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Tue, 31 Oct 2023 11:19:00 -0700 (PDT) Received: from ghost ([12.44.203.122]) by smtp.gmail.com with ESMTPSA id y7-20020a170902b48700b001c5fa48b9a0sm1607836plr.33.2023.10.31.11.18.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 31 Oct 2023 11:19:00 -0700 (PDT) Date: Tue, 31 Oct 2023 11:18:57 -0700 From: Charlie Jenkins To: Emil Renner Berthing Cc: linux-riscv@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Eric Biederman , Kees Cook , Paul Walmsley , Palmer Dabbelt , Albert Ou , Andreas Schwab , Samuel Holland , Nelson Chu Subject: Re: [PATCH v7 2/3] riscv: Add remaining module relocations Message-ID: References: <20231031-module_relocations-v7-0-6f4719b64bf7@rivosinc.com> <20231031-module_relocations-v7-2-6f4719b64bf7@rivosinc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: D5186C0013 X-Stat-Signature: fegfzpqk1pnxdjs4mutowehyataok4pb X-Rspam-User: X-HE-Tag: 1698776341-774363 X-HE-Meta: U2FsdGVkX18YyNAb2QNjT+VwSgLY1FDz/pgcQEyQgKn8Yc62J/gOCnUUEcKAddk79DKfSDsx4kIpbajtsUNBJvn5L0I+B+rllZOBqj7SSZzy1lCnpKsetbqfJUCi+8nXtPGdXw2PIwjozFvyG7GgC6QrST1FcV3N1guzR6zHfyuFz/a2wwpfdNQZZ0HwnSkmbPcTDAXB6PrLhqaYrczLgUjulKiTYi6Sp1Sg+VQQ9o5UKMjiSFKO/FE8yAOvg3QSSYoaGrXMqVSfRhA1k/uQKzZyjMyru5Vtysyk3Qgo4icjaq+ipO3T8pBxKLHzEfPqYW8G16153ETIL2s3nCNOehPfpTR8tcOX09ds4YjtO0fyM8Z15AnVXwNvBf8HKY15YQTMPgrvlvW+xcDoxSw9YxmL4gqmdcMAMEqjToZ5xRRbUgxM1c8pZieozPk/O6i9D2BnQQk7tF5HW41+vn0wAN1Suk/NL2bG3mfJJwB58v5qPAzrHnX2Nyl0J9Jv5X0Jw3KgFOC7w3Ng2xLPzqrZpxUSVqX1IVDQDcFLlWhCb/yiPdzQgU49DVa8142CjBZX5hb+9PGdGlGE0siv6Kpe0vCTxVcouBst8UeAGUs2HK/gXa9VI6sEn0jEkyIbI63mLc4K9U4mBgE3IKHhef+xubSzruASzwPGrSiVQNyXctK0llpExyCLuIrYgDGE4jTaqDWngulvwD6IaLA2Qjsmvgd4p+hhlxRMlGB/S+Lud0NpYJCVzPi1WMGB591S9rB0hndANk79C4Bx6WPzcIv6LpruTigDJ1XW5r3onnjtLWQG6mugi4Xd8JUrXKUKgyZhaq+70nvN3epSq7KTcQbi25JIbePaGTShwD4jtowqVJ+4ZNkMDKDecwoKVMXXSi16DXqIXgUQ23U74cr1XeI9XnABlhIuy0Pc7sPgFLlg3Fmc3Bya8IYU+hu4Bjjlvk8ZcYZhXw17poc0NPaHGlX 7OOEFaY6 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Oct 31, 2023 at 06:43:19AM -0700, Emil Renner Berthing wrote: > Charlie Jenkins wrote: > > 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 | 534 ++++++++++++++++++++++++++++++++++++-- > > 2 files changed, 511 insertions(+), 28 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 a9e94e939cb5..230172ecb26e 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 +17,27 @@ > > #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 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) > > @@ -269,6 +293,12 @@ 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) > > { > > @@ -290,6 +320,12 @@ 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) > > { > > @@ -311,33 +347,470 @@ 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 *)location = (*(u8 *)location - ((u8)v & 0x3F)) & 0x3F; > > + return 0; > > +} > > + > > +static int apply_r_riscv_set6_rela(struct module *me, void *location, Elf_Addr v) > > +{ > > + *(u8 *)location = ((*(u8 *)location & 0xc0) | ((u8)v & 0x3F)); > > Most of these casts are simple enough for here and above I'd consider > something like this for readability: > > u8 *byte = location; > u8 value = v; > > *byte = (*byte & 0xc0) | (value & 0x3f) > > The compiler should generate the same code. > > > + 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 - (unsigned long)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; > > +} > > + > > +/* > > + * Relocations defined in the riscv-elf-psabi-doc. > > + * This handles static linking only. > > + */ > > +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_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, > > + [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_SUB8] = apply_r_riscv_sub8_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, > > + /* 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, > > + [R_RISCV_SET6] = apply_r_riscv_set6_rela, > > + [R_RISCV_SET8] = apply_r_riscv_set8_rela, > > + [R_RISCV_SET16] = apply_r_riscv_set16_rela, > > + [R_RISCV_SET32] = apply_r_riscv_set32_rela, > > + [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, > > + [R_RISCV_SUB_ULEB128] = apply_r_riscv_sub_uleb128, > > + /* 