kernel/include/linux/efi.h, branch linux-5.10.y

efi: Avoid cold plugged memory for placing the kernel

2025-03-13T11:47:19Z

commit ba69e0750b0362870294adab09339a0c39c3beaf upstream. UEFI 2.11 introduced EFI_MEMORY_HOT_PLUGGABLE to annotate system memory regions that are 'cold plugged' at boot, i.e., hot pluggable memory that is available from early boot, and described as system RAM by the firmware. Existing loaders and EFI applications running in the boot context will happily use this memory for allocating data structures that cannot be freed or moved at runtime, and this prevents the memory from being unplugged. Going forward, the new EFI_MEMORY_HOT_PLUGGABLE attribute should be tested, and memory annotated as such should be avoided for such allocations. In the EFI stub, there are a couple of occurrences where, instead of the high-level AllocatePages() UEFI boot service, a low-level code sequence is used that traverses the EFI memory map and carves out the requested number of pages from a free region. This is needed, e.g., for allocating as low as possible, or for allocating pages at random. While AllocatePages() should presumably avoid special purpose memory and cold plugged regions, this manual approach needs to incorporate this logic itself, in order to prevent the kernel itself from ending up in a hot unpluggable region, preventing it from being unplugged. So add the EFI_MEMORY_HOTPLUGGABLE macro definition, and check for it where appropriate. Cc: stable@vger.kernel.org Signed-off-by: Ard Biesheuvel Signed-off-by: Greg Kroah-Hartman

efi: ia64: move IA64-only declarations to new asm/efi.h header

2024-07-18T11:05:50Z

commit 8ff059b8531f3b98e14f0461859fc7cdd95823e4 upstream. Move some EFI related declarations that are only referenced on IA64 to a new asm/efi.h arch header. Cc: Tony Luck Cc: Fenghua Yu Signed-off-by: Ard Biesheuvel Cc: Frank Scheiner Signed-off-by: Greg Kroah-Hartman

efi: memmap: Move manipulation routines into x86 arch tree

2024-07-05T07:12:56Z

[ Commit fdc6d38d64a20c542b1867ebeb8dd03b98829336 upstream ] The EFI memory map is a description of the memory layout as provided by the firmware, and only x86 manipulates it in various different ways for its own memory bookkeeping. So let's move the memmap routines that are only used by x86 into the x86 arch tree. [ardb: minor tweaks for linux-5.10.y backport] Signed-off-by: Ard Biesheuvel Signed-off-by: Greg Kroah-Hartman

efi: random: combine bootloader provided RNG seed with RNG protocol output

2023-01-14T09:16:50Z

commit 196dff2712ca5a2e651977bb2fe6b05474111a83 upstream. Instead of blindly creating the EFI random seed configuration table if the RNG protocol is implemented and works, check whether such a EFI configuration table was provided by an earlier boot stage and if so, concatenate the existing and the new seeds, leaving it up to the core code to mix it in and credit it the way it sees fit. This can be used for, e.g., systemd-boot, to pass an additional seed to Linux in a way that can be consumed by the kernel very early. In that case, the following definitions should be used to pass the seed to the EFI stub: struct linux_efi_random_seed { u32 size; // of the 'seed' array in bytes u8 seed[]; }; The memory for the struct must be allocated as EFI_ACPI_RECLAIM_MEMORY pool memory, and the address of the struct in memory should be installed as a EFI configuration table using the following GUID: LINUX_EFI_RANDOM_SEED_TABLE_GUID 1ce1e5bc-7ceb-42f2-81e5-8aadf180f57b Note that doing so is safe even on kernels that were built without this patch applied, but the seed will simply be overwritten with a seed derived from the EFI RNG protocol, if available. The recommended seed size is 32 bytes, and seeds larger than 512 bytes are considered corrupted and ignored entirely. In order to preserve forward secrecy, seeds from previous bootloaders are memzero'd out, and in order to preserve memory, those older seeds are also freed from memory. Freeing from memory without first memzeroing is not safe to do, as it's possible that nothing else will ever overwrite those pages used by EFI. Reviewed-by: Jason A. Donenfeld [ardb: incorporate Jason's followup changes to extend the maximum seed size on the consumer end, memzero() it and drop a needless printk] Signed-off-by: Ard Biesheuvel Signed-off-by: Jason A. Donenfeld Signed-off-by: Greg Kroah-Hartman

