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Wed, 18 Oct 2023 11:31:04 -0700 (PDT) Date: Wed, 18 Oct 2023 11:31:00 -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 Subject: Re: [PATCH v4 1/2] riscv: Add remaining module relocations Message-ID: References: <20231017-module_relocations-v4-0-937f5ef316f0@rivosinc.com> <20231017-module_relocations-v4-1-937f5ef316f0@rivosinc.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231018_113106_945295_FCA00463 X-CRM114-Status: GOOD ( 36.29 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Wed, Oct 18, 2023 at 05:17:44AM -0700, Emil Renner Berthing wrote: > Charlie Jenkins wrote: > > Add all final module relocations and add error logs explaining the ones > > that are not supported. > > > > Signed-off-by: Charlie Jenkins > > --- > > arch/riscv/include/uapi/asm/elf.h | 5 +- > > arch/riscv/kernel/module.c | 207 +++++++++++++++++++++++++++++++++----- > > 2 files changed, 186 insertions(+), 26 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 7c651d55fcbd..e860726352ac 100644 > > --- a/arch/riscv/kernel/module.c > > +++ b/arch/riscv/kernel/module.c > > @@ -7,6 +7,7 @@ > > #include > > #include > > #include > > +#include > > #include > > #include > > #include > > @@ -268,6 +269,12 @@ static int apply_r_riscv_align_rela(struct module *me, u32 *location, > > return -EINVAL; > > } > > > > +static int apply_r_riscv_add8_rela(struct module *me, u32 *location, Elf_Addr v) > > +{ > > + *(u8 *)location += (u8)v; > > + return 0; > > +} > > + > > static int apply_r_riscv_add16_rela(struct module *me, u32 *location, > > Elf_Addr v) > > { > > @@ -289,6 +296,12 @@ static int apply_r_riscv_add64_rela(struct module *me, u32 *location, > > return 0; > > } > > > > +static int apply_r_riscv_sub8_rela(struct module *me, u32 *location, Elf_Addr v) > > +{ > > + *(u8 *)location -= (u8)v; > > + return 0; > > +} > > + > > static int apply_r_riscv_sub16_rela(struct module *me, u32 *location, > > Elf_Addr v) > > { > > @@ -310,31 +323,149 @@ static int apply_r_riscv_sub64_rela(struct module *me, u32 *location, > > return 0; > > } > > > > -static int (*reloc_handlers_rela[]) (struct module *me, u32 *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, u32 *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, u32 *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, u32 *location, Elf_Addr v) > > +{ > > + *(u8 *)location = (*location - ((u8)v & 0x3F)) & 0x3F; > > + return 0; > > +} > > + > > +static int apply_r_riscv_set6_rela(struct module *me, u32 *location, Elf_Addr v) > > +{ > > + *(u8 *)location = (*(u8 *)location & 0xc0) | ((u8)v & 0x3F); > > + return 0; > > +} > > + > > +static int apply_r_riscv_set8_rela(struct module *me, u32 *location, Elf_Addr v) > > +{ > > + *(u8 *)location = (u8)v; > > + return 0; > > +} > > + > > +static int apply_r_riscv_set16_rela(struct module *me, u32 *location, > > + Elf_Addr v) > > +{ > > + *(u16 *)location = (u16)v; > > + return 0; > > +} > > + > > +static int apply_r_riscv_set32_rela(struct module *me, u32 *location, > > + Elf_Addr v) > > +{ > > + *(u32 *)location = (u32)v; > > + return 0; > > +} > > + > > +static int apply_r_riscv_32_pcrel_rela(struct module *me, u32 *location, > > + Elf_Addr v) > > +{ > > + *(u32 *)location = (u32)v; > > + return 0; > > +} > > + > > +static int apply_r_riscv_plt32_rela(struct module *me, u32 *location, > > + Elf_Addr v) > > +{ > > + *(u32 *)location = (u32)v; > > + return 0; > > +} > > + > > +static int apply_r_riscv_set_uleb128(struct module *me, u32 *location, Elf_Addr v) > > +{ > > + /* > > + * Relocation is only performed if R_RISCV_SET_ULEB128 is followed by > > + * R_RISCV_SUB_ULEB128 so do computation there > > + */ > > + return 0; > > +} > > + > > +static int apply_r_riscv_sub_uleb128(struct module *me, u32 *location, Elf_Addr v) > > +{ > > + if (v >= 128) { > > + pr_err("%s: uleb128 must be in [0, 127] (not %ld) at PC = %p\n", > > + me->name, (unsigned long)v, location); > > + return -EINVAL; > > + } > > + > > + *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, u32 *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 */ > > }; > > Hi Charlie, > > This is not a critique of this patch, but all these callbacks take a > u32 *location and > because of the compressed instructions this pointer may not be > aligned, so a lot of > the callbacks end up doing unaligned access which may fault to an > M-mode handler on > some platforms. > > I once sent a patch to fix this: > https://lore.kernel.org/linux-riscv/20220224152456.493365-2-kernel@esmil.dk/ > > Maybe that's something you want to look into while touching this code anyway. > > /Emil Oh nice, I will pick up that patch and change the "native-endian" wording to be "little-endian" in the commit. - Charlie > > > > int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab, > > @@ -348,6 +479,10 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab, > > unsigned int i, type; > > Elf_Addr v; > > int res; > > + bool uleb128_set_exists = false; > > + u32 *uleb128_set_loc; > > + unsigned long uleb128_set_sym_val; > > + > > > > pr_debug("Applying relocate section %u to %u\n", relsec, > > sechdrs[relsec].sh_info); > > @@ -425,6 +560,28 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab, > > me->name); > > return -EINVAL; > > } > > + } else if (type == R_RISCV_SET_ULEB128) { > > + if (uleb128_set_exists) { > > + pr_err("%s: riscv psABI requires the next ULEB128 relocation to come after a R_RISCV_SET_ULEB128 is an R_RISCV_SUB_ULEB128, not another R_RISCV_SET_ULEB128.\n", > > + me->name); > > + return -EINVAL; > > + } > > + uleb128_set_exists = true; > > + uleb128_set_loc = location; > > + uleb128_set_sym_val = > > + ((Elf_Sym *)sechdrs[symindex].sh_addr + > > + ELF_RISCV_R_SYM(rel[i].r_info)) > > + ->st_value + > > + rel[i].r_addend; > > + } else if (type == R_RISCV_SUB_ULEB128) { > > + if (uleb128_set_exists && uleb128_set_loc == location) { > > + /* Calculate set and subtraction */ > > + v = uleb128_set_sym_val - v; > > + } else { > > + pr_err("%s: R_RISCV_SUB_ULEB128 must always be paired with the first R_RISCV_SET_ULEB128 that comes before it. PC = %p\n", > > + me->name, location); > > + return -EINVAL; > > + } > > } > > > > res = handler(me, location, v); > > > > -- > > 2.34.1 > > > > > > _______________________________________________ > > linux-riscv mailing list > > linux-riscv@lists.infradead.org > > http://lists.infradead.org/mailman/listinfo/linux-riscv _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv