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Wed, 01 Nov 2023 11:33:09 -0700 (PDT) Received: from charlie.ba.rivosinc.com ([64.71.180.162]) by smtp.gmail.com with ESMTPSA id m14-20020a4aab8e000000b00581e090fd1fsm686331oon.8.2023.11.01.11.33.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 01 Nov 2023 11:33:08 -0700 (PDT) From: Charlie Jenkins Date: Wed, 01 Nov 2023 11:33:00 -0700 Subject: [PATCH v9 2/3] riscv: Add remaining module relocations MIME-Version: 1.0 Message-Id: <20231101-module_relocations-v9-2-8dfa3483c400@rivosinc.com> References: <20231101-module_relocations-v9-0-8dfa3483c400@rivosinc.com> In-Reply-To: <20231101-module_relocations-v9-0-8dfa3483c400@rivosinc.com> To: linux-riscv@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Eric Biederman , Kees Cook , Paul Walmsley , Palmer Dabbelt , Albert Ou , Andreas Schwab , Emil Renner Berthing , Samuel Holland , Nelson Chu , Charlie Jenkins X-Mailer: b4 0.12.3 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231101_113310_800339_5642EBF2 X-CRM114-Status: GOOD ( 20.52 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org Add all final module relocations and add error logs explaining the ones that are not supported. Implement overflow checks for ADD/SUB/SET/ULEB128 relocations. Signed-off-by: Charlie Jenkins --- arch/riscv/include/uapi/asm/elf.h | 5 +- arch/riscv/kernel/module.c | 448 +++++++++++++++++++++++++++++++++++--- 2 files changed, 423 insertions(+), 30 deletions(-) diff --git a/arch/riscv/include/uapi/asm/elf.h b/arch/riscv/include/uapi/asm/elf.h index d696d6610231..11a71b8533d5 100644 --- a/arch/riscv/include/uapi/asm/elf.h +++ b/arch/riscv/include/uapi/asm/elf.h @@ -49,6 +49,7 @@ typedef union __riscv_fp_state elf_fpregset_t; #define R_RISCV_TLS_DTPREL64 9 #define R_RISCV_TLS_TPREL32 10 #define R_RISCV_TLS_TPREL64 11 +#define R_RISCV_IRELATIVE 58 /* Relocation types not used by the dynamic linker */ #define R_RISCV_BRANCH 16 @@ -81,7 +82,6 @@ typedef union __riscv_fp_state elf_fpregset_t; #define R_RISCV_ALIGN 43 #define R_RISCV_RVC_BRANCH 44 #define R_RISCV_RVC_JUMP 45 -#define R_RISCV_LUI 46 #define R_RISCV_GPREL_I 47 #define R_RISCV_GPREL_S 48 #define R_RISCV_TPREL_I 49 @@ -93,6 +93,9 @@ typedef union __riscv_fp_state elf_fpregset_t; #define R_RISCV_SET16 55 #define R_RISCV_SET32 56 #define R_RISCV_32_PCREL 57 +#define R_RISCV_PLT32 59 +#define R_RISCV_SET_ULEB128 60 +#define R_RISCV_SUB_ULEB128 61 #endif /* _UAPI_ASM_RISCV_ELF_H */ diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c index 8286d3bb04f4..4b339729d5ec 100644 --- a/arch/riscv/kernel/module.c +++ b/arch/riscv/kernel/module.c @@ -7,6 +7,9 @@ #include #include #include +#include +#include +#include #include #include #include @@ -14,6 +17,38 @@ #include #include +struct used_bucket { + struct list_head head; + struct hlist_head *bucket; +}; + +struct relocation_head { + struct hlist_node node; + struct list_head *rel_entry; + void *location; +}; + +struct relocation_entry { + struct list_head head; + Elf_Addr value; + unsigned int type; +}; + +struct relocation_handlers { + int (*reloc_handler)(struct module *me, void *location, Elf_Addr v); + int (*accumulate_handler)(struct module *me, void *location, + long buffer); +}; + +unsigned int initialize_relocation_hashtable(unsigned int num_relocations); +void process_accumulated_relocations(struct module *me); +int add_relocation_to_accumulate(struct module *me, int type, void *location, + unsigned int hashtable_bits, Elf_Addr v); + +struct hlist_head *relocation_hashtable; + +struct list_head used_buckets_list; + /* * The