From 736e30af583fb6e0e2b8211b894ff99dea0f1ee7 Mon Sep 17 00:00:00 2001 From: Li Zhengyu Date: Fri, 8 Apr 2022 18:09:13 +0800 Subject: [PATCH] RISC-V: Add purgatory This patch adds purgatory, the name and concept have been taken from kexec-tools. Purgatory runs between two kernels, and do verify sha256 hash to ensure the kernel to jump to is fine and has not been corrupted after loading. Makefile is modified based on x86 platform. Signed-off-by: Li Zhengyu Link: https://lore.kernel.org/r/20220408100914.150110-6-lizhengyu3@huawei.com Signed-off-by: Palmer Dabbelt --- arch/riscv/Kbuild | 2 + arch/riscv/Kconfig | 6 +++ arch/riscv/purgatory/.gitignore | 4 ++ arch/riscv/purgatory/Makefile | 95 ++++++++++++++++++++++++++++++++++++++++ arch/riscv/purgatory/entry.S | 47 ++++++++++++++++++++ arch/riscv/purgatory/purgatory.c | 45 +++++++++++++++++++ 6 files changed, 199 insertions(+) create mode 100644 arch/riscv/purgatory/.gitignore create mode 100644 arch/riscv/purgatory/Makefile create mode 100644 arch/riscv/purgatory/entry.S create mode 100644 arch/riscv/purgatory/purgatory.c diff --git a/arch/riscv/Kbuild b/arch/riscv/Kbuild index fb33972..f562c73 100644 --- a/arch/riscv/Kbuild +++ b/arch/riscv/Kbuild @@ -3,5 +3,7 @@ obj-y += kernel/ mm/ net/ obj-$(CONFIG_BUILTIN_DTB) += boot/dts/ +obj-$(CONFIG_ARCH_HAS_KEXEC_PURGATORY) += purgatory/ + # for cleaning subdir- += boot diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 860817a..898052f 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -397,6 +397,12 @@ config KEXEC_FILE If you don't know what to do here, say Y. +config ARCH_HAS_KEXEC_PURGATORY + def_bool KEXEC_FILE + select BUILD_BIN2C + depends on CRYPTO=y + depends on CRYPTO_SHA256=y + config CRASH_DUMP bool "Build kdump crash kernel" help diff --git a/arch/riscv/purgatory/.gitignore b/arch/riscv/purgatory/.gitignore new file mode 100644 index 0000000..38d7d1b --- /dev/null +++ b/arch/riscv/purgatory/.gitignore @@ -0,0 +1,4 @@ +# SPDX-License-Identifier: GPL-2.0-only +purgatory.chk +purgatory.ro +kexec-purgatory.c diff --git a/arch/riscv/purgatory/Makefile b/arch/riscv/purgatory/Makefile new file mode 100644 index 0000000..d4df200 --- /dev/null +++ b/arch/riscv/purgatory/Makefile @@ -0,0 +1,95 @@ +# SPDX-License-Identifier: GPL-2.0 +OBJECT_FILES_NON_STANDARD := y + +purgatory-y := purgatory.o sha256.o entry.o string.o ctype.o memcpy.o memset.o + +targets += $(purgatory-y) +PURGATORY_OBJS = $(addprefix $(obj)/,$(purgatory-y)) + +$(obj)/string.o: $(srctree)/lib/string.c FORCE + $(call if_changed_rule,cc_o_c) + +$(obj)/ctype.o: $(srctree)/lib/ctype.c FORCE + $(call if_changed_rule,cc_o_c) + +$(obj)/memcpy.o: $(srctree)/arch/riscv/lib/memcpy.S FORCE + $(call if_changed_rule,as_o_S) + +$(obj)/memset.o: $(srctree)/arch/riscv/lib/memset.S FORCE + $(call if_changed_rule,as_o_S) + +$(obj)/sha256.o: $(srctree)/lib/crypto/sha256.c FORCE + $(call if_changed_rule,cc_o_c) + +CFLAGS_sha256.o := -D__DISABLE_EXPORTS +CFLAGS_string.o := -D__DISABLE_EXPORTS +CFLAGS_ctype.o := -D__DISABLE_EXPORTS + +# When linking purgatory.ro with -r unresolved symbols are not checked, +# also link a purgatory.chk binary without -r to check for unresolved symbols. +PURGATORY_LDFLAGS := -e purgatory_start -z nodefaultlib +LDFLAGS_purgatory.ro := -r $(PURGATORY_LDFLAGS) +LDFLAGS_purgatory.chk := $(PURGATORY_LDFLAGS) +targets += purgatory.ro purgatory.chk + +# Sanitizer, etc. runtimes are unavailable and cannot be linked here. +GCOV_PROFILE := n +KASAN_SANITIZE := n +UBSAN_SANITIZE := n +KCSAN_SANITIZE := n +KCOV_INSTRUMENT := n + +# These are adjustments to the compiler flags used for objects that +# make up the standalone purgatory.ro + +PURGATORY_CFLAGS_REMOVE := -mcmodel=kernel +PURGATORY_CFLAGS := -mcmodel=medany -ffreestanding -fno-zero-initialized-in-bss +PURGATORY_CFLAGS += $(DISABLE_STACKLEAK_PLUGIN) -DDISABLE_BRANCH_PROFILING +PURGATORY_CFLAGS += -fno-stack-protector -g0 + +# Default KBUILD_CFLAGS can have -pg option set when FTRACE is enabled. That +# in turn leaves some undefined symbols like __fentry__ in purgatory and not +# sure how to relocate those. +ifdef CONFIG_FUNCTION_TRACER +PURGATORY_CFLAGS_REMOVE += $(CC_FLAGS_FTRACE) +endif + +ifdef CONFIG_STACKPROTECTOR +PURGATORY_CFLAGS_REMOVE += -fstack-protector +endif + +ifdef CONFIG_STACKPROTECTOR_STRONG +PURGATORY_CFLAGS_REMOVE += -fstack-protector-strong +endif + +CFLAGS_REMOVE_purgatory.o += $(PURGATORY_CFLAGS_REMOVE) +CFLAGS_purgatory.o += $(PURGATORY_CFLAGS) + +CFLAGS_REMOVE_sha256.o += $(PURGATORY_CFLAGS_REMOVE) +CFLAGS_sha256.o += $(PURGATORY_CFLAGS) + +CFLAGS_REMOVE_string.o += $(PURGATORY_CFLAGS_REMOVE) +CFLAGS_string.o += $(PURGATORY_CFLAGS) + +CFLAGS_REMOVE_ctype.o += $(PURGATORY_CFLAGS_REMOVE) +CFLAGS_ctype.o += $(PURGATORY_CFLAGS) + +AFLAGS_REMOVE_entry.o += -Wa,-gdwarf-2 +AFLAGS_REMOVE_memcpy.o += -Wa,-gdwarf-2 +AFLAGS_REMOVE_memset.o += -Wa,-gdwarf-2 + +$(obj)/purgatory.ro: $(PURGATORY_OBJS) FORCE + $(call if_changed,ld) + +$(obj)/purgatory.chk: $(obj)/purgatory.ro FORCE + $(call if_changed,ld) + +targets += kexec-purgatory.c + +quiet_cmd_bin2c = BIN2C $@ + cmd_bin2c = $(objtree)/scripts/bin2c kexec_purgatory < $< > $@ + +$(obj)/kexec-purgatory.c: $(obj)/purgatory.ro $(obj)/purgatory.chk FORCE + $(call if_changed,bin2c) + +obj-$(CONFIG_ARCH_HAS_KEXEC_PURGATORY) += kexec-purgatory.o diff --git a/arch/riscv/purgatory/entry.S b/arch/riscv/purgatory/entry.S new file mode 100644 index 0000000..0194f45 --- /dev/null +++ b/arch/riscv/purgatory/entry.S @@ -0,0 +1,47 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * purgatory: Runs between two kernels + * + * Copyright (C) 2022 Huawei Technologies Co, Ltd. + * + * Author: Li Zhengyu (lizhengyu3@huawei.com) + * + */ + +.macro size, sym:req + .size \sym, . - \sym +.endm + +.text + +.globl purgatory_start +purgatory_start: + + lla sp, .Lstack + mv s0, a0 /* The hartid of the current hart */ + mv s1, a1 /* Phys address of the FDT image */ + + jal purgatory + + /* Start new image. */ + mv a0, s0 + mv a1, s1 + ld a2, riscv_kernel_entry + jr a2 + +size purgatory_start + +.align 4 + .rept 256 + .quad 0 + .endr +.Lstack: + +.data + +.globl riscv_kernel_entry +riscv_kernel_entry: + .quad 0 +size riscv_kernel_entry + +.end diff --git a/arch/riscv/purgatory/purgatory.c b/arch/riscv/purgatory/purgatory.c new file mode 100644 index 0000000..80596ab --- /dev/null +++ b/arch/riscv/purgatory/purgatory.c @@ -0,0 +1,45 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * purgatory: Runs between two kernels + * + * Copyright (C) 2022 Huawei Technologies Co, Ltd. + * + * Author: Li Zhengyu (lizhengyu3@huawei.com) + * + */ + +#include +#include +#include +#include + +u8 purgatory_sha256_digest[SHA256_DIGEST_SIZE] __section(".kexec-purgatory"); + +struct kexec_sha_region purgatory_sha_regions[KEXEC_SEGMENT_MAX] __section(".kexec-purgatory"); + +static int verify_sha256_digest(void) +{ + struct kexec_sha_region *ptr, *end; + struct sha256_state ss; + u8 digest[SHA256_DIGEST_SIZE]; + + sha256_init(&ss); + end = purgatory_sha_regions + ARRAY_SIZE(purgatory_sha_regions); + for (ptr = purgatory_sha_regions; ptr < end; ptr++) + sha256_update(&ss, (uint8_t *)(ptr->start), ptr->len); + sha256_final(&ss, digest); + if (memcmp(digest, purgatory_sha256_digest, sizeof(digest)) != 0) + return 1; + return 0; +} + +/* workaround for a warning with -Wmissing-prototypes */ +void purgatory(void); + +void purgatory(void) +{ + if (verify_sha256_digest()) + for (;;) + /* loop forever */ + ; +} -- 2.7.4