62-191 reserved for future standard use */ > > + /* 192-255 nonstandard ABI extensions */ > > +}; > > + > > +static bool accumulate_relocations[] = { > > + [R_RISCV_32] = false, > > + [R_RISCV_64] = false, > > + [R_RISCV_RELATIVE] = false, > > + [R_RISCV_COPY] = false, > > + [R_RISCV_JUMP_SLOT] = false, > > + [R_RISCV_TLS_DTPMOD32] = false, > > + [R_RISCV_TLS_DTPMOD64] = false, > > + [R_RISCV_TLS_DTPREL32] = false, > > + [R_RISCV_TLS_DTPREL64] = false, > > + [R_RISCV_TLS_TPREL32] = false, > > + [R_RISCV_TLS_TPREL64] = false, > > + /* 12-15 undefined */ > > + [R_RISCV_BRANCH] = false, > > + [R_RISCV_JAL] = false, > > + [R_RISCV_CALL] = false, > > + [R_RISCV_CALL_PLT] = false, > > + [R_RISCV_GOT_HI20] = false, > > + [R_RISCV_TLS_GOT_HI20] = false, > > + [R_RISCV_TLS_GD_HI20] = false, > > + [R_RISCV_PCREL_HI20] = false, > > + [R_RISCV_PCREL_LO12_I] = false, > > + [R_RISCV_PCREL_LO12_S] = false, > > + [R_RISCV_HI20] = false, > > + [R_RISCV_LO12_I] = false, > > + [R_RISCV_LO12_S] = false, > > + [R_RISCV_TPREL_HI20] = false, > > + [R_RISCV_TPREL_LO12_I] = false, > > + [R_RISCV_TPREL_LO12_S] = false, > > + [R_RISCV_TPREL_ADD] = false, > > + [R_RISCV_ADD8] = true, > > + [R_RISCV_ADD16] = true, > > + [R_RISCV_ADD32] = true, > > + [R_RISCV_ADD64] = true, > > + [R_RISCV_SUB8] = true, > > + [R_RISCV_SUB16] = true, > > + [R_RISCV_SUB32] = true, > > + [R_RISCV_SUB64] = true, > > + /* 41-42 reserved for future standard use */ > > + [R_RISCV_ALIGN] = false, > > + [R_RISCV_RVC_BRANCH] = false, > > + [R_RISCV_RVC_JUMP] = false, > > + /* 46-50 reserved for future standard use */ > > + [R_RISCV_RELAX] = false, > > + [R_RISCV_SUB6] = true, > > + [R_RISCV_SET6] = true, > > + [R_RISCV_SET8] = true, > > + [R_RISCV_SET16] = true, > > + [R_RISCV_SET32] = true, > > + [R_RISCV_32_PCREL] = false, > > + [R_RISCV_IRELATIVE] = false, > > + [R_RISCV_PLT32] = false, > > + [R_RISCV_SET_ULEB128] = true, > > + [R_RISCV_SUB_ULEB128] = true, > > + /* 62-191 reserved for future standard use */ > > + /* 192-255 nonstandard ABI extensions */ > > +}; > > + > > +static int accumulation_not_supported(struct module *me, void *location, long buffer) > > +{ > > + pr_err("%s: Internal error. Only ADD/SUB/SET/ULEB128 should be accumulated.", me->name); > > + return -EINVAL; > > +} > > + > > +static int apply_6_bit_accumulation(struct module *me, void *location, long buffer) > > +{ > > + if (buffer != (buffer & 0x3F)) { > > It may be a matter of taste, but I'd find something like this easier to read: > > if (buffer > 0x3f) { > > To me that more directly conveys that you're just checking if any if the higher > bits are set. > > > + pr_err("%s: value %ld out of range for 6-bit relocation.\n", > > + me->name, buffer); > > + return -EINVAL; > > + } > > + *(u8 *)location = ((*(u8 *)location & 0xc0) | ((u8)buffer & 0x3F)); > > Here the casts also get a bit much. > > > + return 0; > > +} > > + > > +static int apply_8_bit_accumulation(struct module *me, void *location, long buffer) > > +{ > > + if (buffer != (u8)buffer) { > > + 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)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)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. > > + */ > > + while (buffer != 0) { > > + *(u8 *)location = (u8)buffer & 0x7F; > > + buffer >>= 7; > > + *(u8 *)location |= (buffer != 0) << 7; > > + location = (u8 *)location + 1; > > + } > > How about something like > > u8 *p = location; > > while (buffer) { > u8 value = buffer & 0x7f; > > buffer >>= 7; > value |= (!!buffer) << 7; > > *p++ = value; > } > > > This sould do the same as above, but if buffer == 0 it doesn't write anything. > Is that the right thing to do? > All great suggestions, thank you. Yes, that is the right thing to do when buffer == 0. - Charlie > > + return 0; > > +} > > + > > +/* > > + * Need to duplicate