auipc+jalr instruction pair can reach any PC-relative offset * in the range [-2^31 - 2^11, 2^31 - 2^11) @@ -273,6 +308,12 @@ static int apply_r_riscv_align_rela(struct module *me, void *location, return -EINVAL; } +static int apply_r_riscv_add8_rela(struct module *me, void *location, Elf_Addr v) +{ + *(u8 *)location += (u8)v; + return 0; +} + static int apply_r_riscv_add16_rela(struct module *me, void *location, Elf_Addr v) { @@ -294,6 +335,12 @@ static int apply_r_riscv_add64_rela(struct module *me, void *location, return 0; } +static int apply_r_riscv_sub8_rela(struct module *me, void *location, Elf_Addr v) +{ + *(u8 *)location -= (u8)v; + return 0; +} + static int apply_r_riscv_sub16_rela(struct module *me, void *location, Elf_Addr v) { @@ -315,33 +362,369 @@ static int apply_r_riscv_sub64_rela(struct module *me, void *location, return 0; } -static int (*reloc_handlers_rela[]) (struct module *me, void *location, - Elf_Addr v) = { - [R_RISCV_32] = apply_r_riscv_32_rela, - [R_RISCV_64] = apply_r_riscv_64_rela, - [R_RISCV_BRANCH] = apply_r_riscv_branch_rela, - [R_RISCV_JAL] = apply_r_riscv_jal_rela, - [R_RISCV_RVC_BRANCH] = apply_r_riscv_rvc_branch_rela, - [R_RISCV_RVC_JUMP] = apply_r_riscv_rvc_jump_rela, - [R_RISCV_PCREL_HI20] = apply_r_riscv_pcrel_hi20_rela, - [R_RISCV_PCREL_LO12_I] = apply_r_riscv_pcrel_lo12_i_rela, - [R_RISCV_PCREL_LO12_S] = apply_r_riscv_pcrel_lo12_s_rela, - [R_RISCV_HI20] = apply_r_riscv_hi20_rela, - [R_RISCV_LO12_I] = apply_r_riscv_lo12_i_rela, - [R_RISCV_LO12_S] = apply_r_riscv_lo12_s_rela, - [R_RISCV_GOT_HI20] = apply_r_riscv_got_hi20_rela, - [R_RISCV_CALL_PLT] = apply_r_riscv_call_plt_rela, - [R_RISCV_CALL] = apply_r_riscv_call_rela, - [R_RISCV_RELAX] = apply_r_riscv_relax_rela, - [R_RISCV_ALIGN] = apply_r_riscv_align_rela, - [R_RISCV_ADD16] = apply_r_riscv_add16_rela, - [R_RISCV_ADD32] = apply_r_riscv_add32_rela, - [R_RISCV_ADD64] = apply_r_riscv_add64_rela, - [R_RISCV_SUB16] = apply_r_riscv_sub16_rela, - [R_RISCV_SUB32] = apply_r_riscv_sub32_rela, - [R_RISCV_SUB64] = apply_r_riscv_sub64_rela, +static int dynamic_linking_not_supported(struct module *me, void *location, + Elf_Addr v) +{ + pr_err("%s: Dynamic linking not supported in kernel modules PC = %p\n", + me->name, location); + return -EINVAL; +} + +static int tls_not_supported(struct module *me, void *location, Elf_Addr v) +{ + pr_err("%s: Thread local storage not supported in kernel modules PC = %p\n", + me->name, location); + return -EINVAL; +} + +static int apply_r_riscv_sub6_rela(struct module *me, void *location, Elf_Addr v) +{ + u8 *byte = location; + u8 value = v; + + *byte = (*byte - (value & 0x3f)) & 0x3f; + return 0; +} + +static int apply_r_riscv_set6_rela(struct module *me, void *location, Elf_Addr v) +{ + u8 *byte = location; + u8 value = v; + + *byte = (*byte & 0xc0) | (value & 0x3f); + return 0; +} + +static int apply_r_riscv_set8_rela(struct module *me, void *location, Elf_Addr v) +{ + *(u8 *)location = (u8)v; + return 0; +} + +static int apply_r_riscv_set16_rela(struct module *me, void *location, + Elf_Addr v) +{ + *(u16 *)location = (u16)v; + return 0; +} + +static int apply_r_riscv_set32_rela(struct module *me, void *location, + Elf_Addr v) +{ + *(u32 *)location = (u32)v; + return 0; +} + +static int apply_r_riscv_32_pcrel_rela(struct module *me, void *location, + Elf_Addr v) +{ + *(u32 *)location = v - (uintptr_t)location; + return 0; +} + +static int apply_r_riscv_plt32_rela(struct module *me, void *location, + Elf_Addr v) +{ + ptrdiff_t offset = (void *)v - location; + + if (!riscv_insn_valid_32bit_offset(offset)) { + /* Only emit the plt entry if offset over 32-bit range */ + if (IS_ENABLED(CONFIG_MODULE_SECTIONS)) { + offset = (void *)module_emit_plt_entry(me, v) - location; + } else { + pr_err("%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n", + me->name, (long long)v, location); + return -EINVAL; + } + } + + *(u32 *)location = (u32)offset; + return 0; +} + +static int apply_r_riscv_set_uleb128(struct module *me, void *location, Elf_Addr v) +{ + *(long *)location = v; + return 0; +} + +static int apply_r_riscv_sub_uleb128(struct module *me, void *location, Elf_Addr v) +{ + *(long *)location -= v; + return 0; +} + +static int apply_6_bit_accumulation(struct module *me, void *location, long buffer) +{ + u8 *byte = location; + u8 value = buffer; + + if (buffer > 0x3f) { + pr_err("%s: value %ld out of range for 6-bit relocation.\n", + me->name, buffer); + return -EINVAL; + } + + *byte = (*byte & 0xc0) | (value & 0x3f); + return 0; +} + +static int apply_8_bit_accumulation(struct module *me, void *location, long buffer) +{ + if (buffer > U8_MAX) { + pr_err("%s: value %ld out of range for 8-bit relocation.\n", + me->name, buffer); + return -EINVAL; + } + *(u8 *)location = (u8)buffer; + return 0; +} + +static int apply_16_bit_accumulation(struct module *me, void *location, long buffer) +{ + if (buffer > U16_MAX) { + pr_err("%s: value %ld out of range for 16-bit relocation.\n", + me->name, buffer); + return -EINVAL; + } + *(u16 *)location = (u16)buffer; + return 0; +} + +static int apply_32_bit_accumulation(struct module *me, void *location, long buffer) +{ + if (buffer > U32_MAX) { + pr_err("%s: value %ld out of range for 32-bit relocation.\n", + me->name, buffer); + return -EINVAL; + } + *(u32 *)location = (u32)buffer; + return 0; +} + +static int apply_64_bit_accumulation(struct module *me, void *location, long buffer) +{ + *(u64 *)location = (u64)buffer; + return 0; +} + +static int apply_uleb128_accumulation(struct module *me, void *location, long buffer) +{ + /* + * ULEB128 is a variable length encoding. Encode the buffer into + * the ULEB128 data format. + */ + u8 *p = location; + + while (buffer != 0) { + u8 value = buffer & 0x7f; + + buffer >>= 7; + value |= (!!buffer) << 7; + + *p++ = value; + } + return 0; +} + +/* + * Relocations defined in the riscv-elf-psabi-doc. + * This handles static linking only. + */ +static const struct relocation_handlers reloc_handlers[] = { + [R_RISCV_32] = { apply_r_riscv_32_rela }, + [R_RISCV_64] = { apply_r_riscv_64_rela }, + [R_RISCV_RELATIVE] = { dynamic_linking_not_supported }, + [R_RISCV_COPY] = { dynamic_linking_not_supported }, + [R_RISCV_JUMP_SLOT] = { dynamic_linking_not_supported }, + [R_RISCV_TLS_DTPMOD32] = { dynamic_linking_not_supported }, + [R_RISCV_TLS_DTPMOD64] = { dynamic_linking_not_supported }, + [R_RISCV_TLS_DTPREL32] = { dynamic_linking_not_supported }, + [R_RISCV_TLS_DTPREL64] = { dynamic_linking_not_supported }, + [R_RISCV_TLS_TPREL32] = { dynamic_linking_not_supported }, + [R_RISCV_TLS_TPREL64] = { dynamic_linking_not_supported }, + /* 12-15 undefined */ + [R_RISCV_BRANCH] = { apply_r_riscv_branch_rela }, + [R_RISCV_JAL] = { apply_r_riscv_jal_rela }, + [R_RISCV_CALL] = { apply_r_riscv_call_rela }, + [R_RISCV_CALL_PLT] = { apply_r_riscv_call_plt_rela }, + [R_RISCV_GOT_HI20] = { apply_r_riscv_got_hi20_rela }, + [R_RISCV_TLS_GOT_HI20] = { tls_not_supported }, + [R_RISCV_TLS_GD_HI20] = { tls_not_supported }, + [R_RISCV_PCREL_HI20] = { apply_r_riscv_pcrel_hi20_rela }, + [R_RISCV_PCREL_LO12_I] = { apply_r_riscv_pcrel_lo12_i_rela }, + [R_RISCV_PCREL_LO12_S] = { apply_r_riscv_pcrel_lo12_s_rela }, + [R_RISCV_HI20] = { apply_r_riscv_hi20_rela }, + [R_RISCV_LO12_I] = { apply_r_riscv_lo12_i_rela }, + [R_RISCV_LO12_S] = { apply_r_riscv_lo12_s_rela }, + [R_RISCV_TPREL_HI20] = { tls_not_supported }, + [R_RISCV_TPREL_LO12_I] = { tls_not_supported }, + [R_RISCV_TPREL_LO12_S] = { tls_not_supported }, + [R_RISCV_TPREL_ADD] = { tls_not_supported }, + [R_RISCV_ADD8] = { apply_r_riscv_add8_rela, apply_8_bit_accumulation }, + [R_RISCV_ADD16] = { apply_r_riscv_add16_rela, + apply_16_bit_accumulation }, + [R_RISCV_ADD32] = { apply_r_riscv_add32_rela, + apply_32_bit_accumulation }, + [R_RISCV_ADD64] = { apply_r_riscv_add64_rela, + apply_64_bit_accumulation }, + [R_RISCV_SUB8] = { apply_r_riscv_sub8_rela, apply_8_bit_accumulation }, + [R_RISCV_SUB16] = { apply_r_riscv_sub16_rela, + apply_16_bit_accumulation }, + [R_RISCV_SUB32] = { apply_r_riscv_sub32_rela, + apply_32_bit_accumulation }, + [R_RISCV_SUB64] = { apply_r_riscv_sub64_rela, + apply_64_bit_accumulation }, + /* 41-42 reserved for future standard use */ + [R_RISCV_ALIGN] = { apply_r_riscv_align_rela }, + [R_RISCV_RVC_BRANCH] = { apply_r_riscv_rvc_branch_rela }, + [R_RISCV_RVC_JUMP] = { apply_r_riscv_rvc_jump_rela }, + /* 46-50 reserved for future standard use */ + [R_RISCV_RELAX] = { apply_r_riscv_relax_rela }, + [R_RISCV_SUB6] = { apply_r_riscv_sub6_rela, apply_6_bit_accumulation }, + [R_RISCV_SET6] = { apply_r_riscv_set6_rela, apply_6_bit_accumulation }, + [R_RISCV_SET8] = { apply_r_riscv_set8_rela, apply_8_bit_accumulation }, + [R_RISCV_SET16] = { apply_r_riscv_set16_rela, + apply_16_bit_accumulation }, + [R_RISCV_SET32] = { apply_r_riscv_set32_rela, + apply_32_bit_accumulation }, + [R_RISCV_32_PCREL] = { apply_r_riscv_32_pcrel_rela }, + [R_RISCV_IRELATIVE] = { dynamic_linking_not_supported }, + [R_RISCV_PLT32] = { apply_r_riscv_plt32_rela }, + [R_RISCV_SET_ULEB128] = { apply_r_riscv_set_uleb128, + apply_uleb128_accumulation }, + [R_RISCV_SUB_ULEB128] = { apply_r_riscv_sub_uleb128, + apply_uleb128_accumulation }, + /* 62-191 reserved for future standard use */ + /* 192-255 nonstandard ABI extensions */ }; +void process_accumulated_relocations(struct module *me) +{ + /* + * Only ADD/SUB/SET/ULEB128 should end up here. + * + * Each bucket may have more than one relocation location. All + * relocations for a location are stored in a list in a bucket. + * + * Relocations are applied to a temp variable before being stored to the + * provided location to check for overflow. This also allows ULEB128 to + * properly decide how many entries are needed before storing to + * location. The final value is stored into location using the handler + * for the last relocation to an address. + * + * Three layers of indexing: + * - Each of the buckets in use + * - Groups of relocations in each bucket by location address + * - Each relocation entry for a location address + */ + struct used_bucket *bucket_iter; + struct relocation_head *rel_head_iter; + struct relocation_entry *rel_entry_iter; + int curr_type; + void *location; + long buffer; + + list_for_each_entry(bucket_iter, &used_buckets_list, head) { + hlist_for_each_entry(rel_head_iter, bucket_iter->bucket, node) { + buffer = 0; + location = rel_head_iter->location; + list_for_each_entry(rel_entry_iter, + rel_head_iter->rel_entry, head) { + curr_type = rel_entry_iter->type; + reloc_handlers[curr_type].reloc_handler( + me, &buffer, rel_entry_iter->value); + kfree(rel_entry_iter); + } + reloc_handlers[curr_type].accumulate_handler( + me, location, buffer); + kfree(rel_head_iter); + } + kfree(bucket_iter); + } + + kfree(relocation_hashtable); +} + +int