efi: random: reduce seed size to 32 bytes

2022-11-10T17:14:27Z

commit 161a438d730dade2ba2b1bf8785f0759aba4ca5f upstream. We no longer need at least 64 bytes of random seed to permit the early crng init to complete. The RNG is now based on Blake2s, so reduce the EFI seed size to the Blake2s hash size, which is sufficient for our purposes. While at it, drop the READ_ONCE(), which was supposed to prevent size from being evaluated after seed was unmapped. However, this cannot actually happen, so READ_ONCE() is unnecessary here. Cc: # v4.14+ Signed-off-by: Ard Biesheuvel Reviewed-by: Jason A. Donenfeld Acked-by: Ilias Apalodimas Signed-off-by: Greg Kroah-Hartman

efi: Add missing prototype for efi_capsule_setup_info

2022-06-09T08:21:01Z

[ Upstream commit aa480379d8bdb33920d68acfd90f823c8af32578 ] Fixes "no previous declaration for 'efi_capsule_setup_info'" warnings under W=1. Fixes: 2959c95d510c ("efi/capsule: Add support for Quark security header") Signed-off-by: Jan Kiszka Link: https://lore.kernel.org/r/c28d3f86-dd72-27d1-e2c2-40971b8da6bd@siemens.com Signed-off-by: Ard Biesheuvel Signed-off-by: Sasha Levin

efi: use 32-bit alignment for efi_guid_t literals

2021-03-25T08:04:18Z

commit fb98cc0b3af2ba4d87301dff2b381b12eee35d7d upstream. Commit 494c704f9af0 ("efi: Use 32-bit alignment for efi_guid_t") updated the type definition of efi_guid_t to ensure that it always appears sufficiently aligned (the UEFI spec is ambiguous about this, but given the fact that its EFI_GUID type is defined in terms of a struct carrying a uint32_t, the natural alignment is definitely >= 32 bits). However, we missed the EFI_GUID() macro which is used to instantiate efi_guid_t literals: that macro is still based on the guid_t type, which does not have a minimum alignment at all. This results in warnings such as In file included from drivers/firmware/efi/mokvar-table.c:35: include/linux/efi.h:1093:34: warning: passing 1-byte aligned argument to 4-byte aligned parameter 2 of 'get_var' may result in an unaligned pointer access [-Walign-mismatch] status = get_var(L"SecureBoot", &EFI_GLOBAL_VARIABLE_GUID, NULL, &size, ^ include/linux/efi.h:1101:24: warning: passing 1-byte aligned argument to 4-byte aligned parameter 2 of 'get_var' may result in an unaligned pointer access [-Walign-mismatch] get_var(L"SetupMode", &EFI_GLOBAL_VARIABLE_GUID, NULL, &size, &setupmode); The distinction only matters on CPUs that do not support misaligned loads fully, but 32-bit ARM's load-multiple instructions fall into that category, and these are likely to be emitted by the compiler that built the firmware for loading word-aligned 128-bit GUIDs from memory So re-implement the initializer in terms of our own efi_guid_t type, so that the alignment becomes a property of the literal's type. Fixes: 494c704f9af0 ("efi: Use 32-bit alignment for efi_guid_t") Reported-by: Nathan Chancellor Reviewed-by: Nick Desaulniers Reviewed-by: Nathan Chancellor Tested-by: Nathan Chancellor Link: https://github.com/ClangBuiltLinux/linux/issues/1327 Signed-off-by: Ard Biesheuvel Signed-off-by: Greg Kroah-Hartman

Merge branch 'efi/urgent' into efi/core, to pick up fixes

2020-10-12T11:38:31Z

These fixes missed the v5.9 merge window, pick them up for early v5.10 merge. Signed-off-by: Ingo Molnar

efi: efivars: un-export efivars_sysfs_init()

2020-09-29T17:40:57Z

efivars_sysfs_init() is only used locally in the source file that defines it, so make it static and unexport it. Signed-off-by: Ard Biesheuvel

efi: pstore: move workqueue handling out of efivars

2020-09-29T17:40:57Z

The worker thread that gets kicked off to sync the state of the EFI variable list is only used by the EFI pstore implementation, and is defined in its source file. So let's move its scheduling there as well. Since our efivar_init() scan will bail on duplicate entries, there is no need to disable the workqueue like we did before, so we can run it unconditionally. Signed-off-by: Ard Biesheuvel