efi: Split out EFI memory map functions into new file

Also move the functions from the EFI fake mem driver since future
patches will require access to the memmap insertion code even if
CONFIG_EFI_FAKE_MEM isn't enabled.

This will be useful when we need to build custom EFI memory maps to
allow drivers to mark regions as reserved.

Tested-by: Dave Young <dyoung@redhat.com> [kexec/kdump]
Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> [arm]
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Cc: Peter Jones <pjones@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Taku Izumi <izumi.taku@jp.fujitsu.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>

1 files changed, 267 insertions, 0 deletions

diff --git a/drivers/firmware/efi/memmap.c b/drivers/firmware/efi/memmap.c
new file mode 100644
index 000000000000..2df7238eb44e
--- /dev/null
+++ b/drivers/firmware/efi/memmap.c
@@ -0,0 +1,267 @@
+/*
+ * Common EFI memory map functions.
+ */
+
+#define pr_fmt(fmt) "efi: " fmt
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/efi.h>
+#include <linux/io.h>
+#include <asm/early_ioremap.h>
+
+/**
+ * __efi_memmap_init - Common code for mapping the EFI memory map
+ * @data: EFI memory map data
+ * @late: Use early or late mapping function?
+ *
+ * This function takes care of figuring out which function to use to
+ * map the EFI memory map in efi.memmap based on how far into the boot
+ * we are.
+ *
+ * During bootup @late should be %false since we only have access to
+ * the early_memremap*() functions as the vmalloc space isn't setup.
+ * Once the kernel is fully booted we can fallback to the more robust
+ * memremap*() API.
+ *
+ * Returns zero on success, a negative error code on failure.
+ */
+static int __init
+__efi_memmap_init(struct efi_memory_map_data *data, bool late)
+{
+	struct efi_memory_map map;
+	phys_addr_t phys_map;
+
+	if (efi_enabled(EFI_PARAVIRT))
+		return 0;
+
+	phys_map = data->phys_map;
+
+	if (late)
+		map.map = memremap(phys_map, data->size, MEMREMAP_WB);
+	else
+		map.map = early_memremap(phys_map, data->size);
+
+	if (!map.map) {
+		pr_err("Could not map the memory map!\n");
+		return -ENOMEM;
+	}
+
+	map.phys_map = data->phys_map;
+	map.nr_map = data->size / data->desc_size;
+	map.map_end = map.map + data->size;
+
+	map.desc_version = data->desc_version;
+	map.desc_size = data->desc_size;
+	map.late = late;
+
+	set_bit(EFI_MEMMAP, &efi.flags);
+
+	efi.memmap = map;
+
+	return 0;
+}
+
+/**
+ * efi_memmap_init_early - Map the EFI memory map data structure
+ * @data: EFI memory map data
+ *
+ * Use early_memremap() to map the passed in EFI memory map and assign
+ * it to efi.memmap.
+ */
+int __init efi_memmap_init_early(struct efi_memory_map_data *data)
+{
+	/* Cannot go backwards */
+	WARN_ON(efi.memmap.late);
+
+	return __efi_memmap_init(data, false);
+}
+
+void __init efi_memmap_unmap(void)
+{
+	if (!efi.memmap.late) {
+		unsigned long size;
+
+		size = efi.memmap.desc_size * efi.memmap.nr_map;
+		early_memunmap(efi.memmap.map, size);
+	} else {
+		memunmap(efi.memmap.map);
+	}
+
+	efi.memmap.map = NULL;
+	clear_bit(EFI_MEMMAP, &efi.flags);
+}
+
+/**
+ * efi_memmap_init_late - Map efi.memmap with memremap()
+ * @phys_addr: Physical address of the new EFI memory map
+ * @size: Size in bytes of the new EFI memory map
+ *
+ * Setup a mapping of the EFI memory map using ioremap_cache(). This
+ * function should only be called once the vmalloc space has been
+ * setup and is therefore not suitable for calling during early EFI
+ * initialise, e.g. in efi_init(). Additionally, it expects
+ * efi_memmap_init_early() to have already been called.
+ *
+ * The reason there are two EFI memmap initialisation
+ * (efi_memmap_init_early() and this late version) is because the
+ * early EFI memmap should be explicitly unmapped once EFI
+ * initialisation is complete as the fixmap space used to map the EFI
+ * memmap (via early_memremap()) is a scarce resource.
+ *
+ * This late mapping is intended to persist for the duration of
+ * runtime so that things like efi_mem_desc_lookup() and
