm.com>
Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
parent b844470f

drivers/firmware/efi/efi.c

+32 −0
Original line number Diff line number Diff line
@@ -962,6 +962,38 @@ bool efi_is_table_address(unsigned long phys_addr) 
	return false;

}



static DEFINE_SPINLOCK(efi_mem_reserve_persistent_lock);



int efi_mem_reserve_persistent(phys_addr_t addr, u64 size)

{

	struct linux_efi_memreserve *rsv, *parent;



	if (efi.mem_reserve == EFI_INVALID_TABLE_ADDR)

		return -ENODEV;



	rsv = kmalloc(sizeof(*rsv), GFP_KERNEL);

	if (!rsv)

		return -ENOMEM;



	parent = memremap(efi.mem_reserve, sizeof(*rsv), MEMREMAP_WB);

	if (!parent) {

		kfree(rsv);

		return -ENOMEM;

	}



	rsv->base = addr;

	rsv->size = size;



	spin_lock(&efi_mem_reserve_persistent_lock);

	rsv->next = parent->next;

	parent->next = __pa(rsv);

	spin_unlock(&efi_mem_reserve_persistent_lock);



	memunmap(parent);



	return 0;

}



#ifdef CONFIG_KEXEC

static int update_efi_random_seed(struct notifier_block *nb,

				  unsigned long code, void *unused)

include/linux/efi.h

+1 −0
Original line number Diff line number Diff line
@@ -1043,6 +1043,7 @@ extern int __init efi_uart_console_only (void); 
extern u64 efi_mem_desc_end(efi_memory_desc_t *md);

extern int efi_mem_desc_lookup(u64 phys_addr, efi_memory_desc_t *out_md);

extern void efi_mem_reserve(phys_addr_t addr, u64 size);

extern int efi_mem_reserve_persistent(phys_addr_t addr, u64 size);

extern void efi_initialize_iomem_resources(struct resource *code_resource,

		struct resource *data_resource, struct resource *bss_resource);

extern void efi_reserve_boot_services(void);