add_relocation_to_accumulate(struct module *me, int type, void *location, + unsigned int hashtable_bits, Elf_Addr v) +{ + struct relocation_entry *entry; + struct relocation_head *rel_head; + struct hlist_head *current_head; + struct used_bucket *bucket; + unsigned long hash; + + entry = kmalloc(sizeof(*entry), GFP_KERNEL); + INIT_LIST_HEAD(&entry->head); + entry->type = type; + entry->value = v; + + hash = hash_min((uintptr_t)location, hashtable_bits); + + current_head = &relocation_hashtable[hash]; + + /* Find matching location (if any) */ + bool found = false; + struct relocation_head *rel_head_iter; + + hlist_for_each_entry(rel_head_iter, current_head, node) { + if (rel_head_iter->location == location) { + found = true; + rel_head = rel_head_iter; + break; + } + } + + if (!found) { + rel_head = kmalloc(sizeof(*rel_head), GFP_KERNEL); + rel_head->rel_entry = + kmalloc(sizeof(struct list_head), GFP_KERNEL); + INIT_LIST_HEAD(rel_head->rel_entry); + rel_head->location = location; + INIT_HLIST_NODE(&rel_head->node); + if (!current_head->first) { + bucket = + kmalloc(sizeof(struct used_bucket), GFP_KERNEL); + INIT_LIST_HEAD(&bucket->head); + bucket->bucket = current_head; + list_add(&bucket->head, &used_buckets_list); + } + hlist_add_head(&rel_head->node, current_head); + } + + /* Add relocation to head of discovered rel_head */ + list_add_tail(&entry->head, rel_head->rel_entry); + + return 0; +} + +unsigned int initialize_relocation_hashtable(unsigned int num_relocations) +{ + /* Can safely assume that bits is not greater than sizeof(long) */ + unsigned long hashtable_size = roundup_pow_of_two(num_relocations); + unsigned int hashtable_bits = ilog2(hashtable_size); + + /* + * Double size of hashtable if num_relocations * 1.25 is greater than + * hashtable_size. + */ + int should_double_size = ((num_relocations + (num_relocations >> 2)) > (hashtable_size)); + + hashtable_bits += should_double_size; + + hashtable_size <<= should_double_size; + + relocation_hashtable = kmalloc_array(hashtable_size, + sizeof(*relocation_hashtable), + GFP_KERNEL); + __hash_init(relocation_hashtable, hashtable_size); + + INIT_LIST_HEAD(&used_buckets_list); + + return hashtable_bits; +} + int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab, unsigned int symindex, unsigned int relsec, struct module *me) @@ -353,11 +736,13 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab, unsigned int i, type; Elf_Addr v; int res; + unsigned int num_relocations = sechdrs[relsec].sh_size / sizeof(*rel); + unsigned int hashtable_bits = initialize_relocation_hashtable(num_relocations); pr_debug("Applying relocate section %u to %u\n", relsec, sechdrs[relsec].sh_info); - for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) { + for (i = 0; i < num_relocations; i++) { /* This is where to make the change */ location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr + rel[i].r_offset; @@ -375,8 +760,8 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab, type = ELF_RISCV_R_TYPE(rel[i].r_info); - if (type < ARRAY_SIZE(reloc_handlers_rela)) - handler = reloc_handlers_rela[type]; + if (type < ARRAY_SIZE(reloc_handlers)) + handler = reloc_handlers[type].reloc_handler; else handler = NULL; @@ -432,11 +817,16 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab, } } - res = handler(me, location, v); + if (reloc_handlers[type].accumulate_handler) + res = add_relocation_to_accumulate(me, type, location, hashtable_bits, v); + else + res = handler(me, location, v); if (res) return res; } + process_accumulated_relocations(me); + return 0; }