efi/memreserve: Register reservations as 'reserved' in /proc/iomem (ab0eb162) · Commits · 戴 / test

Memory regions that are reserved using efi_mem_reserve_persistent() are recorded in a special EFI config table which survives kexec, allowing the incoming kernel to honour them as well. However, such reservations are not visible in /proc/iomem, and so the kexec tools that load the incoming kernel and its initrd into memory may overwrite these reserved regions before the incoming kernel has a chance to reserve them from further use. Address this problem by adding these reservations to /proc/iomem as they are created. Note that reservations that are inherited from a previous kernel are memblock_reserve()'d early on, so they are already visible in /proc/iomem. Tested-by:

Masayoshi Mizuma <m.mizuma@jp.fujitsu.com> Tested-by:

Bhupesh Sharma <bhsharma@redhat.com> Signed-off-by:

Ard Biesheuvel <ardb@kernel.org> Reviewed-by:

Bhupesh Sharma <bhsharma@redhat.com> Cc: <stable@vger.kernel.org> # v5.4+ Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Arvind Sankar <nivedita@alum.mit.edu> Cc: linux-efi@vger.kernel.org Link: https://lkml.kernel.org/r/20191206165542.31469-2-ardb@kernel.org Signed-off-by:

Ingo Molnar <mingo@kernel.org>

drivers/firmware/efi/efi.c

+26 −2

Original line number	Diff line number	Diff line
		@@ -979,6 +979,24 @@ static int __init efi_memreserve_map_root(void)
		return 0;
		}

		static int efi_mem_reserve_iomem(phys_addr_t addr, u64 size)
		{
		struct resource res, parent;

		res = kzalloc(sizeof(struct resource), GFP_ATOMIC);
		if (!res)
		return -ENOMEM;

		res->name = "reserved";
		res->flags = IORESOURCE_MEM;
		res->start = addr;
		res->end = addr + size - 1;

		/* we expect a conflict with a 'System RAM' region */
		parent = request_resource_conflict(&iomem_resource, res);
		return parent ? request_resource(parent, res) : 0;
		}

		int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
		{
		struct linux_efi_memreserve *rsv;
		@@ -1003,7 +1021,7 @@ int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
		rsv->entry[index].size = size;

		memunmap(rsv);
		return 0;
		return efi_mem_reserve_iomem(addr, size);
		}
		memunmap(rsv);
		}
		@@ -1013,6 +1031,12 @@ int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
		if (!rsv)
		return -ENOMEM;

		rc = efi_mem_reserve_iomem(__pa(rsv), SZ_4K);
		if (rc) {
		free_page((unsigned long)rsv);
		return rc;
		}

		/*
		* The memremap() call above assumes that a linux_efi_memreserve entry
		* never crosses a page boundary, so let's ensure that this remains true
		@@ -1029,7 +1053,7 @@ int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
		efi_memreserve_root->next = __pa(rsv);
		spin_unlock(&efi_mem_reserve_persistent_lock);

		return 0;
		return efi_mem_reserve_iomem(addr, size);
		}

		static int __init efi_memreserve_root_init(void)

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