this a third time to capture the handlers for accumulation. > > + */ > > +static int (*accumulate_handlers[])(struct module *me, void *location, long buffer) = { > > + [R_RISCV_32] = accumulation_not_supported, > > + [R_RISCV_64] = accumulation_not_supported, > > + [R_RISCV_RELATIVE] = accumulation_not_supported, > > + [R_RISCV_COPY] = accumulation_not_supported, > > + [R_RISCV_JUMP_SLOT] = accumulation_not_supported, > > + [R_RISCV_TLS_DTPMOD32] = accumulation_not_supported, > > + [R_RISCV_TLS_DTPMOD64] = accumulation_not_supported, > > + [R_RISCV_TLS_DTPREL32] = accumulation_not_supported, > > + [R_RISCV_TLS_DTPREL64] = accumulation_not_supported, > > + [R_RISCV_TLS_TPREL32] = accumulation_not_supported, > > + [R_RISCV_TLS_TPREL64] = accumulation_not_supported, > > + /* 12-15 undefined */ > > + [R_RISCV_BRANCH] = accumulation_not_supported, > > + [R_RISCV_JAL] = accumulation_not_supported, > > + [R_RISCV_CALL] = accumulation_not_supported, > > + [R_RISCV_CALL_PLT] = accumulation_not_supported, > > + [R_RISCV_GOT_HI20] = accumulation_not_supported, > > + [R_RISCV_TLS_GOT_HI20] = accumulation_not_supported, > > + [R_RISCV_TLS_GD_HI20] = accumulation_not_supported, > > + [R_RISCV_PCREL_HI20] = accumulation_not_supported, > > + [R_RISCV_PCREL_LO12_I] = accumulation_not_supported, > > + [R_RISCV_PCREL_LO12_S] = accumulation_not_supported, > > + [R_RISCV_HI20] = accumulation_not_supported, > > + [R_RISCV_LO12_I] = accumulation_not_supported, > > + [R_RISCV_LO12_S] = accumulation_not_supported, > > + [R_RISCV_TPREL_HI20] = accumulation_not_supported, > > + [R_RISCV_TPREL_LO12_I] = accumulation_not_supported, > > + [R_RISCV_TPREL_LO12_S] = accumulation_not_supported, > > + [R_RISCV_TPREL_ADD] = accumulation_not_supported, > > + [R_RISCV_ADD8] = apply_8_bit_accumulation, > > + [R_RISCV_ADD16] = apply_16_bit_accumulation, > > + [R_RISCV_ADD32] = apply_32_bit_accumulation, > > + [R_RISCV_ADD64] = apply_64_bit_accumulation, > > + [R_RISCV_SUB8] = apply_8_bit_accumulation, > > + [R_RISCV_SUB16] = apply_16_bit_accumulation, > > + [R_RISCV_SUB32] = apply_32_bit_accumulation, > > + [R_RISCV_SUB64] = apply_64_bit_accumulation, > > + /* 41-42 reserved for future standard use */ > > + [R_RISCV_ALIGN] = accumulation_not_supported, > > + [R_RISCV_RVC_BRANCH] = accumulation_not_supported, > > + [R_RISCV_RVC_JUMP] = accumulation_not_supported, > > + /* 46-50 reserved for future standard use */ > > + [R_RISCV_RELAX] = accumulation_not_supported, > > + [R_RISCV_SUB6] = apply_6_bit_accumulation, > > + [R_RISCV_SET6] = apply_6_bit_accumulation, > > + [R_RISCV_SET8] = apply_8_bit_accumulation, > > + [R_RISCV_SET16] = apply_16_bit_accumulation, > > + [R_RISCV_SET32] = apply_32_bit_accumulation, > > + [R_RISCV_32_PCREL] = accumulation_not_supported, > > + [R_RISCV_IRELATIVE] = accumulation_not_supported, > > + [R_RISCV_PLT32] = accumulation_not_supported, > > + [R_RISCV_SET_ULEB128] = apply_uleb128_accumulation, > > + [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_rela[curr_type](me, &buffer, rel_entry_iter->value); > > + kfree(rel_entry_iter); > > + } > > + accumulate_handlers[curr_type](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 hlist_node *first; > > + 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((unsigned long)location, hashtable_bits); > > + > > + current_head = &relocation_hashtable[hash]; > > + first = current_head->first; > > + > > + /* 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) > > @@ -349,11 +822,13 @@ 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; > > @@ -428,11 +903,16 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab, > > } > > } > > > > - res = handler(me, location, v); > > + if (accumulate_relocations[type]) > > + 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; > > } > > > > > > -- > > 2.34.1 > > > > > > _______________________________________________ > > linux-riscv mailing list > > linux-riscv@lists.infradead.org > > http://lists.infradead.org/mailman/listinfo/linux-riscv