From bc93763f178fd04f484ee3e521bbdae57fddb891 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Sat, 30 Jan 2021 13:07:51 +0000 Subject: [PATCH] KVM: arm64: Make gen-hyprel endianness agnostic gen-hyprel is, for better or worse, a native-endian program: it assumes that the ELF data structures are in the host's endianness, and even assumes that the compiled kernel is little-endian in one particular case. None of these assumptions hold true though: people actually build (use?) BE arm64 kernels, and seem to avoid doing so on BE hosts. Madness! In order to solve this, wrap each access to the ELF data structures with the required byte-swapping magic. This requires to obtain the kernel data structure, and provide per-endianess wrappers. This result in a kernel that links and even boots in a model. Fixes: 8c49b5d43d4c ("KVM: arm64: Generate hyp relocation data") Reported-by: Guenter Roeck Tested-by: Guenter Roeck Acked-by: David Brazdil Signed-off-by: Marc Zyngier --- arch/arm64/kvm/hyp/nvhe/Makefile | 1 + arch/arm64/kvm/hyp/nvhe/gen-hyprel.c | 57 ++++++++++++++++++++++++++---------- 2 files changed, 42 insertions(+), 16 deletions(-) diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile index 268be13..ed10fcf 100644 --- a/arch/arm64/kvm/hyp/nvhe/Makefile +++ b/arch/arm64/kvm/hyp/nvhe/Makefile @@ -7,6 +7,7 @@ asflags-y := -D__KVM_NVHE_HYPERVISOR__ ccflags-y := -D__KVM_NVHE_HYPERVISOR__ hostprogs := gen-hyprel +HOST_EXTRACFLAGS += -I$(objtree)/include obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o \ hyp-main.o hyp-smp.o psci-relay.o diff --git a/arch/arm64/kvm/hyp/nvhe/gen-hyprel.c b/arch/arm64/kvm/hyp/nvhe/gen-hyprel.c index 58fe31f..ead02c6 100644 --- a/arch/arm64/kvm/hyp/nvhe/gen-hyprel.c +++ b/arch/arm64/kvm/hyp/nvhe/gen-hyprel.c @@ -25,6 +25,7 @@ */ #include +#include #include #include #include @@ -36,6 +37,8 @@ #include #include +#include + #define HYP_SECTION_PREFIX ".hyp" #define HYP_RELOC_SECTION ".hyp.reloc" #define HYP_SECTION_SYMBOL_PREFIX "__hyp_section_" @@ -121,6 +124,28 @@ static struct { const char *sh_string; } elf; +#if defined(CONFIG_CPU_LITTLE_ENDIAN) + +#define elf16toh(x) le16toh(x) +#define elf32toh(x) le32toh(x) +#define elf64toh(x) le64toh(x) + +#define ELFENDIAN ELFDATA2LSB + +#elif defined(CONFIG_CPU_BIG_ENDIAN) + +#define elf16toh(x) be16toh(x) +#define elf32toh(x) be32toh(x) +#define elf64toh(x) be64toh(x) + +#define ELFENDIAN ELFDATA2MSB + +#else + +#error PDP-endian sadly unsupported... + +#endif + #define fatal_error(fmt, ...) \ ({ \ fprintf(stderr, "error: %s: " fmt "\n", \ @@ -162,12 +187,12 @@ static struct { /* Iterate over all sections in the ELF. */ #define for_each_section(var) \ - for (var = elf.sh_table; var < elf.sh_table + elf.ehdr->e_shnum; ++var) + for (var = elf.sh_table; var < elf.sh_table + elf16toh(elf.ehdr->e_shnum); ++var) /* Iterate over all Elf64_Rela relocations in a given section. */ #define for_each_rela(shdr, var) \ - for (var = elf_ptr(Elf64_Rela, shdr->sh_offset); \ - var < elf_ptr(Elf64_Rela, shdr->sh_offset + shdr->sh_size); var++) + for (var = elf_ptr(Elf64_Rela, elf64toh(shdr->sh_offset)); \ + var < elf_ptr(Elf64_Rela, elf64toh(shdr->sh_offset) + elf64toh(shdr->sh_size)); var++) /* True if a string starts with a given prefix. */ static inline bool starts_with(const char *str, const char *prefix) @@ -178,13 +203,13 @@ static inline bool starts_with(const char *str, const char *prefix) /* Returns a string containing the name of a given section. */ static inline const char *section_name(Elf64_Shdr *shdr) { - return elf.sh_string + shdr->sh_name; + return elf.sh_string + elf32toh(shdr->sh_name); } /* Returns a pointer to the first byte of section data. */ static inline const char *section_begin(Elf64_Shdr *shdr) { - return elf_ptr(char, shdr->sh_offset); + return elf_ptr(char, elf64toh(shdr->sh_offset)); } /* Find a section by its offset from the beginning of the file. */ @@ -247,13 +272,13 @@ static void init_elf(const char *path) /* Sanity check that this is an ELF64 relocatable object for AArch64. */ assert_eq(elf.ehdr->e_ident[EI_CLASS], ELFCLASS64, "%u"); - assert_eq(elf.ehdr->e_ident[EI_DATA], ELFDATA2LSB, "%u"); - assert_eq(elf.ehdr->e_type, ET_REL, "%u"); - assert_eq(elf.ehdr->e_machine, EM_AARCH64, "%u"); + assert_eq(elf.ehdr->e_ident[EI_DATA], ELFENDIAN, "%u"); + assert_eq(elf16toh(elf.ehdr->e_type), ET_REL, "%u"); + assert_eq(elf16toh(elf.ehdr->e_machine), EM_AARCH64, "%u"); /* Populate fields of the global struct. */ - elf.sh_table = section_by_off(elf.ehdr->e_shoff); - elf.sh_string = section_begin(section_by_idx(elf.ehdr->e_shstrndx)); + elf.sh_table = section_by_off(elf64toh(elf.ehdr->e_shoff)); + elf.sh_string = section_begin(section_by_idx(elf16toh(elf.ehdr->e_shstrndx))); } /* Print the prologue of the output ASM file. */ @@ -301,8 +326,8 @@ static void emit_rela_abs64(Elf64_Rela *rela, const char *sh_orig_name) * is `rela->r_offset`. */ printf(".reloc %lu, R_AARCH64_PREL32, %s%s + 0x%lx\n", - reloc_offset, HYP_SECTION_SYMBOL_PREFIX, sh_orig_name, - rela->r_offset); + reloc_offset, HYP_SECTION_SYMBOL_PREFIX, sh_orig_name, + elf64toh(rela->r_offset)); reloc_offset += 4; } @@ -322,7 +347,7 @@ static void emit_epilogue(void) */ static void emit_rela_section(Elf64_Shdr *sh_rela) { - Elf64_Shdr *sh_orig = &elf.sh_table[sh_rela->sh_info]; + Elf64_Shdr *sh_orig = &elf.sh_table[elf32toh(sh_rela->sh_info)]; const char *sh_orig_name = section_name(sh_orig); Elf64_Rela *rela; @@ -333,10 +358,10 @@ static void emit_rela_section(Elf64_Shdr *sh_rela) emit_section_prologue(sh_orig_name); for_each_rela(sh_rela, rela) { - uint32_t type = (uint32_t)rela->r_info; + uint32_t type = (uint32_t)elf64toh(rela->r_info); /* Check that rela points inside the relocated section. */ - assert_lt(rela->r_offset, sh_orig->sh_size, "0x%lx"); + assert_lt(elf64toh(rela->r_offset), elf64toh(sh_orig->sh_size), "0x%lx"); switch (type) { /* @@ -385,7 +410,7 @@ static void emit_all_relocs(void) Elf64_Shdr *shdr; for_each_section(shdr) { - switch (shdr->sh_type) { + switch (elf32toh(shdr->sh_type)) { case SHT_REL: fatal_error("Unexpected SHT_REL section \"%s\"", section_name(shdr)); -- 2.7.4