From: Ard Biesheuvel ard.biesheuvel@linaro.org
commit 18df7577adae6c6c778bf774b3aebcacbc1fb439 upstream.
Ensure that the EFI memreserve entries can be accessed, even if they are located in memory that the kernel (e.g., a crashkernel) omits from the linear map.
Fixes: 80424b02d42b ("efi: Reduce the amount of memblock reservations ...") Cc: stable@vger.kernel.org # 5.0+ Reported-by: Jonathan Richardson jonathan.richardson@broadcom.com Reviewed-by: Jonathan Richardson jonathan.richardson@broadcom.com Tested-by: Jonathan Richardson jonathan.richardson@broadcom.com Signed-off-by: Ard Biesheuvel ard.biesheuvel@linaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/firmware/efi/efi.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)
--- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -1007,14 +1007,16 @@ int __ref efi_mem_reserve_persistent(phy
/* first try to find a slot in an existing linked list entry */ for (prsv = efi_memreserve_root->next; prsv; prsv = rsv->next) { - rsv = __va(prsv); + rsv = memremap(prsv, sizeof(*rsv), MEMREMAP_WB); index = atomic_fetch_add_unless(&rsv->count, 1, rsv->size); if (index < rsv->size) { rsv->entry[index].base = addr; rsv->entry[index].size = size;
+ memunmap(rsv); return 0; } + memunmap(rsv); }
/* no slot found - allocate a new linked list entry */ @@ -1022,7 +1024,13 @@ int __ref efi_mem_reserve_persistent(phy if (!rsv) return -ENOMEM;
- rsv->size = EFI_MEMRESERVE_COUNT(PAGE_SIZE); + /* + * The memremap() call above assumes that a linux_efi_memreserve entry + * never crosses a page boundary, so let's ensure that this remains true + * even when kexec'ing a 4k pages kernel from a >4k pages kernel, by + * using SZ_4K explicitly in the size calculation below. + */ + rsv->size = EFI_MEMRESERVE_COUNT(SZ_4K); atomic_set(&rsv->count, 1); rsv->entry[0].base = addr; rsv->entry[0].size = size;