+ * efi_mem_attributes() always work.
+ *
+ * Returns zero on success, a negative error code on failure.
+ */
+int __init efi_memmap_init_late(phys_addr_t addr, unsigned long size)
+{
+	struct efi_memory_map_data data = {
+		.phys_map = addr,
+		.size = size,
+	};
+
+	/* Did we forget to unmap the early EFI memmap? */
+	WARN_ON(efi.memmap.map);
+
+	/* Were we already called? */
+	WARN_ON(efi.memmap.late);
+
+	/*
+	 * It makes no sense to allow callers to register different
+	 * values for the following fields. Copy them out of the
+	 * existing early EFI memmap.
+	 */
+	data.desc_version = efi.memmap.desc_version;
+	data.desc_size = efi.memmap.desc_size;
+
+	return __efi_memmap_init(&data, true);
+}
+
+/**
+ * efi_memmap_split_count - Count number of additional EFI memmap entries
+ * @md: EFI memory descriptor to split
+ * @range: Address range (start, end) to split around
+ *
+ * Returns the number of additional EFI memmap entries required to
+ * accomodate @range.
+ */
+int __init efi_memmap_split_count(efi_memory_desc_t *md, struct range *range)
+{
+	u64 m_start, m_end;
+	u64 start, end;
+	int count = 0;
+
+	start = md->phys_addr;
+	end = start + (md->num_pages << EFI_PAGE_SHIFT) - 1;
+
+	/* modifying range */
+	m_start = range->start;
+	m_end = range->end;
+
+	if (m_start <= start) {
+		/* split into 2 parts */
+		if (start < m_end && m_end < end)
+			count++;
+	}
+
+	if (start < m_start && m_start < end) {
+		/* split into 3 parts */
+		if (m_end < end)
+			count += 2;
+		/* split into 2 parts */
+		if (end <= m_end)
+			count++;
+	}
+
+	return count;
+}
+
+/**
+ * efi_memmap_insert - Insert a memory region in an EFI memmap
+ * @old_memmap: The existing EFI memory map structure
+ * @buf: Address of buffer to store new map
+ * @mem: Memory map entry to insert
+ *
+ * It is suggested that you call efi_memmap_split_count() first
+ * to see how large @buf needs to be.
+ */
+void __init efi_memmap_insert(struct efi_memory_map *old_memmap, void *buf,
+			      struct efi_mem_range *mem)
+{
+	u64 m_start, m_end, m_attr;
+	efi_memory_desc_t *md;
+	u64 start, end;
+	void *old, *new;
+
+	/* modifying range */
+	m_start = mem->range.start;
+	m_end = mem->range.end;
+	m_attr = mem->attribute;
+
+	for (old = old_memmap->map, new = buf;
+	     old < old_memmap->map_end;
+	     old += old_memmap->desc_size, new += old_memmap->desc_size) {
+
+		/* copy original EFI memory descriptor */
+		memcpy(new, old, old_memmap->desc_size);
+		md = new;
+		start = md->phys_addr;
+		end = md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT) - 1;
+
+		if (m_start <= start && end <= m_end)
+			md->attribute |= m_attr;
+
+		if (m_start <= start &&
+		    (start < m_end && m_end < end)) {
+			/* first part */
+			md->attribute |= m_attr;
+			md->num_pages = (m_end - md->phys_addr + 1) >>
+				EFI_PAGE_SHIFT;
+			/* latter part */
+			new += old_memmap->desc_size;
+			memcpy(new, old, old_memmap->desc_size);
+			md = new;
+			md->phys_addr = m_end + 1;
+			md->num_pages = (end - md->phys_addr + 1) >>
+				EFI_PAGE_SHIFT;
+		}
+
+		if ((start < m_start && m_start < end) && m_end < end) {
+			/* first part */
+			md->num_pages = (m_start - md->phys_addr) >>
+				EFI_PAGE_SHIFT;
+			/* middle part */
+			new += old_memmap->desc_size;
+			memcpy(new, old, old_memmap->desc_size);
+			md = new;
+			md->attribute |= m_attr;
+			md->phys_addr = m_start;
+			md->num_pages = (m_end - m_start + 1) >>
+				EFI_PAGE_SHIFT;
+			/* last part */
+			new += old_memmap->desc_size;
+			memcpy(new, old, old_memmap->desc_size);
+			md = new;
+			md->phys_addr = m_end + 1;
+			md->num_pages = (end - m_end) >>
+				EFI_PAGE_SHIFT;
+		}
+
+		if ((start < m_start && m_start < end) &&
+		    (end <= m_end)) {
+			/* first part */
+			md->num_pages = (m_start - md->phys_addr) >>
+				EFI_PAGE_SHIFT;
+			/* latter part */
+			new += old_memmap->desc_size;
+			memcpy(new, old, old_memmap->desc_size);
+			md = new;
+			md->phys_addr = m_start;
+			md->num_pages = (end - md->phys_addr + 1) >>
+				EFI_PAGE_SHIFT;
+			md->attribute |= m_attr;
+		}
+	}
+}