diff options
Diffstat (limited to 'arch/x86/boot/compressed/kaslr.c')
| -rw-r--r-- | arch/x86/boot/compressed/kaslr.c | 40 |
1 files changed, 28 insertions, 12 deletions
diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c index 454757fbdfe5..9193acf0e9cd 100644 --- a/arch/x86/boot/compressed/kaslr.c +++ b/arch/x86/boot/compressed/kaslr.c @@ -672,6 +672,33 @@ static bool process_mem_region(struct mem_vector *region, } #ifdef CONFIG_EFI + +/* + * Only EFI_CONVENTIONAL_MEMORY and EFI_UNACCEPTED_MEMORY (if supported) are + * guaranteed to be free. + * + * Pick free memory more conservatively than the EFI spec allows: according to + * the spec, EFI_BOOT_SERVICES_{CODE|DATA} are also free memory and thus + * available to place the kernel image into, but in practice there's firmware + * where using that memory leads to crashes. Buggy vendor EFI code registers + * for an event that triggers on SetVirtualAddressMap(). The handler assumes + * that EFI_BOOT_SERVICES_DATA memory has not been touched by loader yet, which + * is probably true for Windows. + * + * Preserve EFI_BOOT_SERVICES_* regions until after SetVirtualAddressMap(). + */ +static inline bool memory_type_is_free(efi_memory_desc_t *md) +{ + if (md->type == EFI_CONVENTIONAL_MEMORY) + return true; + + if (IS_ENABLED(CONFIG_UNACCEPTED_MEMORY) && + md->type == EFI_UNACCEPTED_MEMORY) + return true; + + return false; +} + /* * Returns true if we processed the EFI memmap, which we prefer over the E820 * table if it is available. @@ -716,18 +743,7 @@ process_efi_entries(unsigned long minimum, unsigned long image_size) for (i = 0; i < nr_desc; i++) { md = efi_early_memdesc_ptr(pmap, e->efi_memdesc_size, i); - /* - * Here we are more conservative in picking free memory than - * the EFI spec allows: - * - * According to the spec, EFI_BOOT_SERVICES_{CODE|DATA} are also - * free memory and thus available to place the kernel image into, - * but in practice there's firmware where using that memory leads - * to crashes. - * - * Only EFI_CONVENTIONAL_MEMORY is guaranteed to be free. - */ - if (md->type != EFI_CONVENTIONAL_MEMORY) + if (!memory_type_is_free(md)) continue; if (efi_soft_reserve_enabled() && |