42  //* SPDX-License-Identifier: GPL-2.0-only */ #ifndef _LINUX_RANDOMIZE_KSTACK_H #define _LINUX_RANDOMIZE_KSTACK_H #ifdef CONFIG_RANDOMIZE_KSTACK_OFFSET #include #include #include DECLARE_STATIC_KEY_MAYBE(CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT, randomize_kstack_offset); DECLARE_PER_CPU(u32, kstack_offset); /* * Do not use this anywhere else in the kernel. This is used here because * it provides an arch-agnostic way to grow the stack with correct * alignment. Also, since this use is being explicitly masked to a max of * 10 bits, stack-clash style attacks are unlikely. For more details see * "VLAs" in Documentation/process/deprecated.rst */ void *__builtin_alloca(size_t size); /* * Use, at most, 10 bits of entropy. We explicitly cap this to keep the * "VLA" from being unbounded (see above). 10 bits leaves enough room for * per-arch offset masks to reduce entropy (by removing higher bits, since * high entropy may overly constrain usable stack space), and for * compiler/arch-specific stack alignment to remove the lower bits. */ #define KSTACK_OFFSET_MAX(x) ((x) & 0x3FF) /* * These macros must be used during syscall entry when interrupts and * preempt are disabled, and after user registers have been stored to * the stack. */ #define add_random_kstack_offset() do { \ if (static_branch_maybe(CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT, \ &randomize_kstack_offset)) { \ u32 offset = raw_cpu_read(kstack_offset); \ u8 *ptr = __builtin_alloca(KSTACK_OFFSET_MAX(offset)); \ /* Keep allocation even after "ptr" loses scope. */ \ asm volatile("" :: "r"(ptr) : "memory"); \ } \ } while (0) #define choose_random_kstack_offset(rand) do { \ if (static_branch_maybe(CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT, \ &randomize_kstack_offset)) { \ u32 offset = raw_cpu_read(kstack_offset); \ offset = ror32(offset, 5) ^ (rand); \ raw_cpu_write(kstack_offset, offset); \ } \ } while (0) #else /* CONFIG_RANDOMIZE_KSTACK_OFFSET */ #define add_random_kstack_offset() do { } while (0) #define choose_random_kstack_offset(rand) do { } while (0) #endif /* CONFIG_RANDOMIZE_KSTACK_OFFSET */ #endif "lzC]q@?p@۪bѿ d-= LELFD 4( U]U8EԉUЉME}thpj1hjE̋EEԋ@wtw/btdu%EEEE EEEԋ@t)uhj EPEԋ@@UuhU(EUME}t!}thjVhjE܋EE܃E}uE܃EE!EE@wt=wbtcd}tEE!‹E UoEUeE=tEE!‹EE f Save read value into variable VARNAME.VARNAMEv'one argument expected../../grub-core/commands/memrw.c%x0x%x two arguments expectedread_byteRead 8-bit value from ADDR.ADDRread_wordRead 16-bit value from ADDR.read_dwordRead 32-bit value from ADDR.ADDR VALUE [MASK]write_byteWrite 8-bit VALUE to ADDR.write_wordWrite 16-bit VALUE to ADDR.write_dwordWrite 32-bit VALUE to ADDR.LICENSE=GPLv3+extcmdmemrwDUP +BNfq