From ad69b0b6f9954796875ee4faf6c16c9caca21999 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Thu, 19 Dec 2024 15:30:39 +0100 Subject: efi/libstub: Use cleanup helpers for freeing copies of the memory map The EFI stub may obtain the memory map from the firmware numerous times, and this involves doing a EFI pool allocation first, which needs to be freed after use. Streamline this using a cleanup helper, which makes the code easier to follow. Signed-off-by: Ard Biesheuvel --- drivers/firmware/efi/libstub/randomalloc.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) (limited to 'drivers/firmware/efi/libstub/randomalloc.c') diff --git a/drivers/firmware/efi/libstub/randomalloc.c b/drivers/firmware/efi/libstub/randomalloc.c index c41e7b2091cd..e5872e38d9a4 100644 --- a/drivers/firmware/efi/libstub/randomalloc.c +++ b/drivers/firmware/efi/libstub/randomalloc.c @@ -59,9 +59,9 @@ efi_status_t efi_random_alloc(unsigned long size, unsigned long alloc_min, unsigned long alloc_max) { + struct efi_boot_memmap *map __free(efi_pool) = NULL; unsigned long total_slots = 0, target_slot; unsigned long total_mirrored_slots = 0; - struct efi_boot_memmap *map; efi_status_t status; int map_offset; @@ -130,7 +130,5 @@ efi_status_t efi_random_alloc(unsigned long size, break; } - efi_bs_call(free_pool, map); - return status; } -- cgit v1.2.3 From ba69e0750b0362870294adab09339a0c39c3beaf Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Sat, 1 Feb 2025 18:21:35 +0100 Subject: efi: Avoid cold plugged memory for placing the kernel 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 --- drivers/firmware/efi/efi.c | 6 ++++-- drivers/firmware/efi/libstub/randomalloc.c | 3 +++ drivers/firmware/efi/libstub/relocate.c | 3 +++ include/linux/efi.h | 1 + 4 files changed, 11 insertions(+), 2 deletions(-) (limited to 'drivers/firmware/efi/libstub/randomalloc.c') diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index 8296bf985d1d..7309394b8fc9 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -934,13 +934,15 @@ char * __init efi_md_typeattr_format(char *buf, size_t size, EFI_MEMORY_WB | EFI_MEMORY_UCE | EFI_MEMORY_RO | EFI_MEMORY_WP | EFI_MEMORY_RP | EFI_MEMORY_XP | EFI_MEMORY_NV | EFI_MEMORY_SP | EFI_MEMORY_CPU_CRYPTO | - EFI_MEMORY_RUNTIME | EFI_MEMORY_MORE_RELIABLE)) + EFI_MEMORY_MORE_RELIABLE | EFI_MEMORY_HOT_PLUGGABLE | + EFI_MEMORY_RUNTIME)) snprintf(pos, size, "|attr=0x%016llx]", (unsigned long long)attr); else snprintf(pos, size, - "|%3s|%2s|%2s|%2s|%2s|%2s|%2s|%2s|%2s|%3s|%2s|%2s|%2s|%2s]", + "|%3s|%2s|%2s|%2s|%2s|%2s|%2s|%2s|%2s|%2s|%3s|%2s|%2s|%2s|%2s]", attr & EFI_MEMORY_RUNTIME ? "RUN" : "", + attr & EFI_MEMORY_HOT_PLUGGABLE ? "HP" : "", attr & EFI_MEMORY_MORE_RELIABLE ? "MR" : "", attr & EFI_MEMORY_CPU_CRYPTO ? "CC" : "", attr & EFI_MEMORY_SP ? "SP" : "", diff --git a/drivers/firmware/efi/libstub/randomalloc.c b/drivers/firmware/efi/libstub/randomalloc.c index e5872e38d9a4..5a732018be36 100644 --- a/drivers/firmware/efi/libstub/randomalloc.c +++ b/drivers/firmware/efi/libstub/randomalloc.c @@ -25,6 +25,9 @@ static unsigned long get_entry_num_slots(efi_memory_desc_t *md, if (md->type != EFI_CONVENTIONAL_MEMORY) return 0; + if (md->attribute & EFI_MEMORY_HOT_PLUGGABLE) + return 0; + if (efi_soft_reserve_enabled() && (md->attribute & EFI_MEMORY_SP)) return 0; diff --git a/drivers/firmware/efi/libstub/relocate.c b/drivers/firmware/efi/libstub/relocate.c index 99b45d1cd624..d4264bfb6dc1 100644 --- a/drivers/firmware/efi/libstub/relocate.c +++ b/drivers/firmware/efi/libstub/relocate.c @@ -53,6 +53,9 @@ efi_status_t efi_low_alloc_above(unsigned long size, unsigned long align, if (desc->type != EFI_CONVENTIONAL_MEMORY) continue; + if (desc->attribute & EFI_MEMORY_HOT_PLUGGABLE) + continue; + if (efi_soft_reserve_enabled() && (desc->attribute & EFI_MEMORY_SP)) continue; diff --git a/include/linux/efi.h b/include/linux/efi.h index 053c57e61869..db293d7de686 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -128,6 +128,7 @@ typedef struct { #define EFI_MEMORY_RO ((u64)0x0000000000020000ULL) /* read-only */ #define EFI_MEMORY_SP ((u64)0x0000000000040000ULL) /* soft reserved */ #define EFI_MEMORY_CPU_CRYPTO ((u64)0x0000000000080000ULL) /* supports encryption */ +#define EFI_MEMORY_HOT_PLUGGABLE BIT_ULL(20) /* supports unplugging at runtime */ #define EFI_MEMORY_RUNTIME ((u64)0x8000000000000000ULL) /* range requires runtime mapping */ #define EFI_MEMORY_DESCRIPTOR_VERSION 1 -- cgit v1.2.3