[RFC 1/7] efi/libstub: Ask efi_random_alloc() to skip unusable memory

[Pingfan Liu]

efi_random_alloc() demands EFI_ALLOCATE_ADDRESS when allocate_pages(),
but the current implement can not ensure the selected target locates
inside free area, that is to exclude EFI_BOOT_SERVICES_*,
EFI_RUNTIME_SERVICES_* etc.

Fix the issue by checking md->type.

Signed-off-by: Pingfan Liu <piliu at redhat.com>
Cc: Ard Biesheuvel <ardb at kernel.org>
Cc: Jan Hendrik Farr <kernel at jfarr.cc>
Cc: Philipp Rudo <prudo at redhat.com>
Cc: Lennart Poettering <mzxreary at 0pointer.de>
Cc: Jarkko Sakkinen <jarkko at kernel.org>
Cc: Baoquan He <bhe at redhat.com>
Cc: Dave Young <dyoung at redhat.com>
Cc: Mark Rutland <mark.rutland at arm.com>
Cc: Will Deacon <will at kernel.org>
Cc: Catalin Marinas <catalin.marinas at arm.com>
To: linux-arm-kernel at lists.infradead.org
To: kexec at lists.infradead.org
To: linux-efi at vger.kernel.org
---
 drivers/firmware/efi/libstub/randomalloc.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/firmware/efi/libstub/randomalloc.c b/drivers/firmware/efi/libstub/randomalloc.c
index c41e7b2091cdd..7304e767688f2 100644
--- a/drivers/firmware/efi/libstub/randomalloc.c
+++ b/drivers/firmware/efi/libstub/randomalloc.c
@@ -79,6 +79,8 @@ efi_status_t efi_random_alloc(unsigned long size,
 		efi_memory_desc_t *md = (void *)map->map + map_offset;
 		unsigned long slots;
 
+		if (!(md->type & (EFI_CONVENTIONAL_MEMORY || EFI_PERSISTENT_MEMORY)))
+			continue;
 		slots = get_entry_num_slots(md, size, ilog2(align), alloc_min,
 					    alloc_max);
 		MD_NUM_SLOTS(md) = slots;
@@ -111,6 +113,9 @@ efi_status_t efi_random_alloc(unsigned long size,
 		efi_physical_addr_t target;
 		unsigned long pages;
 
+		if (!(md->type & (EFI_CONVENTIONAL_MEMORY || EFI_PERSISTENT_MEMORY)))
+			continue;
+
 		if (total_mirrored_slots > 0 &&
 		    !(md->attribute & EFI_MEMORY_MORE_RELIABLE))
 			continue;
-- 
2.41.0